Space & Science

NASA astronaut Zena Cardman processes bone cell samples inside the Kibo laboratory module’s Life Science Glovebox on Aug. 28, 2025, as part of an experiment that tests how microgravity affects bone-forming and bone-degrading cells and explore potential ways to prevent bone loss. This research could help protect astronauts on future long-duration missions to the Moon and Mars, while also advancing treatments for millions of people on Earth who suffer from osteoporosis.
Image credit: NASA/Jonny Kim

NASA is sending more science, technology demonstrations, and crew supplies to the International Space Station following the successful launch of the agency’s Northrop Grumman Commercial Resupply Services 23 mission, or Northrop Grumman CRS-23.
The company’s Cygnus XL spacecraft, carrying more than 11,000 pounds of cargo to the orbiting laboratory, lifted off at 6:11 p.m. EDT Sunday on a SpaceX Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida. This mission is the first flight of the larger, more cargo-capable version of the solar-powered spacecraft. 
Cygnus XL is scheduled to be captured at 6:35 a.m. on Wednesday, Sept. 17, by the Canadarm2 robotic arm, which NASA astronaut Jonny Kim will operate with assistance from NASA astronaut Zena Cardman. Following capture, the spacecraft will be installed to the Unity module’s Earth-facing port for cargo unloading.
The resupply mission is carrying dozens of research experiments that will be conducted during Expedition 73, including materials to produce semiconductor crystals in space and equipment to develop improvements for cryogenic fuel tanks. The spacecraft also will deliver a specialized UV light system to prevent the growth of microbe communities that form in water systems and supplies to produce pharmaceutical crystals that could treat cancer and other diseases.
These are just a sample of the hundreds of scientific investigations conducted aboard the station in the areas of biology and biotechnology, Earth and space science, physical sciences, as well as technology development and demonstrations. For nearly 25 years, NASA has supported a continuous U.S. human presence aboard the orbiting laboratory, where astronauts have learned to live and work in space for extended periods of time. The space station is a springboard for developing a low Earth economy and NASA’s next great leaps in exploration, including Artemis missions to the Moon and American astronaut missions to Mars.
NASA’s arrival, capture, and installation coverage are as follows (all times Eastern and subject to change based on real-time operations):
Wednesday, Sept. 17
5 a.m. – Arrival coverage begins on NASA+, Amazon Prime, and more.
6:35 a.m. – Capture of Cygnus XL with the space station’s robotic arm.
8 a.m. – Installation coverage begins on NASA+, Amazon Prime, and more.
All coverage times are estimates and could be adjusted based on operations after launch. Follow the space station blog for the most up-to-date information.
Cygnus XL is scheduled to remain at the orbiting laboratory until March 2026, before it departs and disposes of several thousand pounds of trash through its re-entry into Earth’s atmosphere, where it will harmlessly burn up. The spacecraft is named the S.S. William “Willie” C. McCool, in honor of the NASA astronaut who perished in 2003 during the space shuttle Columbia accident.
Learn more about this NASA commercial resupply mission at:
https://www.nasa.gov/mission/nasas-northrop-grumman-crs-23/
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Josh Finch / Jimi RussellHeadquarters, Washington202-358-1100joshua.a.finch@nasa.gov / james.j.russell@nasa.gov
Steven SiceloffKennedy Space Center, Fla.321-876-2468steven.p.siceloff@nasa.gov
Sandra Jones / Joseph ZakrzewskiJohnson Space Center, Houston281-483-5111sandra.p.jones@nasa.gov / joseph.a.zakrzewski@nasa.gov

NASA’s Northrop Grumman Commercial Resupply Services 23, or Northrop Grumman CRS-23, will deliver more than 11,000 pounds of science and supplies to the International Space Station. This mission will be the first flight of the Cygnus XL, the larger, more cargo-capable version of the company’s solar-powered spacecraft.

The Cygnus XL will launch on a SpaceX Falcon 9 rocket from the Cape Canaveral Space Force Station in Florida.  Following arrival, astronauts aboard the space station will use the Canadarm2 to grapple Cygnus XL before robotically installing the spacecraft to the Unity module’s Earth-facing port for cargo unloading. Stream live launch and arrival coverage on NASA+, Amazon Prime, YouTube.

