On December 4, 1996, a Delta II rocket blasted away from Kennedy Space Center in Florida, carrying the Pathfinder spacecraft on what would be a seven month, 309 million mile journey to Mars.
The launch and transit to the Red Planet went flawlessly, raising hopes that Pathfinder would somehow beat the odds and succeed where more than half of the 20 previous human efforts to visit Mars had failed. Mars has seemed jinxed, or perhaps willfully hostile. But Pathfinder did beat the odds.
At least, most people think so. But not all.
ARE WE REALLY THERE?...
Well before Pathfinder arrived on July 4, conspiracy-minded observers were saying the mission was preordained to fail, or perhaps was not even real in the first place. All those great images might be a movie set, or panoramic views of the desert Southwest, they said. Internet newsgroups are expecially rife with such talk.
On June 26, the Hubble telescope imaged the beginning of one of Mars' fabeled dust storms. The storm, centered more than 600 miles south of where Pathfinder was aimed to land, was unlikely to cause any difficulties, mission specialists assured the press. Conspiracy theorists rolled eyes skyward. A perfect setup for failure, they hinted darkly.
As officially predicted, the storm has had no impact whatsoever on Pathfinder's mission -- officially speaking.
Meanwhile, once landed, the spacecraft's performance seemed so superlative that even Rudolph Rieder of the Max Planck Institute for Chemistry in Germany, the principal spectrometer investigator for Pathfinder, acknowledged to the press that "some people might believe this is a hoax." He quickly added, "We can assure you it is not a hoax."
This CNI News report will proceed in the assumption that Pathfinder did indeed land on Mars and has indeed performed as officially described. While we can't prove this is true, simple logic, along with the unabashedly enthusiastic behavior of the Pathfinder scientists at Pasadena's Jet Propulsion Laboratory, suggests (to us at least) that it is.
With a reported cost of $266 million, Pathfinder exemplifies NASA's new "smarter, faster, cheaper" approach to space exploration. By comparison, the ill-fated Mars Observer that disappeared in 1993 cost approximately one billion dollars.
Pathfinder's mission is to study Mars surface conditions and geology and test technology for remotely operated exploration, which in later missions will include collecting soil and rock samples. Pathfinder cannot test for the presence of life on Mars.
The spacecraft consists of an 800-pound lander and the 22-pound, six-wheeled rover Sojourner. The main lander is designed to analyze the Martian atmosphere, record weather, and take color pictures. Sojourner can go out several hundred feet, carrying cameras and a device to analyze the chemical composition of soil and rocks, but it does not take any samples. Its top speed is under 150 feet per hour.
Radio signals take between 10 and 11 minutes to travel between the lander and receiving stations on earth. Mars rotates on its axis at almost the same speed as earth (a Mars day is 24 hours, 37 minutes, 23 seconds), so radio contact is only possible for about half of each day, when the Mars landing site is aimed toward earth.
The landing site is an ancient floodplain known as Ares Vallis in the northern hemisphere of Mars. Because the area has many distinctive features, including several nearby hills and a small crater, mission specialists have been able to pinpoint exactly where the Pathfinder is located.
The lander was designed to operate a minimum 30 days, while the rover's official mission was designated as only seven days. Once on Mars, it quickly became obvious that both lander and rover would perform many times longer than minimum expectations. Mars weather may prove the limiting factor.
Temperatures at the site can range from about 0 degrees Fahrenheit to minus 125 degrees Fahrenheit during the current summer season. With the Mars year running 687 earth days, it could be anywhere from six to twelve months before the deep cold of Mars winter shuts down Pathfinder for good.
Anticipation was running high at NASA in the hours leading up to Pathfinder's July 4 landing. As if success were a foregone conclusion, Wesley Huntress, Associate Administrator for Space Science, declared on July 3, "We are back, and we are back to stay this time."
NASA Chief Administrator Daniel Goldin, standing by at the Jet Propulsion Laboratory, took a different tack. "The success or failure of this first step doesn't relate to the total program," he declared. "I want people to take risks. I want them to know that if they fail, we will come to them and shake their hands."
At that moment, Pathfinder was blasting toward Mars at more than 12,000 miles per hour, accelerating in the pull of Mars gravity. It was designed for a direct landing, meaning it would not orbit the planet before setting down. By the time Pathfinder entered the thin Martian atmosphere, it was only four minutes from touchdown and traveling at 16,000 miles per hour.
This kind of landing had never been tried in any space mission before. No one knew if it would work. An amazingly intricate sequence of events had to unfold flawlessly, or the Pathfinder would end up as debris on the Martian landscape.
The lander was protected by an outer assembly consisting of forward heatshield and backshell. Hitting the outer atmosphere at an altitude of about 80 miles, the heatshield was designed to withstand more than 100 megawatts of thermal energy as the craft rapidly decelerated.
At a speed of about 900 miles per hour, deceleration g-forces triggered deployment of a 24-foot diameter parachute. Shortly after the chute opened, the heatshield was cast off. The craft slowed to about 65 meters per second.
The lander then separated from the backshell and descended down a 20-meter long kevlar tether. Eight seconds before impact, ground-seeking radar triggered deployment of the lander's airbags.
Four seconds later, at an altitude of about 100 meters, three small rockets on the backshell fired briefly, all but stopping the entire assembly in mid-air. Then, with rockets still firing, the tether was cut at the lander end. The backshell flew upward into the parachute, carrying it well away from the landing zone.
