Johns Hopkins Gazette: March 17, 1997

Rocket Men

Hale-Bopp: Students,
researchers man rockets
to investigate comet

Emil Venere
News and Information

It's T-minus 10 seconds shortly after 8 p.m. in the New Mexico desert, as about 40 scientists huddle in a blockhouse near the launch pad, paying close attention to a rocket poised in the darkness.

The two-stage rocket will carry a Hopkins ultraviolet telescope above the veil of Earth's atmosphere, speeding upward at more than 5,000 miles per hour. Its purpose is to get a clear view of comet Hale-Bopp, a cosmic traveler that has excited astronomers since it was first spotted in 1995.

Only a few hundred yards from the launch site, at the White Sands Missile Range in south-central New Mexico, Stephan McCandliss is watching a bank of monitors.

"The blockhouse is pretty intense," said McCandliss, a research scientist in the Department of Physics and Astronomy. "Of course, the whole thing is intense."

He and Hopkins technician Russ Pelton monitor the mission from the cramped confines of the blockhouse, which has only one narrow window made of thick green glass.

"You hear a wump, and see a bright flash, and it's gone," McCandliss said.

But things look a little different to graduate students Jason McPhate and Eric Burgh, observing the launch from a control center about a mile away.

"It's really impressive because the missile range is located basically in a big valley, between two mountain ranges," said McPhate. "Everything lights up like daylight for six seconds. It's like an extended lightning strike. You've got shadows cast behind you from the launcher."

Then, there is a suspenseful pause. The first stage has exhausted its fuel, and the next stage does not ignite for another six seconds.

"It's always kind of scary to wait for that second stage," said McPhate, 28, a veteran of two previous rocket launches. "You think it's never going to light."

But, if all goes well, the second solid-fuel motor kicks in, and it burns for another 32 seconds, propelling the rocket and its precious scientific cargo to an altitude of about 230 miles, up near the space shuttle's domain.

McPhate and McCandliss hope to be acting out this scenario on April 5, just in time to catch a fleeting view of Hale-Bopp. They are members of a five-member team headed by astrophysicist Paul Feldman, chairman of the Department of Physics and Astronomy.

For eight months they have been building and testing the spectrograph and other components for the rocket mission, paying meticulous attention to minute details.

But they will be the first to admit that rocket-borne research is risky business, offering no guarantees for success no matter how carefully scientists prepare.

So many things can go wrong.

Not surprisingly, the team has had a few close calls. Just something as seemingly innocuous as a few bits of loose solder, or perhaps a small washer rattling around, can cause catastrophic short circuits.

The angst level was cranked up a few notches one night when a key component, the detector that turns light from the telescope into an electronic signal, just stopped working.

"It's 9 o'clock at night; your adrenaline is pumping," McCandliss said. The scientists eventually traced the failure to a bad electrical cable.

"The horror stories go on and on, that's what's nerve-racking," he said.

Weeks before the mission the sensitive spectrograph and other components must pass rigorous tests to make sure that they are sound enough to withstand the tremendous stresses of launch. They are subjected to a vacuum, put on a special table and shaken with great force in every possible direction.

"It's really a painful process," McCandliss said. "Basically, the whole testing and evaluation procedure before launch is a trial by fire, and it is calculated to try to break it. You are constantly trying to break what you have built."

Scientists call it a "mission readiness review," or simply, MR-squared.

Indeed, just getting through the pre-launch testing can cause premature aging.

But it's all worth a few gray hairs, as astronomers strive to take advantage of comet Hale-Bopp's rare visit; it returns to Earth only about once every 3,000 years.

The goal is to learn more about the composition of comets, mushy masses of ice and dust preserved for billions of years in the outer regions of the solar system, far from the sun's warming influence. They are believed to harbor some of the original material from the primordial cloud of gas and dust that astronomers believe condensed, eventually forming the sun and planets.

Comets also may have been major players in Earth's early history, as well; cometary collisions may have deposited water and vital organic compounds needed for life to take hold.

"But, to be honest with you, I always have to say that these measurements will not answer the fundamental question of why there is life on Earth," said Feldman, who has conducted extensive research on comets over the years, using the Hubble Space Telescope, sounding rockets and other instruments.

Astronomers are content to solve such profound questions incrementally, one discovery at a time. And Hale-Bopp promises to provide a few more clues. The Hopkins sounding rocket project could figure prominently in the Hale-Bopp chapter of cometary research.

Hale-Bopp will reach its closest approach to the sun on April 1, causing it to heat up, vaporizing part of its icy core and releasing dust particles, which reflect sunlight as they stream away in a brilliant tail.

By observing ultraviolet light from the comet, astronomers can study the composition of gases produced as the ice vaporizes. Data from such observations tell scientists what the ice is made of, opening a window into the distant past--to a time when the solar system was forming.

Because ultraviolet light is filtered by the atmosphere, astronomers must either use instruments in Earth orbit or on sounding rockets to observe that portion of the spectrum.

The Hubble telescope cannot observe Hale-Bopp as it approaches the sun because to do so would mean pointing it too close to the sun, which could cause dangerous heating.

That leaves the job to sounding rockets.

McPhate will play an integral role, sending commands to maneuvering jets on the rocket to make sure the telescope is lined up with the comet.

The team will have only about five minutes to observe Hale-Bopp before the rocket descends too low in the atmosphere. So, just one inopportune complication could foil the mission.

That's what happened during a similar type of mission in 1995. The astronomers had launched a rocket in Australia to study a region where new stars are forming near the Milky Way galaxy when something went terribly wrong with the high voltage electrical system. Then, transmissions from a nearby television station "stepped on" commands being sent to the rocket, causing a fatal interference.

Suddenly, astronomers were no longer in control of the telescope and the object they had intended to observe disappeared from their computer screen.

"I didn't get any data," McPhate lamented.

But, putting that experience behind him, he is ready to man the controls for Hale-Bopp.

"It's a little stressful, but it's not that bad because you get to practice a lot beforehand," said McPhate, who is specializing in comet research for his doctoral research.

Besides, he noted, "My thesis isn't riding on this."

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