IDA Planar Reflector – This is a reflective element used by visiting spacecraft during docking. The spacecraft bounces a laser off the reflector to compute relative range, velocity, and attitude on approach to the International Space Station. Due to degradation found on the installed reflector, this unit will launch to support a future spacewalk to replace the damaged reflector.

Urine Processing Assembly (UPA) Distillation Assembly – The urine processor on the space station uses filtration and distillation to separate water from wastewater to produce potable water. This unit is launching as a spare.

Reactor Health Sensor – Part of the Environmental Control and Life Support System – Water Processing Assembly, includes two sensors with inlet and outlet ports to measure reactor health. This unit is being launched as a spare.

Pressure Management Device – This is an intravehicular activity system for performing pressurization and depressurization of the space station vestibules between the space station hatch and the hatch of a visiting spacecraft or other module, like the NanoRacks Airlock. During depressurization, most of the air will be added to the space station cabin air to save the valuable resource.

Air Selector Valve – This electro-mechanical assembly is used to direct airflow through the Carbon Dioxide Removal Assembly. Two units are launching as spares.

Major Constituent Analyzer Mass Spectrometer Assembly – This assembly monitors the partial pressure levels of nitrogen, oxygen, hydrogen, methane, water vapor, and carbon dioxide aboard station. This unit is launching as a contingency spare.

Major Constituent Analyzer Mass Sample/Series Pump Assembly – This contains plumbing and a pair of solenoid valves to direct sample gas flow to either of the redundant sample pumps. It draws sample gas from the space station’s atmosphere into the analyzer. This unit is launching as a contingency spare.

Major Constituent Analyzer Sample Distribution Assembly – This isolates the gas sample going to the Mass Spectrometer Assembly. The purpose is to distribute gas samples throughout the analyzer. This unit is launching as a contingency spare.

Charcoal Bed – The bed allows the Trace Contaminant Control System to remove high molecular weight contaminants from the station’s atmosphere. This unit is launching as a spare.

Common Cabin Air Assembly Heat Exchanger – This assembly controls cabin air temperature, humidity, and airflow aboard the space station. This unit is launching as a spare.

Sequential Shunt Unit – This regulates the solar array wing voltage when experiencing high levels of direct sunlight; in doing so, it provides usable power to the station’s primary power system. This unit is launching as a spare.

Solid State Lighting Assembly – This is a specialized internal lighting assembly aboard station. NASA will use one lighting assembly to replace a failed unit and will keep the others as spares.

Remote Power Control Module Type V – This module distributes 120V/DC electrical power and provides current-limiting and fault protection to secondary loads aboard the orbiting laboratory. This module is launching as a spare.

Treadmill Isolator Assembly – The Upper, X, Y, and Z Isolator Assemblies are launching as spares for the space station’s treadmill, where they work together to reduce vibration and force transfer when astronauts are running.

Pump Fan Motor Controller – The controller is an electronic controller to modulate the power to the motor windings, which are coils of conductive wire that are wrapped around its core carrying electric current to drive the motor. Windings are commonly used in household appliances, cars (power steering), pumps, and more.

Quick Don Mask Assembly – This mask is used by the crew, along with the Pre-Breath Assembly, in emergency situations. This unit is launching to replace a unit aboard station.

Anomaly Gas Analyzer – This analyzer senses various gases, like oxygen, carbon dioxide, carbon monoxide, ammonia, and others, along with cabin pressure, water vapor and temperature. Two units are launching as an upgrade to the current analyzer system used on board.

Nitrogen, Oxygen Resupply Maintenance Kit – One tank of nitrogen and one tank of oxygen used for gas replenishment aboard the space station are launching to maintain gas reserves.

Crew and Equipment Translation Aid Luminaire – This is a lighting unit used aboard station to illuminate the astronauts’ equipment cart and surrounding work areas during spacewalks.

Space missions rely on cryogenic fluids — extremely cold liquids like liquid hydrogen and oxygen — for both propulsion and life support systems. These fuels must be kept at ultra-low cryogenic temperatures to remain in liquid form; however, solar heating and other sources of heat increase the rate of evaporation of the liquid and cause the pressure in the storage tank to increase. Current storage methods require venting the cryogenic propellant to space to control the pressure in fuel tanks.

