A much-publicized congressional divide has developed over the administration’s proposed asteroid retrieval mission (ARM). ARM features a robotic capture of a small (few meters across) asteroid and its return to near-Earth (cislunar) space for human examination. Although there are mutterings that (predominantly) Republican opposition developed because a Democratic president proposed it, I believe that this “dust-up” comes from legitimate concerns over how this asteroid mission, without any serious thought or study, was adopted.
The idea to capture an asteroid and return it to cislunar space for examination came out of a 2012 Keck Institute of Space Studies workshop. Although NASA maintains a variety of advisory groups to analyze mission proposals and concepts, inexplicably few in the science or engineering community were given an opportunity to examine and comment on this scheme. While NASA claims that significant benefits will come from the asteroid retrieval mission, attendees considering the idea during a recent meeting of the Small Bodies Assessment Group (SBAG) expressed serious reservations about its feasibility and scientific value.
Many in the space community believe that the asteroid retrieval mission was proposed to paper over the embarrassing and expanding void left after the administration abandoned the Vision for Space Exploration effort to return to the Moon (a program with a history of strong bipartisan Congressional support). They believe that the new Orion/SLS spaceflight system under development currently lacks long-term, sustainable direction and a strategic goal. Confusion over what the administration sees as our national role in space has fanned the divide in space circles and left American space leadership in serious doubt.
After six decades of intense research of meteorites (hands-on study of small asteroids already captured by the Earth), we’ve acquired a comprehensive understanding of the accretion and evolution of the early Solar System. In addition, robotic missions have been sent to several asteroids and small bodies. From these studies, we’ve learned a great deal about the properties and characteristics of these objects. Some asteroids are rubble piles of loosely aggregated debris, while others appear to be largely intact solid rocks. All have experienced impact and are cratered, with landscapes similar to those observed on the Moon and most other planets. When contemplating the possible return of samples from a captured asteroid by the ARM, consider that in the meteorite collections of the world’s museums, we already possess more than 45,000 small samples of these near-Earth objects.
For years, both NASA and the National Science Foundation have been funding asteroid detection programs and observations. The result has been a multi-fold increase in our knowledge of the number and orbits of asteroids, particularly those that encounter Earth’s orbit around the Sun. Because of this long established effort, we possess a good catalog of the biggest (and most potentially dangerous) near-Earth objects. The idea that we can identify potentially hazardous objects and alter their trajectories in space, causing them to miss hitting the Earth, has been under consideration for some time. Several strategies to interdict asteroids have been studied, but to my knowledge, none involve bagging the asteroid and then moving it with solar electric rocket engines. Hazardous asteroids are simply too big (many kilometers across) for such an approach. Thus, as currently configured, the asteroid retrieval mission is not relevant to the problem of asteroid interdiction and the protection of the Earth from catastrophic impacts.
A variety of other alleged benefits from the asteroid retrieval mission likewise do not hold up to scrutiny. The claim that this mission will provide “deep space” flight experience is not unique to ARM – any flight to a destination beyond low Earth orbit gives us this experience. Someday we hope to be able to use the material resources of space, which includes asteroids, but the configuration and limitations of the Orion spacecraft prevent serious resource utilization experiments during the course of the ARM mission. The Orion has no laboratory or processing facilities nor sufficient electrical power to conduct resource extraction and processing experiments. The spacecraft cannot loiter in the vicinity of the retrieved asteroid for any significant length of time. These limitations preclude experimentation with different approaches to resource processing. The ARM mission will not establish or extend our permanent space faring infrastructure nor develop new technology. We’ve been using solar electric propulsion (SEP) for over two decades; the current Dawn mission to the asteroids Vesta and Ceres utilizes SEP.
Perhaps the most disturbing rationale for this manned mission is that in an era of increasingly limited federal funds, we have to “do something.” Such an attitude is amusing coming from those who supported the conclusions of the 2009 Augustine Report; that report outlined something called the “Flexible Path,” whereby we would not aim for a destination but rather, “develop technology” and choose where to go later. The argument that we must “do something” negates that strategy in a particularly indefensible way. Doing nothing is infinitely preferable to doing something when the “something” is a mission so transparently worthless as to bring the entire space effort into disrepute.
But there is another and more pertinent aspect against this rationale. I reject the idea that we cannot afford to go to the Moon. How you go is more important than how much money you spend. Several architecture studies published over the past few years have outlined affordable ways to return to the Moon. A renowned statement made during the presentation of the Augustine study was that America could afford to build the Orion CEV or a lunar lander, but not both simultaneously. As the lunar return effort already was an international partnership, perhaps the Europeans or Japanese would have been interested in building (and more importantly, funding) the lunar lander. This option (and several others designed to lower the cost of lunar return) was presented to (but ignored by) the Augustine committee.
On close examination, none of the claimed benefits of the proposed asteroid mission are valid. There is no rationale for this mission, beyond “flying a mission.” ARM is being sold as an “affordable” choice, however, estimates of low mission costs fly in the face of decades of experience with complex spacecraft and missions. The administration is working to sell this asteroid diversion mission as a new space accomplishment, though in truth, what they’re attempting to divert is public notice of their systematic dismantling of our civil space program. Given this mindset, we will remain Earth-bound indefinitely. Instead of capturing and retrieving an asteroid, we should establish a sustainable presence in cislunar space through resource utilization of the Moon’s known resources, thereby creating a permanent, national spaceflight capability. The next giant leap for mankind requires one small step by the Congress: a return to bipartisan political leadership for space through the re-adoption of the goals endorsed by the three previous Congresses – a return to the Moon.