Liftoff! Liftoff! Liftoff!

Instead of a few expensive missions, NASA's Discovery Program is launching many (relatively) cheap ones: to an asteroid, to a comet and toward the sun. Eight have been picked so far.

By DAVID BALLINGRUD

© St. Petersburg Times,
published July 9, 2001

Spacecraft lands on asteroid!
Rocket to blow hole in comet!
Helicopter to intercept spacecraft returning from sun!

These days, most of NASA's money and effort go toward construction of the international space station and the shuttles -- space trucks, really -- used to haul the building materials to the construction site.

The space station, as we all know, is a massive and costly undertaking, involving many nations -- a technological (yawn) and engineering marvel.

But let's face it. It's a large research lab, orbiting barely above Earth's atmosphere. Of course, work crucial to space exploration will be done there, but it doesn't do much to fire the public imagination.

For that, NASA turns to exploding comets.

Those tabloid-style headlines above describe real missions.

The asteroid landing took place this year. The spacecraft headed for a comet collision will launch in a little more than two years. The third, the Genesis mission to the sun, is being readied for a July 30 launch from Cape Canaveral.

They are part of NASA's Discovery Program, a series of fast, cheap (in relative terms) missions to deep space -- far beyond the low Earth orbit of the space station.

There NASA and its academic collaborators seek answers to what Wes Huntress calls the "gut level human questions: How did all this happen? How did we get here, and are we alone?"

Huntress, former head of space science at NASA, was one of the architects of the Discovery Program. Today he directs the Carnegie Institution's Geophysical Lab in Washington.

The Discovery Program "is a jewel in NASA's constellation," he said. "It is incredibly productive and exciting work."

Formally begun in 1994, the program funds small spacecraft that can be built in 36 months or less, for less than $190-million in development costs, and for a total mission cost of less than $300-million. (Hardly peanuts -- until one considers that the cost of the international space station is put somewhere between $70-billion and $100-billion.)

The key word is fast. Discovery missions are quick off the drawing boards, quick into space and quick back home with the results.

NASA has long looked to the planets for answers to the "fundamental questions," but it has changed the way it goes about it. Until the mid '90s, exploring deep space often involved much larger, much costlier spacecraft.

On its journey to Jupiter, for example, the Galileo spacecraft carried numerous scientific instruments designed by numerous scientific teams. NASA sought proposals, and if a review panel liked your idea, you could bolt your instrument onto Galileo.

Some big spacecraft were successful, Galileo for one, but there were embarrassing failures, too. The $1-billion Mars Observer suddenly went silent as it approached Mars in 1993 and hasn't been heard from since.

"One big mission every 10 years or so was producing episodic data," Huntress said. "We needed a more regular pattern of missions that would sustain the program, sustain the science."

The Discovery Program -- administrator Dan Goldin dubbed it "faster, better, cheaper" -- was NASA's answer.

Things are done differently in Discovery, said David B. Jarrett, who manages the program for NASA. "Here the project is someone's dream," he said. "The scientist comes up with the entire mission; it's a product of someone's imagination, and so what he or she says, goes."

Eight Discovery missions have been selected so far, and a few others are being considered. Here are sketches of a few, including Genesis, next up on the Cape Canaveral launch pad.

A piece of the sun?

After launch from Cape Canaveral, scheduled for July 30, the Genesis spacecraft will journey a million miles toward the sun. Then it will unfold its collectors and "sunbathe," capturing tiny bits of the sun and its solar wind -- ions and other elements -- in gel wafers. Three years later it will pack up and come home, a pretty quick turnaround in space exploration.

"As a scientist, I could spend my entire career waiting for data," Jarrett said. "We wanted these things to fly more often, to get the data returned, to get the answers quicker.

"With the Genesis mission, for example, the scientists are still designing the instruments they will use to analyze the data when it gets back."

As the spacecraft nears Earth, parachutes will slow the descent to the Utah desert. Trained helicopter pilots then will swoop in and snatch the spacecraft from the sky before the gel wafers inside are smashed on the ground. The samples will be analyzed to provide a database on solar material for comparison with material from other solar system bodies.

"The pilots have done this plenty of times in practice, and they have never missed," said project manager Don Burnett.

Burnett awaits the Genesis launch with a mixture of excitement and apprehension. He has been with Cal Tech for 35 years, and Genesis is the first project he has designed more or less on his own. It is much more than an important milestone in a long career, he says.

"It's my last hurrah."

A crash at 20,000 mph

Like a child curious about the workings of a clock, NASA is taking a mighty space hammer to a comet.

The Deep Impact mission of 2004 will send a large copper projectile crashing into the surface of Comet Tempel 1 at more than 20,000 mph. The resulting collision will excavate a crater more than 25 meters deep and 100 meters in diameter, revealing the pristine, never-before-seen interior of these mysterious space travelers. Telescopes on Earth and in space will study what scientists presume will be a plume of debris.

