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Ingenuity Mars Helicopter Gets Off the Ground

NASA’s Ingenuity Mars Helicopter Succeeds in Historic First Flight


NASA’s Ingenuity Mars Helicopter took this shot while hovering over the Martian surface on April 19, 2021
NASA’s Ingenuity Mars Helicopter captured this shot as it hovered over the Martian surface on April 19, 2021, during the first instance of powered, controlled flight on another planet. It used its navigation camera, which autonomously tracks the ground during flight.
Credits: NASA/JPL-Caltech

Monday, NASA’s Ingenuity Mars Helicopter became the first aircraft in history to make a powered, controlled flight on another planet. The Ingenuity team at the agency’s Jet Propulsion Laboratory in Southern California confirmed the flight succeeded after receiving data from the helicopter via NASA’s Perseverance Mars rover at 6:46 a.m. EDT (3:46 a.m. PDT).


“Ingenuity is the latest in a long and storied tradition of NASA projects achieving a space exploration goal once thought impossible,” said acting NASA Administrator Steve Jurczyk. “The X-15 was a pathfinder for the space shuttle. Mars Pathfinder and its Sojourner rover did the same for three generations of Mars rovers. We don’t know exactly where Ingenuity will lead us, but today’s results indicate the sky – at least on Mars – may not be the limit.”


The solar-powered helicopter first became airborne at 3:34 a.m. EDT (12:34 a.m. PDT) – 12:33 Local Mean Solar Time (Mars time) – a time the Ingenuity team determined would have optimal energy and flight conditions. Altimeter data indicate Ingenuity climbed to its prescribed maximum altitude of 10 feet (3 meters) and maintained a stable hover for 30 seconds. It then descended, touching back down on the surface of Mars after logging a total of 39.1 seconds of flight. Additional details on the test are expected in upcoming downlinks.


In this video captured by NASA’s Perseverance rover, the agency’s Ingenuity Mars Helicopter took the first powered, controlled flight on another planet on April 19, 2021.
Credits: NASA/JPL-Caltech/ASU/MSSS

Ingenuity’s initial flight demonstration was autonomous – piloted by onboard guidance, navigation, and control systems running algorithms developed by the team at JPL. Because data must be sent to and returned from the Red Planet over hundreds of millions of miles using orbiting satellites and NASA’s Deep Space Network, Ingenuity cannot be flown with a joystick, and its flight was not observable from Earth in real time.


NASA Associate Administrator for Science Thomas Zurbuchen announced the name for the Martian airfield on which the flight took place.


“Now, 117 years after the Wright brothers succeeded in making the first flight on our planet, NASA’s Ingenuity helicopter has succeeded in performing this amazing feat on another world,” Zurbuchen said. “While these two iconic moments in aviation history may be separated by time and 173 million miles of space, they now will forever be linked. As an homage to the two innovative bicycle makers from Dayton, this first of many airfields on other worlds will now be known as Wright Brothers Field, in recognition of the ingenuity and innovation that continue to propel exploration.”


Ingenuity’s chief pilot, Håvard Grip, announced that the International Civil Aviation Organization (ICAO) – the United Nations’ civil aviation agency – presented NASA and the Federal Aviation Administration with official ICAO designator IGY, call-sign INGENUITY.


These details will be included officially in the next edition of ICAO’s publication Designators for Aircraft Operating Agencies, Aeronautical Authorities and Services. The location of the flight has also been given the ceremonial location designation JZRO for Jezero Crater.


As one of NASA’s technology demonstration projects, the 19.3-inch-tall (49-centimeter-tall) Ingenuity Mars Helicopter contains no science instruments inside its tissue-box-size fuselage. Instead, the 4-pound (1.8-kg) rotorcraft is intended to demonstrate whether future exploration of the Red Planet could include an aerial perspective.


This first flight was full of unknowns. The Red Planet has a significantly lower gravity – one-third that of Earth’s – and an extremely thin atmosphere with only 1% the pressure at the surface compared to our planet. This means there are relatively few air molecules with which Ingenuity’s two 4-foot-wide (1.2-meter-wide) rotor blades can interact to achieve flight. The helicopter contains unique components, as well as off-the-shelf-commercial parts – many from the smartphone industry – that were tested in deep space for the first time with this mission.


“The Mars Helicopter project has gone from ‘blue sky’ feasibility study to workable engineering concept to achieving the first flight on another world in a little over six years,” said Michael Watkins, director of JPL. “That this project has achieved such a historic first is testimony to the innovation and doggedness of our team here at JPL, as well as at NASA’s Langley and Ames Research Centers, and our industry partners. It’s a shining example of the kind of technology push that thrives at JPL and fits well with NASA’s exploration goals.”


Parked about 211 feet (64.3 meters) away at Van Zyl Overlook during Ingenuity’s historic first flight, the Perseverance rover not only acted as a communications relay between the helicopter and Earth, but also chronicled the flight operations with its cameras. The pictures from the rover’s Mastcam-Z and Navcam imagers will provide additional data on the helicopter’s flight.   


“We have been thinking for so long about having our Wright brothers moment on Mars, and here it is,” said MiMi Aung, project manager of the Ingenuity Mars Helicopter at JPL. “We will take a moment to celebrate our success and then take a cue from Orville and Wilbur regarding what to do next. History shows they got back to work – to learn as much as they could about their new aircraft – and so will we.”


Perseverance touched down with Ingenuity attached to its belly on Feb. 18. Deployed to the surface of Jezero Crater on April 3, Ingenuity is currently on the 16th sol, or Martian day, of its 30-sol (31-Earth day) flight test window. Over the next three sols, the helicopter team will receive and analyze all data and imagery from the test and formulate a plan for the second experimental test flight, scheduled for no earlier than April 22. If the helicopter survives the second flight test, the Ingenuity team will consider how best to expand the flight profile.


More About Ingenuity


JPL, which built Ingenuity, also manages the technology demonstration project for NASA. It is supported by NASA’s Science, Aeronautics, and Space Technology mission directorates. The agency’s Ames Research Center in California’s Silicon Valley and Langley Research Center in Hampton, Virginia, provided significant flight performance analysis and technical assistance during Ingenuity’s development.


Dave Lavery is the program executive for the Ingenuity Mars Helicopter, MiMi Aung is the project manager, and Bob Balaram is chief engineer.


For more information about Ingenuity:




More About Perseverance


A key objective for Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith (broken rock and dust).


Subsequent NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.


JPL built and manages operations of the Perseverance rover. JPL is managed for NASA by Caltech in Pasadena, California.



Alana Johnson / Grey Hautaluoma
Headquarters, Washington
202-672-4780 / 202-358-0668 /

DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.

Last Updated: Apr 19, 2021
Editor: Karen Northon
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5G as a wireless power grid


5G has been designed for blazing fast and low-latency communications. To do so, mm-wave frequencies were adopted and allowed unprecedently high radiated power densities by the FCC. Unknowingly, the architects of 5G have, thereby, created a wireless power grid capable of powering devices at ranges far exceeding the capabilities of any existing technologies. However, this potential could only be realized if a fundamental trade-off in wireless energy harvesting could be circumvented. Here, we propose a solution that breaks the usual paradigm, imprisoned in the trade-off between rectenna angular coverage and turn-on sensitivity. The concept relies on the implementation of a Rotman lens between the antennas and the rectifiers. The printed, flexible mm-wave lens allows robust and bending-resilient operation over more than 20 GHz of gain and angular bandwidths. Antenna sub-arrays, rectifiers and DC combiners are then added to the structure to demonstrate its combination of large angular coverage and turn-on sensitivity—in both planar and bent conditions—and a harvesting ability up to a distance of 2.83 m in its current configuration and exceeding 180 m using state-of-the-art rectifiers enabling the harvesting of several μW of DC power (around 6 μW at 180 m with 75 dBm EIRP).


Our era is witnessing a rapid development in the field of millimeter-wave (mm-wave) and Internet of Things (IoT) technologies with a projected 40 billion IoT devices to be installed by 20251. This could result in a huge number of batteries needing to be continuously charged and replaced. The design and realization of energy-autonomous, self-powered systems: the perpetual IoT, is therefore highly desirable. One potential way of satisfying these goals is through electromagnetic energy harvesting. A powerful source for electromagnetic scavenging is mm-wave energy, present in the fifth-generation (5G) of mobile communications bands (above 24 GHz), where the limits of allowable transmitted Effective Isotropic Radiated Power (EIRP) by the Federal Communications Commission (FCC) regulations are pushed beyond (reaches 75 dBm) that of their lower-frequency counterparts. Following the path loss model defined by the 3rd Generation Partnership Project Technical Report 3GPP TR 38.901 (release 16) in outdoor Urban Macro Line of Sight conditions (UMa LOS), the power density expected to be received at 28 GHz for a transmitted power of 75 dBm EIRP is 28 μW cm−2 at a distance of 100 m away from the transmitter. This demonstrates the ability of 5G to create a usable network of wireless power. In addition to the advantage of high transmitted power available at 5G, moving to mm-wave bands allows the realization of modular antennas arrays instead of single elements, thereby allowing a fine scaling of their antenna aperture, which can more than compensate for the high path loss at these frequencies through the addition of extremely-large gains2. However, one limitation accompanies large gain antennas: their inability to provide a large angular coverage. As the relative orientations of the sources and harvesters are generally unknown, the use of large aperture mm-wave harvesters may seem limiting and impossible. Individual rectennas, constituted of small antenna elements, can realistically be DC combined. However, this approach does not increase the turn-on sensitivity (lowest turn-on power) of the overall rectenna system: RF combination is needed.

Beamforming networks (BFNs) are used to effectively create simultaneous beam angular coverage with large-gain arrays, by mapping a set of directions to a set of feeding ports. An important class of these multiple networks is the microwave passive BFN that has been widely used in switched-beam antenna systems and applications. Hybrid combination techniques, based on Butler matrix networks, have been used in previous works for energy harvesting at lower frequencies3,4,—more specifically at 2.45 GHz—to achieve wider angular coverage harvesting. However, these Ultra-High Frequency (UHF) arrays are impractically large for IoT applications and the implementation of their Butler matrices at higher frequencies would necessitate costly high-resolution fabrication. While sub-optimal—because of its large size—in the UHF band, the Rotman lens becomes the BFN of choice in the realm of mm-wave energy harvesting. Compared to their lower frequencies counterpart, fewer implementations are presented in the literature targeting energy harvesting at higher frequencies, more specifically 24 GHz and above. However, these systems later displayed in the table of comparison5,6,7, suffer from a narrow angular coverage.

