Short answers, pulled from the story.
Harrison Schmitt is an American geologist, former NASA astronaut, and former U.S. senator who flew on Apollo 17 in December 1972 as the mission's Lunar Module Pilot. He is the only professional scientist to have walked on the Moon and, since the death of Gene Cernan in 2017, the most recent living person to have done so.
Schmitt collected Troctolite 76535 during the Apollo 17 mission. Scientists have called it without doubt the most interesting sample returned from the Moon; it is the central piece of evidence suggesting that the Moon once possessed an active magnetic field.
Schmitt claims to have taken The Blue Marble, one of the most widely distributed photographic images in existence. His Apollo 17 crewmates Gene Cernan and Ronald Evans made the same claim, so NASA's official position credits all three astronauts together.
Schmitt served one term as a Republican U.S. senator representing New Mexico after defeating two-term Democratic incumbent Joseph Montoya 57% to 43% in 1976. He lost his 1982 bid for re-election to Democrat Jeff Bingaman 54% to 46%. A subsequent appointment as New Mexico's Secretary of Energy, Minerals and Natural Resources in January 2011 ended the following month when he refused to undergo a required background investigation.
Schmitt has rejected the scientific consensus on climate change, arguing that natural factors rather than human activity are the predominant cause and that the risks are overstated. In March 2009 he spoke at a Heartland Institute conference and described climate change as a "stalking horse for National Socialism"; in 2013 he co-authored a Wall Street Journal column with William Happer contending that rising CO2 is not significantly correlated with global warming.
Schmitt proposed the Interlune InterMars Initiative in 1997 to advance private-sector acquisition and use of lunar resources, with a particular focus on lunar helium-3 as a potential fuel for nuclear fusion reactors. The initiative reflected his longstanding argument that returning to the Moon was the most efficient path toward eventual crewed missions to Mars.