Washington: NASA is seeking ideas from US companies for a spacecraft design that can be used for its ambitious Asteroid Redirect Mission (ARM) and a robotic satellite servicing mission in low-Earth orbit.

The US space agency plans to launch the unmanned ARM in early 2020s. This will use a robotic spacecraft to capture a large boulder from the surface of a near-Earth asteroid and move it into a stable orbit around the moon for exploration by astronauts, the US space agency said in a statement.

"The call for ideas from our industry partners is another important milestone for the Asteroid Redirect Mission, a critical capability demonstration mission that's part of our stepping stone approach for sending American astronauts to Mars in the 2030s," explained NASA associate administrator Robert Lightfoot.

NASA has also been studying the "Restore-L" mission concept. In this, a spacecraft would use dexterous robotic systems to grapple and refuel a government satellite in low-Earth orbit.

"Restore-L" will bring operational status capabilities needed for future commercial satellite servicing by demonstrating technologies and reducing risk.

Following its rendezvous and touchdown with the target asteroid, the uncrewed ARM spacecraft will deploy robotic arms to capture a large boulder from its surface.

It will then begin a multi-year journey to redirect the boulder into orbit around the moon. Throughout its mission, the ARM robotic spacecraft will test a number of capabilities needed for future human missions.