In this paper, the authors demonstrate a full implementation of an entirely flexible, bending-resilient and simultaneously high gain and large angular coverage system for 5G/mm-wave energy harvesting based on a Rotman lens. For IoT applications, there is a benefit to making extremely low-profile devices that can conformally fit onto any surface in the environment such as walls, bodies, vehicles, etc. Therefore, thanks to the use of mm-waves, antennas with such features can be readily designed and fabricated. A Rotman lens-based rectenna has been first proposed in8, where a preliminary prototype and approach were presented, resulting in a quasi-flexible system, 80° angular coverage and 21-fold increase in the harvested power compared to a non-Rotman-based system. Here, the previously-predicted potential of 5G-powered nodes for the IoT and long-range passive mm-wave Radio Frequency IDentification (RFID) devices, is further taken advantage of, and effectively demonstrated. In order to do so, a thorough analysis of the lens itself—a structure that was not revealed in8—is first presented, exposing its key design parameters and resulting measured broadband behavior tested in both planar and bent conditions over more than 20 GHz of bandwidth. In addition, a scalability study of the approach, outlining the optimal size of such a system is reported, thereby proving the extent of the capability of providing a combination of good array factor and wide beam coverage. The novelty of this system also lies in the realization of a fully-flexible 28 GHz Rotman-lens-based rectenna system, completed by the design of a new DC combiner on a flexible 125 μm-thin polyimide Kapton substrate. The new DC combiner uses a reduced number of bypass diodes and increases the angular coverage of the system by more than 30% compared to8. Furthermore, the frequency-broadband behavior enabled by the use of the Rotman lens makes the full rectenna system bending-resilient, a property now demonstrated through its characterizations in flexing and conformally-mounted configurations. Finally, the system’s potential for long-range mm-wave harvesting is expressed for the first time, by reporting an unprecedented harvesting range of 2.83 m.

Experiments, results and discussions

Rotman lens scalability study for harvesting applications

The Rotman lens, introduced in the 1960s, constitutes one of the most common and cost-effective designs for BFNs and is commonly utilized to enable multibeam phased array system9 and wide-band operation, thanks to its implementation of true-time-delays10. By properly tuning the shape of the lens according to the geometrical optics approximation with the goal of focalizing plane waves impinging on the antenna side of the lens to different focal points on the beam-ports side of the lens, one achieves a lens-shaped structure with two angles of curvatures: one on the beam-ports side, and the other on the antenna side11. Because the lens is capable of focusing the energy coming from a given direction into its geometrically-associated beam port, the proposed scheme loads each of these ports with a rectifier, thereby channeling the energy coming from any direction to one of the rectifiers as shown in Fig. 1a. This subsection investigates the effect of varying the number of antenna ports Na and beam ports Nb in the Rotman lens on its maximum array factor and angular coverage. The (NaNb) set, resulting in the best combination, will define the Rotman lens design parameters used for this work. Structures of varying sizes were designed using Antenna Magus and identical material parameters (substrate, conductors) as the ones of the presented design, before being simulated in CST STUDIO SUITE 2018. The simulated data was then processed in MATLAB to output the array factors created by the respective lens structures using a modified version of Eq. (1)12, presented next in Eq. (2):


where AFnNakdθθ and ββ are, respectively, the lossless array factor, the antenna number, the total number of antenna ports, the wave vector, the spacing between the elements, the direction of radiation and the difference in phase excitation between the elements. Since this formula describes a lossless array with a single antenna port, we introduced the following equation that takes into account the losses induced by the feeding network as well as the introduction of multiple feeding ports.


where AFjAFj and SnjSnj are, respectively, the array factor for beam port j and the S parameters between antenna ports n and beam ports j. The maximum value of the array factors as well as their total (accounting for the aggregated coverage of all ports) 3 dB beamwidths where then tabulated. The five simulated lenses had the following (NaNb) combinations: (4,3), (8,6) representing the system implemented in this work, (16,12), (32,24) and (64,48). Figure 1b shows the increase in the array factor until reaching a peak of around 7.8 dB for a lens surrounded by 16 antennas and 12 beam ports, after which the array factor starts dropping, down to approximately 5.2 dB for a 64 antennas structure with 48 beam ports. The array factor reduction is explained by the increased losses within the lens accompanied by the increase of complexity and internal reflections, as the lens grows in electrical size. The same plot shows the decrease in angular coverage from 180° with 4 antennas down to 80° with 64 antennas. This study shows that the combination composed of eight antennas and six beam ports, offers a nearly optimal compromise, with these materials, between a high array factor of 5.95 dB and a 120° total angular coverage, while maintaining a reasonable number of antennas and beam ports. It should be noted that the choice of the number of beam ports is related to the 3dB-beamwidth of the individual antennas, the reason for which will be detailed later.

Figure 1

(a) Dual combining (RF + DC) enabled by the use of the Rotman lens between the antennas and the rectifiers, (b) plot of the simulated maximum array factors and angular coverages for different-size Rotman lenses and (c) picture of the fabricated Rotman lens structure.

Flexible broadband Rotman lens design

After setting the number of antenna ports and beam ports, the design was printed on flexible copper-clad Liquid Crystal Polymer (LCP) substrate (εr=3.02εr=3.02 and h=180μmh=180μm) using an inkjet-printed masking technique followed by etching, resulting in the structure shown in Fig. 1c. It should be noted that the use of impedance-matched dummy ports is common with Rotman lenses13,14,15,16. Nevertheless, the goal in the implementation hereby described is not (as is usually the case) the generation of clean beam patterns with low side-lobe levels. Here, the lens’ properties are used for harvesting. Consequently, as long as the presence of the side lobes does not significantly interfere with the level of the array factor at broadside, side lobes are of no concern. Such a structure, including eight antenna ports and six beam ports—and, therefore, six radiating directions—was designed, simulated, and tuned. The structure, shown in Fig. 1c, with the antenna ports connected to matched loads, was then tested in planar and bent configurations—cylinders with different bending radii ranging from 1.5 to 2.5 in. radii—to assess the effect of bending on the S parameters behavior. Figure 2a shows the measured reflection coefficient of the Rotman lens at beam port 4 for four different scenarios, in comparison with the simulated structure in a planar position. The results reveal the Rotman lens’ ability to be mounted on curved surfaces down to a radius R = 1.5″, while maintaining a stable matching and minuscule losses compared to being held in a planar position.

Figure 2

(a) Plot of the simulated and measured reflection coefficients at beam port 4 under planar and bent conditions and (b) Plots of the maximum array factors and angular directions of beam ports P1, P3 and P5 with respect to frequency.

The gain and angular bandwidths of this structure—defined by the frequency range in which the maximum array factor and angular direction per beam are stable within 3 dB and 5° respectively,—are studied next. The ultimate assessment of these properties involves calculating the beams’ magnitude and angular directions over a wide range of frequencies17, in order to ascertain their stability or lack thereof. For this purpose, the maximum array factors were calculated and the beams’ angular directions were extracted and plotted in Fig. 2b for the first, third and fifth beam ports, P1, P3 and P5, representing the edge, secondary and central beams in this symmetrical structure. These plots prove the unique capabilities offered by the Rotman lens; although the Rotman lens is designed at a specific frequency—28 GHz in this work—this analysis proves that both the magnitude and the angular direction of the beams remain relatively stable over a very wide frequency range. In Fig. 2b, three plots refer to the maximum array factors of the three beam ports, where minor fluctuations between 4 and 7 dB are observed over the range from 10 to 43 GHz for ports P3 and P5 and similar fluctuations over a fairly reduced frequency range for the extreme edge beam P1. On the same graph, three plots present the angular direction’s stability of P1, P3 and P5 beams, where P3 (in particular) preserves its angular direction over 33 GHz of bandwidth. The lens’ angular coverage resides between ports 1 and 6 and can be extracted from Fig. 2b. Knowing that the structure is symmetrical and that beam port P1 is at around 54−54∘, the overall structure covers an angle larger than 100° in front of the lens, a result further detailed in the next subsection. It should be noted that such a beamwidth is maintained over a large angular bandwidth exceeding 20 GHz, as shown in Fig. 2b. This study demonstrates the stability and robustness of a low-cost, printed and flexible mm-wave Rotman lens structure, tested with respect to bending and frequency, and supports the choice of such an architecture at the heart of the harvesting system proposed in this work.

Flexible, high-gain and wide-angular-coverage mm-wave Rotman-lens-based antenna array

Eight of the linear antenna sub-arrays introduced in8 were then added to the antenna ports of the array, and its beam-ports were extended by microstrip lines to enable their connection to end-launch 2.92μm2.92μm connectors. The antenna sub-array consists of five serially-fed patch antenna elements, providing an operation centered at 28.55 GHz with a reflection coefficient S11S11 lower than 20−20 dB within this range. Their E-plane beamwidth of about 1818∘ (provided by the five antennas) is appropriate for most use cases, where environments expand mostly horizontally. Its simulations showed a gain of 13 dBi and a H-plane beamwidth of 80° in the plane perpendicular to the linear array. In this configuration, six beams were chosen to intersect at angles providing 3dB lower gain than broadside. Eight antennas provide a 3dB-beamwidth of 15°, which covers a total of 6×18=1086×18∘=108∘ in front of the array. The design was then also printed on flexible LCP substrate, resulting in the structure shown in Fig. 3a, mounted on a 1.5″ radius cylinder. The radiation properties of the lens-based antenna system were simulated using the time-domain solver of CST STUDIO SUITE 2018, resulting in the six gain plots shown in Fig. 3b. The gain of the Rotman lens at every port was also accurately measured using a 20 dBi transmitter horn antenna and by terminating all five remaining ports with a 50Ω50Ω load for every port measurement to guarantee the proper operation of the lens. Both simulated and measured radiation patterns (shown in Fig. 3b) display a remarkable similarity with a measured gain of approximately 17 dBi, and an angular coverage of around 110°, thereby validating the operation of the antenna array. The gains on the first three ports were also measured for the bent structure over a curvature of 1.5″ radius, shown in Fig. 3a and compared to the measured results on a planar surface. The previous subsection in addition to previous works18,19 have demonstrated that the performance of the Rotman lens is not deteriorated by wrapping or folding the structure compared to its conventional planar counterpart. However, after adding the antenna arrays, bending the structure can indeed have effects on its phase response, especially if the structure is large and the bending is severe. Figure 3c shows the gains of P1, P2 and P3 for the two scenarios (three ports only because the structure is symmetrical), demonstrating again the ability of the lens in maintaining a stable gain (especially over the center beams) upon bending. The beam located at the edge, however, suffers additional deterioration in received power under bending, because of the shift of the source away from the broadside of the bent antenna arrays.

