Year In Science

Sunday, January 13, 2002

High, Light, and Handsome

On July 14 in Hawaii, the solar-powered Helios prototype flying wing lifts off slowly but surely during its first test flight.
Photograph courtesy of Nick Galante/PMRF/NASA
Using 14 solar-powered motors producing no more thrust than 14 hair dryers, NASA's Helios made history on August 13 by breaking the altitude record for a nonrocket-powered aircraft. Chugging along at bicycle speeds of about 25 miles per hour, Helios reached its peak altitude of 96,500 feet during a 17-hour flight, taking off and landing at the U.S. Navy's Pacific Missile Range Facility on the island of Kauai. Helios not only smashed the old altitude record of 85,069 feet, held by a Lockheed SR-71 jet, it also proved that in aviation, bigger aircraft that gobble thousands of gallons of fuel per hour aren't always better.

Built by AeroVironment, a private technology company, and managed by NASA's Environmental Research Aircraft and Sensor Technology program, the unpiloted, 247-foot-wingspan Helios represents a new generation of aircraft high on efficiency and utility. Solar cells, 62,120 of them, distributed over the surface of the wing, soak up the sun's rays, providing up to 32 kilowatts of direct-current electricity to power electric motors, computers, and other systems on the aircraft.

Helios and similar aircraft may prove to be extremely cost-effective as high-flying telecommunications and Earth-monitoring satellites. "There's a big gap between the altitudes that existing aircraft can get to and where satellites start doing their work," says Alan Brown, a NASA spokesman. The Helios program is also intended to test the aerodynamics of flying machines in extremely thin air. Because Mars' atmospheric pressure at ground level is comparable to that of Earth's atmosphere at 100,000 feet—a mere 1.4 percent of Earth's air pressure at sea level—an aircraft that can fly in such conditions will help engineers learn how to design aircraft to roam Martian skies.

The next step for Helios will be to sustain ultrahigh altitudes for several weeks. Engineers must first perfect an energy storage system that will stock enough solar juice during the day to power the craft at night. Rechargeable batteries are too heavy for the job, so engineers are planning to try a technology that would use current to separate water into oxygen and hydrogen during the day, and then reverse the process at night via fuel cells to produce electricity. NASA researchers hope that Helios will be finally ready for its first long test flight sometime in 2003.
— Maia Weinstock

"O" marks the landing spot of the NEAR spacecraft on the asteroid Eros. Surface details as small as golf balls are visible in NEAR's images.
Photographs courtesy of NASA/JHUAPL
Launched in 1996, NASA's NEAR Shoemaker spacecraft was designed for a close encounter with the 21-mile- long asteroid Eros—far closer than most of us ever imagined possible. In February, NEAR became the first man-made instrument to land on such a celestial body. "It was the crowning moment of a perfect mission," says Andrew Cheng, the mission's project scientist with the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Asteroids like Eros offer astronomers clues to the formation of the solar system. Near-Earth asteroids are doubly intriguing: One is believed to have collided with our planet 65 million years ago and caused the extinction of the dinosaurs and many other forms of life—an event that could, of course, recur. NEAR (which stands for Near Earth Asteroid Rendezvous) sent back 160,000 images of Eros's crater-pocked surface, showing us huge boulders as high as 16-story buildings that dot the asteroid's surface. "These boulders came from deep within the asteroid, so they give us a look at the inside of this body," says Cheng, adding, "It's as if this asteroid were made up of layers of plywood sheets." Such layering suggests that Eros is a fragment of a much larger body that broke up eons ago. The surface contains areas that are called, for now, "ponds" because they resemble the silted remains of dried-out water holes. "Obviously, they're not," says Cheng. "They may have resulted from the seismic shaking following a collision with other objects—and they're very unusual." Analysis—and speculation—have only just begun.

By happy coincidence, NEAR made a direct landing into a pond and continued to relay gamma-ray data for two weeks, even though its camera lay partially buried in the dust. News of the landing was greeted with universal surprise—everywhere, that is, except at the Johns Hopkins lab, which designed, built, and monitored the spacecraft.

