NASA astronaut Tracy Caldwell Dyson pauses for a portrait while donning her spacesuit and going under water in the Neutral Buoyancy Lab, Monday, July 8, 2019 at NASA's Johnson Space Center in Houston, Texas. Photo Credit: (NASA/Bill Ingalls)

Astronaut Tracy Caldwell Dyson speaks on NASA TV prior to the Green Run hot fire test of the core stage for NASA’s Space Launch System (SLS) rocket at Stennis Space Center near Bay St. Louis, Mississippi, on Saturday, January 16, 2021. NASA conducted a hot fire test of the core stage’s four RS-25 engines on the B-2 Test Stand at Stennis. Scheduled for as long as eight minutes, the engines fired for a little more than one minute to generate a combined 1.6 million pounds of thrust, just as will occur during an actual launch. The hot fire is the final test of the Green Run test series, a comprehensive assessment of the SLS core stage prior to launching the Artemis I mission to the Moon.

Astronaut Tracy Caldwell Dyson speaks with media representatives prior to the Green Run hot fire test of the core stage for NASA’s Space Launch System (SLS) rocket at Stennis Space Center near Bay St. Louis, Mississippi, on Saturday, January 16, 2021. NASA conducted a hot fire test of the core stage’s four RS-25 engines on the B-2 Test Stand at Stennis. Scheduled for as long as eight minutes, the engines fired for a little more than one minute to generate a combined 1.6 million pounds of thrust, just as will occur during an actual launch. The hot fire is the final test of the Green Run test series, a comprehensive assessment of the SLS core stage prior to launching the Artemis I mission to the Moon.

Tracy E. Caldwell, STS-118 astronaut and mission specialist, participates in a training session on the usage of a special device, used to lower oneself from a troubled shuttle, in the Space Vehicle Mockup Facility at the Johnson Space Center. Caldwell is wearing a training version of her shuttle launch and entry suit.

S131-E-008498 (10 April 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 23 flight engineer, floats freely in the Destiny laboratory of the International Space Station while space shuttle Discovery (STS-131) remains docked with the station.

ISS024-E-007737 (10 July 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, uses a vacuum cleaner during housekeeping operations in the Kibo laboratory of the International Space Station.

S98-18638 (29 Oct 1998) --- Astronaut Tracy E. Caldwell, mission specialist.

S131-E-008499 (10 April 2010) --- NASA astronaut Tracy Caldwell Dyson and Japan Aerospace Exploration Agency (JAXA) astronaut Soichi Noguchi, both Expedition 23 flight engineers, pose for a photo in the Destiny laboratory of the International Space Station while space shuttle Discovery (STS-131) remains docked with the station.

S118-E-05503 (9 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, works the controls on the aft flight deck of Space Shuttle Endeavour during flight day two activities.

S118-E-06068 (10 Aug. 2007) --- A look over the shoulder of astronaut Tracy Caldwell, STS-118 mission specialist, on the aft flight deck of the Space Shuttle Endeavour on docking day.

ISS024-E-006791 (25 June 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, uses a communication system in the Destiny laboratory of the International Space Station.

NASA Astronaut and Expeditions 23 and 24 Flight Engineer, Tracy Caldwell Dyson, speaks at a Women's History Month event at NASA Headquarters, Wednesday, March 16, 2011 in Washington. The event entitled Women Inspiring the Next Generation to Reveal the Unknown is a joint venture with NASA and the White House Council on Women and Girls. Caldwell Dyson recently returned from a six-month stay aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

ISS024-E-015187 (23 Sept. 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, makes final preparations for her departure in the Soyuz TMA-18 docked to the Poisk Mini-Research Module 2 (MRM2) of the International Space Station. The Soyuz undocked at 10:02 p.m. (EDT) on Sept. 24, 2010, carrying Caldwell Dyson, along with Russian cosmonauts Alexander Skvortsov and Mikhail Kornienko (both out of frame). Originally scheduled for Sept. 23, the Soyuz undocked a day later due to a Poisk-side hatch sensor problem, which prevented hooks on the Poisk side of the docking interface from opening.

JSC2007-E-33311 (4 May 2007) --- Astronaut Tracy E. Caldwell, mission specialist

JSC2007-E-33315 (4 May 2007) --- Astronaut Tracy E. Caldwell, mission specialist [alternate portrait]

JSC2007-E-33314 (4 May 2007) --- Astronaut Tracy E. Caldwell, mission specialist [alternate portrait]

JSC2007-E-33312 (4 May 2007) --- Astronaut Tracy E. Caldwell, mission specialist [alternate portrait]

S131-E-010088 (14 April 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 23 flight engineer, equipped with a bungee harness, exercises on the Combined Operational Load Bearing External Resistance Treadmill (COLBERT) in the Harmony node of the International Space Station while space shuttle Discovery (STS-131) remains docked with the station.

