By Leonard David
October 15, 2003

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BOULDER, Colorado -- In the grand cosmic scheme of things, it's only a matter of time. Our planet is bound to tangle with an Earth-crossing asteroid, an event sure to make a mess. Some of these space rocks could demolish a city. Other monster boulders, the really big bruisers, could snuff out our civilization.

But why be at the mercy of a menacing asteroid that has Earth in its cross hairs? Now an expert team of astronauts and space scientists has blueprinted a safety strategy for Earth: an asteroid tugboat. The group says NASA is already working on the right recipe of technologies to make the tug a reality. It would be the greatest public safety project in history. Furthermore, they propose a mission to demonstrate the asteroid-tug concept by 2015.

Details of the asteroid tug are unveiled in the November 2003 issue of Scientific American.

Lead author of the article is former astronaut, Rusty Schweickart, Apollo 9's lunar module pilot that put the Moon landing craft through its paces high above Earth in March 1969. Other contributors are Piet Hut, Professor of Interdisciplinary Studies at the Institute for Advanced Study in Princeton, New Jersey, and asteroid specialist, Clark Chapman of the Southwest Research Institute here in Boulder.

One more co-author is NASA astronaut Edward Lu. He is now resident onboard the International Space Station and, in fact, e-mailed final article edits on behalf of his fellow writers while circling Earth.

The asteroid tug test project is dubbed the B612 mission. That's the name of the asteroid in The Little Prince, the well-known young person's book by Antoine de St. Exupery. In fact, late last year, Schweickart, Lu, Hut and Chapman formed the B612 Foundation, a nonprofit group dedicated to developing and demonstrating the capability to deflect asteroids from Earth.

The premise behind the proposal, however, is no child's play. It's a way to ward off the doomsday rock that will sooner or later terrorize humanity.

Ugly date with Earth

Over the years, numbers of schemes to deal with bully asteroids have been proposed. Among them is blasting the beast to smithereens via a nuclear bomb. Another thought is planting a nuclear device on one side of the asteroid, then detonating the bomb to accelerate the space rock slightly in the opposite direction.

"The problem, however, is that the results are neither predictable nor controllable," Schweickart and his colleagues suggest. Also, such an explosion could split the asteroid into pieces, leaving multiple headaches of heavenly flotsam.

Then there's the kamikaze approach. Just crash a large robotic spacecraft into a worrisome asteroid at high speed. This too has its problems. Namely, you could just spin the body or knock off a small chip.

Other ideas are reviewed by the B612 think team and are highlighted in the Scientific American article. In their view, an asteroid is a "push over"... push it just enough to miss an ugly date with Earth.

Given enough warning time, an asteroid tugboat could nestle up to the mini-world, then provide long stints of gentle pressure. The tug would nudge the asteroid ever so slightly, but enough to shift the space rock's orbit so an Earth collision is averted.

Mission possible

The B612 test mission to deflect an asteroid could use Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engines. The VASIMR propulsion unit employs radio waves to ionize a gas and accelerate the plasma to even higher exhaust velocities. Veteran shuttle astronaut, Franklin Chang-Diaz, is exploring this novel, low-thrust propulsion technology.

Other equipment ideal for steering into the B612 project is scattered throughout NASA. Specifically, the space agency's Prometheus Project to design a space-rated nuclear reactor is a plus for any asteroid deflection scheme. Work is underway for a Prometheus flagship mission -- the Jupiter Icy Moons Orbiter (JIMO). Hardware stemming from JIMO, the nuclear power plant, radiator panels, a lengthy truss, and other equipment could help nurture the asteroid tug into being.

The practice B612 mission would verify maneuvering around a target asteroid, rendezvousing with and then attaching itself to the body. No easy set of job tasks.

Additionally, the tug would have to hold tight to its target asteroid. Procedures to deal with a spinning body would have to be ironed out. Once secure to the space rock -- some 655 feet (200-meters) wide -- the tug must use onboard engines for months to accelerate the asteroid in the desired direction.

According to Schweickart and his fellow asteroid tug advocates, the training mission would have a price tag of about $1 billion. They believe that this extraterrestrial exercise could be accomplished by 2015.

"By practicing an asteroid deflection, the B612 mission would show whether the asteroid-tug concept is feasible and, if so, how it should be refined in the event of a real impact threat," the study team writes.

Schweickart told SPACE.com that the B612 proposal is meant to educate public and political communities to the fact that Earth-approaching asteroids are a natural, environmental threat. "Unlike earthquakes, hurricanes, etc., we can actually do something about them. The capability to take this action is within reach of today's -- or tomorrow's -- technology," he said.

Schweickart said the cost of a trial-run asteroid tug mission is quite modest and well within the capability of the NASA budget to handle.

"However, the expenditure necessary to establish an operational system it will require both money and international coordination," Schweickart added, "and both will require a level of determination and commitment that may be hard to come by without strong and clear demand by the general public."

False alarms

Just how much serious attention can the B612 proposal hope to garner?

One factor that might cause more a yawn than action is the number of on-again/off-again threats from the sky. Those are the already numerous predictions and projections that later turned out not to be sure bets.

"Of course, we want our response to the impact threat to be part of a serious, objective approach to a considered evaluation of what the threat is," explains asteroid specialist, Clark Chapman.

"So we don't like the irresponsible treatment of the threat by some individuals and some -- especially British -- news media, although we understand the psychological difficulties of dealing with tiny probabilities of horrible events," Chapman said. On the other hand, he noted that "any news is good news".

"I am not specifically aware of important decision-makers holding views that have explicitly changed -- in either direction -- as a result of the false alarms," Chapman explained.

Wanted: serious consideration

The general message from B612, Chapman concluded, is to try and develop, with private funds, an exciting and important demonstration project that will robustly bring everyone up the learning curve of what to do if a threatening Near Earth Object is eventually found to be heading Earth's way.

"We hope that public concerns about this issue can be translated into real financial contributions to bring these concepts to a point where we could expect serious consideration by one or more space agencies...agencies that have not yet officially put asteroid mitigation into their plans," Chapman noted.

Chapman said that NASA's current Prometheus Project looks like an approach to deep space missions that would be particularly well suited to the B612 proposal.

"Obviously, beyond the mere demonstration of engineering that could conceivably 'save the planet' -- or at least a small part of the planet -- there would be dramatic opportunities to learn about how to deal with a nearly gravity-free body in space," Chapman said, "both to scientifically study asteroids and meteorite parent bodies and to consider eventual asteroid mining operations."

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