Figure 3

(a) Picture of the flexible Rotman-lens-based antenna array, (b) measured (solid lines) and simulated (dashed lines) gains of the antenna array held in a planar position and (c) measured gains of the antenna array for beams P1, P2 and P3 only (because of the symmetry of the structure) in planar and bent conditions.

Fully-flexible 28 GHz Rotman lens-based system

Rotman-lens-based rectenna

In this section, the fully-flexible rectenna system—based on the Rotman lens and a new DC combiner network—is presented. This architecture, shown in Fig. 4a, consists of a series of eight antenna sub-arrays attached to the Rotman lens from one side, facing six rectifiers at the opposite side where DC serial combination is implemented. The basic rectenna elements, that are the antenna and the rectifier, are presented in details in8. The diode used in this work is the MA4E2038 Schottky barrier diode from Macom. The Rotman-based rectenna was first characterized as a function of its received power density. The system was positioned at a specific harvesting angle (approximately 25−25∘) and illuminated with a horn antenna with a gain of 20 dBi, placed at a distance of 52 cm away from the rectenna array, within the far field region starting at 23 cm, and outputting powers ranging from 18 to 25 dBm, corresponding to an RF input power sweep from around − 9 dBm to − 2 dBm. The array was loaded with its optimal load impedance of 1 kΩ, corresponding to the optimal load of a single rectifier—since only one rectifier will be “ON” at a time, given that the Rotman lens focalizes all the power to one beam port depending on the direction of the incoming wave—as detailed earlier. The results of this experiment are shown in Fig. 4b, where the harvested voltages and powers of the array are shown. It can be observed that, at low powers, the Rotman-based rectenna effortlessly produces an output. The Rotman-based rectenna turns on well below − 6 dBm cm−2, which compares quite favorably to the literature6. The output voltage of the rectenna was also measured over its operating frequency range. Like in the first experiment, the system was positioned at the same harvesting angle, at a range of 25 cm away from the source’s horn antenna. The output voltages under open load conditions were recorded and plotted, as shown in Fig. 4c for the Rotman lens-based rectenna, for Pd=9dBm cm2Pd=9dBm cm−2Pd=10.5dBm cm2Pd=10.5dBm cm−2 and Pd=12dBm cm2Pd=12dBm cm−2 incident power densities. The plots present a wide frequency coverage—from 27.8 to 29.6 GHz.

Figure 4

(a) Picture of the fully-flexible Rotman-based rectenna, (b) plot of the measured voltages and output powers versus incident power density for the Rotman-based rectenna and (c) plot of the measured voltages with respect to frequency for the Rotman-based rectenna.

Flexible DC combining network

Power summation is very critical when it comes to the unbalanced rectification outputs produced from realistic RF sources, and can be implemented differently depending on its costs and benefits20.

This paper does not rely on a direct voltage summation topology (i.e. back-to-back RF diodes); however, it introduces a minimalist architecture relying on a total of 2×(N1)2×(N−1) bypass diodes, where N is the number of RF or rectifying diodes. Equipped with a low turn-on voltage of 0.1 V, the Toshiba 1SS384TE85LF bypass diodes used in the DC combiner design create a low resistance current path around all other rectifiers that received very low or close to zero RF power. This topology is optimal when only one diode is turned on, which can be assumed if a single, dominant source of power irradiates this particular design from a given direction. This new combiner circuit is shown in the schematic of Fig. 5a. This simplified schematic—shown for four rectifying diodes—uses different colors to highlight the paths that the current will take for every case where an RF diode turning “ON” while the serially-connected diodes are “OFF”. This DC combiner was then fabricated on a flexible 125μm125μm-thin polyimide Kapton substrate and connected to the Rotman lens-based rectenna through a series of single connectors to make the entire system fully flexible and bendable. The harvested power under a load of 1 kΩ versus the angle of incidence of the mm-wave energy source for the Rotman-lens-based rectenna is compared for both rigid (presented in8, and relying on 2×N2×N bypass diodes) and flexible new DC combiners. For this experiment, a horn transmitter antenna was used to send 25 dBm of RF power at 28.5 GHz to the lens placed 70 cm away, as shown in Fig. 5b, while the array was precisely rotated in angular increments of 5°. Figure 6a shows that the new DC combiner, with a reduced number of diodes, was able to provide a complete angular coverage of almost 110° over the entire lens spectrum as presented in Fig. 3b, thus solving the voltage nulling occurring at the first and last ports, using the rigid DC combiner adopted previously in8. The new DC combiner offers therefore, an increase of more than 30% in the system’s spatial angular in addition to enabling a fully-bendable structure due to the unique fabrication on flexible Kapton substrate and connection to the rectenna using individual interconnects.

Figure 5

(a) Rotman-based rectenna power summation network and (b) picture of the setup used to measure the angular response of the rectenna.

Figure 6

(a) Plot of the measured harvested powers by the rectenna with respect to the source’s incidence angle for the two DC combiners, rigid and flexible and (b) plots of the measured harvested powers and voltages with respect to the incident power density under different load conditions for the Rotman lens rectenna with and without the flexible DC combiner.

As mentioned earlier, the DC combiner is mainly used with the Rotman-lens-based rectenna to automatically direct the active rectifier’s output to a single DC common port, independent of which port this might be. An alternative to the DC combiner in the Rotman lens-based system, would be to manually connect to the active port if the location of the source were known. To study the effect of the implemented DC combiner on the turn-on sensitivity of the system, the output voltage of the rectenna was measured for a specific source location with and without the combiner over a range of RF transmitted power and load variations; the direction was chosen such that the non-DC-combined rectifier would output its maximum power. Figure 6b shows eight different plots where three of them represent the harvested power with a direct connection to the active rectifier for 1 kΩ, 10 kΩ and 100 kΩ conditions. Plotted with the same colors are the other three, representing the harvested power with the addition of the DC combiner for the same load values. The last two plots display the measured voltages with and without the combiner under open load conditions. The rectenna was placed 61 cm away from the transmitter horn antenna and the power was swept from 10 to 25 dBm. The results show the performance superiority in all considered load conditions when the contact is made directly to the rectifier and not through the DC combiner. The lens-based system is able to achieve a turn-on power as low as 15dBm cm2−15dBm cm−2 in this case. This behavior is explained by the voltage drop introduced by the bypass diodes present in the combiner—that consistently decrease the expected output voltage by 0.1 to 0.2 V—when one or two diodes are, respectively, added to the current path. The variation of load values also shows that the rectenna can achieve better efficiencies at lower loads. More importantly, the reduction in the turn-on sensitivity—the minimum power density required output 10 mV—induced by the combiner is only of about 2 dB in loaded conditions, while the combiner enables an increase in the angular coverage of the rectenna system from about 18° to 110°. The remarkable angular and high-power turn-on sensitivity offered by the Rotman-lens-based rectenna are finally benchmarked using the following table for comparison with several state-of-the-art works, as presented in literature. In Table 1, the striking performance of the proposed system is displayed, highlighted by its flexibility and ability of achieving an angular coverage as large as 110° at extremely high turn-on sensitivity, thereby allowing mm-wave long-range harvesting in ad-hoc and conformal-mounting implementations.

Table 1 Performance comparison.

Rectenna system performance under bending

This section displays the operation of the Rotman-lens-based system under different bending scenarios. This and previous work18,19 show that the lens is able to maintain an efficient electromagnetic energy distribution across the output ports under convex and concave flexing conditions. The lens-based rectenna was placed on cylinders with different curvatures, 70 cm away from the transmitter sending 25 dBm of power at 28.5 GHz, as shown on Fig. 7a. The voltage was collected using a load of 1 kΩ for the planar and three bent conditions and plotted in Fig. 7b with respect to the source’s angle of incidence. The graph shows an unprecedented consistency and stability in the system’s scavenging and rectification abilities, knowing that several sub-systems are exposed to warping and the pressures of bending: the antenna sub-arrays, the Rotman lens and the rectifiers. Slight attenuation can be observed at the edges, but the system otherwise performs unimpeded by the bending. This remarkable property qualifies this system as a perfect candidate for use in wearables, smart phones and ubiquitous, conformal 5G energy harvesters for IoT nodes.

Figure 7

(a) Picture of the flexible Rotman lens-based rectenna placed on a 1.5″ radius cylinder and (b) measured harvested powers versus incidence angles for different curvatures, (c) long-range harvesting testing setup.