S118-E-07043 (13 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, uses a communication system near the aft flight deck of Space Shuttle Endeavour during flight day six activities while docked with the International Space Station.

S118-E-05515 (9 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, works the controls on the aft flight deck of Space Shuttle Endeavour during flight day two activities. Astronaut Charlie Hobaugh, pilot, is visible at lower right.

ISS024-E-014263 (11 Sept. 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, looks through a window in the Cupola of the International Space Station. A blue and white part of Earth and the blackness of space are visible through the windows.

ISS024-E-008590 (18 July 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, works with the Microgravity Experiment Research Locker/Incubator (MERLIN) on Express rack 6 in the Destiny laboratory of the International Space Station.

Mary Ellen Caldwell, center, speaks to her daughter NASA Flight Engineer Tracy Caldwell Dyson onboard the International Space Station from the Russian Mission Control Center, Korolev, Russia, Sunday, April 4, 2010. The Soyuz TMA-18 docked to the International Space Station carrying Expedition 23 Soyuz Commander Alexander Skvortsov, Flight Engineer Mikhail Kornienko and NASA Flight Engineer Tracy Caldwell Dyson. Photo Credit: (NASA/Carla Cioffi)

S118-E-06268 (11 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, uses a communication system on the aft flight deck of Space Shuttle Endeavour during flight day four activities.

S118-E-07180 (14 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, poses for a photo on the middeck of Space Shuttle Endeavour while docked with the International Space Station.

S118-E-06124 (10 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, smiles for a photo in the Zvezda Service Module of the International Space Station following the docking with the Space Shuttle Endeavour.

Expedition 24 Flight Engineer Tracy Caldwell Dyson exits the helicopter after her flight from the Soyuz TMA-18 spacecraft landing site near Arkalyk, Kazakhstan to Karaganda, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson returned from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

NASA Astronaut and Expeditions 23 and 24 Flight Engineer, Tracy Caldwell Dyson, speaks at a Women's History Month event at NASA Headquarters, Wednesday, March 16, 2011 in Washington. The event entitled Women Inspiring the Next Generation to Reveal the Unknown is a joint venture with NASA and the White House Council on Women and Girls. Caldwell Dyson recently returned from a six-month stay aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

Expedition 24 Flight Engineer Tracy Caldwell Dyson talks to her husband on a satellite phone shortly after landing in the Soyuz TMA-18 spacecraft with fellow crew members Commander Alexander Skvortsov and Mikhail Kornienko near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 24 Flight Engineer Tracy Caldwell Dyson is helped out of the Soyuz TMA-18 spacecraft shortly after landing with fellow crew members Commander Alexander Skvortsov and Mikhail Kornienko near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 24 Flight Engineer Tracy Caldwell Dyson is helped out of the Soyuz TMA-18 spacecraft shortly after landing with fellow crew members Commander Alexander Skvortsov and Mikhail Kornienko near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

NASA Astronaut and Expeditions 23 and 24 Flight Engineer, Tracy Caldwell Dyson, far left, speaks at a Women's History Month event at NASA Headquarters, Wednesday, March 16, 2011 in Washington. The event entitled Women Inspiring the Next Generation to Reveal the Unknown is a joint venture with NASA and the White House Council on Women and Girls. Caldwell Dyson recently returned from a six-month stay aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

Expedition 24 Flight Engineer Tracy Caldwell Dyson signs the inside of the Russian helicopter that took her from the Soyuz TMA-18 spacecraft landing site near Arkalyk, Kazakhstan to Karaganda, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson returned from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

S131-E-007943 (7 April 2010) --- The four women currently on the International Space Station pose for a photo in the Zvezda Service Module while space shuttle Discovery remains docked with the station. From the left are NASA astronaut Dorothy Metcalf-Lindenburger and Japan Aerospace Exploration Agency (JAXA) astronaut Naoko Yamazaki, both STS-131 mission specialists; along with NASA astronauts Tracy Caldwell Dyson, Expedition 23 flight engineer; and Stephanie Wilson, STS-131 mission specialist.

ISS015-E-22145 (12 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, looks over her shoulder for a photo while working the controls on the aft flight deck of Space Shuttle Endeavour while docked with the International Space Station.

