NASA astronaut Chris Williams and Roscosmos cosmonauts Sergey Kud-Sverchkov and Sergei Mikaev are wrapping up their 241‑day mission aboard the International Space Station.

The crew and its Soyuz MS-28 spacecraft will undock from the orbiting laboratory’s Rassvet module at 3:02 a.m. EDT Sunday, July 26, heading for a parachute-assisted landing at 6:26 a.m. (3:26 p.m. local time) on the steppe of Kazakhstan, southeast of Dzhezkazgan.

NASA’s live return coverage will stream through a variety of platforms. Learn where to watch online:

https://www.nasa.gov/live

Williams and his crewmates will complete 3,856 orbits and travel more than 102 million miles before returning to Earth. The flight marks the first mission for Williams and Mikaev and the second for Kud‑Sverchkov.

After landing, the crew will fly by helicopter to Karaganda, Kazakhstan, where recovery teams are based. Williams then will return to NASA’s Johnson Space Center in Houston, while Kud‑Sverchkov and Mikaev head back to their training base in Star City, Russia.

NASA’s live return coverage is as follows (all times Eastern and subject to change based on real-time operations):

Saturday, July 25

9:40 a.m. – Coverage of the Space Station Expedition 74/75 change of command ceremony begins.

Kud‑Sverchkov will transfer command of the orbital complex to NASA astronaut Jessica Meir. Expedition 75 officially begins when Soyuz MS‑28 undocks.

11:10 p.m. – Coverage of crew farewells and hatch closing begins.

11:30 p.m. – Hatch closing

Sunday, July 26

2:30 a.m. – Coverage of undocking begins.

3:02 a.m. – Undocking

5:15 a.m. – Coverage of deorbit and landing begins.

5:32 a.m. – Deorbit burn

6:26 a.m. – Landing

For more than 25 years, people have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and making research breakthroughs not possible on Earth. The space station helps NASA understand and overcome the challenges of human spaceflight, expand commercial opportunities in low Earth orbit, and build on the foundation for long-duration missions to the Moon, as part of the Artemis program, and to Mars.

To learn more about International Space Station research, operations, and its crews, visit:

www.nasa.gov/station

-end-

Joshua Finch / Jimi Russell
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov / james.j.russell@nasa.gov

Leah Cheshier / Anna Schneider
Johnson Space Center, Houston
281-483-5111
leah.d.cheshier@nasa.gov / anna.c.schneider@nasa.gov

Background

Human exploration of Mars will expose crews to a persistent, fine particulate environment whose physicochemical properties and health implications remain only partly understood. Because no samples of authentic Martian airborne dust have been returned to Earth, NASA must rely on lunar dust toxicology, Martian regolith simulants, and extensive rover/lander geochemical and mineralogical datasets to develop an initial, risk‑informed Permissible Exposure Limit (PEL). The Johnson Space Center (JSC) Lunar and Martian Dust Risk Custodian, the JSC Toxicology group, and the OCHMO Standards team worked together to draft a preliminary standard for incorporation into NASA-STD-3001 NASA Spaceflight Human-System Standard, Volume 2: Human Factors, Habitability, and Environmental Health.

The Martian Dust Limit Working Group was assembled to review this draft standard and associated evidence. Across two working sessions in February 2026, panel members reviewed mission architecture drivers, the current scientific understanding of Martian dust composition, and the toxicological evidence base supporting the establishment of a Mars dust PEL. Discussions emphasized the critical interplay between dust standards and Mars mission design elements including Extravehicular Activity (EVA) cadence, dust ingress characteristics, and the performance of habitat environmental control systems; these features highlight the need for a limit that is conservative, verifiable, and adaptable as the Mars architecture evolves. Panel members for the Working Group were David Damby, Claire Horwell, Brian Hynek, Shaunna Morrison, and Joyce Tsuji; NASA presenters were Katie Borremans, Elizabeth Rampe, and Torin McCoy; the OCHMO organizers/moderators were Douglas Ebert, David Francisco, and Kim Lowe. The Working Group meetings were also attended by members of Space Medicine and Operations group and JSC Toxicology.