Long-range harvesting

As described earlier, one of the main appeals of the proposed approach is its ability to use the high EIRPs allowed for 5G base-stations while guaranteeing an extended beam angular coverage, which is a necessary feature for ad-hoc ubiquitous harvesting implementations. In order to demonstrate the lens based-rectenna for longer-distance harvesting and detect that maximum range, a high-performance antenna system—comprised of a 19 dBi conical horn antenna and a 300 mm-diameter PTFE dielectric lens (for high directivity) providing an additional 10 dB of gain—was used as shown in Fig. 7c. With a transmitted power of 25 dBm (and an associated EIRP of approximately 54 dBm), corresponding to an incident power density of approximately − 6 dBm cm−2, the lens-based rectenna displayed an extended range of 2.83 m under open load conditions, with an output voltage around 10 mV, thereby demonstrating (to our knowledge) the longest-ranging rectenna demonstration at mm-wave frequencies. With a transmitter emitting the allowable 75 dBm EIRP, the theoretical maximum reading range of this rectenna could extend to 16 m. In addition, the use of advanced diodes—designed for applications within the 5G bands and enabling rectifiers’ sensitivities similar to that common at lower (UHF) frequencies—are showing a potential path towards achieving a turn-on sensitivity of the rectifiers as low as − 30 dBm21,22. If this were practically applied to the Rotman lens system presented in this work, the harvesting range could be extended beyond 180 m (where the received power density for a transmitted power of 75 dBm is 7.8μW cm27.8μW cm−2), which is only slightly smaller than the recommended cell size of 5G networks23. This observation enables the striking idea that future 5G networks could be used not only for tremendously-rapid communications, but also as a ubiquitous wireless power grid for IoT devices.


Through the use of the Rotman lens, this paper demonstrates that the usual paradigm constrained by the (often considered fundamental) trade-off between the angular coverage and the turn-on sensitivity of a wireless harvesting system can be broken. Using the reported architecture, one can design and fabricate flexible mm-wave harvesters that can cover wide areas of space while being electrically large and benefit from the associated improvements in link budget (from source to harvester) and, more importantly, turn-on sensitivity. The approach has been shown, however, to only be scalable up to the degree where the additional incremental losses introduced by the growing lens counterbalance the increase in the aperture of the rectenna. Nevertheless, this inflection point only appears (in the particular context considered in this paper) after the arraying of 16 elements, or up to a scale of 8λ. In the 5G Frequency Range 2 (FR2), this translates to harvesters of 4.5 cm to 9.6 cm in size, which are perfectly suited for wearable and ubiquitous IoT implementations. With the advent of 5G networks and their associated high allowed EIRPs and the availability of diodes with high turn-on sensitivities at 5G frequencies, several μWμW of DC power (around 6 μWμW with 75 dBm EIRP) can be harvested at 180 m. Such properties may trigger the emergence of 5G-powered nodes for the IoT and, combined with the long-range capabilities of mm-wave ultra-low-power backscatterers24, of long-range passive mm-wave RFIDs.


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This work was supported by the Air Force Research Laboratory and the NSF-EFRI. The work was performed in part at the Georgia Tech Institute for Electronics and Nanotechnology, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the National Science Foundation (Grant ECCS-1542174).

Author information



A.E. and J.H. conceived the idea, designed, and simulated the antenna arrays, rectifiers, Rotman lens, DC combiners and full rectennas. They also performed the measurements, interpreted results and wrote the paper. M.T. supervised the research and contributed to the general concept and interpretation of the results. All authors reviewed the manuscript.

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Correspondence to Aline Eid.

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Eid, A., Hester, J.G.D. & Tentzeris, M.M. 5G as a wireless power grid. Sci Rep 11, 636 (2021).

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Whitest-ever paint could help cool Earth, study shows


New paint reflects 98% of sunlight as well as radiating infrared heat into space, reducing need for air conditioning

Prof Xiulin Ruan, a professor of mechanical engineering, with a sample of the paint.
Prof Xiulin Ruan, a professor of mechanical engineering, with a sample of the paint. Photograph: Jared Pike/Purdue University
 Environment editor



The whitest-ever paint has been produced by academic researchers, with the aim of boosting the cooling of buildings and tackling the climate crisis.

The new paint reflects 98% of sunlight as well as radiating infrared heat through the atmosphere into space. In tests, it cooled surfaces by 4.5C below the ambient temperature, even in strong sunlight. The researchers said the paint could be on the market in one or two years.


White-painted roofs have been used to cool buildings for centuries. As global heating pushes temperatures up, the technique is also being used on modern city buildings, such as in Ahmedabad in India and New York City in the US.

Currently available reflective white paints are far better than dark roofing materials, but only reflect 80-90% of sunlight and absorb UV light. This means they cannot cool surfaces below ambient temperatures. The new paint does this, leading to less need for air conditioning and the carbon emissions they produce, which are rising rapidly.

“Our paint can help fight against global warming by helping to cool the Earth – that’s the cool point,” said Prof Xiulin Ruan at Purdue University in the US. “Producing the whitest white means the paint can reflect the maximum amount of sunlight back to space.”

Infrared image shows how a sample of the ‘whitest paint’ (the dark purple square in the middle) cools the board below ambient temperature.
An infrared image shows how a sample of the ‘whitest paint’ (the dark purple square in the middle) cools the board below ambient temperature. Photograph: Joseph Peoples/Purdue University

Ruan said painting a roof of 93 sq metres (1,000 sq ft) would give a cooling power of 10 kilowatts: “That’s more powerful than the central air conditioners used by most houses.”

The new paint was revealed in a report in the journal ACS Applied Materials & Interfaces. Three factors are responsible for the paint’s cooling performance. First, barium sulphate was used as the pigment which, unlike conventional titanium dioxide pigment, does not absorb UV light. Second, a high concentration of pigment was used – 60%.


Third, the pigment particles were of varied size. The amount of light scattered by a particle depends on its size, so using a range scatters more of the light spectrum from the sun. Ruan’s lab had assessed more than 100 different materials and tested about 50 formulations for each of the most promising. Their previous whitest paint used calcium carbonate – chalk – and reflected 95.5% sunlight.

The barium sulphate paint enables surfaces to be below the ambient air temperature, even in direct sunlight, because it reflects so much of the sun’s light and also radiates infrared heat at a wavelength that is not absorbed by air. “The radiation can go through the atmosphere, being directly lost to deep space, which is extremely cold,” said Ruan.

The researchers said the ultra-white paint uses a standard acrylic solvent and could be manufactured like conventional paint. They claim the paint would be similar in price to current paints, with barium sulphate actually cheaper than titanium dioxide. They have also tested the paint’s resistance to abrasion, but said longer-term weathering tests were needed to assess its long-term durability.

Ruan said the paint was not a risk to people’s eyesight: “Our surface reflects the sunlight diffusely, so the power going in any particular direction is not very strong. It just looks bright white, a bit whiter than snow.”

A patent for the paint has been filed jointly by the university and research team, which is now working with a large corporation towards commercialisation: “We think this paint will be made widely available to the market, in one or two years, I hope, if we do it quickly.”

Lukas Schertel, a light-scattering expert at the University of Cambridge, UK, who was not part of the research team, said: “Using paint for cooling is not new but has still a high potential to improve our society, as it is widely used. This study makes a step towards commercially relevant solutions. If further improved, I am convinced such technology can play a role in reducing carbon emissions and having a global impact.”

Cool roofs: beating the midday sun with a slap of white paint
Read more

Schertel said the high concentration of pigment in the paint and the relatively thick layers used raised questions of cost: “Pigment is the main cost in paint.” Ruan said his team hoped to optimise the paint so it can be used in thinner layers, perhaps by using new materials, so it will be easier to apply and lower cost.

Andrew Parnell, who works on sustainable coatings at the University of Sheffield, UK, said: “The principle is very exciting and the science [in the new study] is good. But I think there might be logistical problems that are not trivial. How many million tonnes [of barium sulphate] would you need?”

Parnell said a comparison of the carbon dioxide emitted by the mining of barium sulphate with the emissions saved from lower air conditioning use would be needed to fully assess the new paint. He also said green roofs, on which plants grow, could be more sustainable where practical.

Project Drawdown, a charity that assesses climate solutions, estimates that white roofs and green roofs could avoid between 600m and 1.1bn tonnes of carbon dioxide by 2050, roughly equivalent to two to three years of the UK’s total annual emissions.


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Mindless US Academic Career System Almost Killed off the Virus Vaccine

How Our Brutal Science System Almost Cost Us A Pioneer Of mRNA Vaccines

Pfizer and BioNTech's COVID-19 vaccine. (Matthew Horwood/Getty Images)
Pfizer and BioNTech’s COVID-19 vaccine. (Matthew Horwood/Getty Images)

Lately, my social media feeds have been filled with “vaxxies” — selfies of health care friends getting COVID-19 vaccines and gushing about how the shots brought them hope or relief. Many express gratitude for the science that yielded the vaccines.

When I got my own shot — after working the chaotic first surge at an understaffed hospital in March and April — I felt an added emotion: awe.

When can I get a vaccine? Is it safe? What are the side effects? Get this info & more in your inbox each week. Sign up now.

You see, I witnessed some of the early scientific heartbreaks that came before the historic vaccine victories. And I found myself simply awestruck by the scientists I knew who persevered in spite of our system of scientific research.

The system helped lead to progress, but it also demoralized a junior researcher to the point that anyone of less grit and determination would have just given up long before the groundwork for today’s vaccines was laid.

An Existential Career Threat

Here’s my story: 20 years ago, I worked part-time in a tumble-down laboratory in a dusty corner of an old medical school building at the University of Pennsylvania, where I was an undergrad. For three years, I studied HIV replication in T-cells under researchers Drew Weissman and Katalin Karikó.

These days, they are coronavirus vaccine heroes, but back then, their very early work on mRNA vaccines aimed to fight HIV. After spending my first four months in the lab on an experiment that never worked, I learned that good science is really, really hard.

I didn’t know it at the time, but I also absorbed what I later could describe as the sociology of science — how the sausage is made — and it wasn’t always pretty.

From the photo album of author David Scales (second from right), the 2001 lab team that included Katalin Karikó (third from left.)
From the photo album of author David Scales (second from right), the 2001 lab team that included Katalin Karikó (third from left.)

While Weissman was an expert at designing experiments, I remember him most for his generosity. He made sure all contributors in the lab shared the credit, from the lab tech and lowly undergrad all the way to fellow researcher Karikó.

Still, Karikó was struggling. Her science was fantastic, but she was less adept at the competitive game of science. She tried again and again to win grants, and each time, her applications were rejected.