S118-E-06826 (11 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, prepares a beverage at the galley on the middeck of Space Shuttle Endeavour while docked with the International Space Station during flight day four activities.

S118-E-05521 (9 Aug. 2007) --- Astronauts Scott Kelly (right), STS-118 commander, and Tracy Caldwell, mission specialist, look over procedures checklists on the middeck of Space Shuttle Endeavour during flight day two activities.

ISS015-E-22201 (12 Aug. 2007) --- During a focused inspection of apparent damage on the underside of the shuttle, astronauts Barbara R. Morgan (left) and Tracy Caldwell, both STS-118 mission specialists, work at the aft flight deck controls of Space Shuttle Endeavour while docked with the International Space Station.

JSC2009-E-226239 (28 Oct. 2009) --- Astronaut Tracy Caldwell, Expedition 23/24 flight engineer, attired in a training version of her Extravehicular Mobility Unit (EMU) spacesuit, participates in a spacewalk training session in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Divers are in the water to assist Caldwell in her rehearsal, which is intended to help prepare her for work on the exterior of the International Space Station.

JSC2009-E-226223 (28 Oct. 2009) --- Astronaut Tracy Caldwell, Expedition 23/24 flight engineer, dons a training version of her Extravehicular Mobility Unit (EMU) spacesuit in preparation for a spacewalk training session in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Astronaut Shannon Walker, Expedition 24/25 flight engineer, assisted Caldwell.

JSC2009-E-226227 (28 Oct. 2009) --- Astronaut Tracy Caldwell, Expedition 23/24 flight engineer, dons a training version of her Extravehicular Mobility Unit (EMU) spacesuit in preparation for a spacewalk training session in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Astronaut Shannon Walker, Expedition 24/25 flight engineer, assisted Caldwell.

Expedition 24 Flight Engineers Tracy Caldwell Dyson, left, Commander Alexander Skvortsov, center and Mikhail Kornienko sit in chairs outside the Soyuz Capsule just minutes after they landed near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. prepares to have her Russian Sokol suit pressure checked at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. has her Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crew members Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 Flight Engineer Tracy Caldwell Dyson says a few words during the State Commission meeting to approve the Soyuz launch of Caldwell Dyson, Expedition 23 Soyuz Commander Alexander Skvortsov and Expedition 23 Flight Engineer Mikhail Kornienko on Thursday, April 1, 2010 in Baikonur, Kazakhstan. The crew is kept in a separate room with a glass window in order to help maintain their health. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. prepares to have her Russian Sokol suit pressure checked at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. has her Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crew members Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

NASA's Tracy Caldwell Dyson, left, looks on as Expedition 23 Soyuz Commander Alexander Skvortsov answers a reporters' question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 Flight Engineer Tracy Caldwell Dyson answers a reporters' question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. prepares to have her Russian Sokol suit pressure checked at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 Flight Engineer Tracy Caldwell Dyson performs the traditional door signing Friday, April 2, 2010 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Caldwell Dyson was launched onboard the Soyuz rocket later that day with Expedition 23 Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko on a mission to the International Space Station (ISS). Photo Credit: (NASA/Carla Cioffi)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. prepares to have her Russian Sokol suit pressure checked at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 24 Commander Alexander Skvortsov laughs after being given fresh fruit and vegetables shortly after landing in the Soyuz TMA-18 spacecraft with fellow crew members Tracy Caldwell Dyson and Mikhail Kornienko near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

NASA astronaut Tracy Caldwell Dyson speaks with college students after the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington. She moderated a panel discussion with NASA Administrator Jim Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke. Photo Credit: (NASA/Aubrey Gemignani)

Expedition 24 Flight Engineer Tracy Caldwell Dyson, left, Expedition 24 Commander Alexander Skvortsov, center, and Expedition 24 Flight Engineer Mikhail Kornienko answer reporters questions in traditional Kazakh dress during a post flight ceremony and press conference at the Karaganda airport in Kazakhstan on Saturday, Sept. 25, 2010. The Soyuz TMA-18 spacecraft, carrying Expedition 24 Commander Alexander Skvortsov and Flight Engineers Tracy Caldwell Dyson and Mikhail Kornienko, landed, near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

PHOTO DATE: 10-27-09 LOCATION: Bldg 9NW, ISS Mockup SUBJECT: Expedition 23 astronaut Tracy Caldwell during Regenerative ECLSS training with instructor Cindy Koester. PHOTOGRAPHER: James Blair

S118-E-06869 (11 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, floats in the Unity node of the International Space Station while Space Shuttle Endeavour remains docked with the station.

