Watch our interview with two International Space Station astronauts

After years of studies, test-firings and a survey of U.S. industry in preparation for launch of a Mars Sample Return mission in 2026, NASA has settled on a solid-fueled design for a miniature rocket with a first-of-its-kind purpose: Launching a payload from Mars for a trip back to Earth.

Officials from NASA, research institutions and companies involved in the development and launch of the Transiting Exoplanet Survey Satellite briefed reporters in the mission Sunday, the day before its scheduled liftoff from Cape Canaveral.

NASA hopes to begin launching astronauts to the space station aboard Boeing and SpaceX capsules in the 2017 timeframe, but managers expect to still send crews up aboard Russian spacecraft as a hedge against problems that could force some astronauts to make an emergency landing.