Israeli vest provides effective radiation protection, surprising discoveries in the asteroid Bennu sample, another Voyager spacecraft malfunction, and a new strategy for achieving Mars orbit. This Week in Space

Radiation Protection Vest Surpasses Expectations

StemRad, the Israeli-American company, recently presented experimental data to senior officials at NASA regarding the performance of their protective vest used in the Artemis 1 mission. Oren Milstein, CEO and co-founder of StemRad, expressed his satisfaction with the results in a conversation with the Davidson Institute website. "The results exceeded our expectations,'' he said, "Initially, it seemed too good to be true, but after months of thorough data analysis and consultations with experts from various organizations, we are confident in the vest's effectiveness.”

The company was established over a decade ago, driven by the lessons learned from the nuclear reactor accident in Fukushima, Japan. It became evident that fully shielding the entire body from radioactive radiation was not a practical solution. Recognizing the need for a more effective approach, the company was founded with a focus on protecting the body's most radiation-sensitive areas, particularly the internal organs and the pelvic bone, which houses a significant portion of the body's bone marrow. This innovative approach aimed to ensure the safety and functionality of emergency crews in such challenging environments.

Based on this understanding, the concept for a product that would provide similar protection for astronauts from the high levels if radiation in space was conceived. Although astronauts do not operate near nuclear reactors emitting radioactive radiation, they can be exposed to high levels of radiation consisting of charged particles emitted by the sun, especially during periods of high solar activity, known as ‘solar storms’. Unlike the lead-made protective vests designed to shield emergency teams on Earth from gamma radiation, the astronaut vest, named AstroRad, utilizes compressed polyethylene, which effectively absorbs high-energy charged particles like protons.

In the Artemis 1 mission, which took place about a year ago, an unmanned Orion spacecraft was launched on a 25-day journey around the Moon to test its functionality and systems before subsequent manned missions – first circling the Moon and then heading for a lunar landing. In a joint initiative of the Israeli Space Agency, the German Space Agency (DLR), NASA, and the spacecraft manufacturer Lockheed Martin, two mannequins equipped with numerous radiation sensors were placed inside. The first mannequin, named Zohar, wore the protective vest, while the second mannequin, Helga, served as a control experiment without the vest. Jordan Huri, StemRad's chief scientist in the experiment, explained, "Both mannequins were equipped with dozens of active sensors, both on and inside their bodies, continuously measuring and documenting radiation levels. Zohar also had an additional set of sensors on the exterior of the protective vest. In addition, their bodies were coated with thousands of passive sensors that measure cumulative radiation exposure.”

During the Artemis 1 mission, no notable incidents of heightened solar activity were recorded. Consequently, the primary source of radiation exposure occurred as the spacecraft traversed the Van Allen belts – regions abundant in charged particles formed by the influence of Earth's magnetic field, which protects us from much of this radiation. The raw experiment data showed that Zohar indeed absorbed significantly less radiation than Helga, but the data were limited due to the experimental setup. For example, the mannequins absorbed minimal radiation from behind because they were seated facing forward, with their backs towards the spacecraft's service module, which blocked most of the radiation.

Therefore, the researchers used the data collected to simulate what protection the vest would provide to astronauts moving freely in the spacecraft. They also examined potential scenarios during strong solar storms, using data from two such events in 1972 and 1989, which posed significant radiation threats to astronauts in space.

"According to our data, Zohar would have absorbed 60 percent less radiation than Helga in the 1972 event without the vest, equivalent to about 1,500 X-rays. When assessing protection for the pelvic bone, which houses most of the bone marrow, the difference was around 90 percent", detailed Huri.

During a solar storm, astronauts aboard the Orion spacecraft are expected to seek refuge in a designated spacecraft area defined as a 'radiation shelter.' These are essentially small spaces beneath the spacecraft's seats, where equipment and supplies can be arranged to provide optimal protection. However, staying in these shelters for extended periods, let alone multiple days, can be challenging and can severely limit the astronauts' ability to carry out their routine tasks.

The vest could allow the astronauts, or at least some of them, to leave the shelter temporarily and perform essential activities. StemRad emphasizes that the vest is not intended to replace the spacecraft's radiation shelter but rather complement it. Besides offering immediate protection against injuries like radiation sickness that could jeopardize astronauts' lives, the vest reduces radiation exposure level, thus allowing an astronaut who was in space during a solar storm to stay within the permissible radiation exposure limits, which would otherwise impede them from participating in future space missions.

