jsc2017e114835 (Aug. 22, 2018) --- 2017 NASA Astronaut Candidate Matthew Dominick.

jsc2017e067114 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Kayla Barron in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067113 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Raja Chari in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067119 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Frank Rubio in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067117 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Jonny Kim in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067123 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Bob Hines in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067124 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Zena Cardman in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067122 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Jasmin Moghbeli in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067116 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Warren Hoburg in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067120 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Loral O'Hara in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067121 (June 6, 2017) --- NASA portrait of 2017 Astronaut Candidate Jessica Watkins in front of a T-38 trainer aircraft at Ellington Field near NASA’s Johnson Space Center in Houston, Texas.

NASA's 2017 astronaut candidates toured aircraft hangar at Armstrong Flight Research Center, in Southern California. After tour of aircraft hangar and briefing on the use of aircraft for flight research, the astronauts practiced flying the X-57 simulator. Starting with the fuselage of a Tecnam P20067T, the X-57 Maxwell electric propulsion airplane is being built and could lead to the development of electric propulsion-powered aircraft, which would be quieter, more efficient and environmentally friendly than today's commuter aircraft.

jsc2017e118351 (Oct. 15, 2017) --- 2017 NASA Astronaut Candidate Jessica Watkins.

jsc2017e118421 (Oct. 25, 2017) --- 2017 NASA Astronaut Candidate Kayla Baron.

jsc2017e118314 (Oct. 24, 2017) --- 2017 NASA Astronaut Candidate Warren Hoburg.

jsc2017e114853 (Aug. 22, 2017) --- 2017 NASA Astronaut Candidate Raja Chari.

jsc2017e114858 (Aug. 22, 2017) --- 2017 NASA Astronaut Candidate Bob Hines.

jsc2017e118354_alt (Oct. 19, 2017) --- 2017 NASA Astronaut Candidate Jonny Kim.

jsc2017e116316 (Sept. 15, 2017) --- 2017 NASA Astronaut Candidate Zena Cardman.

jsc2017e116310 (Sept. 15, 2017) --- 2017 NASA Astronaut Candidate Jasmin Moghbeli.

jsc2017e114795 (Aug. 22, 2018) --- 2017 NASA Astronaut Candidate Frank Rubio.

jsc2017e114808 (Aug. 22, 2018) --- 2017 NASA Astronaut Candidate Loral O'Hara.

jsc2017e067125 (June 6, 2017) --- The members of the 2017 NASA Astronaut Class are (from left) Zena Cardman, Jasmin Moghbeli, Jonny Kim, Frank Rubio, Matthew Dominick, Warren Hoburg, Robb Kulin, Kayla Barron, Bob Hines, Raja Chari, Loral O' Hara and Jessica Watkins. Photo Credit: NASA/Robert Markowitz

jsc2017e118962 (September 21, 2017) --- 2017 NASA astronaut candidate Zena Cardman readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e119012 (September 21, 2017) --- 2017 NASA astronaut candidate Warren Hoburg readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118973 (September 21, 2017) --- 2017 NASA astronaut candidate Jessica Watkins readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e119000 (September 21, 2017) --- 2017 NASA astronaut candidate Warren Hoburg readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118991 (September 21, 2017) --- 2017 NASA astronaut candidate Jonny Kim undergoes helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118989 (September 21, 2017) --- 2017 NASA astronaut candidate Jonny Kim readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118970 (September 21, 2017) --- 2017 NASA astronaut candidate Frank Rubio readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118959 (September 21, 2017) --- 2017 NASA astronaut candidate Zena Cardman readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118967 (September 21, 2017) --- 2017 NASA astronaut candidate Loral O’Hara undergoes helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e118966 (September 21, 2017) --- 2017 NASA astronaut candidate Loral O’Hara readies for helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e067273 (June 6, 2017) --- NASA’s 2017 Astronaut Candidate Class stopped for a group photo while getting fitted for flight suits at Ellington Airport near NASA’s Johnson Space Center in Houston, Texas.

jsc2017e067274 (June 6, 2017) --- NASA’s 2017 Astronaut Candidate Class stopped for a group photo while getting fitted for flight suits at Ellington Airport near NASA’s Johnson Space Center in Houston, Texas.

