Gerstenmaier said that a feasibility study is supposed to be finished in thirty days, but he already realizes that adding a manned crew will set back the planned launch of the SLS by three years because of launch platform changes that will be needed at the Kennedy Space Center. If it proves impossible to launch with a crew aboard by late 2019, he said, NASA would stick to the current plan of a crew on EM-2 in 2021.
The SLS rocket is now scheduled to make its debut flight, Exploration Mission 1 (EM-1), in sometime in late 2018 or early 2019.
NASA's next generation rocket Space Launch System (SLS) is now scheduled to send an unmanned capsule to orbit the Moon, but the White House has asked the government-run space agency to look into the possibility of making the rocket's debut launch a manned mission.
"The space shuttle really wasn't built to be flown unmanned, and we would have had to do an very bad lot to make that happen", former astronaut Bob Crippen, the pilot on the first shuttle flight, said in an interview with Space.com.
NASA's human exploration chief said Friday that his boss and the Trump administration requested the feasibility study. It is building new deep space capabilities to take humans farther into the solar system, to Mars. Getting the test flights out of the way early could let the real work begin quicker than expected.
He denied any pressure on the agency regarding the induction of crew ahead of schedule and said no funding or time guidelines have been provided.
NASA expects to issue its report in about a month.
The main priority, he said, would be to ensure it can be done while limiting the potential risks to the crew's safety.
Echoing that sentiment was William Hill, a deputy associate administrator: "We will let the identified risk and benefits drive this, as well as the data".
Meanwhile, a recent report of the Aerospace Safety Advisory Panel advised NASA that only a compelling reason should warrant sending astronauts on the initial flight.
Containing memorabilia and toys but no people, the capsule was launched into an extremely long orbit of Earth in 2014 by a Delta IV rocket, and splashed down into the Pacific. The new EM 1 - 2 hybrid mission would likely fall somewhere between the two dates originally proposed. "But in the assessment, we strongly advise that NASA carefully and cautiously weigh the value proposition for flying crew on EM-1".