Eventually, in the mid-1990s, she suffered the academic indignity of demotion, meaning she was taken off the academic ladder that leads to becoming a professor. We never discussed it personally because by the time I joined the lab, Karikó’s history was still only discussed in hushed tones as a cautionary tale for young scientists.

I learned that while universities pay the salaries of many of their professors in English or anthropology, they expect faculty in the medical schools to pay their own way with either clinical work or external research funding. This puts tremendous financial pressure on eager young medical researchers, sometimes leading them not to the projects that are most needed or that they are most passionate about, but to the projects that will get them funding.

Karikó lived that nightmare, but stuck to her passions. She was too committed to the promise of mRNA to switch to other, perhaps more easily fundable projects. Eventually, the university stopped supporting her.

It’s hard to describe what this moment means to people who have never worked in science at a university, but it is more than the frustration of an experiment not working or laudable work going unrecognized. It is an existential career threat. Everything you have worked for your entire life is suddenly in jeopardy. It is a forced career change on the assumption that if you can’t get the grants, you’re not a good enough scientist.

Clearly, this was a false assumption in Karikó’s case. She was a dynamo, with a passion for science that rubbed off on those around her. I remember one lab meeting where she arrived with a copy of Science or Nature magazine, absorbed in a new study that showed some cool biological feature of how cells reacted under stress. It wasn’t her area of research, yet she was still in awe of the beauty and intricacy our cells are imbued with, and her enthusiasm was infectious.

A Scientist To Her Core

She also shared jaw-dropping anecdotes about working as a scientist in the Eastern Bloc, from the cutthroat competition in school to the practice of smoking cigarettes in the lab (except when someone opened a container of very flammable ether).

For Karikó, who had persevered under those extraordinarily difficult circumstances in communist Hungary, demotion was particularly bitter. Most people in such circumstances end up leaving the university, but she pressed on.

I think she had to. Mark Doty, a poet, visited and gave a talk my senior year at Penn. Afterwards, a student and aspiring poet asked when and how Doty knew he was willing to endure the sacrifices it took to be a poet, with all the rejections, the financial struggle and the economic instability.

Doty said that he couldn’t not be a poet. He tried other things and just wasn’t happy. For him, it wasn’t a choice. Seeing Karikó get so excited about scientific findings that weren’t even related to her research, I got a similar sense about her too: she couldn’t not be a scientist. It was baked into her bones. Luckily for us, now.

It’s the secret you don’t learn in school. We know doing good science is hard. But it isn’t only difficult because divining nature’s secrets is a unique challenge. It is unbelievably, brutally difficult for all of the other non-science skills that are needed but not explicitly taught: writing grants (“grantsmanship”), getting invited to speak at conferences, building collaborative research relationships, having the political awareness to attract allies and mentors within a department or university who can help find support for you.

It’s the sociology of doing science at a university that makes science even harder than it already is. Usually, stories like Karikó’s end in obscurity and disappointment. Add in being a woman and an immigrant, and it makes her perseverance even more inspiring.

You Were Right, Kati

For me, seeing such an impressive mentor struggle so hard acted as a powerful push away from doing science. I spent a year abroad studying history and philosophy of science, learning the social processes by which scientific facts become solidified, then studied medicine and sociology.

But lately, I have found myself drawn back to science, as empirical facts are dismissed with a tweet. If anything, the problems Karikó faced have gotten worse over the past 20 years. It is high time for scientists to save science. But, at its best, science can produce beauty, wonder and, occasionally, through the hard work of very dedicated individuals, it can produce technologies that save millions of lives.

The coronavirus vaccine has demonstrated that we need good science – and good scientists – now more than ever. And we need to make sure that they stay in science, one way or another.

Academic science failed Karikó. But when she contacted me in 2015, I saw she had moved to the private sector, a common path for researchers when a university stops offering support. I was glad to see she had landed on her feet. And now, I watch in awe, like the rest of the world, as the technology she helped developed leads to one of the most spectacular victories in the history of science – a vaccine for a deadly pandemic developed in less than one year.

So, my vaccination day was an emotional one. As the lipid-encapsulated mRNA molecules went into my arm, I reminisced about Kati and Drew, and the lab circa 2000. And I thought: You were right, Kati. You were right.

The recent "vaxxie" of author David Scales (courtesy David Scales).
The recent “vaxxie” of author David Scales (courtesy David Scales).

Dr. David Scales is a physician and assistant professor of medicine at Weill Cornell Medical College. He can be found on Twitter @davidascales. The views and opinions expressed in this piece are those of the author and do not necessarily reflect the official policy or position of Weill Cornell Medical College.

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The story of mRNA. And The Story of a Professor Who was Demoted by Idiotic Bosses

ANDOVER, Mass. — The liquid that many hope could help end the Covid-19 pandemic is stored in a nondescript metal tank in a manufacturing complex owned by Pfizer, one of the world’s biggest drug companies. There is nothing remarkable about the container, which could fit in a walk-in closet, except that its contents could end up in the world’s first authorized Covid-19 vaccine.

Pfizer, a 171-year-old Fortune 500 powerhouse, has made a billion-dollar bet on that dream. So has a brash, young rival just 23 miles away in Cambridge, Mass. Moderna, a 10-year-old biotech company with billions in market valuation but no approved products, is racing forward with a vaccine of its own. Its new sprawling drug-making facility nearby is hiring workers at a fast clip in the hopes of making history — and a lot of money.

In many ways, the companies and their leaders couldn’t be more different. Pfizer, working with a little-known German biotech called BioNTech, has taken pains for much of the year to manage expectations. Moderna has made nearly as much news for its stream of upbeat press releases, executives’ stock sales, and spectacular rounds of funding as for its science.


Each is well-aware of the other in the race to be first.

But what the companies share may be bigger than their differences: Both are banking on a genetic technology that has long held huge promise but has so far run into biological roadblocks. It is called synthetic messenger RNA, an ingenious variation on the natural substance that directs protein production in cells throughout the body. Its prospects have swung billions of dollars on the stock market, made and imperiled scientific careers, and fueled hopes that it could be a breakthrough that allows society to return to normalcy after months living in fear.


Both companies have been frequently name-checked by President Trump. Pfizer reported strong, but preliminary, data on Monday, and Moderna is expected to follow suit soon with a glimpse of its data. Both firms hope these preliminary results will allow an emergency deployment of their vaccines — millions of doses likely targeted to frontline medical workers and others most at risk of Covid-19.

There are about a dozen experimental vaccines in late-stage clinical trials globally, but the ones being tested by Pfizer and Moderna are the only two that rely on messenger RNA.

For decades, scientists have dreamed about the seemingly endless possibilities of custom-made messenger RNA, or mRNA.

Researchers understood its role as a recipe book for the body’s trillions of cells, but their efforts to expand the menu have come in fits and starts. The concept: By making precise tweaks to synthetic mRNA and injecting people with it, any cell in the body could be transformed into an on-demand drug factory.

But turning scientific promise into medical reality has been more difficult than many assumed. Although relatively easy and quick to produce compared to traditional vaccine-making, no mRNA vaccine or drug has ever won approval.

Even now, as Moderna and Pfizer test their vaccines on roughly 74,000 volunteers in pivotal vaccine studies, many experts question whether the technology is ready for prime time.

“I worry about innovation at the expense of practicality,” Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and an authority on vaccines, said recently. The U.S. government’s Operation Warp Speed program, which has underwritten the development of Moderna’s vaccine and pledged to buy Pfizer’s vaccine if it works, is “weighted toward technology platforms that have never made it to licensure before.”

Whether mRNA vaccines succeed or not, their path from a gleam in a scientist’s eye to the brink of government approval has been a tale of personal perseverance, eureka moments in the lab, soaring expectations — and an unprecedented flow of cash into the biotech industry.

It is a story that began three decades ago, with a little-known scientist who refused to quit.

Volume 90%
Scientists can now design genetic material called mRNA to help us build immunity to certain viruses, including SARS-CoV-2, the coronavirus that causes Covid-19.HYACINTH EMPINADO/STAT

Before messenger RNA was a multibillion-dollar idea, it was a scientific backwater. And for the Hungarian-born scientist behind a key mRNA discovery, it was a career dead-end.

Katalin Karikó spent the 1990s collecting rejections. Her work, attempting to harness the power of mRNA to fight disease, was too far-fetched for government grants, corporate funding, and even support from her own colleagues.

It all made sense on paper. In the natural world, the body relies on millions of tiny proteins to keep itself alive and healthy, and it uses mRNA to tell cells which proteins to make. If you could design your own mRNA, you could, in theory, hijack that process and create any protein you might desire — antibodies to vaccinate against infection, enzymes to reverse a rare disease, or growth agents to mend damaged heart tissue.

In 1990, researchers at the University of Wisconsin managed to make it work in mice. Karikó wanted to go further.

The problem, she knew, was that synthetic RNA was notoriously vulnerable to the body’s natural defenses, meaning it would likely be destroyed before reaching its target cells. And, worse, the resulting biological havoc might stir up an immune response that could make the therapy a health risk for some patients.

It was a real obstacle, and still may be, but Karikó was convinced it was one she could work around. Few shared her confidence.

“Every night I was working: grant, grant, grant,” Karikó remembered, referring to her efforts to obtain funding. “And it came back always no, no, no.”

By 1995, after six years on the faculty at the University of Pennsylvania, Karikó got demoted. She had been on the path to full professorship, but with no money coming in to support her work on mRNA, her bosses saw no point in pressing on.

She was back to the lower rungs of the scientific academy.

“Usually, at that point, people just say goodbye and leave because it’s so horrible,” Karikó said.

There’s no opportune time for demotion, but 1995 had already been uncommonly difficult. Karikó had recently endured a cancer scare, and her husband was stuck in Hungary sorting out a visa issue. Now the work to which she’d devoted countless hours was slipping through her fingers.

“I thought of going somewhere else, or doing something else,” Karikó said. “I also thought maybe I’m not good enough, not smart enough. I tried to imagine: Everything is here, and I just have to do better experiments.”

