NASA has put the word out to scientists, engineers, stargazers and dreamers in the U.S. and around the world -- the agency needs help capturing an asteroid and moving it into the moon's orbit so that it can be studied as part of efforts to protect the Earth from dangerous space rocks.

NASA scientists held a meeting in Washington, D.C. Tuesday, to outline the goals of the asteroid initiative which range from tracking and observing asteroids, to constructing robotics and solving the practical challenges of getting humans deep into space, towing an asteroid and defending the Earth from rogue space rocks.

The space agency issued a Request for Information (RFI), seeking new ideas and strategies for the ambitious mission, which comes after several asteroids came in relatively close proximity to Earth in recent months.

"Basically, what we're going to do is capture and redirect a seven- to 10-metre, approximately 500-ton near-Earth asteroid to a stable orbit in trans-lunar space, probably a deep retrograde orbit around the Moon. And this will enable an astronaut mission to the asteroid as early as 2021," said William Gerstenmaier, NASA’s associate administrator of human explorations and operations.

He outlined a hypothetical scenario involving the asteroid 2009BD, which NASA put together as a test scenario modelling whether such an initiative would even be possible.

In order to reach the asteroid it would take an unmanned, robotic vehicle roughly 1.8 years, or 671 days of travel time. Then the craft would essentially attach to the object and "redirect" its trajectory towards the moon.

"We take advantage of the fact it's coming back so we don't have to change velocity in that direction,” Gerstenmaier said. “All we have to do is redirect it such that we can use the Earth's gravity, use the lunar gravity to add some more delta velocity to the object and the space craft and then we can put it into a deep retrograde orbit around the moon.”

Once the asteroid is safely in the moon's orbit, astronauts could visit it numerous times, carry out spacewalks and conduct tests, collect samples for possible future mining missions, and study how an asteroid hurtling towards Earth could be redirected away from the planet.

However, Gerstenmaier and his colleagues conceded the concept is still in its very early stages, and NASA is open to any and all suggestions.

"We look to the creativity we have here in this audience to helps us find ways to do this in a slightly different manner," he said.

Another option would be to travel to a larger asteroid, possibly hundreds of kilometres in diameter, to test whether such a massive object could be redirected by a spacecraft, essentially throwing if off course and away from Earth.

The space craft could then be re-launched from the asteroid in order to search for a boulder on the lunar? surface, which could be launched into space and directed back to the moon.

Following are some of the goals set out in the RFI, which are also expected to support efforts to plan a future human mission to Mars:

  • Testing and development of a Solar Electric Propulsion system -- the only means of travel that could propel a space ship far enough to reach an asteroid and redirect its course.
  • To rendezvous, grapple and interact with an asteroid, as well as testing of deep space navigation and communications.
  • To learn more about human operations and risk management beyond low earth orbit.
  • To test strategies for storing or caching equipment for future return missions.