Crew Splits Day Between Relaxing, Spacesuit Work, and Cardiac Research
NASA astronauts (at center, from left) Jessica Meir and Chris Williams work outside the International Space Station during a spacewalk to replace a malfunctioning wrist joint on the Canadarm2 robotic arm on June 30, 2026.
NASA
Four Expedition 74 astronauts had a light duty day on Wednesday following the previous day’s spacewalk for external robotics maintenance. The remaining three crew members from Roscosmos focused on cardiac research and lab maintenance aboard the International Space Station.
NASA flight engineers Chris Williams and Jessica Meir concluded their second spacewalk together on Tuesday after successfully replacing a malfunctioning wrist joint on the Canadarm2 robotic arm. The duo spent seven hours and 20 minutes on Canadarm2’s fourth repair job since its installation on April 26, 2001. Initial checkouts of the arm by flight controllers on the ground indicate the arm is functioning well and additional checkouts and verification will continue in the coming days.
Williams and Meir slept in on Wednesday and relaxed for a few hours afterward before photographing their spacesuit gloves for inspection and refilling the water tanks that help keep a spacesuit’s temperature stable during a spacewalk. Flight engineers Jack Hathaway of NASA and Sophie Adenot of ESA (European Space Agency), who monitored and assisted the spacewalkers on Tuesday, also slept in and relaxed during the first half of their shift. Finally, all four astronauts joined each other for a standard post-spacewalk conference with mission controllers on Earth and discussed their experience during the robotics repair job.
The orbiting laboratory’s commander Sergey Kud-Sverchkov and flight engineer Sergei Mikaev had a busy research schedule Wednesday studying how weightlessness affects mental performance and the circulatory system. Kud-Sverchkov and Sergei Mikaev first logged onto to a pair of computer tablets and participated in a test that provided increasingly difficult tasks that required the pair’s coordination. Results may reveal how teamwork, decision‑making, and concentration change during long missions in space and lead to improved mission training techniques.
The two cosmonauts also took turns wearing arm, wrist, and finger cuffs measuring their blood pressure. Next, the duo attached light‑based sensors to their forehead, fingers, and toes to study how blood flows through tiny vessels, or the microcirculatory system, in the skin. Doctors will use the insights for early detection of space-caused circulation issues to protect crew health and the development of advanced medical technology on Earth.
Roscosmos flight engineer Andrey Fedyaev spent most of his shift inside the Nauka science module cleaning smoke detectors. At the end of his shift, Fedyaev downloaded and read data collected from radiation detectors that Williams and Meir wore on their spacesuits during Tuesday’s spacewalk.
This sequence begins with an artist’s concept showing the Milky Way galaxy as seen from above, with the estimated positions of spiral arms based on previous data. Next is an updated artist’s concept of the Milky Way, where the positions of the two spiral arms most distant from the center of the galaxy have been adjusted based on newly processed X-ray data from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton. Both arms may be more distant than previously thought.
NASA/CXC/A. Hobart
A new result using NASA’s Chandra X-ray Observatory shows that the outer spiral arms in the Milky Way galaxy may reach wider than previously thought. This finding may lead astronomers to adjust their understanding of our home galaxy’s structure.
A team of astronomers made this discovery by making precise measurements of distances to dust clouds in the Milky Way’s spiral arms using data from both NASA’s Chandra and XMM-Newton, an ESA (European Space Agency) mission with NASA contributions. The results are described in a new paper published Wednesday in the Astronomy & Astrophysics journal.
The researchers determined the distances by studying rings around gamma-ray bursts, some of the brightest bursts of light in the universe, which arise from the collapse of massive stars or the merger of neutron stars. They are located at enormous distances, well beyond the confines of our galaxy.
An artist’s concept showing the Milky Way galaxy as seen from above, with the estimated positions of spiral arms based on previous data, in blue. Overlaid on this is an updated view of the Milky Way showing different positions for the two outermost spiral arms, shown in red and bordered by dashed lines. Both arms may be more distant than previously thought, based on newly processed X-ray data from Chandra and XMM.
NASA/CXC/SAO/M.Weiss
This distance measurement technique capitalized on the phenomenon of light echoes, where the light from the gamma-ray burst bounced off dust clouds in the spiral arms. The diameters of the rings in X-rays give the distances to Earth, with larger rings being generated by dust clouds closer to us.
“This is a very direct way – relying only on geometry – to precisely measure distances to the Milky Way’s spiral arms,” said Beatrice Vaia, who led the study while a PhD student in a joint program between Scuola Universitaria Superiore IUSS Pavia and University of Trento in Italy. “Most other methods rely on assumptions about how the Milky Way rotates, which become increasingly uncertain in the outer regions of our galaxy.”