The Martian Dust Limit Working Group Primary Goals

Evaluate NASA’s proposed derivation of this initial standard

The panel concluded that NASA’s approach to deriving a 30‑day continuous PEL of 0.1 mg/m³ is reasonable and appropriately conservative for early short‑stay missions. This value originates from the established lunar 30‑day PEL (0.4 mg/m³), reduced by a 3x database uncertainty factor to account for knowledge gaps in Martian dust toxicity, higher iron content, amorphous constituents, and differences between simulants and actual dust. Members supported this framework, noting that a continuous limit applied using measured time‑weighted averages is more practical than making assumptions tied to fixed dust clearance rates given the diversity of spacecraft designs. They also acknowledged that near‑term exposures will be peak‑driven (e.g., post‑EVA suit ingress) and therefore recommended that the standard explicitly address the need to manage short‑duration spikes.

Identify chemical constituents requiring further scrutiny

The panel affirmed that overall dust mass remains the primary near‑term engineering concern, but several chemical constituents warrant attention. Chromium 6⁺, manganese, and perchlorate were all considered low‑risk in the context of inhaled Martian dust, provided the overall dust PEL is applied (see below). However, perchlorate was recommended for broader agency‑level exposure management across multiple intake routes (e.g., ingestion due to in situ crop growth). Iron was discussed in detail due to its high abundance in Martian regolith and its potential to generate Reactive Oxygen Species (ROS), though current toxicology shows no clear link between iron‑driven ROS and pulmonary harm; still, knowledge gaps led the panel to prioritize iron for further study and potential Spacecraft Maximum Allowable Concentration (SMAC) development. Arsenic was judged unlikely to pose meaningful risk at present.

Weigh the merits of an overall dust limit versus separate SMACs

Chemical constituents embedded within Martian dust were evaluated with respect to whether independent SMACs are warranted. Based on rover observations indicating predominantly trivalent chromium, low airborne perchlorate, and manganese concentrations well below conservative SMAC thresholds at the proposed PEL, the group agreed that the overall dust limit is likely sufficiently protective for expected 30‑day missions. However, panel members advised that SMACs be maintained for select constituents such as perchlorate and manganese for mission‑planning crosschecks. From the requirement perspective, an overall Martian dust PEL approach was favored for practicality and clarity, with constituent-specific SMACs retained or developed only where they add tangible operational value.

Refine the standard’s technical language for operational use

The working group also refined the standard language to ensure clarity and consistency in implementation. Members recommended that the limit apply to a specified time‑weighted average measurement period but also making it explicit that the requirement is for protection during continuous exposure. They encouraged incorporation of peak‑exposure management within the rationale, and highlighted uncertainties related to iron content, nanophase iron, and oxidative potential so that future revisions can incorporate emerging scientific insight.

Martian Dust Contamination Limits

The new requirement established for NASA-STD-3001 is as follows:

[V2 6253] The system shall limit the concentrations of Martian dust particles less than 10 μm in size in the habitable atmosphere below a 24-hour time-weighted average of 0.1 mg/m3 during exposure scenarios lasting up to 30 days in duration.

Conclusions

Taken together, the working group’s deliberations reinforce that an initial Martian dust standard must balance conservatism with operational feasibility while accommodating architectural and scientific uncertainty. The proposed requirement provides a defensible, evidence‑informed foundation for design, verification, and risk communication. As additional Martian data and toxicological research become available, this standard should be periodically revisited to ensure continued protection of crew health during human exploration of Mars.

For more information on the results of the working group, see link to the special publication below:

NASA and its partners will discuss the upcoming crew rotation mission to the International Space Station during a pair of news conferences on Monday, Aug. 3, from the agency’s Johnson Space Center in Houston.

