Outside experts are responding to NASA's call to lasso an asteroid, providing the agency's Asteroid Retrieval Mission (ARM) planners with new momentum for the two-phase strategy to resume U.S. human deep-space exploration while demonstrating capabilities to find and deflect asteroids that pose an impact threat to Earth.

NASA's 2014 budget plans include $105 million to ramp up a notional scheme for the 2018 launch of a robotic spacecraft that would corral a yet-to-be-selected asteroid in the 5-10-meter (16.5-33-ft.), 500-metric-ton range. Once captured, the asteroid would be maneuvered into a distant, stable, retrograde orbit around the Moon. Astronauts launched on the first piloted test flight of the Orion/Space Launch System crew exploration vehicle/heavy-lift rocket combination would rendezvous with the asteroid over a three-week mission, perhaps as early as 2021.

NASA recently concluded an Asteroid Initiative Idea Synthesis workshop at the agency's Lunar Planetary Institute focused on 96 submissions from small businesses, traditional aerospace companies, NASA's international partners and other government agencies in response to a June request for proposals. The agency is seeking ideas for developing an asteroid-deflection capability as well as a road map for future human deep-space exploration that would stretch to Mars by the mid-2030s. The workshop drew 138 participants for 79 presentations across a half-dozen key ARM fronts: asteroid observation, capture mechanisms, redirection and deflection, astronaut crew systems, strategic partnering, and greater public engagement.

The proposed initiative, which has no set cost or strong congressional backing yet, would start with the launch of a robotic spacecraft developed to capture a target asteroid, then move it into a retrograde orbit around the Moon. Two astronauts aboard the Orion crew exploration vehicle would rendezvous and dock with the capture craft.

One challenge for the mission will be avoiding the “ride 'em cowboy” moments that could break up a fragile target or damage the capture spacecraft. “Basically, the spin state of the target dominates the capture process,” says Brian Wilcox of NASA's Jet Propulsion Laboratory and lead for that phase of the agency's ARM reference mission. “If the target was not spinning, most people would agree the process is not that challenging a task. It's the spin and the tumbling that are really the key issues.”

The composition of a relatively small asteroid that is solid and fine-grained like a dirt clod, or a rubble pile collection of larger fragments, ranks close behind as a mission concern. Like the spin rate, composition may be difficult to characterize until NASA's robotic capture craft pulls alongside. Anything less than a solid body, turning or tumbling at 1 rpm or more, becomes a major challenge, Wilcox says.

NASA's reference mission would rendezvous and then extend an inflatable structure around the asteroid. Wedge-shaped internal air bags would fill to control and stop any spin and tumble before the spacecraft treks back to the Moon.

The workshop featured plenty of advice on—and a range of alternatives to—the bag-and-cinch strategy that is the agency's current baseline. They range from planting and extending long tethers from the surface of an uncontrolled asteroid to embracing the space rock with long inflatable booms or big robotic fingers. More than one-third of the proposals selected for discussion dealt with ARM's robotic-capture phase.

Two outlined proposals would equip the capture craft with devices to plant a reeled tether up to 5 km (3 mi.) long on the asteroid's surface. Once on the surface, the tether could be extended to slowly damp out the rotations.

One presentation, by Harold Gerrish of NASA's Marshall Space Flight Center, shares a heritage with space shuttle tethered-satellite missions flown in 1992 and 1996. Tethers Unlimited, of Bothell, Wash., proposed the use of free-flying CubeSats to deploy nets and tethers for capture and control after the primary spacecraft rendezvous with the asteroid target.

Northrop Grumman offered another strategy in which a capture craft is equipped with sensors, guidance and propulsion to characterize and match the motion of the target before deploying two clamshell-like AstroMesh capture panels. After enclosing the asteroid, internal webbing would secure it for the lunar leg of the mission.

Canada's MDA Corp. drew on the company's experience with the space shuttle's robot arm to propose a 3-5-fingered capture mechanism. The robotic fingers could be enhanced with inflatables to clamp and secure the ARM mission target, whether it is a solid object or a collection of asteroid fragments, says company representative Paul Fulford.

In addition to asteroid taming, companies are building new business relationships to compete for the mission. Planetary Resources Inc., the startup asteroid mining company, and NASA have formed the first public/private partnership under the space agency's Asteroid Grand Challenge (AGC) initiative to accelerate the search for near-Earth objects (NEO) that pose a collision threat by using government sky surveys and crowd-sourced algorithms. The known asteroids in the Solar System number 620,000, which is estimated to be less than 1% of the total.

Under a non-reimbursable Space Act Agreement, Planetary Resources will attempt to increase the total by guiding crowd-sourcing challenges and extending the online availability of NASA-funded sky survey data. NASA will develop and manage the competitions as well as assess the value of the most promising algorithm submissions.

The initial competition, based on the Asteroid Zoo platform from Planetary Resources and Zooniverse, is planned for early 2014.

Technologies drawn from the two ventures would set the stage for a human Mars mission in the mid-2030s while expanding asteroid awareness using “citizen science” and developing deflection capabilities.

“This partnership uses NASA resources in innovative ways,” says Lindley Johnson, NASA's NEO program executive.

After its 2009 founding, Planetary Resources carried out a successful Kickstarter campaign, raising more than $1.5 million from 18,000 contributors to finance Arkyd, a space telescope project. The private observatory will search for near-Earth asteroids rich in water, precious metals and other potential resources that could fuel a space economy. The company's investors include Google's CEO, Larry Page, and executive chairman, Eric Schmidt

All data developed and used by the AGC will be open-source and publicly available.

“While improving the algorithms to detect NEOs helps gain more data, additional surveys, telescopes and capability put to the search will also assist in completing the task of compiling a comprehensive open-source catalog,” says Chris Lewicki, president and chief engineer of Bellevue, Wash., based Planetary Resources.

Plans for an industry day in March 2014 that would follow the White House release of the 2015 federal budget proposal, seem far out for many of the workshop participants, who had already waited more than six weeks longer than expected for the workshop due to the government shutdown. “We do need to think about having engagement before March,” says Michele Gates, chair of the workshop and a senior technical advisor to NASA's Human Exploration and Operations Directorate. “We will definitely take the feedback and consider what we can do sooner.”