Expedition 24 Flight Engineer Tracy Caldwell Dyson shakes hands with NASA Astronaut and Chief of the Astronaut Office Peggy Whitson shortly after landing in the Soyuz TMA-18 spacecraft with fellow crew members Commander Alexander Skvortsov and Mikhail Kornienko near the town of Arkalyk, Kazakhstan on Saturday, Sept. 25, 2010. Russian Cosmonauts Skvortsov and Kornienko and NASA Astronaut Caldwell Dyson, are returning from six months onboard the International Space Station where they served as members of the Expedition 23 and 24 crews. Photo Credit: (NASA/Bill Ingalls)

NASA astronaut Tracy Caldwell Dyson, moderates a panel discussion with NASA Administrator Jim Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask the panelists questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. Photo Credit: (NASA/Aubrey Gemignani)

S118-E-07701 (17 Aug. 2007) --- Astronaut Tracy Caldwell, on the mid deck of the Space Shuttle Endeavour, brushes her hair as she prepares to participate in the shuttle crew's supply transfer chores. Tomorrow the mission specialist is scheduled to orchestrate the intravehicular support for the crew's final spacewalk, a role she has filled on three previous occasions on this her first space flight.

Expedition 23 prime and backup crew members, from left, NASA's Tracy Caldwell Dyson, Russian Aleksander Skvortsov, Russian Mikhail Kornienko, NASA's Scott Kelly, Russian Alexander Samokutyayev, and Russian Andrei Borisenko are seen during the State Commission meeting to approve the Soyuz launch of Caldwell Dyson, Skvortsov and Kornienko, Thursday, April 1, 2010 in Baikonur, Kazakhstan. The crew is kept in a separate room with a glass window in order to help maintain their health. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 Flight Engineer Mikhail Kornienko of Russia, top, NASA Flight Engineer Tracy Caldwell Dyson of the U.S. and Soyuz Commander Alexander Skvortsov of Russia, bottom, wave farewell from the bottom of the Soyuz rocket at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Kornienko, Caldwell Dyson and Skvortsov launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010 at 10:04 a.m. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, left, Soyuz Commander Alexander Skvortsov or Russia, and Flight Engineer Mikhail Kornienko of the Russia, right, have their Russian Sokol suits prepared for launch by a technicians at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson, Skvortsov and Kornienko and launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 crew members, from left, NASA’s Tracy Caldwell Dyson, Russian Alexander Skvortsov and Russian Mikhail Kornienko pose for photographers during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 Flight Engineer Mikhail Kornienko of Russia, top, NASA Flight Engineer Tracy Caldwell Dyson of the U.S. and Soyuz Commander Alexander Skvortsov of Russia, bottom, wave farewell from the bottom of the Soyuz rocket at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Kornienko, Caldwell Dyson and Skvortsov launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010 at 10:04 a.m. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 crew members, from left, NASA’s Tracy Caldwell Dyson, Russian Alexander Skvortsov and Russian Mikhail Kornienko are seen during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, left, speaks during the State Commission meeting at the Cosmonaut Hotel while her colleagues Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko, right, listen on Thursday, April 1, 2010 in Baikonur, Kazakhstan. The State Commission meeting approves the Soyuz launch of Caldwell Dyson, Skvortsov and Kornienko to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 Soyuz Commander Alexander Skvortsov, center, holds up a poster of the Expedition 23 crew while Flight Engineer Tracy Caldwell Dyson and Flight Engineer Mikhail Kornienko, right, smile during the State Commission meeting held at the Cosmonaut Hotel, Thursday, April 1, 2010 in Baikonur, Kazakhstan. The State Commission meeting approves the Soyuz launch of Caldwell Dyson, Skvortsov and Kornienko to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 crew members, from left, NASA's Tracy Caldwell Dyson, Russian Alexander Skvortsov and Russian Mikhail Kornienko are seen during the State Commission meeting to approve the Soyuz launch of Skvortsov, Caldwell Dyson and Mikhail Kornienko on Thursday, April 1, 2010 in Baikonur, Kazakhstan. The crew is kept in a separate room with a glass window in order to help maintain their health. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. prepares to have her Russian Sokol suit pressure checked at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. prepares to have her Russian Sokol suit pressure checked at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. has her Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crew members Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 crew members, from left, NASA’s Tracy Caldwell Dyson, Russian Alexander Skvortsov and Russian Mikhail Kornienko pose for photographers during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

JSC2009-E-226213 (28 Oct. 2009) --- Astronaut Tracy Caldwell, Expedition 23/24 flight engineer, gets help in the donning of a training version of her Extravehicular Mobility Unit (EMU) spacesuit in preparation for a spacewalk training session in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center.

