U.S. Vice President Mike Pence, right, is shown the Mars 2020 spacecraft descent stage from inside the Spacecraft Assembly Facility (SAF) by JPL Director Michael Watkins, left, and NASA Mars Exploration Manager Li Fuk at NASA's Jet Propulsion Laboratory, Saturday, April 28, 2018 in Pasadena, California. Mars 2020 is a Mars rover mission by NASA's Mars Exploration Program with a planned launch in 2020. Photo Credit: (NASA/Bill Ingalls)

U.S. Vice President Mike Pence gives commands to a rover nicknamed "Scarecrow" as NASA Mars Exploration Manager Li Fuk, left, Mars Curiosity Engineering Operations Team Chief Megan Lin, JPL Director Michael Watkins, and daughter of Mike Pence, Charlotte Pence, right, look on, Saturday, April 28, 2018 in Pasadena, California. Scarecrow is used to test mobility of rovers on Mars. Photo Credit: (NASA/Bill Ingalls)

U.S. Vice President Mike Pence, 2nd from right, is shown the Mars 2020 spacecraft descent stage from inside the Spacecraft Assembly Facility (SAF) by JPL Director Michael Watkins, to the Vice President's left, and NASA Mars Exploration Manager Li Fuk at NASA's Jet Propulsion Laboratory, Saturday, April 28, 2018 in Pasadena, California. Mars 2020 is a Mars rover mission by NASA's Mars Exploration Program with a planned launch in 2020. Photo Credit: (NASA/Bill Ingalls)

Second Lady Karen Pence gives commands to a rover nicknamed "Scarecrow" as NASA Mars Exploration Manager Li Fuk, left, Mars Curiosity Engineering Operations Team Chief Megan Lin, Vice President Mike Pence, daughter of Mike Pence, Charlotte Pence, and JPL Director Michael Watkins, right, look on, Saturday, April 28, 2018 in Pasadena, California. Scarecrow is used to test mobility of rovers on Mars. Photo Credit: (NASA/Bill Ingalls)

U.S. Vice President Mike Pence, 5th from left, joined by his wife Karen Pence, left, and daughter Charlotte Pence. 2nd from left, view the Vehicle System Test Bed (VSTB) rover in the Mars Yard during a tour of NASA's Jet Propulsion Laboratory, Saturday, April 28, 2018 in Pasadena, California. NASA Mars Exploration Manager Li Fuk, 2nd from left, JPL Director Michael Watkins, Mars Curiosity Engineering Operations Team Chief Megan Lin, and MSL Engineer Sean McGill, right, helped explain to the Vice President and his family how they use these test rovers. Photo Credit: (NASA/Bill Ingalls)