SAN FRANCISCO — Developing the capability to launch human missions to asteroids would aid humanity’s ability to foil a potentially devastating asteroid strike and help spur its march to Mars, a new report finds.
What is most needed to make manned asteroid missions possible, the report concludes, is a comprehensive survey of the near-Earth object (NEO) population, which would greatly aid planning efforts.
The new report, titled “Target NEO: Open Global Community NEO Workshop,” is anchored in views expressed by experts who gathered at George Washington University (GWU) in Washington in February. But this latest appraisal includes extensive peer review and refined findings from a number of follow-up meetings, both in the United States and abroad.
The key question posed by the GWU workshop: What information about NEOs is still needed to support a robust, sustainable human exploration program?
While this question prompted a variety of recommendations, a primary conclusion by the participants is the need for a space-based survey telescope to greatly expand the catalog of accessible asteroid targets for human exploration.
There is a growing list of stakeholders supportive of NEO exploration, said Paul Abell, lead scientist for planetary small bodies at the Astromaterials Research and Exploration Science Directorate of NASA’s Johnson Space Center in Houston.
“This report is timely,” Abell said in an interview.
Small bodies have become a magnet for multiple interest groups in the U.S. and abroad, Abell said, be they space scientists, astrobiologists, planetary defense planners or NEO specialists who eye the rocky worlds as resource nodes.
For example, NASA recently selected a mission called Osiris-Rex that will be the first U.S. mission to carry samples from an asteroid back to Earth.
Japanese space officials are moving forward on their Hayabusa 2 asteroid explorer. Russia is readying its Phobos-Grunt spacecraft to explore a moon of Mars, and Canada is pressing forward on its dual-purpose microsatellite, NEOSSat.
Then there are the new, surprising data flooding in from NASA’s Dawn probe that is taking a long look at Vesta, the second-largest object in the main asteroid belt between Mars and Jupiter.
“It shows you that every time we go places, we’re always surprised and there’s so much to learn,” Abell said. “That’s the fun part of science and exploration.”
The “Target NEO” report points out that programs and planned missions to asteroids may be leveraged for mutual benefit in terms of data exchange. It also recommends coordination with the European Space Agency and other space agencies on a planetary defense demonstration mission.
Steppingstones to Mars
As for dispatching astronauts to asteroids, the report envisions that a target NEO will need to be discovered several years in advance to provide enough lead time to deliver robotic precursor missions, plan the human mission and deliver the crew to the chosen destination.
Abell also said that piloted flight to a NEO would hone techniques that could enable an exploration mission to Mars.
Operating at an asteroid or Mars would be completely different from working at the Moon, on the space shuttle or aboard the international space station.
Both asteroids and Mars, for example, would have much greater lags in communication times. So deep-space missions would require the sharpening of true autonomy acumen, as well as a great deal of confidence in redundant hardware, deep-space propulsion, life support gear and radiation shielding.
A major report finding is that human spaceflight know-how — the body of data required to support the flinging of flesh outward to a NEO, a journey that would take many months roundtrip — “is severely limited at this time.”
Furthermore, behavioral health support and the psychological and sociological issues associated with a NEO-bound crew cramped up in relatively small quarters “are also significant concerns that increase the risk to the mission.”
Overall, the report flags the fact that deep-space missions do not afford the abort opportunities and psychological comfort provided by rapid return to our home planet — a hallmark of missions in cis-lunar space, particularly those carried out in low Earth orbit.
The bottom line: Far more work is necessary to support human sojourns outside of the Earth’s protective magnetosphere. A biological bugaboo is the acute and long-term physiological effects of space radiation on the human body.
“We will soon begin writing the next chapter of our human spaceflight saga, and a near-Earth object may be humanity’s first destination beyond the Earth-Moon system,” said Brent Barbee, editor of the report and a flight dynamics engineer at NASA’s Goddard Space Flight Center in Greenbelt, Md. “There are many decisions to be made regarding how we approach that challenge.”
Barbee said that he and his colleagues hope the new workshop report will be a valuable reference that helps inform critical decision-making. And there are a number of decisions forthcoming to help focus on NEO visitation questions.
One of the most important messages in the report, Barbee said, is the wisdom of deploying a space-based survey telescope capable of detecting a significant portion of the undiscovered NEO population.
While there are several capable NEO survey ideas that exist at varying degrees of maturity, the report recommends that more study of these potential concepts is necessary to objectively scrutinize them against a common set of requirements and in a way that permits direct cost comparison.
“Only a few of the currently known NEOs offer potentially feasible human mission opportunities during the 2025-2030 timeframe, and those NEOs are very small in size. A space-based survey has the capacity to escape the geometrical observing constraints which hinder ground-based surveys and thus discover many more NEOs relatively quickly, including a better set of candidate NEO destinations,” Barbee said. “Those discoveries would simultaneously benefit the science, exploration and planetary defense communities.”