Astronauts Tracy Caldwell Dyson, flight engineer on Expeditions 23 and 24, left, and Doug Wheelock, Expedition 24 flight engineer and commander of Expedition 25, discuss their mission to the International Space Station during a visit to NASA Headquarters in Washington, Wednesday, March 16, 2011. (NASA/Paul E. Alers)

Astronauts Tracy Caldwell Dyson, flight engineer on Expeditions 23 and 24, left, and Doug Wheelock, Expedition 24 flight engineer and commander of Expedition 25, discuss their mission to the International Space Station during a visit to NASA Headquarters in Washington, Wednesday, March 16, 2011. (NASA/Paul E. Alers)

Expedition 23 Flight Engineer Tracy Caldwell Dyson waves farewell to well wishers as she departs the Cosmonaut Hotel on the morning of the Soyuz launch to the International Space Station on Friday, April 2, 2010 in Baikonur, Kazakhstan. Photo Credit: (NASA/Carla Cioffi)

Astronauts Tracy Caldwell Dyson, flight engineer on Expeditions 23 and 24, left, and Doug Wheelock, Expedition 24 flight engineer and commander of Expedition 25, discuss their mission to the International Space Station during a visit to NASA Headquarters in Washington, Wednesday, March 16, 2011.

NASA Deputy Administrator Lori Garver, far left at table, answers a students question at a Women's History Month event at NASA Headquarters, Wednesday, March 16, 2011 in Washington. Garver is joined on the panel by NASA astronaut Tracy Caldwell Dyson, center, and NASA Aerospace Engineer Sabrina Thompson. The event entitled Women Inspiring the Next Generation to Reveal the Unknown is a joint venture with NASA and the White House Council on Women and Girls. Photo Credit: (NASA/Carla Cioffi)

Expedition 23 crew members NASA’s Tracy Caldwell Dyson (second from left), Russian Alexander Skvortsov and Russian Mikhail Kornienko (right) pose for photographers during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 Flight Engineer Tracy Caldwell Dyson, left, and Soyuz Commander Alexander Skvortsov wave farewell to well wishers as they depart the Cosmonaut Hotel on the morning of their Soyuz launch to the International Space Station on Friday, April 2, 2010 in Baikonur, Kazakhstan. Photo Credit: (NASA/Carla Cioffi)

NASA Administrator Jim Bridenstine speaks at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask panelists, Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. NASA astronaut Tracy Caldwell Dyson moderated the panel discussion. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Tracy Caldwell Dyson, moderates a panel discussion with NASA Administrator Jim Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask the panelists questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. Photo Credit: (NASA/Aubrey Gemignani)

S118-E-09265 (18 Aug. 2007) --- Astronauts Barbara R. Morgan (left) and Tracy Caldwell, both STS-118 mission specialists, pose with a photo of astronauts Clay Anderson and Sunita Williams, both Expedition 15 flight engineers, near a hatch on the International Space Station while Space Shuttle Endeavour remains docked with the station.

S118-E-06141 (11 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, works the controls of the shuttle's remote manipulator system (RMS) robotic arm from the aft flight deck of Space Shuttle Endeavour in support of the mission's first planned session of extravehicular activity (EVA) while docked with the International Space Station.

JSC2009-E-226238 (28 Oct. 2009) --- Attired in training versions of their Extravehicular Mobility Unit (EMU) spacesuits, astronauts Tracy Caldwell, Expedition 23/24 flight engineer; and Doug Wheelock (mostly obscured), Expedition 24 flight engineer and Expedition 25 commander, are about to be submerged in the waters of the Neutral Buoyancy Laboratory (NBL) near NASA's Johnson Space Center. Divers are in the water to assist the crew members in their rehearsal, which is intended to help prepare them for work on the exterior of the International Space Station.

S118-E-06142 (11 Aug. 2007) --- Astronaut Tracy Caldwell, STS-118 mission specialist, refers to a procedures checklist while working the controls of the shuttle's remote manipulator system (RMS) robotic arm from the aft flight deck of Space Shuttle Endeavour in support of the mission's first planned session of extravehicular activity (EVA) while docked with the International Space Station.

