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Expedition 73 aboard the International Space Station (ISS) continues to perform its scheduled science and maintenance activities on humanity’s premier orbiting outpost, now more than a quarter-century old. The Station has a new commander and a new set of crew members on the U.S. side of the complex, as four astronauts departed this week to conclude their tour of duty on board ISS.
The Crew-11 mission successfully launched on Friday, Aug. 1, at 11:43 AM EDT (15:43 UTC) and docked just over 14 hours later on Saturday, Aug. 2, at 06:26 UTC. Crew Dragon Endeavour set a new record for the shortest time from launch to docking; previous Crew Dragon missions to ISS typically took around 19 hours to dock with the Station after launch.
After Endeavour docked to the zenith port on the Station’s Harmony node module, the ISS temporarily hosted 11 crew members. Crew-11’s astronauts settled into life aboard the orbiting outpost while also being assisted by Crew-10’s members, who were “handing the baton” to Crew-11’s Zena Cardman, Michael Fincke, Kimiya Yui, and Oleg Platonov.
Sergey Ryzhikov (L) and Takuya Onishi (R) shaking hands during the ISS change of command ceremony. (Credit: NASA)
During the joint operations period, Station commander Takuya Onishi handed off his command responsibility to Roscosmos’ Sergey Ryzhikov. Ryzhikov will command ISS and the Expedition 73 crew until December, when he and his Soyuz MS-27 crewmates leave the Station and return to Earth, while Onishi returns to Earth after becoming the third Japanese to command ISS.
Crew-10’s Anne McClain, Nichole Ayers, Takuya Onishi, and Kirill Peskov boarded Crew Dragon Endurance and undocked from the Station on Friday, Aug. 8 at 22:15 UTC before splashing down off the southern California coast on Saturday, Aug. 9 at 8:33 AM PDT (15:33 UTC). They returned to Earth with critical science samples aboard the Polar mobile cold storage locker.
During their stay on ISS, Crew-10’s astronauts worked on many experiments, including studies on physical and mental change in astronauts during spaceflight and blood flow from the brain to the heart in microgravity. ISS crews stay on the Station for up to six months or so at a time, enabling a large database of how astronauts adapt to spaceflight.
Takuya Onishi in the Kibo module with the JEM Internal Ball Camera 2. (Credit: NASA)
Their science program also included studies on future lunar navigation techniques, various plant and seed experiments, investigations into how cells sense gravity, crystallization research, and tests on robots that could free astronauts from performing certain tasks, among other projects.
Crew-11 also has an extensive science program to look forward to. Highlights of Crew-11’s science program include a study on producing stem cells in microgravity, work on a potential alternative to antibiotics, an experiment to produce nutrients that can remain viable for years in the space environment, and a Japanese plant cell division experiment using tobacco cells and green algae.
Crew-11’s astronauts also may be tasked with a spacewalk on the U.S. segment that Crew-10 did not do. Crew-10 astronauts McClain and Ayers conducted EVA-93. On May 1, they worked on installing a modification kit for new solar arrays as well as an antenna relocation. The modification kit installation was not completed and was set aside for the next spacewalk, EVA-94.
Astronaut Anne McClain during EVA-93. (Credit: NASA)
However, EVA-94 has not yet been conducted, and will be left for a future crew, very possibly for the Crew-11 astronauts. Whenever this spacewalk takes place, the astronauts will be tasked with completing the solar array medication kit installation on the P4 truss at the 2A location, as well as several other tasks.
Besides the change of command, the crew handover, and the return of Crew-10 to Earth that have already happened, the CRS-33 cargo resupply mission is also scheduled for this month. CRS-33, using Cargo Dragon C211 on its third flight, is currently set to launch on Thursday, Aug. 21, at 3:57 AM EDT (07:57 UTC) from Space Launch Complex-40 at the Cape Canaveral Space Force Station.
Other cargo missions to the Station are only a little bit further down the line. Progress MS-32 is scheduled to fly from Site 31/6 at Baikonur Cosmodrome in Kazakhstan on Sept. 11 at 13:49 UTC, while the NG-23 Cygnus cargo mission is set to fly on a Falcon 9 from Florida no earlier than this September. The NG-22 mission was supposed to fly earlier this year but was canceled after the Cygnus spacecraft suffered an accident during transport to Florida.
Cutaway illustration of the HTV-X. (Credit: JAXA)
Japan’s HTV-X is scheduled to make its first flight to ISS no earlier than this October. The HTV-X is a follow-on spacecraft to the earlier Kounotori vehicle, which helped supply the Station from 2009 to 2020, and will be able to carry pressurized and unpressurized cargo to ISS like Kounotori did. Like Kounotori, HTV-X is disposed of with a destructive reentry in Earth’s atmosphere.
HTV-X was designed to reduce mass and costs while increasing the amount of payload it could carry to the Station. The spacecraft will also be able to generate more power than Kounotori and will support late cargo loading. HTV-X will be launched by the H3-24L variant with four strap-on solid rocket boosters, and it will be berthed to the Station using its Canadian-built robotic arm.
Another new cargo spacecraft, Sierra Space’s DreamChaser Tenacity, was supposed to fly to the Station, but Tenacity is still in work and may not fly this year. When the DreamChaser becomes operational, it will add an intact down mass cargo capability that currently only Cargo Dragon offers.
Axiom Space’s Payload, Power, and Thermal Module shell at Thales Alenia. (Credit: Axiom Space)
The current Expedition 73 post Crew-10 complement, with the Crew-11 astronauts, along with Soyuz MS-27’s Ryzhikov, Alexey Zubritsky, and NASA’s Jonny Kim, will be working on their scientific and maintenance tasks while also assisting with cargo loading and unloading from the upcoming visiting vehicles.
While Expedition 73 continues, decisions are being made on the ground about the coming budget for the Station as well as construction on its possible successors. VAST’s Haven Demo, designed to test key systems aboard its coming space station, is scheduled to fly later this year, while Thales Alenia in Europe has completed the shell of Axiom Space’s first space station module.
(Lead image: Inside the ISS Cupola. Credit: NASA))