Katalin Kariko
Katalin Karikó, a senior vice president at BioNTech overseeing its mRNA work, in her home office in Rydal, Penn.JESSICA KOURKOUNIS FOR THE BOSTON GLOBE

In time, those better experiments came together. After a decade of trial and error, Karikó and her longtime collaborator at Penn — Drew Weissman, an immunologist with a medical degree and Ph.D. from Boston University — discovered a remedy for mRNA’s Achilles’ heel.

The stumbling block, as Karikó’s many grant rejections pointed out, was that injecting synthetic mRNA typically led to that vexing immune response; the body sensed a chemical intruder, and went to war. The solution, Karikó and Weissman discovered, was the biological equivalent of swapping out a tire.

Every strand of mRNA is made up of four molecular building blocks called nucleosides. But in its altered, synthetic form, one of those building blocks, like a misaligned wheel on a car, was throwing everything off by signaling the immune system. So Karikó and Weissman simply subbed it out for a slightly tweaked version, creating a hybrid mRNA that could sneak its way into cells without alerting the body’s defenses.

“That was a key discovery,” said Norbert Pardi, an assistant professor of medicine at Penn and frequent collaborator. “Karikó and Weissman figured out that if you incorporate modified nucleosides into mRNA, you can kill two birds with one stone.”

That discovery, described in a series of scientific papers starting in 2005, largely flew under the radar at first, said Weissman, but it offered absolution to the mRNA researchers who had kept the faith during the technology’s lean years. And it was the starter pistol for the vaccine sprint to come.

And even though the studies by Karikó and Weissman went unnoticed by some, they caught the attention of two key scientists — one in the United States, another abroad — who would later help found Moderna and Pfizer’s future partner, BioNTech.

Derrick Rossi, a native of Toronto who rooted for the Maple Leafs and sported a soul patch, was a 39-year-old postdoctoral fellow in stem cell biology at Stanford University in 2005 when he read the first paper. Not only did he recognize it as groundbreaking, he now says Karikó and Weissman deserve the Nobel Prize in chemistry.

“If anyone asks me whom to vote for some day down the line, I would put them front and center,” he said. “That fundamental discovery is going to go into medicines that help the world.”

Derrick Rossi one of the founders of Moderna
Derrick Rossi, one of the founders of Moderna, in his Newton, Mass., home. He ended his affiliation with the company in 2014.SUZANNE KREITER/THE BOSTON GLOBE

But Rossi didn’t have vaccines on his mind when he set out to build on their findings in 2007 as a new assistant professor at Harvard Medical School running his own lab.

He wondered whether modified messenger RNA might hold the key to obtaining something else researchers desperately wanted: a new source of embryonic stem cells.

In a feat of biological alchemy, embryonic stem cells can turn into any type of cell in the body. That gives them the potential to treat a dizzying array of conditions, from Parkinson’s disease to spinal cord injuries.

But using those cells for research had created an ethical firestorm because they are harvested from discarded embryos.

Rossi thought he might be able to sidestep the controversy. He would use modified messenger molecules to reprogram adult cells so that they acted like embryonic stem cells.

He asked a postdoctoral fellow in his lab to explore the idea. In 2009, after more than a year of work, the postdoc waved Rossi over to a microscope. Rossi peered through the lens and saw something extraordinary: a plate full of the very cells he had hoped to create.

Rossi excitedly informed his colleague Timothy Springer, another professor at Harvard Medical School and a biotech entrepreneur. Recognizing the commercial potential, Springer contacted Robert Langer, the prolific inventor and biomedical engineering professor at the Massachusetts Institute of Technology.

On a May afternoon in 2010, Rossi and Springer visited Langer at his laboratory in Cambridge. What happened at the two-hour meeting and in the days that followed has become the stuff of legend — and an ego-bruising squabble.

Langer is a towering figure in biotechnology and an expert on drug-delivery technology. At least 400 drug and medical device companies have licensed his patents. His office walls display many of his 250 major awards, including the Charles Stark Draper Prize, considered the equivalent of the Nobel Prize for engineers.

As he listened to Rossi describe his use of modified mRNA, Langer recalled, he realized the young professor had discovered something far bigger than a novel way to create stem cells. Cloaking mRNA so it could slip into cells to produce proteins had a staggering number of applications, Langer thought, and might even save millions of lives.

“I think you can do a lot better than that,” Langer recalled telling Rossi, referring to stem cells. “I think you could make new drugs, new vaccines — everything.”

Langer could barely contain his excitement when he got home to his wife.

“This could be the most successful company in history,” he remembered telling her, even though no company existed yet.

Three days later Rossi made another presentation, to the leaders of Flagship Ventures. Founded and run by Noubar Afeyan, a swaggering entrepreneur, the Cambridge venture capital firm has created dozens of biotech startups. Afeyan had the same enthusiastic reaction as Langer, saying in a 2015 article in Nature that Rossi’s innovation “was intriguing instantaneously.”

Within several months, Rossi, Langer, Afeyan, and another physician-researcher at Harvard formed the firm Moderna — a new word combining modified and RNA.

Springer was the first investor to pledge money, Rossi said. In a 2012 Moderna news release, Afeyan said the firm’s “promise rivals that of the earliest biotechnology companies over 30 years ago — adding an entirely new drug category to the pharmaceutical arsenal.”

But although Moderna has made each of the founders hundreds of millions of dollars — even before the company had produced a single product — Rossi’s account is marked by bitterness. In interviews with the Globe in October, he accused Langer and Afeyan of propagating a condescending myth that he didn’t understand his discovery’s full potential until they pointed it out to him.

“It’s total malarkey,” said Rossi, who ended his affiliation with Moderna in 2014. “I’m embarrassed for them. Everybody in the know actually just shakes their heads.”

Rossi said that the slide decks he used in his presentation to Flagship noted that his discovery could lead to new medicines. “That’s the thing Noubar has used to turn Flagship into a big company, and he says it was totally his idea,” Rossi said.

Afeyan, the chair of Moderna, recently credited Rossi with advancing the work of the Penn scientists. But, he said, that only spurred Afeyan and Langer “to ask the question, ‘Could you think of a code molecule that helps you make anything you want within the body?’”

Langer, for his part, told STAT and the Globe that Rossi “made an important finding” but had focused almost entirely “on the stem cell thing.”

Robert Langer
Robert Langer, the prolific inventor and MIT biomedical engineering professor, is a Moderna co-founder.PAT GREENHOUSE/THE BOSTON GLOBE

Despite the squabbling that followed the birth of Moderna, other scientists also saw messenger RNA as potentially revolutionary.

In Mainz, Germany, situated on the left bank of the Rhine, another new company was being formed by a married team of researchers who would also see the vast potential for the technology, though vaccines for infectious diseases weren’t on top of their list then.

A native of Turkey, Ugur Sahin moved to Germany after his father got a job at a Ford factory in Cologne. His wife, Özlem Türeci had, as a child, followed her father, a surgeon, on his rounds at a Catholic hospital. She and Sahin are physicians who met in 1990 working at a hospital in Saarland.

The couple have long been interested in immunotherapy, which harnesses the immune system to fight cancer and has become one of the most exciting innovations in medicine in recent decades. In particular, they were tantalized by the possibility of creating personalized vaccines that teach the immune system to eliminate cancer cells.

Both see themselves as scientists first and foremost. But they are also formidable entrepreneurs. After they co-founded another biotech, the couple persuaded twin brothers who had invested in that firm, Thomas and Andreas Strungmann, to spin out a new company that would develop cancer vaccines that relied on mRNA.

That became BioNTech, another blended name, derived from Biopharmaceutical New Technologies. Its U.S. headquarters is in Cambridge. Sahin is the CEO, Türeci the chief medical officer.

“We are one of the leaders in messenger RNA, but we don’t consider ourselves a messenger RNA company,” said Sahin, also a professor at the Mainz University Medical Center. “We consider ourselves an immunotherapy company.”

Like Moderna, BioNTech licensed technology developed by the Pennsylvania scientist whose work was long ignored, Karikó, and her collaborator, Weissman. In fact, in 2013, the company hired Karikó as senior vice president to help oversee its mRNA work.

But in their early years, the two biotechs operated in very different ways.

In 2011, Moderna hired the CEO who would personify its brash approach to the business of biotech.

Stéphane Bancel was a rising star in the life sciences, a chemical engineer with a Harvard MBA who was known as a businessman, not a scientist. At just 34, he became CEO of the French diagnostics firm BioMérieux in 2007 but was wooed away to Moderna four years later by Afeyan.

Moderna made a splash in 2012 with the announcement that it had raised $40 million from venture capitalists despite being years away from testing its science in humans. Four months later, the British pharmaceutical giant AstraZeneca agreed to pay Moderna a staggering $240 million for the rights to dozens of mRNA drugs that did not yet exist.

Moderna CEO Stéphane Bancel at the company’s offices in Cambridge, Mass.ARAM BOGHOSIAN FOR STAT

The biotech had no scientific publications to its name and hadn’t shared a shred of data publicly. Yet it somehow convinced investors and multinational drug makers that its scientific findings and expertise were destined to change the world. Under Bancel’s leadership, Moderna would raise more than $1 billion in investments and partnership funds over the next five years.

Moderna’s promise — and the more than $2 billion it raised before going public in 2018 — hinged on creating a fleet of mRNA medicines that could be safely dosed over and over. But behind the scenes the company’s scientists were running into a familiar problem. In animal studies, the ideal dose of their leading mRNA therapy was triggering dangerous immune reactions — the kind for which Karikó had improvised a major workaround under some conditions — but a lower dose had proved too weak to show any benefits.

Moderna had to pivot. If repeated doses of mRNA were too toxic to test in human beings, the company would have to rely on something that takes only one or two injections to show an effect. Gradually, biotech’s self-proclaimed disruptor became a vaccines company, putting its experimental drugs on the back burner and talking up the potential of a field long considered a loss-leader by the drug industry.

Meanwhile BioNTech has often acted like the anti-Moderna, garnering far less attention.

In part, that was by design, said Sahin. For the first five years, the firm operated in what Sahin called “submarine mode,” issuing no news releases, and focusing on scientific research, much of it originating in his university lab. Unlike Moderna, the firm has published its research from the start, including about 150 scientific papers in just the past eight years.

