APL glories in asteroid mission Off we go: Hopkins' Applied Physics Lab designed, built and will control the spacecraft, and it brought it in early and under budget.

February 07, 1996|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

The first spacecraft ever sent to orbit an asteroid is set for launch next Friday from the Kennedy Space Center. And scientists and managers at the Johns Hopkins University's Applied Physics Laboratory in Laurel are already claiming it as a triumph.

APL experts not only designed and built the 1,800-pound vehicle; they will also control the entire flight from a new command center in Laurel. It is the first time a NASA planetary mission has been run from a non-NASA facility.

If it succeeds, the Near Earth Asteroid Rendezvous (NEAR) craft will arrive at an asteroid called Eros -- 120 million miles from Earth -- in January 1999. From an orbit as close as 15 miles to Eros, NEAR will spend nearly a year sending back pictures and other data that could shed light on the origins of the solar system.

But that's not APL's only boast.

The laboratory put NEAR on the launch pad in less time -- and for more than a million dollars less -- than it promised NASA when it took the job in 1993. Officials at APL think that may be another first for a NASA space science mission.

Wesley Hentress, associate administrator of NASA's office of space science, called it a "pretty good performance." He said APL "proved we can develop a highly focused planetary mission for far less money" than has been assumed in the past.

Dr. Stamatios M. Krimigis, head of APL's space department, said, "We have raised the bar other people will have to jump over."

NEAR is the first of NASA's new Discovery series of spacecraft, meant to provide scientists with "faster, better, cheaper" access to space. Each must be developed in less than three years and for less than $150 million.

NEAR has taken just 26 months, and cost $120 million.

There will be other costs. Next Friday's launch atop an unmanned Delta II rocket will cost about $50 million. And managing the spacecraft from launch until the mission's end in December 1999 will cost another $40 million.

But when compared with a venture like the $1.3 billion Galileo mission to Jupiter, NEAR looks to space scientists like a lot of bang for the taxpayers' buck.

"We hope that the end result is that there will be more science done within NASA's space science budget," Dr. Krimigis said.

Eros was chosen as NEAR's destination, in part, because it is "relatively easy to get to," said Dr. Joseph Veverka, of Cornell University, who heads the Near Infrared Spectroscopy team for NEAR.

Most asteroids orbit the sun in a band, 150 million miles wide, sandwiched between the orbits of Mars and Jupiter. But some, including Eros, wander out of the asteroid belt and into the inner solar system during each orbit.

In 1975, Eros came within 14 million miles of Earth. That makes it a "near-Earth" asteroid, a class of perhaps 2,000 whose orbits approach or cross Earth's -- making them candidates for collisions. An asteroid much smaller than Eros is believed to have smashed into Earth 65 million years ago, causing a mass extinction that ended the age of dinosaurs.

Eros was discovered in 1898. Only about 23 miles long and 8 or 9 miles through, it would fit easily inside Howard County.

After launch, NEAR will head out past the orbit of Mars, the first spacecraft to venture that far from the sun on solar power alone. In June 1997 it will streak past a 38-mile-long asteroid called Mathilde 205 million miles from Earth.

In January 1998, the golf cart-size spacecraft will swing within 300 miles of Earth for a gravitational boost toward Eros, 120 million miles out.

In January 1999, APL controllers will jockey the spacecraft into a 62-mile-high orbit, making Eros the smallest celestial body ever orbited by a spacecraft.

Two other asteroids have been photographed by spacecraft. But neither was closer than 600 miles. NEAR's Multispectral Imager will take pictures of Eros "in exquisite detail" as the spacecraft moves to within 15 miles, said Dr. Veverka. Its shape will reveal whether it is a solid fragment of a larger body, or a loose collection of boulders. The character of its rotation will suggest its history of collisions.

A laser altimeter will measure the distance from the spacecraft to Eros, gradually assembling a detailed topographic map. Its gravity field will be revealed by its tug on NEAR, which will cause subtle changes in its radio signals.

All this data combined will allow scientists to determine Eros' density, and any density variations deep inside the asteroid.

Meanwhile, X-ray, gamma-ray and infrared spectrometers will analyze the space radiation reflected from Eros, revealing the asteroid's chemistry. That, in turn, will suggest the conditions and forces that formed it.

Scientists have long suspected that the meteorites they've collected on Earth include chunks of asteroids.

The mission will end in December 1999 when Eros' maneuvering fuel is spent. Controllers may then crash NEAR onto Eros, snapping pictures until impact.

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