'Following the initial promising results, we conducted an additional six months of analysis, including collaboration with experts from the Oak Ridge National Laboratory in Tennessee, who will also co-author forthcoming papers. I feel proud of the results as both a scientist and a businessman,' Milstein said. 'I feel good about the results as a scientist, not just as a businessman.'

The protected mannequin absorbed 60 percent less radiation, and 90 percent less in particularly sensitive areas. Helga (right) and Zohar with the protective vest in the Orion spacecraft before the Artemis 1 mission | Photo: NASA/LM/DLR

"We presented the data to Jim Free, the Associate Administrator for the Exploration Systems Development Mission Directorate at NASA Headquarters and the manager of the Artemis program, and his response was 'we could not have hoped for better results'," said Milstein. "In light of this success, we are discussing with NASA the possibility of reducing the vest's mass in certain areas to optimize its use in space missions where every gram is important, without compromising most of the radiation protection." According to Huri, reducing the vest's mass by 50 percent will only offset 25 percent of its protective capacity, thanks to its innovative design, which features varying thicknesses in the protective layer, tailored to the different risk levels to the organs it protects.

"Currently, we are negotiating with NASA, through the Israeli Space Agency, on incorporating the vest into upcoming Artemis missions. It is not certain that it will be  included in Artemis 2, which is a relatively short mission with an expected low level of radiation exposure, but we aim to incorporate it in Artemis 3, which is supposed to take humans to their first landing on the moon as part of the program, and naturally, in the missions that will follow.”

StemRad is now working on optimizing the protection layers. In parallel, they are working to improve the human engineering of the vest, in another experiment conducted in collaboration with NASA on the International Space Station. 'Four NASA female astronauts wore our vests on the station for extended periods to evaluate its comfort in routine activities, including sleeping while wearing the vest. Astronaut Eytan Stibbe also wore it during last year’s 'Rakia' mission, noted Milstein. “The next stage in development will involve vests that can be adjusted in size and tailored to individual astronauts, naturally with different models for men and women.”

In the meantime, on Earth, the company recorded its first major sales deal of protective vests to security forces, signing a contract to provide 360 protective vests to the United States National Guard, valued at approximately five million dollars. “The National Guard in Israel is somewhat equivalent to the Home Front Command, and its members are tasked with responding in case of a nuclear reactor accident as well as terrorist or military attacks involving nuclear weapons,” Milstein explained. “The deal was finalized after a lot of testing of our vest, involving prolonged negotiations that included collaboration with Congress on funding this protection. We hope this will be the first of many deals, not only with security organizations but also with other emergency services, such as fire departments, and of course, with other countries around the world

Focusing on shielding specific body areas enables  the development of a relatively lightweight suit, comfortable to wear for extended periods. The radiation suit supplied to the American National Guard | Photo: STEMRAD


An Asteroid Full of Surprises

Two and a half months after the successful landing of the capsule with the sample collected from the asteroid Bennu, NASA's team faces a challenge: they have yet to open the main sample collection container. The delay is attributed to the damage to two of the 35 screws that seal the container. NASA is currently producing new screws that will allow opening the container. The reason for the significant delay is the need to produce screws from a neutral material to prevent any reaction with or contamination of the sample. 

Despite this setback, researchers have already managed to collect no less than 70 grams of sand and rock samples outside the main container, a quantity sufficient to deem the mission a success, even without access to the container’s contents. The largest sample is a 3.5 cm long stone, which is believed to have prevented the outer container from closing properly after the sample collection and led to the loss of some of the collected material. So far, researchers from the University of Arizona, who are responsible for analyzing the sample composition, have completed their examination of over a thousand particles of material larger than half a millimeter. Most are dark in color, but some have an unusual bright outer layer rich in magnesium, sodium, and phosphorus. Such a composition rarely seen in meteorites that have reached Earth, and the researchers are trying to understand its significance. 'We are quite scratching our heads about this,' admitted the research team leader, Dante Lauretta.

