Amateur stargazers and professional astronomers alike are in for an unusual treat later this week. This weekend, an asteroid named 2002-NY-40 will hurtle past the Earth, a relative hair's-breadth away in astronomical terms, on its three-year long orbit around the sun. The close fly-by means the tumbling asteroid a small chunk of the planetary debris that litters our solar system, will be bright enough to see from earth using only a small telescope. Scientists are hopeful they'll glean useful knowledge from this rare brush with an asteroid, and they are confident the space rock poses no threat to Earth at least not anytime soon.
Asteroid 2002 NY40 measures about 800 meters across and will soar past earth Saturday at only one point three times the distance of the Moon, making it visible to an earth-bound observer with the aid of a small telescope or even binoculars. According to officials at the U.S. space agency, NASA, these kinds of visible fly-bys are extremely rare. By their records, the last near-Earth passage of a large asteroid was in 1925. Because of the lack of asteroid chasers back then, the fly-by wasn't discovered until this year.
Grant Stokes is the principle investigator for LINEAR, the Lincoln Near Earth Asteroid Research project at MIT, the Massachusetts Institute of Technology, in Cambridge. Mr. Stokes' group is responsible for identifying a great majority of the larger near-earth asteroids for NASA. Mr. Stokes is excited about the possibility of seeing NY40 up close. "[From] the estimates that I've seen, it's certainly not going to be visible to the naked eye, but with a relatively small telescope, if people are persistent I think they can go find it. If you go out on the web there are a couple of places that show anticipated spots of where it will be as a function of time. The other thing that will be interesting about it is, the signature will be just a little dot in the sky, but it will be moving and I think it will move in a perceptible way so you can actually tell the difference between it and the stars."
Astronomers will be studying the shape and motion of NY40 so they can better track its orbit. NASA will also be able to better understand the asteroid's composition using a radio telescope. Mr. Stokes believes increasing our knowledge of an asteroid's makeup is also an important goal. Most are believed to be rich in iron ore "By understanding what they're made of, you learn a lot more about how the solar system is composed and potentially how things got the way they are," he says. "And there are certainly people that think that, in fact, if you go out to them, you could mine interesting things. Also, in the unlikely event you find one that's going to crash into the earth and you want to take some kind of a mitigation action, then it becomes very critical what it is."
Most scientists now believe a large asteroid perhaps ten times the size of NY 40 struck the earth about 65 million years ago, devastating the global environment and wiping out a large percentage of the plants and animals on Earth, including the dinosaurs. NASA stresses that while such large asteroid impacts are potentially very dangerous, the chance of such a collision is extremely remote.
On July 24 of this year, the British Broadcasting Corporation's online news service raised public concern over another asteroid named 2002 NT-7 that some scientists believe has a slight chance of colliding with earth in the year 2019. The headline ran Space Rock on 'Collision Course'. Jon Giorgini is a senior engineer at NASA's Jet Propulsion Laboratory in Pasadena, California.
He says that after more research was conducted, it became quite apparent that NT-7 was not likely to collide with earth: "Additional observations have really shrunk that risk down," he says. "Those initial reports don't reflect the current knowledge of the asteroid. We've learned more about it. Well when you look at the surface of planets such as Mars and Venus or Mercury or even the earth's moon, you see that they're just littered with crater sites. It's pretty good evidence that planets are hit by asteroids. The time scale though is often very large compared to normal human time scales."
As for asteroid NY40, Dr. Giorgini says that while it will come relatively close to earth this week, it poses no danger now or within the next few decades. "It's really just a science experiment that's going to be conducted. It's interesting. We'll probably learn a lot about it. All these asteroids, when we turn the radar on them and we see their shapes, every one is unique and different. Each one is a strange little world out there spinning in space," he says. "I think it's an interesting thing that will happen, but it's certainly nothing to be worried about. It's just a science experiment."
But NASA scientists, as well as a team of astronomers at the University of Pisa, continue to study the possibilities of a future collision between NY-40 and the Earth. They say long-term projections of NY-40's solar orbit show a number of very close encounters. But according to Sky and Telescope Magazine, both the U.S. and Italian teams have concluded there is only a remote chance that NY-40 will hit the Earth anytime this century.
In the meantime, for information on where you might see asteroid 2002 NY 40 in the night sky August 17 or 18, visit NASA's Internet site, NASA.gov. Information on the LINEAR project can be found on MIT's website, MIT.edu.