WASHINGTON — NASA has decided to push back the launch of the robotic part of its Asteroid Redirect Mission (ARM) by a year to late 2021 to allow for more time for studies of the mission concept and its key technologies, an agency official said March 2.

At a meeting of the NASA Advisory Council’s human exploration and operations committee here, Michele Gates, program director for ARM at NASA Headquarters, said the delay in the robotic part of ARM would also postpone a later crewed mission to the boulder the robotic mission would return to cislunar space.

“That is intended to enable the early design study work for the spacecraft bus,” Gates said of the delay in the robotic mission launch. It will, she added, also allow for more planning work on the mission ahead of later reviews.

Gates said the delay specifically will stretch out ongoing work in the robotic mission’s phase A, which will culminate in a review known as Key Decision Point B planned for this summer. NASA will also extend phase B, which will start after that review. “We think that buys us some risk buy-down,” she said of the extended schedule.

Under the new schedule, the ARM robotic mission would launch in December 2021, instead of December 2020 as previously planned. That would delay later crewed mission by a year as well, to December 2026. “We understand this, we’re accepting this, and we’re folding that into our early preformulation work that we’re beginning to do” on the crewed mission, she said.

That delay will not affect the mission’s cost. Gates said the robotic mission is still using a cost cap of $1.25 billion, excluding launch and operations. A formal cost and schedule estimate has yet to be developed for the robotic element of ARM.

NASA has been working on several parts of the robotic spacecraft, in many cases with industry. In January, NASA’s Jet Propulsion Laboratory awarded contracts to Boeing Phantom Works, Lockheed Martin Space Systems, Orbital ATK and Space Systems Loral to study designs for the spacecraft’s bus, taking advantage of systems already commercially available. Those study contracts are scheduled to last six months and are valued at about $1 million each.

NASA’s Space Technology Mission Directorate is also preparing to award a contract for the electric propulsion system the ARM robotic spacecraft will use to travel to and from the asteroid. Gates said the agency is evaluating proposals and expects to make an award by late spring.

The latest delay is not the first time NASA has pushed back either the robotic or crewed elements of ARM. When the agency first announced plans for ARM in 2013, it projected launching the robotic mission to as early as 2017, redirecting the asteroid into cislunar space by 2021. The asteroid would then be visited by astronauts on Exploration Mission 2 (EM-2), the first crewed Orion mission then planned for launch in 2021.

While current schedules have delayed the launch of EM-2 to at late as 2023, NASA no longer expects to send astronauts to an asteroid on that mission or ones immediately thereafter. “Exploration Mission 5 or 6 would be the asteroid crewed mission,” said Bill Gerstenmaier, NASA associate administrator for human exploration and operations, said in an presentation to the committee earlier in the day.