Despite a century of awareness of the Milky Way’s spiral arms, astronomers are still working toward precise characterization of its arms because of Earth’s position within one. Dust and gas also block the view to other arms.
The researchers used three different gamma-ray bursts to determine the distances to three spiral arms in the Milky Way. In order of increasing distances from the Galactic Center, they are the Perseus, the Outer, and the Outer Scutum-Centaurus arms. Along the direction of one of the bursts, they found that both the Outer and Outer Scutum-Centaurus arms are about 10% more distant than astronomers previously thought.
“The differences are small, but any revision of these distances is important because they are so fundamental for understanding our galaxy,” said co-author Ilaria Fornasiero, who was a PhD student in the same program as the leading author. “For example, this could mean that astronomers have to revise estimates of the mass of the galaxy, because that affects how wide the arms stretch.”
The images include X-ray data from Chandra and optical data from Pan-STARRS. The composite image shows X-ray rings generated by a gamma-ray burst (GRB), a bright X-ray source located outside our galaxy. In a phenomenon called light echoes, the X-rays from the GRB bounced off dust clouds in the spiral arms of our galaxy. The diameters of the rings in the Chandra data give the distances of the dust clouds to Earth, with larger rings being generated by dust clouds closer to us. The GRB is located at the center of the circles defining the rings, to the left of the X-ray data outlined by the white square.
The team also used their data to estimate that the dust cloud in the most distant arm is about 3,500 light-years wide. These findings show that their measurements apply to the full thickness of the spiral arm, rather than a random, isolated dust cloud that may not fully be representative of the arm’s location.
While this technique provided major improvements in accuracy according to the researchers, it may be difficult to use it for further measurements because bright gamma-ray bursts that are visible through the plane of the galaxy are rare.
“We’re relying on the universe to provide us with these events, and so far, over 25 years, we’ve only found a handful that we can use,” said co-author Andrea Tiengo of Scuola Universitaria Superiore IUSS Pavia. “That said, we will continue to be on the lookout for more.”
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
This release features a short video and a series of images, all related to an updated understanding of our home galaxy’s structure. By studying rings of X-ray light echoes, researchers now believe that two of the Milky Way’s spiral arms may be more distant from the center of the galaxy than previously thought.
The updated understanding of the structure of the Milky Way is highlighted in a short video, which compares two artist concept images. In both images, our spiral Milky Way galaxy is shown face-on. It has a bright white core with several arms that spiral out from the center, like long thin clouds corkscrewing counterclockwise. The two longest arms make a full rotation of the spiral galaxy, and curve all the way around to the upper right of the images.
The first image in the video shows the previous understanding of the Milky Way. Here, the two longest arms are curled around the core in a fairly tight spiral. In the second image, which represents the updated understanding, the two longest arms are more loosely spiraled. Visually, this means there is more open space between the curving arms, which are further away from the bright galaxy core. The video fades back and forth between the two artist concept images to illustrate the structural differences between the two understandings.
These findings are further shown by a static image which overlays the new understanding on top of the earlier understanding. In this artist’s concept illustration, dotted lines and different colors are used to differentiate between the two.
A team of astronomers made this discovery by studying gamma-ray bursts that bounce off of dust clouds in the galaxy’s spiral arms. The resulting rings of X-rays, known as light echoes, were detected and mapped by NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton. In a supplemental data image, the light echoes resemble concentric arches of neon blue dots trailing across a speckled sky.
Identifying the position of the Milky Way’s spiral arms through X-ray light echoes has allowed astronomers to use geometry, rather than assumptions about galaxy rotation, to better understand the structure of our galaxy.
NASA Seeks Volunteers for New Yearlong Simulated Moon, Mars Mission
A research volunteer uses augmented reality goggles to perform astronaut-like tasks during a simulated space mission. Participants selected for NASA’s first Moon and Mars Exploration Analog mission also will perform tasks in immersive, interactive environments while living inside habitats that simulate traveling to and living on the Moon and Mars.
Credit: NASA
NASA is recruiting research participants for the agency’s next simulated deep space mission. Beginning no earlier than August 2027, research volunteers will spend one year living and working in interplanetary environments at the agency’s Johnson Space Center in Houston, operating under isolated conditions expected during crewed missions to the Moon or Red Planet.
Insights from this new, yearlong experience, called the Moon and Mars Exploration Analog, can be used to help keep astronauts safe and mission-ready during future planetary surface operations. The results also could inform plans for a sustained lunar presence through the agency’s Moon Base and future Artemis missions.
