Asteroid Retrieval Feasibility Study
Creators: name: Brophy, John
name: Culick, Fred
name: Friedman, Louis
Publisher: name: Keck Institute for Space Studies
Year: 2012

description: This report describes the results of a study sponsored by the Keck Institute for Space Studies (KISS)
to investigate the feasibility of identifying, robotically capturing, and returning an entire Near-Earth
Asteroid (NEA) to the vicinity of the Earth by the middle of the next decade. The KISS study was
performed by people from Ames Research Center, Glenn Research Center, Goddard Space Flight
Center, Jet Propulsion Laboratory, Johnson Space Center, Langley Research Center, the California
Institute of Technology, Carnegie Mellon, Harvard University, the Naval Postgraduate School,
University of California at Los Angeles, University of California at Santa Cruz, University of Southern
California, Arkyd Astronautics, Inc., The Planetary Society, the B612 Foundation, and the Florida
Institute for Human and Machine Cognition. The feasibility of an asteroid retrieval mission hinges on
finding an overlap between the smallest NEAs that could be reasonably discovered and characterized
and the largest NEAs that could be captured and transported in a reasonable flight time. This overlap
appears to be centered on NEAs roughly 7 m in diameter corresponding to masses in the range of
250,000 kg to 1,000,000 kg. To put this in perspective, the Apollo program returned 382 kg of Moon
rocks in six missions and the OSIRIS-REx mission proposes to return at least 60 grams of surface
material from a NEA by 2023. The present study indicates that it would be possible to return a
~500,000-kg NEA to high lunar orbit by around 2025.
The idea of exploiting the natural resources of asteroids dates back over a hundred years, but only
now has the technology become available to make this idea a reality. The feasibility is enabled by three
key developments: the ability to discover and characterize an adequate number of sufficiently small
near-Earth asteroids for capture and return; the ability to implement sufficiently powerful solar electric
propulsion systems to enable transportation of the captured NEA; and the proposed human presence in
cislunar space in the 2020s enabling exploration and exploitation of the returned NEA.
Placing a 500-t asteroid in high lunar orbit would provide a unique, meaningful, and affordable
destination for astronaut crews in the next decade. This disruptive capability would have a positive
impact on a wide range of the nation’s human space exploration interests. It would provide a high-value
target in cislunar space that would require a human presence to take full advantage of this new resource.
It would offer an affordable path to providing operational experience with astronauts working around
and with a NEA that could feed forward to much longer duration human missions to larger NEAs in
deep space. It would provide an affordable path to meeting the nation’s goal of sending astronauts to a
near-Earth object by 2025. It represents a new synergy between robotic and human missions in which
robotic spacecraft retrieve significant quantities of valuable resources for exploitation by astronaut crews
to enable human exploration farther out into the solar system. A key example of this is that water or
other material extracted from a returned, volatile-rich NEA could be used to provide affordable
shielding against galactic cosmic rays. The extracted water could also be used for propellant to transport
the shielded habitat. These activities could jump-start an entire in situ resource utilization (ISRU)
industry. The availability of a multi-hundred-ton asteroid in lunar orbit could also stimulate the
expansion of international cooperation in space as agencies work together to determine how to sample
and process this raw material. The capture, transportation, examination, and dissection of an entire NEA
would provide valuable information for planetary defense activities that may someday have to deflect a
much larger near-Earth object. Finally, placing a NEA in lunar orbit would provide a new capability for
human exploration not seen since Apollo. Such an achievement has the potential to inspire a nation. It
would be mankind’s first attempt at modifying the heavens to enable the permanent settlement of
humans in space.
The report that follows outlines the observation campaign necessary to discover and characterize
NEAs with the right combination of physical and orbital characteristics that make them attractive targets
for return. It suggests that with the right ground-based observation campaign approximately five
attractive targets per year could be discovered and adequately characterized. The report also provides a
conceptual design of a flight system with the capability to rendezvous with a NEA in deep space,
perform in situ characterization of the object and subsequently capture it, de-spin it, and transport it to
lunar orbit in a total flight time of 6 to 10 years. The transportation capability would be enabled by a
~40-kW solar electric propulsion system with a specific impulse of 3,000 s. Significantly, the entire
flight system could be launched to low-Earth orbit on a single Atlas V-class launch vehicle. With an
initial mass to low-Earth orbit (IMLEO) of 18,000 kg, the subsequent delivery of a 500-t asteroid to
lunar orbit represents a mass amplification factor of about 28-to-1. That is, 28 times the mass launched
to LEO would be delivered to high lunar orbit, where it would be energetically in a favorable location to
support human exploration beyond cislunar space. Longer flight times, higher power SEP systems, or a
target asteroid in a particularly favorable orbit could increase the mass amplification factor from 28-to-1
to 70-to-1 or greater. The NASA GRC COMPASS team estimated the full life-cycle cost of an asteroid
capture and return mission at ~$2.6B.