Space watchers, adjust your calendars. NASA says that the next Orion mission won't carry astronauts after all. In February, the agency's Acting Administrator Robert Lightfoot asked for a feasibility study on the possibility of moving the timetable forward and making Exploration Mission-1 (EM-1) a manned mission. However, after weighing the project's technical factors and risks, NASA has decided to keep with the original plan for an unmanned EM-1, with the first manned mission to launch in 2021.

The second flight of the Orion crew capsule, EM-1 is scheduled to lift off in 2019 atop the Space Launch System rocket. The purpose of the mission is to send the spacecraft and its service module on a translunar trajectory, where it will loop around the Moon and then return to Earth for a splashdown at sea. This test is intended to act as a precursor to a new generation of manned deep space missions to cislunar orbit and, eventually, Mars.

The February request by the Trump administration was made in hopes of picking up the pace of NASA's return to manned missions, which it abandoned with the retirement of the Space Shuttle in 2011. NASA says that it looked at all the relevant factors and weighed them against the risks. The study found that it was technically feasible to modify the Orion in its present form and alter the mission plan to accommodate a crew, but that the upgrades would be too difficult in the time required to warrant the possible dangers.

According to a NASA statement, the findings of the study will be used to improve pre-flight development of Orion for EM-1.

"We're considering additional ground testing of the heat shield prior to EM-1 as well as the possibility of advancing the ascent abort test for the Orion launch abort system based on findings from the study," says William Gerstenmaier, associate administrator for NASA's Human Exploration and Operations Mission Directorate. "Conducting these tests in advance of EM-1 would provide additional data that will advance our systems knowledge faster and possibly improve the robustness of the overall plan for sending humans into deep space."