NASA is looking for applicants for the approximately year-long mission simulation, which will take place in two confined habitats. In addition to specific physical and education requirements, volunteers must be willing to take part in a multi-day selection process and pass NASA’s physical and psychological assessments, found on the Moon and Mars Exploration Analog web page. Candidates also should have a strong desire for unique, rewarding experiences, and interest in contributing to NASA’s work to prepare for extended stays on the lunar surface and the first crewed mission to Mars.
The Moon and Mars Exploration Analog evolves elements of the agency’s HERA (Human Exploration Research Analog) and CHAPEA (Crew Health And Performance Exploration Analog) missions into a single, integrated mission to streamline how researchers evaluate astronaut adaptation across the full range of potential mission scenarios. Using the HERA habitat as a spacecraft and the CHAPEA habitat as a base, the volunteers will live and work in confined, isolated environments that simulate months-long flights to and from other planetary surfaces. They also will mimic surface operations, including mock Mars walks and using a rover to travel to exploration sites located beyond the main habitat.
Throughout the Moon and Mars Exploration Analog mission, researchers will study crew health and performance under resource limitations and mission demands. These missions also help NASA assess and validate hardware, technologies, protocols, requirements, and other systems designed to support crew health and performance on long-duration deep space missions, all without leaving Earth. The effort will provide valuable data for NASA’s Human Research Program, which innovates ways to keep astronauts healthy and mission-ready.
As part of the Golden Age of innovation and exploration, NASA will send astronauts on increasingly difficult missions to explore more of the Moon for scientific discovery, economic benefits, establish an enduring human presence on the lunar surface, and to build on the foundation for the first crewed missions to Mars.
For more about NASA’s Human Research Program, visit:
LINK Spacecraft Set for Mission to Boost NASA’s Swift Observatory
A Katalyst engineer runs tests on LINK while the satellite is inside the Pegasus XL rocket attached to the Stargazer aircraft at NASA’s Wallops Flight Facility.
NASA/Ron Beard
A first-of-its-kind mission to raise the orbit of NASA’s Neil Gehrels Swift Observatory is poised for launch no earlier than Thursday, July 2, 5:09 a.m. EDT (9:09 p.m. UTC+12), from Kwajalein Atoll, part of the Republic of the Marshall Islands in the South Pacific Ocean. A robotic servicing spacecraft called LINK, built by Katalyst Space, will blast into orbit on a Northrop Grumman Pegasus XL rocket attached to the belly of the company’s Stargazer aircraft, shown here in this photograph from the evening of Tuesday, June 16, 2026.
After launch, LINK will attempt to rendezvous with, grapple, and slowly raise Swift’s altitude over several months, preventing it from re-entering Earth’s atmosphere later this year. If this daring mission is successful, it will be the first time a commercial robotic mission has captured a NASA spacecraft that is both uncrewed and not originally designed to be serviced in space.
NASA’s Webb Studies How Planet Survived Death of its Star
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NASA’s Webb Studies How Planet Survived Death of its Star
Exoplanet WD 1856 b, shown in this artist’s concept, is a gas giant that orbits its star at a distance 50 times closer than Earth orbits the Sun. Observations by NASA’s James Webb Space Telescope determined the planet’s temperature and detected molecules in its atmosphere.
Credits: Artwork: NASA, ESA, CSA, Ralf Crawford (STScI)
NASA’s James Webb Space Telescope is giving us new insight into the far-future of solar systems like our own, as the agency continues to reveal the secrets of the universe and our place in it. Billions of years ago, a Sun-like star nearing the end of its life swelled tremendously in size to become a red giant before ejecting its outer layers, leaving a hot, remnant core known as a white dwarf. As a red giant, the star should have engulfed and destroyed any nearby planets. Yet astronomers have found a Jupiter-sized exoplanet orbiting the white dwarf every 34 hours at a separation of less than 2 million miles (3 million kilometers).
To solve the mystery of how this exoplanet survived, an international team of astronomers used NASA’s James Webb Space Telescope to watch the Jupiter-sized exoplanet WD 1856 b transit its host star, measuring the planet’s temperature and detecting molecules in its atmosphere. They found the planet is significantly warmer than expected and determined how it most likely reached its very tight orbit around the white dwarf star. The results are a window into the future of planets like Jupiter after the death of the Sun, billions of years into the future.
The results published Wednesday in the journal Nature.
WD 1856 b was discovered in 2020 by scientists using NASA’s TESS (Transiting Exoplanet Survey Satellite) and the retired Spitzer Space Telescope. It orbits the white dwarf WD 1856+534, which is located about 80 light-years from Earth. “The planet is about the size of Jupiter, but the white dwarf it orbits is the size of Earth, so the planet is seven times larger than its star,” said lead author Ryan MacDonald of the University of St. Andrews in the United Kingdom.
