Prestigious Fellowship for Israeli Researcher:
This Week in Space

Understanding Black Holes

Theoretical astrophysicist Dr. Itai Linial is one of 24 young researchers awarded this year’s prestigious NASA fellowship through the Edwin Hubble Astrophysics Fellowship Program. Currently based in New York for a postdoctoral position at Columbia University and the Institute for Advanced Study in Princeton, Linial investigates high-energy astrophysical phenomena—such as the violent disintegration of stars as they are consumed by black holes.

As part of the program, Linial was named one of nine Einstein Fellows—scientists whose work tackles fundamental questions about the universe and how it works. The fellowship provides full funding for three years of research at New York University (NYU).

Linial began his academic journey at the Hebrew University of Jerusalem. His doctoral research, under the supervision of Prof. Re’em Sari, focused on the early radiation emitted by supernovae—explosions of massive stars. “We studied the properties of the first flashes of radiation we can detect in such explosions,” Linial told the Davidson Institute website. “Our predictions may soon be tested using data from the Israeli space telescope ULTRASAT, currently being developed at the Weizmann Institute of Science and scheduled for launch in the coming years.”

His PhD work earned him the Rothschild Fellowship from the Israel Academy of Sciences and Humanities and Yad Hanadiv. During his postdoctoral research, Linial shifted his focus to theoretical aspects of high-energy processes occurring near the supermassive black holes located at the centers of most galaxies. “I study events such as stellar disruption to better understand how such supermassive black holes form and what their environments look like,” he explained.

Exploring how supermassive black holes form and what their environments look like. Itai Linial | Photo: Romy Attas

The research proposal that earned him the prestigious fellowship focuses on a strange phenomenon known as Quasi-Periodic Eruptions (QPEs)—brief, bright X-ray flares that last about an hour and recur every few hours.

“When a black hole tears apart and consumes a star, some of the leftover gas forms a disk around the black hole,” Linial said. “In the model I proposed to explain QPEs, the eruptions are caused by another star orbiting the black hole. As it passes through this accretion disk, it collides with material inside it, and we observe that collision as a burst of X-rays. Our prediction was that such events would be seen following a stellar disruption. A few months ago, during observations of a similar disruption event, such periodic flares were indeed detected, as we had expected.”

“It’s a tremendous honor to receive this fellowship,” he added. “Only 24 researchers were selected from about 700 applicants. For me, it’s a chance to lead my own research, focus on it full-time, work with leading scientists in the field, and build a network with other fellows, which will hopefully lead to scientific collaborations. This is a rapidly advancing field of study, with many new discoveries, and I hope to be at the forefront of its research in the years ahead.”

A model explaining the quasi-periodic eruptions (QPEs): a star orbiting a black hole passes through its accretion disk | Illustration: Liat Feli, VectorMine, Shutterstock

Israeli Experiment Aboard Private Mission

Last Monday, the Fram-2 mission launched from Cape Canaveral, Florida, carrying four private astronauts aboard SpaceX’s Dragon Resilience spacecraft. This marks the first crewed flight in a polar orbit—meaning the spacecraft circles the Earth perpendicular to its axis of rotation, passing over both poles on each orbit. The mission is named after the Fram, the Norwegian ship that explored the polar regions in the late 19th and early 20th centuries.

The mission commander and founder is 43-year-old Chinese billionaire Chun Wang, currently residing in Malta, who made his fortune in cryptocurrency mining. The crew includes 38-year-old Jannicke Mikkelsen from Norway, a 3D imaging and augmented reality specialist; 30-year-old Rabea Rogge from Germany, a polar researcher and PhD candidate working on the development of autonomous vehicles for extreme environments; and 63-year-old Eric Philips from Australia, an adventurer and expert in polar expeditions and gear design. This is the first spaceflight for all four.

The mission is expected to last up to five days, during which the crew will carry out a range of observations and experiments, some of them related to the polar regions. They will use a special observation dome installed on the spacecraft. The astronauts will also perform other experiments, including physiological studies on themselves to examine the effects of microgravity on the human body—and even conduct the first-ever X-ray scan in space.

Unique observations over the poles. Photo from the Dragon spacecraft during the Fram-2 mission | Source: SpaceX

An additional scientific payload aboard the mission is a miniature autonomous lab developed by the Israeli company SpacePharma, which specializes in compact laboratories for research and product development in microgravity conditions. Preliminary studies suggest that materials produced in space may have unique medical potential—for instance, proteins crystallized in microgravity can form spatial structures different from those produced on Earth. In this experiment, SpacePharma is testing the production—or more precisely, the crystallization—of a specific antibody for a pharmaceutical company.

“The experiment was originally scheduled to take place on the International Space Station but was delayed due to the postponed launch of the Cygnus supply spacecraft,” SpacePharma CEO Yossi Yamin told the Davidson Institute website. “In a very short time, we managed to establish collaboration with the Fram-2 mission, and the lab was ready for launch within just a few weeks. The biggest challenge was accelerating the experimental timeline: on the space station, the process was to take about a month—but here, we have just over three days—so we’ll need to speed up the process tenfold.”

One of the experiment’s goals is to test the performance of the company’s automated system under extreme conditions—some of which result from the mission’s unique polar orbit. This trajectory likely exposes the spacecraft to higher radiation levels, as Earth's magnetic field offers less shielding over the poles. Another difference is that this mission does not involve docking with the space station, which is constantly subject to vibrations due to its size and complexity—a factor absent in the small spacecraft. It will be interesting to see whether this has any effect. Other extreme conditions, such as variations in temperature and acidity, will be artificially introduced inside the lab.

