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NASA hails a picture perfect Mars landingSent first images of planet in 21 years
By David L. Chandler, Globe Staff, 7/5/97
Mission managers hugged and cheered as every step in a long and complex sequence of untried methods unfolded almost without a hitch.
The first set of pictures were successfully returned from the surface of Earth's sister planet as expected yesterday at about 7:38 p.m. EDT. The pictures showed a rolling terrain strewn with everything from small jagged rocks to huge boulders all the way to the horizon. Scientists cheered wildly as the pictures began to appear on their screens.
"These pictures are breathtaking," said NASA head Daniel Goldin. "It's a day I've waited for for a number of years."
"I'm ecstatic, absolutely ecstatic," said deputy project scientist Brian Muirhead after the robotic craft completed its landing cushioned by large airbags, unfolded its four-sided structure, and began transmitting data to Earth. Speaking for the whole Pathfinder team, he said "we're just totally in love with our baby."
Vice President Al Gore phoned his congratulations to the team for their Independence Day success, saying that "a new way of doing missions -- faster, better, cheaper -- is certainly borne out by this success today."
The only problem encountered so far is that a clump of airbag material seems to be in the way of the ramp that the small rover vehicle, called Sojourner, is supposed to use to crawl down to the surface. Managers were planning a maneuver last night to pull that airbag material in and clear the way, and did not expect it to pose any serious obstacle. But that meant the rover's drive to the surface was likely to be delayed until today, instead of yesterday as they had hoped.
But the scientists on the team were just elated at the variety of rocks and distant landforms seen in the first pictures, which spanned only one-quarter of the lander's field of view. "There are obviously large boulders in that field," said chief scientist Matthew Golombek. "That's kind of what you'd expect from this kind of flood field. And there are certainly plenty of rocks to look at."
One of the mission's key objectives is to take pictures and analyze the chemistry of a variety of Mars rocks, and their hopes were more than satisfied by the great variety seen even in the first few images.
Golombek said the hard part would be deciding which rocks to look at first. "The first thing you do is you take these glorious pictures and see what looks similar, what looks different, look at the colors and the textures, and figure out what can our little bitty buddy get to."
The two-foot-long rover is expected to venture no more than 90 feet from the lander, but in the initial days it will stay much closer.
For mission planners, the pictures were an exhilarating end to a day that had been filled with mostly suspenseful waits for tiny bits of information that would reveal the outcome of their years of planning. A powerful antenna was pointed directly at Earth to begin transmitting pictures and detailed data last night. Everything appeared to work perfectly, and the final landing place appeared to have enough smooth patches among the rocky field to be safe for the rover vehicle Sojourner to begin exploring, once the airbags were fully retracted out of the way.
Earlier in the day, there were long minutes of suspense as the 1,766-pound spacecraft hurtled into the Martian atmosphere at 16,600 m.p.h., then shouts of joy and hugs galore in mission control when a faint signal showed that the craft had made it to the surface at 1:07 p.m. EDT and was still functioning.
That was closely followed by another round of cheers when a second signal indicated that the four-sided craft had landed base-down -- making the whole process of unfolding itself like a huge flower into its working configuration that much easier than if it had to tip itself over first.
The successful landing, said chief engineer Rob Manning, meant that during its descent to the surface "the spacecraft successfully fired off 41 pyrotechnic devices -- that all had to work -- on the Fourth of July."
These pyrotechnics, mostly small devices akin to a cherry bomb, were used to release various components such as the heat shield and the parachute used to slow the craft, and to inflate the cocoon of airbags that protected the craft as it hit the surface and bounced and rolled its way to a resting place.
NASA Administrator Daniel Goldin said later that "this is a revolution just of the type that founded our country. They weren't afraid of taking risks, weren't afraid of doing things differently, just like our Pathfinder team. I think this mission is going to change the history of the space program."
The landing involved a sequence of events and components many of which had never been tried before on any space mission, so the mood in the mission control center here grew palpably more anxious as the moment of the landing approached.
Mission managers had expected to be mostly in the dark about what had happened on Mars until about four hours after the landing, because the radio waves that would signal that key events had been successfully accomplished were expected to be so faint that picking them up at all was a long shot. "It's really a matter of some luck" whether the signal could be received, mission manager Richard Cook had said just before the landing.
The fact that the craft landed right side up improved the strength of the signal, and meant the team on Earth received far more information about the craft's successes early on than they expected.
Successive rounds of applause, cheering, and hugging rocked mission control, as signals indicated that the airbags had been deflated and pulled out of the way, then that the three "petals" of the craft had opened fully, exposing the cameras, weather sensors, and radio transmitters to the Martian environment. More signals showed the craft was lying almost perfectly flat on the surface -- tilted by only 2 degrees -- almost ensuring that the rover would have an easy time rolling off onto the Martian surface.
Manning, whose job was to oversee Pathfinder's entry into the Martian atmosphere and its descent and landing on the planet -- a sequence referred to here as EDL -- yesterday joked that "all indications so far are very, very good. . . . This is the end of EDL, and I'm out of a job."
The detailed data about what happened during the descent was not received until almost four hours after the entry, showing that all systems were functioning perfectly. The first pictures came in about 2 hours later, revealing the lander in perfect condition amid a rock-strewn plain similar to those that had been seen by the Viking landers 21 years ago.
The mission's landing was a successful demonstration of the National Aeronautics and Space Administration's new philosophy of building spacecraft smaller, less expensively, and much more quickly than in earlier missions. The last time a spacecraft reached Mars and worked properly was the Viking mission in 1976, which cost the equivalent of more than $3 billion in 1997 dollars. Pathfinder was built for $220 million.
The craft, launched in December on a Delta rocket, traveled 309 million miles to reach its destination, and according to preliminary calculations yesterday landed within 30 miles of its intended target. That was far closer than mission planners expected: Their hope was simply to get it somewhere within a 120-mile-by-60-mile ellipse.
The area where the lander appears to have ended up was one that Pieter Kallemyn, who headed the navigation team, said got the scientists "all excited. They said `that's where we really want to go.' "
That's because it lies close enough to the tallest feature in the immediate area -- an "island" rising about 1,500 feet above the surrounding flood plain.
All in all, the mission's planners could hardly have foreseen such a flawless performance. "This was way beyond our expectations," Muirhead said yesterday. "I don't think any of us expected today to go as well as it has."
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