"Privately, a lot of us always thought that we were going to land on the asteroid," says Cheng, revealing a closely held secret. "But because it was risky, we were never officially allowed to make that our objective."
— Curtis Rist

The End Is Mir
The friends and family of NASA biologist John Uri, who was in charge of close to 100 scientific experiments on the Russian space station Mir, had one piece of advice for him this year: Trade in your ratty old car. "I'd had the car for 14 years, and everybody thought it was time to get rid of it," Uri says, "and I kept saying, 'But it still runs.' My philosophy was, if it's still working, why get rid of it?"

That is also exactly how he felt about Mir, which was 15 years old this year. Sure, it was a rambling wreck that had never recovered from a collision with a supply ship in 1997, and its technology was hopelessly outdated. But it got the job done. Uri was disappointed when, on March 23, the Russians decided to let it drop out of the sky and plunge into an empty section of the Pacific Ocean near Fiji.

The fiery end of the space station provoked both fear (some thought Mir might arrive bearing mutant species of bacteria and fungi) and whimsy (Taco Bell floated a target in the ocean). But for researchers who study the long-term effects of weightlessness on humans, organisms, and objects, Mir's demise was a loss. The craft was the first continuously occupied outpost in space and gave researchers the means to conduct experiments not for just a week or two, the typical length of a space-shuttle flight, but for months on end. A plant seed, for instance, could germinate, sprout, grow, reproduce, and start a second generation. Hundreds of runs on dozens of experiments could be performed each year. The breakthroughs Mir researchers made in fields as diverse as biotechnology, materials science, and X-ray astronomy were impressive.

Mir was also a quirky place—Russian crews would stash bottles of alcohol behind panels like squirrels hiding walnuts—and it attracted a lot of nonastronauts in its time. As part of a program of state-sponsored promotions, 71 visitors from 12 different countries flew aboard the station. Still, Mir remained a science outpost to the end, and American astronauts lived and worked there for most of its last four years, happy to have the opportunity. Although Uri still insists there was plenty of life left in the station, even he finally seemed to recognize that old technology can't hang on forever. So not long after Mir hit the Pacific, he traded in his old clunker for a shiny new Jaguar.
— Jeffrey Winters

My Favorite Martian
2001 Mars Odyssey carries a spectrometer at the end of a 20-foot-long boom. The instrument will measure the planet's composition by the gamma rays each of the elements emits.
Illustration courtesy of NASA/JPL
For planetary scientists, Mars has been frustrating: Fewer than a third of the missions to Mars over the past 41 years have returned any useful data. After two fiascoes in 1999, NASA's next best hopes are pinned on 2001 Mars Odyssey, which began orbiting the planet on October 24. Odyssey is armed with three instruments designed to measure radiation levels and map out the mineral and elemental composition of the surface in blocks as small as 60 feet on a side. "We'll be able to characterize the surface by more than just seeing the shape of the land," says Odyssey's project scientist, Stephen Saunders of NASA's Jet Propulsion Laboratory in Pasadena, California. "We'll be able to tell what it's actually made of."

One goal is to match these mineral maps to suspected water features found by earlier probes, such as the Mars Global Surveyor. If the features are lined with residual salts, as one would expect of ancient, dried-up lakes or riverbeds, NASA may target them as future landing sites.
— Jeffrey Winters

Salami in Space
The next time you're lounging around somewhere in outer space and you don't feel like cooking, consider giving Pizza Hut a call. In May it made the universe's first fast-food delivery to the space station, teaming up with Russian scientists to develop a pizza that could endure the 240-mile journey to the International Space Station. Hoping to keep the pie as traditional as possible, Pizza Hut marketers proposed a thin crust with pepperoni topping. "The pepperoni didn't hold," says Patty Sullivan, Pizza Hut's director of public relations, because it grew mold during the 60-day trial period. The Russian scientists then suggested tongue as an alternative. "We said, 'Wow, that's really not a seller for us,'" says Sullivan. Finally, a cold, vacuum-sealed, salami-topped pizza went up on a routine payload. The cosmonauts cooked it themselves in a small warming oven and did not complain that the delivery took longer than the usual 30 to 40 minutes. Salami is not available at Pizza Huts here on Earth, nor is vacuum-sealing. "We deliver our pizzas hot and made correctly," says Sullivan.
— Michael M. Abrams

Women and Children First?
The International Space Station's funding was slashed this year, and among the items eliminated was a seven-person emergency escape pod. Although the station was designed to house seven astronauts, only three-person crews can live there now because its Russian Soyuz escape capsule holds only three.

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