WASHINGTON, May 12 (Xinhua) -- The first integrated flight of NASA's Space Launch System (SLS) rocket and Orion spacecraft has been delayed to 2019 and will not have a crew aboard, the U.S. space agency said Friday.
In February, NASA began an effort looking at the feasibility of putting astronauts aboard the first flight, known as Exploration Mission-1, or EM-1, which was originally scheduled for November 2018.
"It is technically capable of launching crew on EM-1, but after evaluating cost, risk and technical factors in a project of this magnitude, it would be difficult to accommodate changes needed to add crew at this point in mission planning," it said in a statement.
"The effort confirmed that the baseline plan to fly EM-1 without crew is still the best approach to enable humans to move sustainably beyond low Earth orbit."
As part of the assessment, NASA also reviewed the schedule for EM-1, including production schedules across the enterprise, anticipated budgets and appropriations, and the ongoing impact of the February tornado that directly affected the Michoud Assembly Facility in Louisiana.
"As a result of these factors, NASA will adjust the target launch date for the EM-1 mission to 2019, and will execute its normal process in the coming weeks to determine an official revised launch date," it said.
NASA did not say if the second test mission, known as EM-2, which will carry crew beyond the moon, will be affected.
Currently, EM-2 was scheduled to take place in 2021.
EM-1 and EM-2 are the first two in a broad series of exploration missions that will take U.S. astronauts to deep space, and eventually to Mars.
"NASA will continue to work with the Administration and Congress as we move toward a crewed flight test on EM-2 and, right now, we are very focused on accomplishing the EM-1 flight test," NASA acting Administrator Robert Lightfoot said.