A Picture-Perfect Landing for NASA’s Mission Back to Mars
In a spectacular success for NASA’s return to Mars after a 21-year absence, the Pathfinder spacecraft bounced safely off the rocky surface of the Red Planet at just after 10 a.m. on the Fourth of July and coasted to a halt right on target, and--more astonishingly--right-side up.
By late afternoon, its camera began transmitting the first pictures of the Martian surface since the Viking spacecraft’s images taken in 1976. Pathfinder’s initial scratchy black and white images showed a rough, barren landscape of rocks and boulders.
The sight of the six wheels of the little 22-pound rover Sojourner were as beautiful as a newborn baby to the engineers who designed it and set it on its seven-month 300-million mile journey in December. The boulder-strewn landscape--interrupted with high rocky mounds--is in the middle of Ares Valles, a plain created during a huge flood billions of years ago when Mars’ now bone-dry surface flowed with running water and possibly teamed with microscopic life.
“What a birthday today!” said NASA chief Dan Goldin, saying the picture-perfect mission reinstated the United States as “masters of our solar system.”
“What a way to celebrate the Fourth of July,” said Ed Stone, director of the Jet Propulsion Laboratory in Pasadena, who said the practically perfect landing ushered in a “new era of Mars exploration.”
Vice President Al Gore phoned to offer “congratulations on doing an outstanding job,” and “happy Fourth of July. The whole country is very proud of what you’re doing.”
The picture-perfect landing had mission controllers pinching themselves, said flight director Robert Cook, and wondering “Is this real?”
“I’m ecstatic,” said deputy project manager Brian Muirhead. “We are on the surface of Mars. This was way beyond our expectations.” The entire entry into the Martian atmosphere and landing on its surface, he said, was “absolutely perfect.”
The only glitch was that one of the air bags that protected the craft during its bouncing landing on Mars appeared to be draped over the edge of one of the solar panels. While this did not affect the overall success of the mission, it did mean that Sojourner might have to wait until today before it rolls over the ramp and onto the Martian soil.
Mission controllers will send an order to Pathfinder to lift up one of its petals and retract the cables that pull in the air bags, tucking them neatly under the solar panels and out of the way. If this is successful, the rover should be deployed sometime early Saturday.
The success of the risky mission, said Goldin, was a fitting tribute to the revolutionary founders of our country who “weren’t afraid of taking risks” and “doing things differently.”
NASA has presented the Pathfinder mission as a high-risk road test of technology that will be used to explore the universe in new ways--using small, cheap, expendable spacecraft instead of expensive once-in-a-decade shots that risk everything on a single mission.
The well-behaved spacecraft appeared to have descended, deployed its parachute and retrorockets and landed with a precision that astonished JPL scientists. It even phoned home early, sending out a weak but comforting signal that prompted project director Tony Spear to dance a little jig in the flight control center.
“Believe me, we didn’t expect to see this stuff this soon,” said Muirhead, who hadn’t expected such good news for several hours. “This is nirvana.”
The signal was so weak, said Muirhead, it was like “picking up a candle from 120 miles.”
The first 15-second pulse was sent out by the craft after its parachute deployed, but before its air bags opened to cushion its descent. A few minutes later, a second signal--sent out by a tiny antenna “no bigger than your thumb,” said Muirhead, told controllers that Pathfinder had not only landed--but was standing upright.
“I’ve got a grin that goes from ear to ear and it’s not going away,” said project scientist Matthew Golombek.
Goldin walked around the flight control center giving out hugs and congratulations like cigars. Mars program director Donna Shirley wiped tears from her eyes. “The signal told them the parachute worked, the heat shield worked, the air bags worked, it all worked.”
Even better, the little spacecraft apparently landed on smooth ground; if it had landed in a rough spot or depression, the weak signal never would have made its way over the Martian horizon to Earth. Luckier still, it landed on its base--one of four “petals” in the pyramid-shaped craft. “What are the odds of that?” asked Rob Manning, chief flight engineer, joking that he was a little disappointed that the engineers didn’t get to try out the mechanisms they had built into the Pathfinder to flip it upright, in case it landed on one of its sides.
According to preliminary data taken during the landing, the air-bag-encased spacecraft bounced hard at least three times up to a height of about 50 feet. Mars had a few surprises in store, however. For example, when the rockets fired to slow the spacecraft during its descent, Pathfinder was traveling faster than expected--about 140 mph. The implication, said Manning, is that the atmosphere may be thinner than expected and “we don’t understand the atmosphere of Mars as well as we thought we did.”
The temperature on the surface was warmer than expected, Sim Schofield said, JPL team leader for the weather package. But he warned that that might not be an accurate reading because the weather mast carrying meteorological instruments had not yet been deployed, and the sensors might be picking up warmth from the spacecraft itself.
A very tired Golombek told a packed pressroom how he and colleagues had been frantically checking out the local Martian terrain about 2 a.m.--fearful that the craft was about to land on the side of a rocky island that might have an unacceptably steep slope. They considered giving the craft a boost that might shove it off to one side--but all the other landing possibilities looked even more precarious than the one Pathfinder seemed to be headed for.
As it turned out, none of that was necessary. The craft landed in a field of small craters, etched in a herringbone pattern that seemed to suggest they were impacts created by matter ejected from a larger crater. That was good news for the geologists because the impacts might have dug underneath the surface to expose hidden minerals.
Like the first step on the moon, the first scratch images from Pathfinder were a small step for the spacecraft, but a huge leap for NASA’s return to Mars after a 21-year absence. Over the next 10 years, 10 missions are planned that will scout the Martian landscape, collect rock samples and prepare for a human mission. Pathfinder was designed and launched before traces of possible ancient fossil life were found on a Martian meteorite last summer. However, that possible discovery has certainly added excitement to its technological success.
Although the spacecraft had safely survived its “wild ride,” said Cook, the mission controllers “are still in the middle of it.” Once the cameras send back images showing that it’s safe to unfurl the ramps for the rover, Sojourner will make its way down toward the Mars surface at the rate of one-half-inch per second. Almost immediately, it will place its sophisticated “nose”--an alpha proton X-ray spectrometer--on the soil to analyze its composition.
The detector will not be able to look for signs of life--or even evidence of fossils. However, it will be able to deduce something about the environment, and perhaps detect the past presence of water. Because water is perhaps the single most important ingredient for life, second to carbon, finding traces of water boosts the chances that living things once populated the planet.
Pathfinder’s primary task is to test the technology that will take NASA into the future. Mars Global Surveyor, another relatively low-cost spacecraft, is already on its way to Mars and will slip into orbit and begin mapping the planet in September. Then, in 1998, when the orbital paths of Mars and Earth bring them close together once more, yet another pair of spacecraft will head for the planet next door. One of them will carry tiny penetrators that dig into the Martian surface, looking for water.
Future missions might be able to dig even deeper. However, researchers believe that any current life on Mars--if it exists--must lie deep beneath the surface, shielded from the intense radiation and harsh chemistry that destroys all organic substances on Mars’ dry surface.
To dig deep enough to find life would probably require human-piloted missions with astronauts who could remain on Mars for several years. For the immediate future, said Goldin, such missions are simply too expensive and too hazardous to astronaut safety.
* WATCHING TOGETHER
Hundreds gather for Planetfest ‘97, spellbound by a live feed from Mission Control. B1
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Independence Day in Space
NASA’s Pathfinder landed Friday on Mars, and cheering Jet Propulsion Laboratory scientists above quickly declared the mission off to a successful start. “This is our first interplanetary celebration of the birth of our nation,” one scientist said. The landing marks the beginning of a new era of Mars exploration.