In 2013, the firm began disclosing its ambitions to transform the treatment of cancer and soon announced a series of eight partnerships with major drug makers. BioNTech has 13 compounds in clinical trials for a variety of illnesses but, like Moderna, has yet to get a product approved.

When BioNTech went public last October, it raised $150 million, and closed with a market value of $3.4 billion — less than half of Moderna’s when it went public in 2018.

Despite his role as CEO, Sahin has largely maintained the air of an academic. He still uses his university email address and rides a 20-year-old mountain bicycle from his home to the office because he doesn’t have a driver’s license.

Then, late last year, the world changed.

MODERNA - Norwood facility
Moderna’s facility in Norwood, Mass.ALEX HOGAN/STAT

Shortly before midnight, on Dec. 30, the International Society for Infectious Diseases, a Massachusetts-based nonprofit, posted an alarming report online. A number of people in Wuhan, a city of more than 11 million people in central China, had been diagnosed with “unexplained pneumonia.”

Chinese researchers soon identified 41 hospitalized patients with the disease. Most had visited the Wuhan South China Seafood Market. Vendors sold live wild animals, from bamboo rats to ostriches, in crowded stalls. That raised concerns that the virus might have leaped from an animal, possibly a bat, to humans.

After isolating the virus from patients, Chinese scientists on Jan. 10 posted online its genetic sequence. Because companies that work with messenger RNA don’t need the virus itself to create a vaccine, just a computer that tells scientists what chemicals to put together and in what order, researchers at Moderna, BioNTech, and other companies got to work.

A pandemic loomed. The companies’ focus on vaccines could not have been more fortuitous.

Moderna and BioNTech each designed a tiny snip of genetic code that could be deployed into cells to stimulate a coronavirus immune response. The two vaccines differ in their chemical structures, how the substances are made, and how they deliver mRNA into cells. Both vaccines require two shots a few weeks apart.

The biotechs were competing against dozens of other groups that employed varying vaccine-making approaches, including the traditional, more time-consuming method of using an inactivated virus to produce an immune response.

Moderna was especially well-positioned for this moment.

Forty-two days after the genetic code was released, Moderna’s CEO Bancel opened an email on Feb. 24 on his cellphone and smiled, as he recalled to the Globe. Up popped a photograph of a box placed inside a refrigerated truck at the Norwood plant and bound for the National Institute of Allergy and Infectious Diseases in Bethesda, Md. The package held a few hundred vials, each containing the experimental vaccine.

Moderna was the first drug maker to deliver a potential vaccine for clinical trials. Soon, its vaccine became the first to undergo testing on humans, in a small early-stage trial. And on July 28, it became the first to start getting tested in a late-stage trial in a scene that reflected the firm’s receptiveness to press coverage.

The first volunteer to get a shot in Moderna’s late-stage trial was a television anchor at the CNN affiliate in Savannah, Ga., a move that raised eyebrows at rival vaccine makers.

Along with those achievements, Moderna has repeatedly stirred controversy.

On May 18, Moderna issued a press release trumpeting “positive interim clinical data.” The firm said its vaccine had generated neutralizing antibodies in the first eight volunteers in the early-phase study, a tiny sample.

But Moderna didn’t provide any backup data, making it hard to assess how encouraging the results were. Nonetheless, Moderna’s share price rose 20% that day.

Some top Moderna executives also drew criticism for selling shares worth millions, including Bancel and the firm’s chief medical officer, Tal Zaks.

In addition, some critics have said the government has given Moderna a sweetheart deal by bankrolling the costs for developing the vaccine and pledging to buy at least 100 million doses, all for $2.48 billion.

That works out to roughly $25 a dose, which Moderna acknowledges includes a profit.

In contrast, the government has pledged more than $1 billion to Johnson & Johnson to manufacture and provide at least 100 million doses of its vaccine, which uses different technology than mRNA. But J&J, which collaborated with Beth Israel Deaconess Medical Center’s Center for Virology and Vaccine Research and is also in a late-stage trial, has promised not to profit off sales of the vaccine during the pandemic.

Over in Germany, Sahin, the head of BioNTech, said a Lancet article in January about the outbreak in Wuhan, an international hub, galvanized him.

“We understood that this would become a pandemic,” he said.

The next day, he met with his leadership team.

“I told them that we have to deal with a pandemic which is coming to Germany,” Sahin recalled.

He also realized he needed a strong partner to manufacture the vaccine and thought of Pfizer. The two companies had worked together before to try to develop mRNA influenza vaccines. In March, he called Pfizer’s top vaccine expert, Kathrin Jansen.

“I asked her if Pfizer was interested in teaming up with us, and she, without any discussion, said, ‘Yes, we would love to do that,’” Sahin recalled.

Philip Dormitzer, chief scientific officer for viral vaccines at Pfizer, said developing a coronavirus vaccine is “very much in Pfizer’s comfort zone as a vaccine company with multiple vaccine products.”

Pfizer has about 2,400 employees in Massachusetts, including about 1,400 at its Andover plant, one of three making the vaccine for the New York-based company in the U.S.

Pfizer, through its partnership with BioNTech, isn’t taking any money upfront from the government. Rather, the federal government will pay the partners $1.95 billion for at least 100 million doses if the vaccine gets approved.

Pfizer CEO Albert Bourla, who rose through the ranks after more than 25 years with the company, said in a September interview with “Face the Nation” that if the Pfizer-BioNTech vaccine fails, his company will absorb the financial loss. He said Pfizer opted not to take government funding up front to shield the drug giant from politics.

“I wanted to liberate our scientists from any bureaucracy,” he said. “When you get money from someone, that always comes with strings.”

Top executives at Pfizer also have sold far less stock compared to Moderna since the pandemic began.

BioNTech executives haven’t sold any shares since the company went public last year, according to Securities and Exchange Commission records. Still, the soaring share prices of BioNTech and Moderna have made both Sahin and Bancel billionaires, according to Forbes.

Some experts worry about injecting the first vaccine of this kind into hundreds of million of people so quickly.

“You have all these odd clinical and pathological changes caused by this novel bat coronavirus, and you’re about to meet it with all of these vaccines with which you have no experience,” said Paul Offit, an infectious disease expert at Children’s Hospital of Philadelphia and an authority on vaccines.

Blood samples from volunteers
Blood samples from volunteers participating in Moderna’s Phase 3 Covid-19 vaccine trial wait to be processed in a lab at the University of Miami Miller School of Medicine.TAIMY ALVAREZ/AP

Several other drug makers have also developed experimental mRNA vaccines for the coronavirus, but are not as far along, including CureVac, another German biotech, and Translate Bio, which has partnered with the French vaccine giant Sanofi Pasteur.

Pfizer began its late-stage trial on July 27 — the same day as Moderna — with the first volunteers receiving injections at the University of Rochester. It announced its promising early results from that trial on Monday, and hopes to have sufficient data this month to seek emergency use authorization of the vaccine for at least some high-risk people.

Moderna may not be far behind. Its spokesperson Ray Jordan said Monday that executives suspected Pfizer would release some preliminary late-stage trial data before Moderna, in part because of the dosing schedule of the rival vaccines. Recipients of Pfizer’s vaccine get two doses three weeks apart, while recipients of Moderna’s get two doses four weeks apart.

Striking a magnanimous note, he described Pfizer’s news as “an important step for mRNA medicine.”

“We’ve said that the world needs more than one Covid-19 vaccine,” Jordan said. “We remain on track.”

Mark Arsenault of the Globe staff contributed reporting.

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Israel Sabotages Iran Nuclear Site

Analysts: Fire at Iran nuclear site hit centrifuge facility

July 3, 2020
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This photo released Thursday, July 2, 2020, by the Atomic Energy Organization of Iran, shows a building after it was damaged by a fire, at the Natanz uranium enrichment facility some 200 miles (322 kilometers) south of the capital Tehran, Iran. A fire burned the building above Iran’s underground Natanz nuclear enrichment facility, though officials say it did not affect its centrifuge operation or cause any release of radiation. The Atomic Energy Organization of Iran sought to downplay the fire Thursday, calling it an “incident” that only affected an “industrial shed.” (Atomic Energy Organization of Iran via AP)


DUBAI, United Arab Emirates (AP) — A fire and an explosion struck a centrifuge production plant above Iran’s underground Natanz nuclear enrichment facility early Thursday, analysts said, one of the most-tightly guarded sites in all of the Islamic Republic after earlier acts of sabotage there.

The Atomic Energy Organization of Iran sought to downplay the fire, calling it an “incident” that only affected an under-construction “industrial shed,” spokesman Behrouz Kamalvandi said. However, both Kamalvandi and Iranian nuclear chief Ali Akbar Salehi rushed after the fire to Natanz, a facility earlier targeted by the Stuxnet computer virus and built underground to withstand enemy airstrikes.

The fire threatened to rekindle wider tensions across the Middle East, similar to the escalation in January after a U.S. drone strike killed a top Iranian general in Baghdad and Tehran launched a retaliatory ballistic missile attack targeting American forces in Iraq.

While offering no cause for Thursday’s blaze, Iran’s state-run IRNA news agency published a commentary addressing the possibility of sabotage by enemy nations such as Israel and the U.S. following other recent explosions in the country.

“The Islamic Republic of Iran has so far has tried to prevent intensifying crises and the formation of unpredictable conditions and situations,” the commentary said. But ”the crossing of red lines of the Islamic Republic of Iran by hostile countries, especially the Zionist regime and the U.S., means that strategy … should be revised.”

The fire began around 2 a.m. local time in the northwest corner of the Natanz compound in Iran’s central Isfahan province, according to data collected by a U.S. National Oceanic and Atmospheric Administration satellite that tracks fires from space.

Images later released by Iranian state media show a two-story brick building with scorch marks and its roof apparently destroyed. Debris on the ground and a door that looked blown off its hinges suggested an explosion accompanied the blaze.

“There are physical and financial damages and we are investigating to assess,” Kamalvandi told Iranian state television. “Furthermore, there has been no interruption in the work of the enrichment site. Thank God, the site is continuing its work as before.”