WD 1856 b orbits extremely close to its host star, a distance 50 times closer than Earth orbits the Sun. If WD 1856 b had originally been orbiting at that distance, it would have been obliterated while the star was a red giant. How did it survive the death of its host star and end up in its current position?
Image: Exoplanet WD 1856 b (Artist’s Concept)
Exoplanet WD 1856 b, shown in this artist’s concept, is a gas giant that orbits its star at a distance 50 times closer than Earth orbits the Sun. Observations by NASA’s James Webb Space Telescope determined the planet’s temperature and detected molecules in its atmosphere.
Artwork: NASA, ESA, CSA, Ralf Crawford (STScI)
How big, how hot
The new study used Webb to watch the planet passing in front of its star. This transit yielded unique information about the planet’s mass, which is between four and eleven times the mass of Jupiter.
The team also was able to determine the planet’s temperature. During the transit, light from the star was partly blocked, but infrared light was reduced less than other wavelengths. The difference was infrared light emitted by the planet from its own heat. The data indicated that the planet has a temperature of about 260 degrees Fahrenheit (126 degrees Celsius) — significantly hotter than it would be if its only source of heat was the light from the white dwarf. This puzzling discovery turned out to be the key fact that proved how the planet must have reached its current orbit.
Christopher O’Connor of Northwestern University in Illinois, a co-author on the paper, was responsible for tracing the temperature of the planet back in time. O’Connor said, “The big question is how WD 1856 b ended up where it is today, and there are two theories. One is that the planet was swallowed by the host star as it was dying, and managed to survive on the inside. The other is that migration took place due to the gravitational effect of other objects in the system. The white dwarf is part of a triple star system, and the companion stars could have influenced WD 1856 b’s orbit.”
The researchers realized that there was no source of energy present to generate that heat today, so it must be residual energy from an earlier time when the planet was heated. Using models of how sub-stellar objects like WD 1856 b cool down over time, coupled with the new data from Webb, the team was able to project its temperature back in time and deduce how long ago the heating must have happened. The timing is key to determining whether the heating was from being engulfed by the red giant or occurred during an inward migration
They concluded that the heating most likely happened between 3 and 5.5 billion years after the star became a white dwarf. In this scenario, the planet was on a wide orbit that kept it safe from the star during its destructive red giant phase, and only migrated to its present location later on. “As the planet moved inward, its interactions with the strong gravity of the white dwarf will have caused it to warm up considerably, and it has been cooling ever since,” said O’Connor.
Light from the star passing through the planet’s atmosphere also picked up information about its chemical composition. “We saw the telltale signatures of small cloud particles and hydrocarbons, most likely methane, which is the first time we have seen an atmosphere on a planet transiting a dead star,” said co-author Victoria Boehm of Cornell University. “We recently observed four more transits of WD 1856 b with Webb to take a deeper look into its atmospheric chemistry and can’t wait to see the results.”
Image: Exoplanet WD 1856 b (Transmission Spectrum)
NASA’s James Webb Space Telescope measured the constituents of exoplanet WD 1856 b as it passed in front of its star, finding signs of methane. WD 1856 b orbits a white dwarf star the size of Earth. As a result, the planet blocks more than half of the star’s light.
Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI)
Solar system’s possible future
In approximately five billion years, the Sun will run out of hydrogen fuel in its core and swell up more than 100 times larger than it is now into a red giant star. It will then shed its outer layers and end its life as a white dwarf star. Mercury, Venus, and possibly the Earth will be destroyed by the red giant. However, the fate of the more distant planets, particularly the gas giants, is unclear. Finding and studying planets in orbit around the remnants of Sun-like stars after their death is a means of learning what might happen in our own solar system in the far future.
“We’re used to looking back in time when we use telescopes, but this is the first time we have been able to look forward to what might happen to the outer planets around the remnant of a Sun-like star,” said MacDonald. “It’s like using a time machine to peer into the distant future of our solar system.”
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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Related Images & Videos
Exoplanet WD 1856 b (Artist’s Concept)
Exoplanet WD 1856 b, shown in this artist’s concept, is a gas giant that orbits its star at a distance 50 times closer than Earth orbits the Sun. Observations by NASA’s James Webb Space Telescope determined the planet’s temperature and detected molecules in its atmosphere.
Exoplanet WD 1856 b (Transmission Spectrum)
NASA’s James Webb Space Telescope measured the constituents of exoplanet WD 1856 b as it passed in front of its star, finding signs of methane. WD 1856 b orbits a white dwarf star the size of Earth. As a result, the planet blocks more than half of the star’s light.