Expedition 23 crew members NASA Flight Engineer Tracy Caldwell Dyson, left, Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko, right, leave the Cosmonaut Hotel on the morning of their launch on a Soyuz rocket to the International Space Station, Friday, April 2, 2010, in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 Flight Engineer Tracy Caldwell Dyson, left, Expedition 23 Soyuz Commander Alexander Skvortsov and Expedition 23 Flight Engineer Mikhail Kornienko, right, talk with family and colleagues from behind glass prior to their launch onboard a Soyuz rocket to the International Space Station (ISS), Friday, April 2, 2010 in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, left, talks with Soyuz Commander Alexander Skvortsov of Russia, while Flight Engineer Mikhail Kornienko of Russia has his Russian Sokol suit prepared for launch at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. The Expedition 23 crew members launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. (Photo Credit: NASA/Bill Ingalls)

Expedition 23 Flight Engineer Tracy Caldwell Dyson talks with family and colleagues from behind glass prior to her launch onboard a Soyuz rocket with Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia to the International Space Station (ISS), Friday April 2, 2010 in Baikonur, Kazakhstan. Photo Credit: (NASA/Carla Cioffi)

The crew of Expedition 23 are seen on a large TV screen in the Russian Mission Control Center in Korolev, Russia, Sunday, April 4, 2010, shortly after the Soyuz TMA-18 spacecraft docked to the International Space Station and delivered Expedition 23 Flight Engineers Alexander Skvortsov, Mikhail Kornienko and Tracy Caldwell Dyson. Clockwise from top right are NASA astronaut TJ Creamer, NASA astronaut Tracy Caldwell Dyson, Russian cosmonaut Alexander Skvortsov, Russian cosmonaut Mikhail Kornienko, JAXA (Japan Aerospace Exploration Agency) astronaut Soichi Noguchi and Expedition 23 commander Russian cosmonaut Oleg Kotov . Photo Credit: (NASA/Carla Cioffi)

NASA astronaut Tracy Caldwell Dyson, left, moderates a panel discussion with NASA Administrator Jim Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask the panelists questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. Photo Credit: (NASA/Aubrey Gemignani)

NASA Administrator Jim Bridenstine poses for a photo with college students after the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where they were able to ask panelists, Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke, questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. NASA astronaut Tracy Caldwell Dyson moderated the panel discussion. Photo Credit: (NASA/Aubrey Gemignani)

NASA Administrator Jim Bridenstine, second from left, speaks at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask panelists, Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, second from right, and NASA Deputy Associate Administrator for Exploration, Steve Clarke, right, questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. NASA astronaut Tracy Caldwell Dyson, left, moderated the panel discussion. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Tracy Caldwell Dyson, left, moderates a panel discussion with NASA Administrator Jim Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask the panelists questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. Photo Credit: (NASA/Aubrey Gemignani)

Nick Hague, left, and Christina Koch, two astronauts currently living and working on the International Space Station, are seen on the screen during a live uplink and panel discussion with NASA Administrator Jim Bridenstine, center, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, right, and NASA Deputy Associate Administrator for Exploration, Steve Clarke, not pictured, at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington. NASA astronaut Tracy Caldwell Dyson, left, moderated the panel discussion. Photo Credit: (NASA/Aubrey Gemignani)

NASA Administrator Jim Bridenstine takes a selfie with college students after the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where they were able to ask panelists, Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke, questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. NASA astronaut Tracy Caldwell Dyson moderated the panel discussion. Photo Credit: (NASA/Aubrey Gemignani)

A video profile of a NASA employee is seen as NASA astronaut Tracy Caldwell Dyson, moderates a panel discussion with NASA Administrator Jim Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, and NASA Deputy Associate Administrator for Exploration, Steve Clarke at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington. The students were able to ask the panelists questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. Photo Credit: (NASA/Aubrey Gemignani)

NASA Administrator Jim Bridenstine, second from left, speaks at the "Future of Space" STEM event, Monday, April 29, 2019 at NASA Headquarters in Washington, where college students were able to ask panelists, Bridenstine, NASA Associate Administrator for the Human Exploration and Operations Mission Directorate, Bill Gerstenmaier, second from right, and NASA Deputy Associate Administrator for Exploration, Steve Clarke, right, questions as well as speak with two astronauts currently on the International Space Station, Nick Hague and Christina Koch. NASA astronaut Tracy Caldwell Dyson, left, moderated the panel discussion. Photo Credit: (NASA/Aubrey Gemignani)