NASA’s Zero Boil-Off Tank Noncondensables (ZBOT-NC) experiment is the continuation of Zero Boil-Off studies gathering crucial data to optimize fuel storage systems for space missions. The experiment will launch aboard Northrop Grumman’s 23rd resupply mission to the International Space Station.

Even with multilayer insulation, heat unavoidably seeps into cryogenic fuel tanks from surrounding structures and the space environment, causing an increase in the liquid temperature and an associated increase in the evaporation rate. In turn, the pressure inside the tank increases. This process is called “boil-off” and the increase in tank pressure is referred to as “self-pressurization.”

Venting excess gas to the environment or space when this process occurs is highly undesirable and becomes mission-critical on extended journeys. If crew members used current fuel storage methods for a years-long Mars expedition, all propellant might be lost to boil-off before the trip ends.

NASA’s ZBOT experiments are investigating active pressure control methods to eliminate wasteful fuel venting. Specifically, active control through the use of jet mixing and other techniques are being evaluated and tested in the ZBOT series of experiments.

ZBOT-NC further studies how noncondensable gases (NCGs) affect fuel tank behavior when present in spacecraft systems. NCGs don’t turn into liquid under the tank’s operating conditions and can affect tank pressure.

The investigation, which is led out of Glenn Research Center, will operate inside the Microgravity Science Glovebox aboard the space station to gather data on how NCGs affect volatile liquid behavior in microgravity. It’s part of an effort to advance cryogenic fluid management technologies and help NASA better understand low-gravity fluid behavior.

Researchers will measure pressure and temperature as they study how these gases change evaporation and condensation rates. Previous studies indicate the gases create barriers that could reduce a tank’s ability to maintain proper pressure control — a potentially serious issue for extended space missions.

The research directly supports Mars missions and other long-duration space travel by helping engineers design more efficient fuel storage systems and future space depots. The findings may also benefit scientific instruments on space telescopes and probes that rely on cryogenic fluids to maintain the extremely low temperatures needed for operation.

The investigation could improve tank design models for medical, industrial, and energy production applications that depend on long-term cryogenic storage on Earth.

Space changes you. It strengthens some muscles, weakens others, shifts fluids within your body, and realigns your sense of balance. NASA’s Human Research Program works to understand—and sometimes even counter—those changes so astronauts can thrive on future deep space missions.  Astronauts aboard the International Space Station work out roughly two hours a day to protect bone density, muscle strength and the cardiovascular system, but the longer they are in microgravity, the harder it can be for the brain and body to readapt to gravity’s pull. After months in orbit, returning astronauts often describe Earth as heavy, loud, and strangely still. Some reacclimate within days, while other astronauts take longer to fully recover.
Adjusting to Gravity  

The crew of NASA’s SpaceX Crew-7 mission— NASA astronaut Jasmin Moghbeli, ESA (European Space Agency) astronaut Andreas Mogensen, JAXA (Japan Aerospace Exploration Agency) astronaut Satoshi Furukawa, and Roscosmos cosmonaut Konstantin Borisov—landed in March 2024 after nearly 200 days in space. One of the first tests volunteer crew members completed was walking with their eyes open and then closed.  
“With eyes closed, it was almost impossible to walk in a straight line,” Mogensen said. In space, vision is the primary way astronauts orient themselves, but back on Earth, the brain must relearn how to use inner-ear balance signals. Moghbeli joked her first attempt at the exercise looked like “a nice tap dance.”   
“I felt very wobbly for the first two days,” Moghbeli said. “My neck was very tired from holding up my head.” She added that, overall, her body readapted to gravity quickly.  
Astronauts each recover on their own timetable and may encounter different challenges. Mogensen said his coordination took time to return. Furukawa noted that he could not look down without feeling nauseated. “Day by day, I recovered and got more stable,” he said. 

