Serial entrepreneur Elon Musk says SpaceX is developing a plan for trips to Mars that will eventually cost just $500,000 per seat. Musk founded SpaceX 10 years ago and interplanetary

The Soyuz TMA-15 spacecraft at the Baikonur Cosmodrome in Kazakhstan. (Credit: RSC Energia) HOUSTON — Appearing before a House oversight panel this week, NASA’s chief human spaceflight official and two