NASA is mandated with the task of flying humans to an asteroid by the mid-2020s. But such a mission would be fraught with technical challenges, danger and — you guessed it — expense. So, rather than blasting a team of astronauts into deep space to play a game of “catch” with a speeding lump of space rock, the US space agency will be given approval for a more slimline option — NASA will send a robot on an asteroid fishing expedition.

A hooked asteroid will be tamed and delivered to a rendezvous point of our choosing (much closer to home) to allow a manned expedition easy access. This wouldn’t only be great for science, it could also drive significant technologies intended for robotic asteroid deflection and, perhaps, mining techniques.

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The asteroid capture concept has won over the White House Office of Science and Technology Policy, which has given it approval for the 2014 fiscal year to begin work. The mission could launch as early as 2017. Discovery News received confirmation from a White House official that the plan, revealed by comments made by Sen. Bill Nelson (D-Fla.) on Friday, will receive a $100 million allocation of NASA’s budget. Presented to Congress on Wednesday, the funds will go toward identifying asteroid candidates for capture. The news was first leaked last month by Aviation Week.

“It really is a clever concept,” Nelson said during Friday’s press conference in Orlando, Fla. “Go find your ideal candidate for an asteroid. Go get it robotically and bring it back.”

So, how will this asteroid retrieval plan work?

The feasibility of identifying an asteroid with the exact orbital characteristics for a manned mission has been under much scrutiny since Obama laid out NASA’s asteroid challenge. Not only would the asteroid need to be of the near-Earth category, it would need to come close enough to allow a manned expedition a decent rendezvous window to carry out useful science and get home safely. Naturally, such a deep-space chase would be wrought with danger for the crew.

In 2011, the Keck Institute for Space Studies (KISS) at the California Institute of Technology (Caltech) assembled a team of planetary scientists, astronauts and asteroid experts in an effort to minimize the costs and risks associated with an asteroid mission, while maximizing scientific gains. The study’s solution was to identify a small space rock for robotic capture and study by a manned expedition.

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The study’s asteroid, ideally measuring 7 meters across with a mass of 500,000 kilograms (550 tons), would be captured by a spacecraft using a deployable capture bag (pictured top). Once secured, the spacecraft would steer the mass toward a region of gravitational stability known as the Earth-moon Lagrangian (EML2) point. This gravitational “island” has also been eyed as the potential location for a lunar farside space station — if you can park an asteroid there, a manned outpost could even use resources on a captured asteroid to sustain a station or act as a mining staging post, theoretically.

With the asteroid locked in its gravitational parking lot, NASA will launch a manned expedition to the tamed asteroid, allowing unlimited access to a scientifically bountiful objective.

Before the Keck plan, it was estimated that a 2025 asteroid rendezvous mission could take up to a year to complete; the Keck proposal would slash the human mission duration to weeks or even days. It would also be safer for the human crew and much cheaper — coming in at an estimated total cost of $2.65 billion. The Orion crew vehicle, that is currently undergoing development, launched atop NASA’s next-generation Space Launch System (SLS), would provide the astronaut “shuttle service” to the asteroid. (The cost of developing Orion and SLS are a part of a separate allocation of NASA funds.)

The official confirmation of funds being allocated for this plan comes shortly after NASA Administrator Charlie Bolden went on the record to say that the US space agency wouldn’t lead a manned mission to the moon in his lifetime.

“NASA is not going to the Moon with a human as a primary project probably in my lifetime. And the reason is, we can only do so many things.” Bolden said at the Space Studies Board and the Aeronautics and Space Engineering Board in Washington on Thursday. Bolden emphasized that, under his watch, NASA would pursue the human-asteroid mission as a stepping stone to the far grander objective of spearheading a mission to Mars. The moon, he says, doesn’t work into that equation — although NASA would be happy to “be involved” in a lunar mission should another nation take the lead.

To many, capturing a small asteroid and bringing it back to the Earth-moon system may seem like a “soft option,” but it would fulfill NASA’s mid-term aim of sending astronauts to an asteroid. However, in this case, I believe the most exciting component will actually be the robotic “capture” of a small asteroid.

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In light of the Feb. 15 fireball over the Russian city of Chelyabinsk, there have been increased calls for improved asteroid detection methods. Although the vast majority of extinction-level near-Earth asteroids have been identified and are not thought to pose a danger to Earth for the foreseeable future, smaller asteroid hazards are out there, hiding below the resolution limit of our space hazard observatories. The Chelyabinsk meteor exploded in the atmosphere, pummeling the ground with powerful shock waves that injured over 1,500 people. That particular asteroid measured only 17 to 20 meters across and had a mass of 11,000 tons before it hit the atmosphere.

The Keck study target is half the size of the Chelyabinsk asteroid, but the unmanned capture and control technique required to make the mission possible could be an invaluable prototype ahead of a larger scale asteroid impact mitigation system. Also, learning about the composition of a small asteroid will inevitably help us characterize its larger cousins. Sending astronauts to the Earth-moon L2 point to study the captured space rock would be the proof of concept that humans can indeed deflect small asteroids and use them for followup studies. The embryonic asteroid mining industry will no doubt be watching these technological developments with great interest.

Sadly, it looks as if the human component of the “asteroid mission” has been relegated to second fiddle. Although this manned asteroid mission will still send humans further away from the Earth than ever before (well beyond lunar orbit) and will inevitably push developments in spacecraft design, contributing to the long-term NASA goal of getting astronaut boots onto Mars, this plan lacks the “wow” factor of a big-budget big-asteroid deep space rendezvous mission. In this risk-adverse, low-budget manned spaceflight arena, it might be the only realistic option on the table for NASA.

Image: Artist’s impression of the robotic asteroid capture spacecraft. Credit: Keck Institute for Space Studies