The International Space Station (ISS) has its third female skipper, following Thursday’s change-of-command ceremony in which Russian cosmonaut Sergei Ryzhikov relinquished the helm and handed on-orbit authority over to NASA astronaut Shannon Walker. And with Expedition 65 now officially underway, the coming days, weeks and months will produce an unusual configuration with no fewer than three ISS commanders within the same expedition.
And as Walker herself takes charge, she will earn the singular honor—assuming Dragon Resilience departs as scheduled on 28 April—for the shortest command of the sprawling multi-national orbital outpost: less than two weeks.
The arrival of Soyuz MS-18 crewmen Oleg Novitsky, Pyotr Dubrov and Mark Vande Hei at the station on 9 April increased the incumbent Expedition 64 team to ten members; the largest number of humans to have simultaneously occupied the ISS since the final Space Shuttle visit in July 2011.
With the undocking of Soyuz MS-17 and crew members Sergei Ryzhikov, Sergei Kud-Sverchkov and Kate Rubins on Friday, Expedition 64 will come to an end and Expedition 65 will commence under Walker’s command. “Expeditions do not start and end with change of command,” NASA’s Rob Navias told AmericaSpace. “They start and stop from Soyuz undocking to Soyuz undocking.”
That means, for the first time, an ISS expedition will see not one, but three commanders. With Crew-2 astronauts Shane Kimbrough, Megan McArthur, Aki Hoshide and Thomas Pesquet due to launch next Thursday aboard Dragon Endeavour, they will initially fall under Walker’s command.
But on 27 April, the day before Crew-1 returns to Earth, Walker will hand over the ISS to Hoshide, who becomes only the second Japanese citizen to helm the station. He will lead Expedition 65 through the summer months, until Pesquet takes command to become the first French ISS skipper.
“Hoshide hands over command to Pesquet at a TBD date prior to their return,” Mr. Navias explained, adding that Pesquet will become the third Expedition 65 commander.
But with Crew-2 currently due to land on 31 October—and with Soyuz MS-18 expected to undock on the 17th of that month—it is possible that Pesquet will assume command at the end of Expedition 65 or more likely at the start of Expedition 66.
But it is Walker’s period of command that is unusual, for she will lead the first portion of Expedition 65 for less than two weeks, far shorter than any previous increment. Significantly, and for the first time in ISS history, she was chosen to be the ISS commander whilst in orbit. And with Pesquet having been himself named to lead the station in the last few weeks, Mr. Navias explained that all crew members “are cross-trained in all responsibilities”, rendering it possible to slot individuals into command at short notice.
“With an expanded number of crew members on board,” Mr. Navias told us, “the partnership decided to give more people a chance to command the station, even for a brief period of time.” Walker becomes only the third woman to lead the ISS, following Peggy Whitson—who did so twice on Expedition 16 in 2007-2008 and more recently on Expedition 51 in 2017—and Suni Williams, who commanded Expedition 33 in the summer and early fall of 2012.
For her part, Walker graciously accepted command, and the station’s ceremonial “key”, from outgoing skipper Ryzhikov on Thursday. She noted that it was “truly an honor and a privilege” to accept the role, adding that the “teamwork and camaraderie has made it very special”. And she offered a shout-out to ISS Deputy Program Manager Kenny Todd, who retires at the end of April.
Walker, who marks a cumulative 315 days in space today across her two missions, is currently the fourth most experienced female spacefarer, behind Williams, Christina Koch and world record-holder Whitson. When she returns to Earth on 28 April, she will move into third place behind Koch. Born in Houston, Texas, on 4 June 1965, Walker studied physics at Rice University and earned her degree in 1987.
She then joined the Rockwell Space Operations Company at NASA’s Johnson Space Center (JSC) in Houston, Texas, as a shuttle robotics flight controllers. Walker took a leave of absence in 1990 to return to Rice. She gained a master’s degree and doctorate in space physics in 1992 and 1993, respectively, with a research emphasis upon the interaction of the solar wind with the atmosphere of Venus.
Upon receipt of her PhD, Walker returned to NASA in a variety of roles within the ISS Program at JSC, working robotics integration and in 1998 joined the ISS Mission Evaluation Room (MER) as a manager for co-ordinating on-orbit problem resolution on the station. Subsequent positions of increasing responsibility saw her rise to become technical lead of the MET and deputy and acting manager of the On-Orbit Engineering Office.
Selected by NASA as an astronaut candidate in May 2004, Walker completed two years of training and evaluation, before entering a number of technical roles within the astronaut office. In November 2008, she was named to Expedition 24/25 and flew a six-month mission to the space station, launching in June 2010 aboard Soyuz TMA-19 from the Baikonur Cosmodrome in Kazakhstan. Walker returned to Earth the following November after 163 days in space.
Over the next several years, she completed a variety of different activities in the astronaut office, commanding the 15th NASA Extreme Environment Mission Operations (NEEMO-15) in the Aquarius undersea lab in October 2011 and serving as assistant to the chief of the astronaut office for the ISS Program.
In March 2017, she was named as backup to Joe Acaba for his short-notice ISS increment on Expedition 53/54. She later served as chief of the Assigned Crew Branch of the office from spring 2018 until shortly before her assignment as a member of Crew-1 in March 2020. Launched last November aboard Dragon Resilience, Walker formed part of the station’s first seven-member long-duration crew.