An audience member asks Brian Muirhead, Pre-project Manager of Mars Sample Return at NASA’s Jet Propulsion Laboratory a question after he gave a keynote titled “Mars Sample Return Mission Concept Status” at the 70th International Astronautical Congress, Wednesday, Oct. 23, 2019 at the Walter E. Washington Convention Center in Washington. Photo Credit: (NASA/Aubrey Gemignani)

Brian Muirhead, Pre-project Manager of Mars Sample Return at NASA’s Jet Propulsion Laboratory answers a question by NASA Chief Scientist, Jim Green, after giving a keynote titled “Mars Sample Return Mission Concept Status” at the 70th International Astronautical Congress, Wednesday, Oct. 23, 2019 at the Walter E. Washington Convention Center in Washington. Photo Credit: (NASA/Aubrey Gemignani)

Brian Muirhead, Pre-project Manager of Mars Sample Return at NASA’s Jet Propulsion Laboratory is seen during a keynote titled “Mars Sample Return Mission Concept Status” at the 70th International Astronautical Congress, Wednesday, Oct. 23, 2019 at the Walter E. Washington Convention Center in Washington. Photo Credit: (NASA/Aubrey Gemignani)

Brian Muirhead, Pre-project Manager of Mars Sample Return at NASA’s Jet Propulsion Laboratory is seen during a keynote titled “Mars Sample Return Mission Concept Status” at the 70th International Astronautical Congress, Wednesday, Oct. 23, 2019 at the Walter E. Washington Convention Center in Washington. Photo Credit: (NASA/Aubrey Gemignani)

NASA Chief Scientist, Jim Green, asks Brian Muirhead, Pre-project Manager of Mars Sample Return at NASA’s Jet Propulsion Laboratory a question after he gave a keynote titled “Mars Sample Return Mission Concept Status” at the 70th International Astronautical Congress, Wednesday, Oct. 23, 2019 at the Walter E. Washington Convention Center in Washington. Photo Credit: (NASA/Aubrey Gemignani)