Bennu is believed to be a relic from the early days of the solar system, its composition reflecting that of the disk from which the planets were formed. It also contains organic materials, including carbon and hydrogen compounds, some of which exist in the form of cyclic compounds, which, according to researchers, may have served as the building blocks of life on Earth, and possibly elsewhere.

Handling the container in a controlled environment, to avoid contaminating materials that have been preserved for over four billion years. Sample analysis lab at the Johnson Space Center in Texas | Photo: NASA/Kimberly Allums

Veteran Spacecraft Faces New Challenges

The Voyager 1 spacecraft, the first functioning spacecraft to leave the boundaries of the solar system, is again facing a malfunction that hinders its normal operation. The spacecraft continues to receive commands from the control center, but fails to transmit back crucial information, including data about the spacecraft's own systems. This failure is likely due to a malfunction in the Flight Data System (FDS), which is responsible for collecting information from the spacecraft's systems and transmitting it through its communication system.

NASA estimates that even if they manage to fix the malfunction, finding the solution will take several weeks. This difficulty is partly due to the fact that the spacecraft, like its twin Voyager 2, was launched into space 46 years ago and was built with 1970s technology. Another challenging factor is the immense distance of the spacecraft from Earth, which stands at approximately 24 billion kilometers, meaning that each command sent to it, or any response it sends back to us, reaches its destination only after 22.5 hours.

About a year and a half ago, the spacecraft's engineers faced another data transmission malfunction and ultimately managed to overcome it after several months of work.

Dealing with malfunctions outside the solar system. Simulation of the Voyager 1 spacecraft in space | Source: NASA-JP

Recomputing Entry into Orbit

In 1971, the American Mariner 9 was the first spacecraft ever to successfully enter orbit around Mars. Since then, numerous other spacecraft have followed suit, all employing a similar method: the spacecraft approaches Mars at high speed, then engages its engines for deceleration, counteracting its flight direction to slow down sufficiently to be captured by Mars' gravitational field and settle into orbit. This requirement necessitates a relatively large spacecraft from the outset, increasing launch costs and the overall mission expenses.

The possible alternative, at least in theory, is to harness the planet's atmosphere itself for deceleration. For this, the spacecraft would need to be directed to traverse through Mars' upper atmosphere and deploy a device that will increase drag force, thereby slowing its velocity. Upon reaching the desired velocity, the braking apparatus would be released, and the spacecraft would exit the atmosphere on the opposite side, positioning itself into the target orbit.

This concept, known as Aerocapture, or 'capture using air,' was initially proposed as far back as the 1960s. It offers two distinct advantages: it allows the spacecraft to carry less fuel and enables it to reach its destination at a higher velocity, thereby shortening the overall flight time from Earth to Mars. Nevertheless, despite its potential benefits, Aerocapture has never been attempted, either around Mars or anywhere else, mainly due to the relatively high risk of failure, which could result in the loss of the spacecraft and completely thwart the mission.

The European Space Agency (ESA) recently funded development and feasibility studies by two groups whose proposals were selected at a competition – one by the company Ariane and the other led by Vorticity. Each company submitted two proposals: one for a spacecraft to be launched to Mars as a primary mission, and the other to test the idea on a secondary payload spacecraft that would fly to Mars as part of a separate mission. Both ideas are fundamentally similar, based on an inflatable cone-shaped device that will create the necessary drag force, attached to a heat shield that will envelop the spacecraft itself. Once the spacecraft decelerates sufficiently, it will release the drag device, and after exiting the atmosphere, it will detach from the heat shield and enter the desired orbit without additional fuel consumption.

“We will thoroughly analyze the two proposals, discuss specific points with experts, and compile a more focused list of the required developments. We hope this will lead to the development of a Mars mission, with scientific use to be made of the spacecraft after the aerocapture,” said ESA engineer Andrew Ball, who oversaw the project. He estimates that such a mission could be launched in the next decade to test the technology. “Even if we do not continue with the development of this particular concept, other opportunities may arise to use the technology. For example, it could be used to return objects from Earth orbit, such as the upper stage of launch rockets, so there might even be an economic opportunity here.”


Decelerating without engine activation. The stages of the Aerocapture maneuver around Mars | Illustration: ESA


Translated with the assistance of ChatGTP. Revised, expanded and edited by the staff of the Davidson Institute of Science Education