Mission leadership will provide an overview of NASA’s SpaceX Crew‑13 mission at 12 p.m. EDT. Next, crew members will discuss their training and mission preparations at 2 p.m. This is Crew-13’s final media availability prior to traveling to the agency’s Kennedy Space Center in Florida for launch.

NASA will stream these events live. Learn where to watch online:

https://www.nasa.gov/live

The Crew-13 mission will carry NASA astronauts Jessica Watkins and Luke Delaney, CSA (Canadian Space Agency) astronaut Joshua Kutryk, and Roscosmos cosmonaut Sergey Teteryatnikov to the orbiting laboratory. The crew will launch aboard a SpaceX Dragon spacecraft on the company’s Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida no earlier than mid-September.

International media attending in person must email the NASA Johnson newsroom at jsccommu@mail.nasa.gov by 5 p.m., Tuesday, July 21. United States-based media attending in person must respond by 5 p.m., Thursday, July 30. Media joining virtually must respond by 10 a.m. the day of the event. NASA’s media accreditation policy is available online.

Briefing participants are as follows (all times Eastern and subject to change based on real-time operations):

12 p.m.: Mission Overview News Conference

• Joel Montalbano, deputy associate administrator, Human Spaceflight Mission Directorate, NASA Headquarters
• Dana Weigel, manager, Low Earth Orbit Program, NASA Johnson
• Mathieu Caron, director, Astronauts, Life Sciences, and Space Medicine, CSA
• Julianna Scheiman, director, NASA Science and Dragon Programs, SpaceX

2 p.m.: Crew-13 News Conference

• Jessica Watkins, commander, NASA
• Luke Delaney, pilot, NASA
• Joshua Kutryk, mission specialist, CSA
• Sergey Teteryatnikov, mission specialist, Roscosmos

Following the news conference, crew members will be available for limited media interviews. All interview requests must be submitted by 5 p.m. on July 30, to the NASA Johnson newsroom at: jsccommu@mail.nasa.gov.

This will be the second flight to the space station for Watkins, who was selected as a NASA astronaut in 2017. Watkins grew up in Lafayette, Colorado, and earned an undergraduate degree in geological and environmental sciences from Stanford University, as well as a doctorate in geology from the University of California, Los Angeles. As a geologist, she studied the Martian surface and was a member of the Curiosity rover science team at NASA’s Jet Propulsion Laboratory in Southern California. Watkins first launched to the space station as a crew member aboard NASA’s SpaceX Crew-4 mission, spending a total of 170 days in space across space station Expeditions 67/68 in 2022. She will be the first NASA astronaut to launch aboard a SpaceX Dragon spacecraft twice.

Selected as a NASA astronaut in 2021, Delaney earned a bachelor’s degree in mechanical engineering at the University of North Florida and a master’s degree in aerospace engineering at the Naval Postgraduate School. The Florida native is a distinguished naval aviator who participated in exercises throughout the Asia Pacific region and conducted missions in support of Operation Enduring Freedom. As a test pilot, Delaney evaluated developmental aircraft systems and served as a test pilot instructor. He also worked as a research pilot at NASA’s Langley Research Center in Hampton, Virginia, where he supported airborne science missions. This is the first spaceflight for Delaney.

The Crew-13 mission also is the first spaceflight for Kutryk. Prior to his selection as a CSA astronaut in 2017, he served as a CF-18 fighter pilot, flying missions in support of Canada’s NATO, U.N., and North American Aerospace Defense Command commitments. A native of Fort Saskatchewan, Alberta, Kutryk also worked as an experimental and operational test pilot at the Aerospace Engineering Test Establishment in Cold Lake, Alberta. Kutryk received a bachelor’s degree in mechanical engineering from the Royal Military College of Canada in Kingston, Ontario, and he is a distinguished graduate of the United States Air Force Test Pilot school in Edwards, California. He has master’s degrees in space studies, flight test engineering, and defense studies.