NASA astronaut Loral O’Hara returned in April 2024 after 204 days in space. She said she felt almost completely back to normal a week after returning to Earth. O’Hara added that her prior experience as an ocean engineer gave her insight into space missions. “Having those small teams in the field working with a team somewhere else back on shore with more resources is a good analog for the space station and all the missions we’re hoping to do in the future,” she said. 
NASA astronaut Nichole Ayers, who flew her first space mission with NASA’s SpaceX Crew-10, noted that the brain quickly adapts to weightlessness by tuning out the vestibular system, which controls balance. “Then, within days of being back on Earth, it remembers again—it’s amazing how fast the body readjusts,” she said. 

When NASA astronaut Frank Rubio landed in Kazakhstan in September 2023, he had just completed a record 371-day mission—the longest single U.S. spaceflight.  
Rubio said his body adjusted to gravity right away, though his feet and lower back were sore after more than a year without weight on them. Thanks to consistent workouts, Rubio said he felt mostly recovered within a couple of weeks.  
Mentally, extending his mission from six months to a year was a challenge. “It was a mixed emotional roller coaster,” he said, but regular video calls with family kept him grounded. “It was almost overwhelming how much love and support we received.” 
Crew-8 astronauts Matt Dominick, Jeanette Epps, Michael Barratt, and cosmonaut Alexander Grebenkin splashed down in October 2024 after 235 days on station. Dominick found sitting on hard surfaces uncomfortable at first. Epps felt the heaviness of Earth immediately. “You have to move and exercise every day, regardless of how exhausted you feel,” she said.  
Barratt, veteran astronaut and board certified in internal and aerospace medicine, explained that recovery differs for each crew member, and that every return teaches NASA something new. 
Still a Challenge, Even for Space Veterans  

Veteran NASA astronauts Suni Williams and Butch Wilmore returned from a nine-month mission with Crew-9 in early 2025. Despite her extensive spaceflight experience, Williams said re-adapting to gravity can still be tough. “The weight and heaviness of things is surprising,” she said. Like others, she pushed herself to move daily to regain strength and balance.  

NASA astronaut Don Pettit, also a veteran flyer, came home in April 2025 after 220 days on the space station. At 70 years old, he is NASA’s oldest active astronaut—but experience did not make gravity gentler.  During landing, he says he was kept busy, “emptying the contents of my stomach onto the steppes of Kazakhstan.” Microgravity had eased the aches in his joints and muscles, but Earth’s pull brought them back all at once.  
Pettit said his recovery felt similar to earlier missions. “I still feel like a little kid inside,” he said. The hardest part, he explained, isn’t regaining strength in big muscle groups, but retraining the small, often-overlooked muscles unused in space. “It’s a learning process to get used to gravity again.”  
Recovery happens day by day—with help from exercise, support systems, and a little humor. No matter how long an astronaut is in space, every journey back to Earth is unique. 
The Human Research Program help scientists understand how spaceflight environments affect astronaut health and performance and informs strategies to keep crews healthy for future missions to the Moon, Mars, and beyond. The program studies astronauts before, during, and after spaceflight to learn how the human body adapts to living and working in space. It also collects data through Earth-based analog missions that can help keep astronauts safer for future space exploration.  
To learn more about how microgravity affects the human body and develop new ways to help astronauts stay healthy, for example, its scientists conduct bedrest studies – asking dozens of volunteers to spend 60 days in bed with their heads tilted down at a specific angle.  Lying in this position tricks the body into responding as it would if the body was in space which allows scientists to trial interventions to hopefully counter some of microgravity’s effects.  Such studies, through led by NASA, occur at the German Aerospace Center’s Cologne campus at a facility called :envihab – a combination of “environment” and “habitat.”  
Additional Earth-based insights come from the Crew Health and Performance Exploration Analog (CHAPEA) and the Human Exploration Research Analog (HERA) at NASA’s Johnson Space Center in Houston. Both analogs recreate the remote conditions and scenarios of deep space exploration here on Earth with volunteer crews who agree to live and work in the isolation of ground-based habitats and endure challenges like delayed communication that simulates the type of interactions that will occur during deep space journeys to and from Mars. Findings from these ground-based missions and others will help NASA refine its future interventions, strategies, and protocols for astronauts in space. 
NASA and its partners have supported humans continuously living and working in space since November 2000. After nearly 25 years of continuous human presence, the space station remains the sole space-based proving ground for training and research for deep space missions, enabling NASA’s Artemis campaign, lunar exploration, and future Mars missions.