Pioneers of Promise
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Love at Second Sight
By Joanne Cavanaugh Simpson
Chickening out before the first date, slipping into orbit on the second rendezvous, and now in the midst of a yearlong getting-to-know-you courtship, the spacecraft known as NEAR is exploring the mysteries of 433 Eros, an elusive asteroid named for the Greek god of love.
The spacecraft (NEAR stands for Near Earth Asteroid Rendezvous) is the first man-made object to orbit an asteroid. Its findings could uncover clues about the origins of our solar system and Earth itself.
The $216 million mission, developed and operated by Hopkins's Applied Physics Laboratory (APL), is in the vanguard of cheaper, faster space missions sponsored by the National Aeronautics and Space Administration (NASA). "The difficulty of space [exploration] is not how you deal with success but how you deal with failure, and the potential of failure, and still come back," a beaming Daniel S. Goldin, NASA administrator, said after the orbit was confirmed. "It's a first step. The NEAR mission has a long way to go."
In a public relations coup for a space agency beleaguered by the loss of the Mars Polar Lander probe, NEAR locked into the subtle gravitational pull of 433 Eros, right on schedule, on Valentine's Day. Their embrace took place more than 160 million miles from Earth, after NEAR's four-year journey.
"Who says engineers couldn't be romantic?" quipped Sen. Barbara Mikulski (D-Md.) at the celebratory luncheon at APL, which featured a barbershop quartet singing "Let Me Call You Sweetheart" and centerpieces filled with candy hearts. In pictures transmitted by NEAR the day before, APL mission director Robert Farquhar even spotted an aptly shaped crater on the asteroid.
"This may be a love asteroid with a heart-shaped crater," Mikulski told the audience of NASA TV and about 500 people who gathered at APL, "but Americans are wondering whether we'll be hit by one."
A rogue asteroid is believed to have hit Earth 65 million years ago, leading to the demise of the dinosaurs. The potato-shaped Eros, at 21 miles long and 8 miles wide, is about twice the size of Manhattan. The second largest of the near-Earth asteroids, Eros crosses Mars's orbit but doesn't yet cross Earth's path. But a few close encounters, the closest at 14 million miles in January 1975, have made Eros an object of intense study.
Over the course of the year, NEAR will orbit the rock--at distances ranging from 300 miles to 22 miles and closer--an especially difficult feat because the asteroid's gravitational pull is one-thousandth of Earth's. Using on-board instruments, scientists will study the asteroid's physical and chemical features, and evolutionary history--gathering data on Eros's shape, rotation, and cratered surface, plus whether Eros is a solid body or a pile of rubble. Using a near-infrared spectrometer, for example, researchers have searched the face of Eros to map its mineralogy. "We need to understand the physical characteristics if we are ever called upon to deflect an asteroid," said Carl Pilcher, an administrator in NASA's Office of Space Science. "We'd like to know how asteroids would respond to whatever force we have."
Asteroids like Eros should also hold clues to the nature of planets, meteorites, and the early moments of our corner of the universe. Early data shows Eros may be a hunk of a former planet. "An asteroid contains many of the building blocks of terrestrial planets," said Andrew Cheng, APL NEAR project scientist. "They were created at a time very close to the beginning of the solar system, four and a half billion years ago."
A year and a half ago, NEAR missed its date with Eros when a spacecraft computer aborted a burn maneuver set to pace the asteroid's speed and match its location. NEAR was in communicado for a day and lost 64 pounds of fuel. "That was a dark day, but once we picked up the spacecraft again, I knew there would be no problem," said Farquhar. APL scientists snapped photos of NEAR's intended as the spacecraft whizzed by it, 2,378 miles away.
NEAR's eventual destination, if NASA is amenable, is a touchdown on the surface--a parting kiss. NEAR could then rise to 500 meters to shoot and transmit a last photograph of the craft's own footprint. "Toward the end," Farquhar points out, "on the last day, it will run out of money and run out of fuel and Sir Isaac Newton will bring down the spacecraft to the surface."
For more information on NEAR's latest data and photos, check out the mission website, http://near.jhuapl.edu.
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