Nasa lays out wild plan to corral asteroid

US agency asks Congress to fund audacious US$2.6b mission to capture small asteroid and drag it to a place where astronauts can visit it

PUBLISHED : Sunday, 07 April, 2013, 12:00am
UPDATED : Sunday, 07 April, 2013, 6:08am


It has been a while since Nasa has been known as a place for space cowboys.

But the nickname could make a comeback if the US space agency can pull off a new mission that even supporters admit sounds buck-wild: corralling an asteroid with a spacecraft so future astronauts can go visit it.

Obama administration officials said the operation had the potential to jump-start a human exploration programme that had floundered since the 2011 retirement of the space shuttle. The White House will include US$105 million to begin work on the project in its 2014 budget.

"This mission will send humans farther than they have ever been before, and [it would be the] first ever redirection of [an] asteroid for exploration and sampling," Nasa officials said in a mission outline presented to Congress last week.

If lawmakers approve, the plan calls on Nasa to launch an unmanned spacecraft as soon as 2017 on a mission to "capture" a small asteroid and drag it near the moon, possibly to a point roughly 446,000 kilometres from earth where competing gravitational forces would allow it to "sit" there.

Astronauts, riding a new Nasa rocket and capsule, then would visit the asteroid as early as 2021.

The plan faces several hurdles - and not just the rocket science.

Foremost is convincing Congress, and a sceptical public, that spending an estimated US$2.6 billion on the mission is a worthwhile investment. That is in addition to the US$3 billion annually that Nasa already devotes to building its new Space Launch System rocket and Orion capsule.

"[The mission] is [as] audacious as sending humans to the moon," Lou Friedman, who co-authored a report last year that suggested the idea. "It will restore confidence in America's technological capability and Nasa's can-do spirit."

As proposed, the asteroid mission would begin with research - US$78 million in 2014 to begin design work on the robotic spacecraft that would capture the asteroid, and an additional US$27 million to begin searching the cosmos for an asteroid to grab. The ideal rock would be six to nine metres in diameter and weigh 500 tonnes.

A study done last year by the Keck Institute for Space Studies, a think tank based at the California Institute of Technology, envisioned a small probe that would launch aboard an Atlas V rocket. Once in space, it would use its solar-electric engines to cruise to an asteroid and then attempt to capture it in a cup-shaped container described as an "inflatable asteroid capture bag."

Even Nasa admits this stage would be the "most technically challenging aspect of the mission", as the asteroid would be travelling at thousands of kilometres per hour and spinning rapidly. The probe would have to first match the asteroid's speed and spin. It would then position itself so that the asteroid drifts into its storage space - and pull it shut like a drawstring bag.

The probe would then tug the asteroid to an orbit near the moon to await a visit by Nasa astronauts. The Keck study estimated the whole operation could take six to 10 years, although Nasa officials insist they can do it sooner to meet their 2021 deadline of a human mission.

But there's still the question of why. From Nasa's perspective, the mission checks several boxes.

First, it gives purpose to the huge new SLS rocket and Orion capsule that are costing Nasa about US$3 billion a year to build, with a first test flight scheduled no earlier than 2017. The SLS has been criticised as a "rocket to nowhere" - as its mission has been defined only vaguely since the programme's 2011 unveiling - and this would give it a goal.