By Robert Roy Britt
"Give me a place to stand, and I will move the Earth."
-- Archimedes, circa 235 BC
For a long time now, Earthlings have been threatening to move heaven and Earth in order to get this or that accomplished. Politicians promise to do so before every election. Moms seem to manage, at least metaphorically, to do it every day. Now a group of scientists says it could be done for real.
Well, heaven might have to stay put. But with existing technology, some advance planning and a little orbital energy, courtesy of a redirected asteroid, Earth's distance from the Sun could be increased by 50 percent in just a few billion years.
It's a scheme that could save the planet, at least for a while. Because if Earth stays in its current orbit, we are doomed.
Hot death
Just as sure as the Sun comes up every morning, it is scheduled to die. Experts give it some 7 billion years, when it will turn into a bloated red giant. As the name implies, a red giant is a star swelled to gargantuan proportions. Earth would be first engulfed in heat and light, then vaporized.
Well before then, things will turn real nasty. In just a billion years, the Sun could be 11-percent brighter, scientists say, rendering Earth an inhospitable greenhouse. In 3.5 billion years, the Sun could be 40-percent brighter than it is today.
With our demise so clear on the cosmic horizon, astrophysicist Fred Adams of the University of Michigan and NASA's Gregory Laughlin got to wondering in recent years how the planet might be saved by gravitational interaction with a passing star. They ran computer simulations of possible encounters over the next 3.5 billion years, finding last year that the odds of the Earth being completely ejected from the solar system are one-in-100,000.
Slim odds. And life in the frigidity of deep space would be no summer picnic.
So Adams and Laughlin, along with Don Korycansky of the University of California, Santa Cruz, began to discuss consider how human intervention might bring about a more suitable long-term orbit, one that gradually expands with the aging Sun.
Their idea, which evolved from interaction with a star to rerouting a giant space rock to save Earth, will be published in an upcoming issue of the journal Astrophysics and Space Science.
Just an idea
"This is not an urgent problem," Adams stressed, adding that the researchers merely wanted to prove -- on paper -- that such a scheme was possible. "And we are in no way advocating policy."
Call it mathematical recreation.
After working for years and to determine the fate of the entire universe -- with results published in the 1999 book, The Five Ages of the Universe: Inside the Physics of Eternity -- the researchers spent two weeks modeling our escape because, Adams said, scientists and reporters kept asking, "What happens to Earth? Is there a way out?"
They started with a simulated comet or asteroid 62 miles (100 kilometers) wide, about six times larger than the one thought to have killed off the dinosaurs 65 million years ago. The solar system has plenty of objects like this -- in the main Asteroid Belt between Mars and Jupiter, and farther out in the Kuiper Belt. The trick is to find one that's headed our way, then use a small amount of energy to guide it, like a spacecraft, onto a new course through our solar system.
Here's what you do:
Using humans or robotic spacecraft, attach retrorockets -- like those that maneuver spacecraft -- to the rock. Alter its course of so that it passes near Earth. The planet then steals some of the space rock's orbital energy and uses it to move into an orbit slightly farther from the Sun. (NASA employs a similar technique to propel spacecraft, sending them around a planet in order to boost them into new trajectories at higher speeds.)
Send the comet or asteroid back out around Jupiter and Saturn, where it will regain orbital energy by robbing it from the giant planets. (In effect, Earth is ultimately getting its orbital boost from Jupiter and Saturn.) Make the rock continue on a long, elliptical orbit that goes way the heck out there -- 325 times the distance from Earth to the Sun.
Bring the rock back around Earth every 6,000 years or so, and each time the planet will creep outward a few more miles. The goal: An ultimate retreat of several million miles (kilometers).
Can this really be done?
Dr. Benny J. Peiser's thinks so. A researcher at Liverpool John Moores University, Peiser studies various ways the cosmos might smash up or destroy our planet. He spends a lot of time thinking about how to keep comets and asteroids away from Earth.
Peiser views the work by Adams and his colleagues as feasible and relevant, but only after we survive the next couple of centuries.
"In the short-term," Peiser said, "we have only one cosmic problem to worry about: Whether or not humanity will get that far at all."
Peiser is talking about a surprise attack by a comet or asteroid that could plunge Earth into another Ice Age, or worse. Researchers around the globe are scrambling to catalog the thousands of asteroids that could be on the prowl, circling the Sun in odd orbits that suddenly bring them dangerously close to Earth.
"But once we've solved that problem, and I am confident that we are on course to succeed," he said, "we can focus on other extravagant attempts to save life on our little planet from becoming extinct."
Not pie-in-the-sky
Most of the technology is already available to divert an asteroid, Adams and others said. And in the case of trying to change Earth's orbit, we have a few million years to get started.
"It's not any pie-in-the-sky kind of thing," he said in a telephone interview. "All you have to do is just drive out to the edge of the solar system."
But it does require some precise planning and execution, and there are some possible side effects.
For one, we might inadvertently lose our Moon. And Mars might eventually have to move over, too, in order to make room for our escape. Finally, the scheme would bring a potentially dangerous space rock to within a cosmic whisker of Earth on each pass -- just 10,000 miles (16,000 kilometers). That's a close shave that could even make the hair on Bruce Willis' bald head stand up.
"You have to do the calculations very precisely and change the asteroid's orbit very carefully," Adams cautions. "Because if you screw up, you're actually going to hit the Earth with the asteroid, and you're going to kill the dinosaurs again."
Yes, that would be us. |
