Simplicity may be key to the NEAR's success 1st spacecraft built to orbit an asteroid should arrive in 1999


If you want to build something reliable, and you must do it quickly on a tight budget, you'd better keep it simple.

That's why the Near Earth Asteroid Rendezvous (NEAR) spacecraft -- set for launch today from the Cape Canaveral Air Station in Florida -- has no antennas to unfold. There are no booms to extend, and no instrument platforms to swivel on NEAR, the first spacecraft sent to orbit an asteroid.

If it succeeds, the craft will arrive at an asteroid called Eros -- 245 million miles from Earth -- in January 1999 and spend nearly a year sending back data that could shed light on the origins of the solar system.

With less than three years and $150 million to work with, engineers who built the spacecraft at the Johns Hopkins University's Applied Physics Laboratory in Laurel settled instead a blend of simplicity, clever design and innovative management.

Their solutions have been called "revolutionary" by Wesley F. Huntress, who heads NASA's office of space science.

The APL effort, so far, has "proved we can develop highly focused planetary missions for far less money and they need not be high-risk," he said.

The next test will be in the scientific payoff. But first NEAR must be launched.

Late yesterday, the 1,800-pound spacecraft was reported ready for launch atop a Delta II rocket. Liftoff is set for 3:53 p.m. To reach Eros in 1999, NEAR must be launched during the next 16 days, and within daily launch windows only a few minutes long. A delay beyond March 2 would postpone the mission for a year.

Launch officials were confident yesterday they could meet that deadline, although they said there was a 40 percent chance that today's attempt would be scrubbed by an approaching cold front.

NEAR's destination is a rock 25 miles long, about the size of Howard County. NEAR will orbit for 11 months, flying as close as 9 miles above the surface while sending back pictures and other scientific data.

It's the first spacecraft in the National Aeronautics and Space Administration's new Discovery series, created to design and launch planetary missions in less than three years, and at a cost under $150 million each. After NEAR, NASA hopes to launch a new Discovery mission every 18 months on average.

APL engineers produced NEAR in 26 months for $112 million -- 10 months and $1 million less than their contract allowed. NASA's Jet Propulsion Laboratory, by comparison, took 12 years and $1.3 billion to design and launch the Galileo mission to Jupiter.

NEAR's builders say Discovery's tight time and budget constraints forced them to stay focused on the essentials.

"If you compare the spacecraft we proposed to NASA when we started, it is virtually identical to the spacecraft we delivered. And that's not typical in this industry," said Andrew G. Santo, the project's spacecraft systems engineer.

Also key, he said, was APL's complete control of the project. Normally, NASA's Jet Propulsion Laboratory in Pasadena, Calif., would have technical oversight over a planetary mission.

At APL, the same people making the engineering decisions were also responsible for their cost implications. The streamlined management held down costs, and saved time.

Rather than stretch for the ultimate in performance, NEAR's engineers looked for ways to makes things clever and simple.

* NEAR's communications antenna is a solid dish. That avoids mechanical failures like that on Galileo, where a high-gain antenna failed to unfold, sharply limiting the amount of data the Jupiter mission will return.

* NEAR's electricity will come from four solid solar panels. Unlike the complex, troublesome window-shade design on the Hubble Space Telescope, NEAR's panels are designed to spring into place like saloon doors.

* Because the sun and Earth will be close together in the sky as seen from Eros, NEAR's designers were able to give the spacecraft fixed solar panels and a fixed antenna that both point in the same direction. That eliminated the need to equip both systems with complex pointing mechanisms. Both can be aimed by firing the spacecraft's thrusters.

* NEAR's scientific instruments, too, are fixed, aimed steadily at Eros once in orbit. Their only moving parts are a scan mirror and a wheel that moves various filters in front of a camera.

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