This mission will be Teteryatnikov’s first trip to the orbiting laboratory. He graduated from the Naval Academy, St. Petersburg, Russia, in 2011 as an engineer specializing in ship power plant operations. Before his selection as a test cosmonaut, Teteryatnikov served in various naval engineering roles, including undersea vessels and specialized engine room operations. He was selected for the Gagarin Research and Test Cosmonaut Training Center Cosmonaut Corps in 2021 and has served as a test cosmonaut since 2023.

For more information about the mission, visit:

https://www.nasa.gov/mission/nasas-spacex-crew-13

-end-

Joshua Finch / Jimi Russell
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov / james.j.russell@nasa.gov

Leah Cheshier / Anna Schneider
Johnson Space Center, Houston
281-483-5111
leah.d.cheshier@nasa.gov / anna.c.schneider@nasa.gov

In April 2026, NASA’s Office of the Chief Health and Medical Officer (OCHMO) initiated a working group to review updated VTE case information, additional data gathered revealing altered blood flow status within a cohort of astronauts, and discuss progress of research and clinical activities intended to mitigate the risk of VTE during spaceflight with new evidence-based clinical practice recommendations.

Recommendations

The following is a summary of the working group’s recommendations:

• The working group’s conclusions emphasized that stasis in the left internal jugular vein (IJV) is consistently viewed as a dominant risk factor for VTE in microgravity, though there is active debate regarding the relative contributions of slow qualitative flow, endothelial factors and/or retrograde flow.
• Limitations of current in-flight ultrasound capabilities to accurately measure stasis/slow flow was cited as a concern, especially if using only stasis as a factor for indicating the need for prophylaxis.
• Additional review of assessing stasis with ultrasound in-flight was recommended.
• After reviewing the risk factors, additional discussions following the working group led to the majority of the panel agreeing that stasis and retrograde flow warranted use of prophylaxis.
• The working group also recommended assessing all other risk factors other than stasis to also determine when prophylaxis is warranted.
• Based on a literature review and summary of the panel contributions, a VTE Risk Score for Astronauts Algorithm was developed, which includes providing anticoagulation prophylaxis for stasis alone, or a combination of other thrombosis risk factors that are weighted by terrestrial literature.

Risk of Venous Thromboembolism During Spaceflight

NASA initially formed a working group in October 2024 after diagnosing venous thromboembolisms (VTEs) in astronauts during ISS missions. Experts reviewed case data, updated Clinical Practice Guidelines, and examined possible causes.

NASA astronaut Anil Menon, along with Roscosmos cosmonauts Pyotr Dubrov and Anna Kikina, arrived safely at the International Space Station Tuesday, bringing the orbiting laboratory’s crew to 10 for about the next two weeks.

The trio launched aboard the Soyuz MS-29 spacecraft at 10:47 a.m. EDT (7:47 p.m. local time) from the Baikonur Cosmodrome in Kazakhstan. After a three-hour, two-orbit journey, the spacecraft docked at 1:52 p.m. with the station’s Prichal module.

Following hatch opening, expected about 4 p.m., the new arrivals will be welcomed by the space station Expedition 74 crew: NASA astronauts Jessica Meir, Jack Hathaway, and Chris Williams; ESA (European Space Agency) astronaut Sophie Adenot; and Roscosmos cosmonauts Sergey Kud-Sverchkov, Sergei Mikaev, and Andrey Fedyaev.

NASA’s live coverage of hatch opening begins at 3:30 p.m. on NASA+, Amazon Prime, and YouTube. Learn how to watch NASA content through a variety of online platforms, including social media.

During his stay aboard the station, Menon will conduct scientific research and technology demonstrations aimed at advancing human space exploration and benefiting life on Earth. He will continue research to refine in-space production of semiconductor crystals to enable the large-scale manufacturing of components needed for high-performance computers, artificial intelligence, and improved medical devices. Menon also will perform ultrasound using augmented reality and artificial intelligence methods that could eliminate the need for medical support from Earth on future space missions. He will be a test subject helping researchers understand how blood flow is affected in space to protect future astronauts. He also will test bioprinting vascular constructs in microgravity to improve understanding of the aging process to advance therapeutic developments.

