Authors Take a Space Flight of Fancy
The year is 2061. The place, Halley’s comet.
In the weightlessness of outer space, an expedition of scientists and engineers maneuvers a landing craft onto the dirty icescape of this celestial visitor.
Quickly, they begin to tunnel into the comet and prepare to jolt it into an orbit near a space colony, where it will be mined for water, carbon dioxide and gaseous elements that would otherwise evaporate in its luminous tail.
Farfetched?
It is the plot of his latest science-fiction novel, but UC Irvine physicist Gregory Benford says man probably will have the technology to harness and mine comets for basic, life-sustaining elements when Halley’s comet returns in the 21st Century.
The key to future space exploration and long-term colonization will be a ready source of water, carbon dioxide, ammonia and methane, the light gaseous compounds known as “volatiles” that make up comets, says Benford, 45. He is an award-winning science-fiction writer and scientist whose specialties are high-energy astrophysics and plasma physics.
“Space colonies (will) need volatiles for all life processes, including food production and creation of biospheres, as well as for rocket fuel,” Benford says. “While lifting these compounds up from Earth is enormously expensive, they easily can be mined from comets.”
Stephen J. Edberg, an astronomer with the Jet Propulsion Laboratory in Pasadena and the International Halley Watch, said many things must be confirmed first about comets to know whether Benford’s theory will hold up.
“The biggest question to me is how do you hold onto this thing,” Edberg said. “We haven’t even seen the nucleus yet. We don’t know if you could land on it. If you did, would you sink right in and float to the center of it? We don’t know.”
Uncertainties aside, Edberg said, “It sounds like a pretty damn good idea to me. I wouldn’t try it with Halley’s, but there are other smaller comets out there.”
Even Benford and co-author David Brin, an award-winning science-fiction writer and comet specialist at the California Space Institute at UC San Diego, would concede that their novel, “Heart of the Comet,” is based on scant data about one of the least understood bodies in the solar system.
Comets, according to accepted theory, are thought to be primordial clusters of ice, rock and dust formed 4.6 billion years ago along with the solar system.
Data from two Soviet spacecraft passing within 5,600 miles of Halley’s comet in the last week reveal an elongated core surrounded by a dense cloud of fine dust particles, small rocks and boulders.
Scientists on Thursday were expected to get their closest look yet when the European spacecraft Giotto flew within 320 miles of the comet’s nucleus. Giotto could either lend scientific credence to Benford’s 10th novel or make it outdated even before it hits the bookstores this month.
“I don’t think it will be invalidated,” Benford said, adding that Soviet probes Vega 1 and Vega 2 have so far tended to confirm their fictional image of a comet.
“One, because we know the rest of the solar system is bone dry. Two, you can’t recycle light elements forever. So you need a supply to support manned outposts. And comets are energetically convenient to bring near colonies.”
The reason they are convenient, he explained, is that “comets are steerable; moons and planets are not.” Explosive evaporation at the surface would act “like a rocket blowing off gases all the time,” he said.
By directing the stream of gases with giant sheets or netting, Benford said, small movements of the comet could be controlled. Jolting it from an established orbit would require a more complex series of maneuvers making use of natural forces like the gravitational effect of passing by Jupiter.
Another Buck Rogers-esque way to change its path would involve firing electromagnetic guns from Halley’s surface when the comet is in the outer reaches of the solar system and is moving at its slowest.
All this would require living on the comet. Because of deadly radiation in space, home would be in tunnels bored below the surface.
Those underground chambers, which also would protect man from periodic, life-threatening solar storms, could be reused by inhabitants of space colonies as a sort of bomb shelter against those same storms, he said.
Just to be sure that they had the science down accurately, Benford and Brin submitted their manuscript to many of the nation’s top comet experts. One was Edberg’s colleague, Donald Yeomans, chairman of the International Halley Watch, who appears as a minor character. Yeomans and JPL astrodynamicist Louis D’Amario calculated the exact orbit of Halley on its next two swings around the sun in 2061 and 2137.
Asked if the eons-old orbit of Halley’s Comet wasn’t too integral to man’s history to disturb, Benford responded, “It’s more sacrilegious to harpoon whales.”
On the other hand, harnessing Halley requires a 90-year investment in their book. “So what you’d really want to do is capture one with a three- or four-year orbit,” Benford said. “Selecting Halley’s is just a romantic idea on our part.”
Besides, said 35-year-old Brin, a part-time researcher at the space institute in San Diego, “Halley will probably be a solar system park by then.”
The Giotto space probe plunged into Halley’s Comet, but it gave scientists a good look first.