jsc2018e060323 (06/20/2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli and Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons during earth and planetary science training in Rio Grande del Norte National Monument Upper Gorge Area near Questa, N.M. Photo Credit: (NASA/Norah Moran)

jsc2019e054874 (09-16-19) --- 2017 NASA astronaut candidate Frank Rubio during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e054997 (09-16-19) --- 2017 NASA astronaut candidates gather for data collection during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e054955 (09-16-19) --- 2017 NASA astronaut candidate Bob Hines during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e054977 (09-16-19) --- 2017 NASA astronaut candidates gather during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e054910 (09-16-19) --- 2017 NASA astronaut candidate Kayla Barron during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2017e111693 (08-23-2017) --- (From left, foreground) 2017 NASA astronaut candidates Jessica Watkins, Loral O’Hara, (from left, background) Zena Cardman and Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. (NASA/David DeHoyos)

jsc2017e118972 (September 21, 2017) --- (From left) 2017 NASA astronaut candidates Jessica Watkins and Frank Rubio and Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons are lowered into the training pool during helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e049894 (05-18-18) ---(From left) 2017 NASA astronaut candidate Jessica Watkins, Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons, and NASA astronaut candidates Bob Hines and Frank Rubio are instructed on International Space Station tools associated with their spacesuits at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/James Blair)

jsc2017e067166 (06/07/2017) --- United States Vice President Mike Pence congratulates NASA's 12 new astronaut candidates at the agency's Johnson Space Center in Houston. The 2017 astronaut candidate class -- Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Bob Hines, Warren “Woody” Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins – were chosen from amid a record number of people applying. Photo Credit: (NASA/James Blair)

jsc2018e052122 (May 30, 2018) --- (From left) 2017 NASA astronaut candidate Jonny Kim prepares for his next assignment as Canadian Space Agency astronaut candidates Joshua Kutryk (standing), Jennifer Sidey-Gibbons, and NASA astronaut candidate Bob Hines look on during wilderness survival training at the U.S. Navy’s Survival, Evasion, Resistance, and Escape School in Brunswick, Maine. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e052153 (May 30, 2018) --- 2017 NASA astronaut candidate Jessica Watkins preps her station with fellow candidate Loral O’Hara looking on during wilderness survival training at the U.S. Navy’s Survival, Evasion, Resistance, and Escape School in Brunswick, Maine. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e1117823 (08-23-2017) --- (From left) 2017 Astronaut candidates Jessica Watkins of NASA, Jennifer Sidey-Gibbons of CSA, and Loral O’Hara of NASA give a thumbs up after successful water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e111785 (08-23-2017) --- 2017 NASA astronaut candidate Loral O’Hara awaits next steps by instructors during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e111790 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Jessica Watkins (right) works alongside instructors. Photo Credit: (NASA/David DeHoyos)

jsc2017e111697 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidates Warren Hoburg (center) and Jonny Kim (right) work alongside their instructors. (NASA/David DeHoyos)

jsc2017e111799 (08-23-2017) ---2017 NASA astronaut candidate Zena Cardman awaits next steps by instructors during water survival training at NASA’s Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e111798 (08-23-2017) --- 2017 NASA astronaut candidate Zena Cardman awaits next steps by instructors during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e118980 (September 21, 2017) --- 2017 NASA astronaut candidates Kayla Barron (left) and Zena Cardman (right) receive guidance from training instructors during helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e111705 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, Texas, NASA astronaut candidate Jonny Kim (right) works alongside instructors. Photo Credit: (NASA/David DeHoyos)

jsc2017e1117812 (08-23-2017) --- 2017 NASA astronaut candidate Jessica Watkins awaits next steps by instructors during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e111736 (08-23-2017) ---2017 NASA astronaut candidate Warren Hoburg awaits next steps by instructors during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e111703 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Jonny Kim (right) is fitted for training gear by instructors. (NASA/David DeHoyos)

jsc2017e111750 (08-23-2017) --- 2017 NASA astronaut candidate Kayla Barron awaits next steps by instructors during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e1117836 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Zena Cardman (foreground) and Warren Hoburg (background) work alongside divers. Photo Credit: (NASA/David DeHoyos)

jsc2017e1117879 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Jessica Watkins works alongside divers. Photo Credit: (NASA/David DeHoyos)

jsc2017e118961 (September 21, 2017) --- (From left) 2017 NASA astronaut candidates Zena Cardman, Kayla Barron, and Warren Hoburg await next steps and instruction during helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e111780 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Loral O’Hara is fitted for training gear by instructors. Photo Credit: (NASA/David DeHoyos)

jsc2017e1117804 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Jonny Kim (left) works alongside divers. Photo Credit: (NASA/David DeHoyos)

jsc2017e1117884 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Jessica Watkins is guided through training by divers. Photo Credit: (NASA/David DeHoyos)

jsc2017e111782 (08-23-2017) --- 2017 NASA astronaut candidate Zena Cardman awaits next steps by instructors during water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/David DeHoyos)

jsc2017e111702 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, NASA astronaut candidate Warren Hoburg (right) works alongside his instructors. Photo Credit: (NASA/David DeHoyos)