“This is a trial run for the future—to see how the lab performs under extreme conditions or in the event of equipment or environmental malfunctions,” said Yamin. The Fram-2 experiment marks SpacePharma’s 11th mission in space. The company has previously launched two satellites of its own and conducted eight experiments aboard the International Space Station.

Fram-2 is also set to be SpaceX’s first crewed mission to splash down in the Pacific Ocean, off the coast of California, rather than near Florida. The change is intended to reduce the risk of debris falling over populated areas— such as fragments of the spacecraft’s heat shield that may detach during reentry. After splashdown, the SpacePharma experiment system will be transported to Tampa, Florida, where the findings will be analyzed in a lab to determine how the proteins crystallized in space.

A full lab within a device smaller than a shoebox. The autonomous experiment lab developed by Israeli company SpacePharma | Photo: SpacePharma

Farewell in Deep Space

Roughly 12 years after its launch, engineers at the European Space Agency have powered down the instruments of the revolutionary Gaia space telescope, which mapped the sky with an unprecedented level of detail and scope. The mission ended after the spacecraft exhausted its supply of cold gas, essential for fine adjustments and operations. Until now, Gaia had operated around the L2 point—1.5 million kilometers from Earth—where the gravitational balance between Earth and the Sun enabled it to maintain a stable position with a spectacular view of the cosmos, while consuming very little fuel. Following the shutdown of its instruments, Gaia was directed into a more distant orbit around the Sun, to prevent it from becoming space debris around Earth or interfering with future space activity.

“Gaia is a foundational tool supporting research across fields—from our solar system to the Milky Way and even distant galaxies,” said Prof. Shay Zucker of Tel Aviv University, speaking to the Davidson Institute. Zucker is part of Gaia’s scientific team, alongside Prof. Tsevi Mazeh, also of Tel Aviv University, who heads the mission’s black hole detection team. “We’re saying goodbye to the spacecraft itself—but not to the mission. We’re still processing the data it collected, and only next year do we expect to publish a summary of the data from Gaia’s first five years. It’s estimated that full data publication won’t be completed until 2030, and analysis will continue for many years beyond that.”

Zucker led the search for exoplanets—planets orbiting stars outside our solar system—using data from Gaia. His team focused on the transit method, which involves detecting slight, periodic dips in a star’s brightness that may indicate a planet passing in front of it.  “In Gaia’s third data release, we published a list of such exoplanets, although they were also observed by the TESS space telescope. In the next data release, there will be more planets. Gaia scanned the entire sky multiple times, so we can use its long-term monitoring to detect planets with longer orbital periods—ones that other telescopes may have missed.”

Zucker led Gaia’s search for exoplanets—planets orbiting stars beyond our solar system—focusing on the transit method, which detects subtle, periodic dips in a star’s brightness that may signal a planet passing in front of it. “In Gaia’s third data release, we published a list of such exoplanets, though they were also observed by the TESS space telescope. In the next release, we expect to add more planets. Since Gaia scanned the entire sky multiple times, we can use its long-term monitoring to find planets with longer orbital periods—ones other telescopes might miss.”

Discoveries made using the Gaia space telescope span nearly every field in astronomy and astrophysics—from asteroids passing near Earth to quasars located millions of light-years away. “It’s estimated that around 14,000 scientific papers have been based on Gaia’s data—an average of about 2,000 papers per year,” Zucker concluded. “It’s a massive scientific endeavor, and it doesn’t feel like it’s ending, because the data processing will continue for years to come.”

Saying goodbye to the spacecraft, but not to the mission. Years of data processing still ahead. Illustration of the Gaia telescope against the Milky Way | Source: ESA

The Crux of Bone Loss in Space

For many years, it has been known that astronauts lose bone and muscle mass during extended stays in microgravity. A new study involving mice vividly demonstrates just how significant this bone loss can be. Led by researchers from NASA and the Blue Marble Space Institute of Science in Seattle, the study examined the bone structure of female mice sent to the International Space Station aboard SpaceX’s Dragon spacecraft, where they remained for 37 days—the longest rodent study conducted in space to date.

The researchers focused on the femur bones in the mice’s hind legs, as these typically bear most of the body’s weight on Earth. They compared the bones of the spaceflight mice with those of two control groups: one kept on Earth under similar environmental conditions, and another housed in small enclosures that significantly restricted their movement.To rule out stress-related effects from launch and handling, the Earth-based mice underwent similar handling procedures.

The results showed that the femurs of the spaceflight mice had significantly larger holes compared to those of the control mice. While the restricted-movement control mice also showed large holes in their bones, these were less pronounced than those observed in the microgravity group.

The researchers also examined changes in the structure of lumbar vertebrae. In humans, these vertebrae support a substantial portion of body weight, but in quadrupeds like mice, their role in weight-bearing is much smaller. Correspondingly, changes in bone density in this region were much less pronounced. This finding supports the conclusion that microgravity—rather than radiation or other environmental factors—is the primary driver of bone loss in space. In other words, in the absence of mechanical loading, bones begin to break down and lose density.

If this is indeed the case, dietary interventions alone are unlikely to significantly mitigate the problem. The most effective current countermeasure remains physical exercise and other resistance-based activities that mimic the effects of gravity.

Marked change in bone density. Head of a mouse femur after 37 days in space (right) compared to a mouse kept under similar conditions on Earth | Source: Research article