Why?

Scientists don't know much about comets, but they do believe they are the remainders of material formed in the coldest part of our solar system at the beginning of time, and that impacts from comets played a major role in the evolution of the Earth.

The spacecraft will be made up of two parts: a larger spacecraft carrying a smaller "smart impactor." The 770-pound impactor is powered by a battery with enough juice to navigate on its own for a day. It will be released about half a million miles from its target, then maneuver into the comet's path.

Then, boom.

We are promised pictures. The impactor has a camera and will take pictures right up to the explosive climax of the mission, NASA says. A television broadcast is planned, too.

After separation from the impactor, the flyby spacecraft will monitor the impact. It will also gather entirely new data on the structure and composition of the comet's interior and transmit it to Earth.

Despite a lack of experience in comet collisions, NASA expects no measurable change to the comet's orbit and no threat to Earth.

To mysterious Mercury and distant Pluto

NASA had planned a mission to Pluto and its moon Charon in 2004 but abandoned the idea when costs began to climb. It quickly restored the mission, however, when Congress began feeling pressure from a curious public, and from scientists who complained that Pluto, with an atmosphere that freezes and vanishes when the planet moves too far from the sun, would not be amenable to study again for 200 years.

So for now, the agency has picked two teams to prepare proposals to journey to Pluto and Charon -- and keep the cost under $500-million.

The teams each will receive $450,000 and have three months to develop their proposals. NASA is expected to choose one this fall.

The Pluto mission represents an opportunity to visit the only planet not yet explored by spacecraft.

Pluto is the most distant planet known and the largest member of the Kuiper Belt. Kuiper Belt Objects, NASA says, are composed of material left over after the formation of the other planets, and thus may shed light on how that process took place.

A more certain mission is the $256-million journey to another neglected planet, Mercury. The Messenger orbiter is being prepared for launch in 2004 and a five-year trip to the tiny planet. Messenger will be only the second spacecraft to visit Mercury. Mariner 10 flew past it three times in 1974 and 1975 but gathered data on less than half the planet.

Messenger's instruments will provide the first images of the entire planet and collect detailed information on the composition and structure of Mercury's crust, its geologic history and its atmosphere. In a prepared statement, Jay Bergstralh, chief scientist for NASA's Solar System Exploration Division, called Messenger "the most complex and challenging Discovery-class mission we have ever attempted.

"Conducting a yearlong mission to orbit a planet only 36-million miles from the sun for relatively low cost is an amazing concept."

Earlier success grabbing headlines

For a small program within a large agency, Discovery has shown a knack for attracting attention. Of course, it helps when the purpose of a mission (at least in part) is to learn how to save Earth from runaway asteroids.

About 3:05 p.m. Feb. 12, a small spacecraft called NEAR Shoemaker touched down on the barren, rocky surface of 433 Eros about 200-million miles from Earth, successfully completing history's first landing on an asteroid.

During the final 3 miles of descent, the spacecraft snapped 69 detailed pictures, the highest resolution images ever obtained of an asteroid, showing features as small as 1 centimeter -- less than half an inch -- across.

NASA researchers have found more than 350 near-Earth asteroids more than a half-mile in diameter. From this, they estimate 500 to 1,000 similar-sized objects could be spinning around the solar system. Fortunately, none has an orbit that will bring it anywhere near Earth in the near future, they say.

But they haven't found them all. And if one were coming, mankind's only course would be to try to change its path. The NEAR mission demonstrates that mankind can approach an asteroid with precision, and perhaps detonate a nuclear device to change its orbit.

Another crash landing in space illustrates the let's-give-it-a-shot attitude found in the Discovery Program.

The Lunar Prospector spacecraft was launched in January 1998, and spent about 18 months in lunar orbit, using instruments to map the magnetic, chemical and gravitational makeup of Earth's familiar neighbor.

Then, as the mission neared its end, things got interesting.

On July 31, 1999, with at least 20 of the world's major observatory telescopes recording the event, the $63-million spacecraft nose-dived out of orbit and plunged into a crater on the moon at almost 4,000 mph.

The spacecraft eventually would have crashed to the lunar surface anyway. But by deliberately crashing it into a particular crater at the moon's south pole, scientists hoped to find water in the dust raised by the collision.

They didn't, but typically, they didn't take no for an answer.

"Failure to prove that water ice exists in the lunar polar regions does not suggest that it is absent," a mission summary stated, "but rather that this experiment ... has not provided the conclusive evidence that was being sought."

- David Ballingrud covers science issues. He can be reached at (727) 893-8245 or ballingrud@sptimes.com.

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