In Washington, the State Department said that U.S. officials were “monitoring reports of a fire at an Iranian nuclear facility.”

“This incident serves as another reminder of how the Iranian regime continues to prioritize its misguided nuclear program to the detriment of the Iranian people’s needs,” it said.

The site of the fire corresponds to a newly opened centrifuge production facility, said Fabian Hinz, a researcher at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies in Monterey, California.

Hinz said he relied on satellite images and a state TV program on the facility to locate the building, which sits in Natanz’s northwest corner.

David Albright of the Institute for Science and International Security similarly said the fire struck the production facility. His institute previously wrote a report on the new plant, identifying it from satellite pictures while it was under construction and later built.

Iranian nuclear officials did not respond to a request for comment about the analysts’ comments. However, any damage to the facility would be a major setback, said Hinz, who called the fire “very, very suspicious.”

“It would delay the advancement of the centrifuge technology quite a bit at Natanz,” Hinz said. “Once you have done your research and development, you can’t undo that research and development. Targeting them would be very useful” for Iran’s adversaries.

Natanz, also known as the Pilot Fuel Enrichment Plant, is among the sites now monitored by the International Atomic Energy Agency after Iran’s 2015 nuclear deal with world powers. That deal saw Iran agree to limit its uranium enrichment in exchange for the lifting of economic sanctions.

The IAEA said in a statement it was aware of reports of the fire. “We currently anticipate no impact on the IAEA’s safeguards verification activities,” the Vienna-based agency said.

Natanz became a flashpoint for Western fears about Iran’s nuclear program in 2002, when satellite photos showed Iran building an underground facility at the site, some 200 kilometers (125 miles) south of the capital, Tehran. In 2003, the IAEA visited Natanz, which Iran said would house centrifuges for its nuclear program, buried under some 7.6 meters (25 feet) of concrete.

Natanz today hosts the country’s main uranium enrichment facility. In its long underground halls, centrifuges rapidly spin uranium hexafluoride gas to enrich uranium. Currently, the IAEA says Iran enriches uranium to about 4.5% purity — above the terms of the nuclear deal but far below weapons-grade levels of 90%. Workers there also have conducted tests on advanced centrifuges, according to the IAEA.

The U.S. under President Donald Trump unilaterally withdrew from the nuclear deal in May 2018, setting up months of tensions between Tehran and Washington. Iran now is breaking all the production limits set by the deal, but still allows IAEA inspectors and cameras to watch its nuclear sites.


Natanz remains of particular concern to Tehran as it has been targeted for sabotage before. The Stuxnet malware, widely believed to be an American and Israeli creation, disrupted and destroyed centrifuges at Natanz amid the height of Western concerns over Iran’s nuclear program.

Satellite photos show an explosion last Friday that rattled Iran’s capital came from an area in its eastern mountains that analysts believe hides an underground tunnel system and missile production sites. Iran has blamed the blast on a gas leak in what it describes a “public area.”

Another explosion from a gas leak at a medical clinic in northern Tehran killed 19 people Tuesday.

Yoel Guzansky, a senior fellow at Israel’s Institute for National Security Studies and former Iran analyst for the prime minister’s office, said he didn’t know if there was an active sabotage campaign targeting Tehran. However, he said the series of explosions in Iran feel like “more than a coincidence.”

“Theoretically speaking, Israel, the U.S. and others have an interest to stop this Iran nuclear clock or at least show Iran there’s a price in going that way,” he said. “If Iran won’t stop, we might see more accidents in Iran.”

Late Thursday, the BBC’s Persian service said it received an email prior to the announcement of the Natanz fire from a group identifying itself as the Cheetahs of the Homeland, claiming responsibility for an attack on the centrifuge production facility at Natanz. This group, which claimed to be dissident members of Iran’s security forces, had never been heard of before by Iran experts and the claim could not be immediately authenticated by the AP.


Associated Press writers Joseph Krauss in Jerusalem and Matthew Lee in Washington contributed to this report.

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Natanz blackout is Nuclear Terrorism

Iran calls Natanz atomic site blackout ‘nuclear terrorism’

April 11, 2021
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FILE – This file photo released Nov. 5, 2019, by the Atomic Energy Organization of Iran, shows centrifuge machines in the Natanz uranium enrichment facility in central Iran. The facility lost power Sunday, April 11, 2021, just hours after starting up new advanced centrifuges capable of enriching uranium faster, the latest incident to strike the site amid negotiations over the tattered atomic accord with world powers. Iran on Sunday described the blackout an act of “nuclear terrorism,” raising regional tensions. (Atomic Energy Organization of Iran via AP, File)

DUBAI, United Arab Emirates (AP) — Iran on Sunday described a blackout at its underground Natanz atomic facility an act of “nuclear terrorism,” raising regional tensions as world powers and Tehran continue to negotiate over its tattered nuclear deal.

While there was no immediate claim of responsibility, suspicion fell immediately on Israel, where its media nearly uniformly reported a devastating cyberattack orchestrated by the country caused the blackout.

If Israel was responsible, it further heightens tensions between the two nations, already engaged in a shadow conflict across the wider Middle East. Israeli Prime Minister Benjamin Netanyahu, who met Sunday with U.S. Defense Secretary Lloyd Austin, has vowed to do everything in his power to stop the nuclear deal.

Details remained few about what happened early Sunday morning at the facility, which initially was described as a blackout caused by the electrical grid feeding its above-ground workshops and underground enrichment halls.

Ali Akbar Salehi, the American-educated head of the Atomic Energy Organization of Iran, who once served as the country’s foreign minister, offered what appeared to be the harshest comments of his long career, which included the assassination of nuclear scientists a decade ago. Iran blames Israel for those killings as well.

He pledged to “seriously improve” his nation’s nuclear technology while working to lift international sanctions.

Salehi’s comments to state TV did not explain what happened at the facility, but his words suggested a serious disruption.

“While condemning this desperate move, the Islamic Republic of Iran emphasizes the need for a confrontation by the international bodies and the (International Atomic Energy Agency) against this nuclear terrorism,” Salehi said.

The IAEA, the United Nations’ body that monitors Tehran’s atomic program, earlier said it was aware of media reports about the incident at Natanz and had spoken with Iranian officials about it. The agency did not elaborate.

However, Natanz has been targeted by sabotage in the past. The Stuxnet computer virus, discovered in 2010 and widely believed to be a joint U.S.-Israeli creation, once disrupted and destroyed Iranian centrifuges at Natanz amid an earlier period of Western fears about Tehran’s program.


Natanz suffered a mysterious explosion at its advanced centrifuge assembly plant in July that authorities later described as sabotage. Iran now is rebuilding that facility deep inside a nearby mountain. Iran also blamed Israel for the November killing of a scientist who began the country’s military nuclear program decades earlier.

Multiple Israeli media outlets reported Sunday that an Israeli cyberattack caused the blackout in Natanz. Public broadcaster Kan said the Mossad was behind the attack. Channel 12 TV cited “experts” as estimating the attack shut down entire sections of the facility.

While the reports offered no sourcing for their information, Israeli media maintains a close relationship with the country’s military and intelligence agencies.

“It’s hard for me to believe it’s a coincidence,” Yoel Guzansky, a senior fellow at Tel Aviv’s Institute for National Security Studies, said of Sunday’s blackout. “If it’s not a coincidence, and that’s a big if, someone is trying to send a message that ‘we can limit Iran’s advance and we have red lines.’”

It also sends a message that Iran’s most sensitive nuclear site is “penetrable,” he added.

Netanyahu later Sunday night toasted his security chiefs, with the head of the Mossad, Yossi Cohen, at his side on the eve of his country’s Independence Day.

“It is very difficult to explain what we have accomplished,” Netanyahu said of Israel’s history, saying the country had been transformed from a position of weakness into a “world power.”

Israel typically doesn’t discuss operations carried out by its Mossad intelligence agency or specialized military units. In recent weeks, Netanyahu repeatedly has described Iran as the major threat to his country as he struggles to hold onto power after multiple elections and while facing corruption charges.

Speaking at the event Sunday night, Netanyahu urged his security chiefs to “continue in this direction, and to continue to keep the sword of David in your hands,” using an expression referring to Jewish strength.

Meeting with Austin on Sunday, Israeli Defense Minister Benny Gantz said Israel viewed America as an ally against all threats, including Iran.

“The Tehran of today poses a strategic threat to international security, to the entire Middle East and to the state of Israel,” Gantz said. “And we will work closely with our American allies to ensure that any new agreement with Iran will secure the vital interests of the world, of the United States, prevent a dangerous arms race in our region, and protect the state of Israel.”

The Israeli army’s chief of staff, Lt. Gen. Aviv Kochavi, also appeared to reference Iran.

The Israeli military’s “operations in the Middle East are not hidden from the eyes of the enemy,” Kochavi said. “They are watching us, seeing (our) abilities and weighing their steps with caution.”

On Saturday, Iran announced it had launched a chain of 164 IR-6 centrifuges at the plant. Officials also began testing the IR-9 centrifuge, which they say will enrich uranium 50 times faster than Iran’s first-generation centrifuges, the IR-1. The nuclear deal limited Iran to using only IR-1s for enrichment.

Since then-President Donald Trump’s withdrawal from the Iran nuclear deal in 2018, Tehran has abandoned all the limits of its uranium stockpile. It now enriches up to 20% purity, a technical step away from weapons-grade levels of 90%. Iran maintains its atomic program is for peaceful purposes.

The nuclear deal had granted Tehran sanctions relief in exchange for ensuring its stockpile never swelled to the point of allowing Iran to obtain an atomic bomb if it chose.

On Tuesday, an Iranian cargo ship said to serve as a floating base for Iran’s paramilitary Revolutionary Guard forces off the coast of Yemen was struck by an explosion, likely from a limpet mine. Iran has blamed Israel for the blast. That attack escalated a long-running shadow war in Mideast waterways targeting shipping in the region.


Associated Press writers Nasser Karimi in Tehran, Iran, and Josef Federman and Ilan Ben Zion in Jerusalem contributed to this report.