Expedition 75 is scheduled to begin on Sunday, July 26, following the departure of Williams, Kud-Sverchkov, and Mikaev, as they conclude an eight-month science mission aboard the orbital outpost.

Watch the change of command ceremony at 9:40 a.m. on Saturday, July 25, as station command transfers from Kud-Sverchkov to Meir, live on NASA+.

Learn more about International Space Station, crews, research, and operations at:

https://www.nasa.gov/station

-end-

Joshua Finch / Jimi Russell
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov / james.j.russell@nasa.gov

Sandra Jones
Johnson Space Center, Houston
281-483-5111
sandra.p.jones@nasa.gov

NASA astronaut Anil Menon will launch aboard the Roscosmos Soyuz MS-29 spacecraft to the International Space Station on Tuesday, July 14, accompanied by cosmonauts Pyotr Dubrov and Anna Kikina, where they will join the Expedition 74 crew advancing scientific research.

Menon, Dubrov, and Kikina will lift off at 10:47 a.m. EDT (7:47 p.m. Baikonur time) from the Baikonur Cosmodrome in Kazakhstan. Live launch and docking coverage is available on NASA+, Amazon Prime, and the agency’s YouTube channel. Learn how to watch NASA content through a variety of online platforms, including social media.

After a two-orbit, three-hour trip to the station, the spacecraft will automatically dock at 1:56 p.m. to the Prichal module. Shortly afterward, hatches will open between the Soyuz and the orbiting laboratory.

Once aboard, the trio will join NASA astronauts Jessica Meir, Jack Hathaway, and Chris Williams, ESA (European Space Agency) astronaut Sophie Adenot, and Roscosmos cosmonauts Sergey Kud-Sverchkov, Sergei Mikaev, and Andrey Fedyaev.

NASA’s coverage schedule is as follows (all times Eastern and subject to change based on real-time operations):

Tuesday, July 14

9:45 a.m. – Launch coverage begins on NASA+, Amazon Prime, and YouTube.

10:47 a.m. – Launch

1:10 p.m. – Rendezvous and docking coverage begins on NASA+, Amazon Prime, and YouTube.

1:56 p.m. – Docking

3:30 p.m. – Hatch opening and welcome coverage begins on NASA+, Amazon Prime, and YouTube.

3:55 p.m. – Hatch opening

Menon, Dubrov, and Kikina will spend about eight months aboard the orbital complex as International Space Station Expedition 74/75 crew members before returning to Earth in April 2027. This will be Menon’s first spaceflight and the second for both Dubrov and Kikina.

During his stay on the station, Menon will conduct scientific research and technology demonstrations aimed at advancing human space exploration and benefiting life on Earth. He will continue research to refine in-space production of semiconductor crystals to enable the large-scale manufacturing of components needed for high-performance computers, artificial intelligence, and improved medical devices. Menon also will perform ultrasound using augmented reality and artificial intelligence methods that could eliminate the need for medical support from Earth on future space missions. He will be a test subject helping researchers understand how blood flow is affected in space to protect future astronauts. He also will test bioprinting vascular constructs in microgravity to improve understanding of the aging process to advance therapeutic developments.   

For more than 25 years, people have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and making research breakthroughs not possible on Earth. The space station helps NASA understand and overcome the challenges of human spaceflight, expand commercial opportunities in low Earth orbit, and build on the foundation for long-duration missions to the Moon, as part of the Artemis program, and to Mars.

To learn more about International Space Station research, operations, and its crews, visit:

www.nasa.gov/station

-end-

Joshua Finch / Jimi Russell
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov / james.j.russell@nasa.gov

Sandra Jones
Johnson Space Center, Houston
281-483-5111
sandra.p.jones@nasa.gov

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.
 
To apply, visit:

 NASA Analogs Recruiting

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:

https://www.nasa.gov/hrp/