The APL built and controls the NEAR spacecraft -- a NASA Discovery-class mission that is part of the "cheaper, better faster" family of space probes. APL engineering teams developed the craft over a fast-paced 26 months at the relative bargain-basement cost of about $108 million.
"Were right on track and ready to slow the spacecraft down to walking speed," Farquhar told SPACE.com.
On Monday, February 14, at 10:33 a.m. EST, small thrusters on the spacecraft will fire, slowing it enough to be caught by Eros weak gravity.
"Things are looking very good," said Lucy-Ann McFadden, a science team member and an astronomer from the University of Maryland in College Park. "Were starting to see more craters on the asteroids surface. The images are showing us things we didnt see before."
This is
. In December 1998, the spacecraft failed in its first attempt to rendezvous with Eros. Those still-unexplained problems caused the mission to be aborted. Fast-thinking ground controllers were able to put the spacecraft on a path that returned it a little over a year later to the asteroids doorstep like a persistent suitor for another try.While asteroid Eros is shaped like a tuber, its no small potato. The object measures 21 by 8 miles (33 by 13 kilometers) -- about twice the size of the island of Manhattan, New York -- and is about 8 miles thick.
Some scientists say it looks like a giant shoe, flipping heel over toe, every five hours.
"We're more certain that we're going to get complete coverage. The flybygave us more confidence, allowing us to better sequence and plan our experiments."
NEARs accidental flyby of Eros 13 months ago gave scientists a valuable peek at Eros, enough to hone navigation strategies to circle it at ever closer distances.
"Were more certain that were going to get complete coverage," McFadden said. "The flyby gave us more confidence, allowing us to better sequence and plan our experiments."
Still, as the spacecraft closes in on Eros, there is no doubt that surprises await.
"The images will get better and better, and at higher and higher resolution. So invariably, when you get close to one of these solar system objects for the first time, you get a lot of surprises," said Donald Yeomans, NEARs radio science team leader, and an asteroid expert at the Jet Propulsion Laboratory in Pasadena, California.
"You can depend on Mother Nature pulling the rug out from under you. Then you find that theres something entirely different that youre facing," Yeomans said.
NEAR has already sent surprising data back to Earth.
In June 1997, the spacecraft scored a ballistic bonus on the way to Eros, zipping by the asteroid 253 Mathilde. Photos relayed from the probe showed Mathilde to be bruised, battered and pockmarked with huge craters. In fact, scientists were amused that it looked to be more craters than asteroid.
"In the past, we thought of asteroids as bits of rock. But then we went by Mathilde," Yeomans said. "That thing had such a low density. If it were a little bit lighter, it would float. So that doesnt sound like rock to me. Perhaps its a rubble pile held together by little more than self-gravity."
"Eros, on the other hand, has a higher density and is more likely to be a monolithic chunk of rock," he said.
McFadden is eager to have a first of its kind, in-your-face look at Eros.
Details about its makeup will help link meteorites that are picked up on Earth to the asteroid belt that orbits the sun between Jupiter and Mars. Knowing more about Eros also may help fill in the blanks in the database compiled by astronomers with telescopes on Earth. If nothing else, it should reveal key clues about how our solar system formed long ago.
Or as McFadden put it: "Well be able to look back in time."
Not bad for a labor of love.
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