jsc2018e035917 (April 11, 2018) ---2017 NASA astronaut candidate Matthew Dominick wears a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e035916 (April 11, 2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli is helped into a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e035904 (April 11, 2018) --- 2017 NASA astronaut candidate Matthew Dominick wears a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e035922 (April 11, 2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli wears a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e095931 (November 7, 2018) --- 2017 NASA astronaut candidate Jonny Kim prepares for underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Robert Markowitz)

jsc2018e095935 (November 7, 2018) --- 2017 NASA astronaut candidate Kayla Barron prepares for underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Robert Markowitz)

jsc2018e064842 (07/18/2018) --- 2017 NASA astronaut candidate Bob Hines in a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Norah Moran)

jsc2018e095941 (November 7, 2018) --- 2017 NASA astronaut candidate Jonny Kim is lowered into the training pool for spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Robert Markowitz)

jsc2018e035760 (04-12-2018) --- 2017 NASA astronaut candidate Zena Cardman is being helped into a spacesuit prior to underwater training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory. Photo Credit: (NASA/David DeHoyos)

jsc2018e064835 (07/18/2018) --- 2017 NASA astronaut candidate Bob Hines in a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Norah Moran)

jsc2018e096694 (November 16, 2018) --- 2017 NASA astronaut candidate Raja Chari is lowered into the training pool for spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Robert Markowitz)

jsc2018e094739 (November 05, 2018) --- 2017 NASA astronaut candidate Warren Hoburg is lowered into the training pool for spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e095924 (November 7, 2018) --- 2017 NASA astronaut candidate Jonny Kim prepares for underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Robert Markowitz)

jsc2018e064837 (07/18/2018) --- 2017 NASA astronaut candidate Jessica Watkins in a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Norah Moran)

jsc2018e035910 (April 11, 2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli wears a spacesuit prior to underwater spacewalk training at NASA’s Johnson Space Center Neutral Buoyancy Laboratory. Photo Credit: (NASA/Josh Valcarcel)

jsc2018e035915 (April 11, 2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli is helped into a spacesuit prior to underwater spacewalk training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e111727 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons (right) is fitted for training gear by instructors. Photo Credit: (NASA/David DeHoyos)

jsc2017e118963 (September 21, 2017) --- 2017 Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons is all smiles during helicopter water survival training at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2017e1117871 (08-23-2017) --- During water survival training in 2017 at NASA Johnson Space Center’s Neutral Buoyancy Laboratory in Houston, Canadian Space Agency astronaut candidate Jennifer Sidey-Gibbons is guided through training by divers. Photo Credit: (NASA/David DeHoyos)

jsc2019e055001 (09-16-19) --- 2017 NASA astronaut candidate Loral O’Hara scans her sample during data collection during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e055036 (09-17-19) --- 2017 NASA astronaut candidate Warren Hoburg examines samples during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2018e032531 (03-30-18) --- 2017 NASA astronaut candidate Warren Hoburg practices procedures alongside trainers during T-38 flight simulator training in Houston. Photo Credit: (NASA/James Blair)

jsc2018e035272 (April 09, 2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli during T-38 engine maintenance training at Ellington Field in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2019e054791 (09-15-19) --- 2017 NASA astronaut candidate Jessica Watkins takes notes during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2018e035282 (April 09, 2018) --- 2017 NASA astronaut candidate Zena Cardman during T-38 engine maintenance training at Ellington Field in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2019e055475 (09-19-19) --- 2017 NASA astronaut candidates hike as a team with their field instructors during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e055210 (09-18-19) --- 2017 NASA astronaut candidates take a break with their field instructors during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e055078 (09-17-19) --- 2017 NASA astronaut candidates Warren Hoburg (left) and Jonny Kim (right) input field data during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2018e032520 (03-30-18) --- 2017 NASA astronaut candidate Kayla Barron practices procedures during T-38 flight simulator training in Houston. Photo Credit: (NASA/James Blair)

jsc2018e035270 (April 09, 2018) --- 2017 NASA astronaut candidate Jasmin Moghbeli during T-38 engine maintenance training at Ellington Field in Houston. Photo Credit: (NASA/Josh Valcarcel)

jsc2019e055340 (09-19-19) --- 2017 NASA astronaut candidates hike as a team with their field instructors during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e054952 (09-16-19) --- 2017 NASA astronaut candidates Matthew Dominick and Loral O’Hara during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)

jsc2019e055491 (09-19-19) --- 2017 NASA astronaut candidates gather to discuss further instruction with their field instructor during geology training in Arizona. Photo Credit: (NASA/Bill Stafford)