The lander then free-fell to the surface, bouncing on its airbags as it hit. The first bounce was probably more than fifty feet high and may have carried the lander 100 meters down-range.
JPL mission specialists were able to determine, some days later, that the lander had bounced more than sixteen times before coming to rest.
Considering the complexity of the landing procedure, tension ran high in the minutes before impact. The nail-biting ended abruptly at 10:07:25 a.m. Pacific Daylight Time, when mission control received the first faint signal from Pathfinder, proving success.
Pathfinder landed upright and functional, within 30 miles of its intended target -- in space terms, a near-perfect hit.
Scientists at JPL leaped to their feet and cheered. Some looked slightly misty-eyed.
KUDOS AND HONORS...
President Clinton wasted no time praising the achievement.
"Our return to Mars today marks the beginning of a new era in the nation's space exploration program," he declared that afternoon.
"The Mars Pathfinder is the first of a series of probes we are sending to Mars over the next decade. The information we gather on our neighbor planet will help us better understand our own world and perhaps provide further clues on the origins of our solar system. This mission also underscores our new way of doing business at the National Aeronautics and Space Administration (NASA). We were able to accomplish this mission in one-third the time and at a fraction of the cost of the first Viking mission to Mars."
"I congratulate the Mars Pathfinder team at NASA and the Jet Propulsion Laboratory for their pioneering vision and spirit in accomplishing this remarkable feat. Their success in developing the Pathfinder mission is a testament to the ingenuity and 'can do' attitude of the American people."
With the landing safely achieved and wondrous images of the Martian landscape flooding in, NASA announced on Saturday, July 5 that the lander would be renamed to honor the late astronomer Carl Sagan, who had been a consultant on every previous NASA exploratory mission.
"In the midst of our joy, we also felt Carl's absence," said Louis Friedman, executive director of the Planetary Society. "This is the first arrival of a U.S. spacecraft at Mars that Carl ever missed."
Sagan died in December, 1996 from bone marrow disease. He was 62. The Pathfinder spacecraft was officially renamed the Carl Sagan Memorial Station.
THE EXPLORATION BEGINS...
At about 4:30 p.m. PDT on July 4, the spacecraft began transmitting photographs of rocky terrain stretching out to the horizon, as well as its unfolded petal-like solar panels and the air bags that softened its landing.
Initial shots were taken to assess the condition of Pathfinder and the rover. The photos also included sky shots to test the camera's ability to move freely.
The first images, in black and white, were startling for their clarity as well as the austere beauty of the Martian landscape. Color images began coming in about two hours later.
"This is a fantastic landscape.... This is what we're here for," said Peter Smith, the University of Arizona scientist who developed the Pathfinder lander's camera.
The pictures portrayed rocky, red plains beneath a salmon-colored sky. Two hills marked the near horizon about one kilometer away.
Later, when the lander's camera was raised on a boom, it was able to observe a much larger hill, more than 1,000 feet high, about 20 miles away.
"This site has substantially more relief than any other place we've ever seen on Mars," said project scientist Matthew Golombek.
Scientists quickly zeroed in on several nearby rocks that would soon become the objects of intensive scrutiny. Apparently giddy with excitement, the scientists began dubbing the rocks with whimsical names such as "Barnacle Bill," "Yogi" and "Scoobie Doo."
THE ROVER DEPLOYS...
A slight glitch in Sojourner's onboard computer delayed initial deployment of the robotic rover, which had been scheduled for early Saturday. At first, mission specialists could not determine why Sojourner was not responding to instructions. Later, they surmised that the rover had re-set its own computer Friday night and was awaiting the equivalent of a startup command.
By Saturday afternoon, Pathfinder lowered a ramp and the diminutive Sojourner -- often likened in size and shape to a microwave oven -- began its slow roll down to the ground.
"She is the robotic equivalent of Neil Armstrong on Mars," said rover scientist Henry Moore.
Mission scientists spoke of the foot-high Sojourner in terms most people reserve for pets, or favorite friends. On Sunday afternoon, as they prepared the rover for its first full day on martian soil, they played the theme to the television show "Mad About You" in the control room.
Studying Sojourner's distinctive pair of tracks in the red Martian dust, geologists said the surface seemed like a thin dusting of flour over a harder layer.
WHERE WATER ONCE FLOWED...
Among the first conclusions reported by mission scientists was that the surrounding terrain of Ares Vallis showed clear signs of having been flooded by rapidly moving water, probably billions of years ago. The nearby low hills also showed horizontal bands of color, thought to indicate the action of water.
Because the search for life on Mars is a central theme of NASA's long-term Mars exploration strategy, one of Pathfinder's chief concerns is to determine whether water once flowed across the landing site, and if so, for how long.
"Mars may even be more water-rich than Earth is. We really don't know," Golombek said.
By July 8, mission scientists were declaring that floods bigger than any ever seen on Earth once swept across the spot where Mars Pathfinder now sits.
New pictures showed boulders stacked by powerful currents, giant ripples in the rocky landscape and stains left behind by long-evaporated puddles.
The floods, they surmised, would have covered a swath hundreds of miles wide and run hundreds or even thousands of feet deep.
What is not yet clear, however, is whether stable bodies of water existed on Mars for extended periods of time. If so, the prospect of life greatly improves.
AN INTERNET EVENT...
From the moment Pathfinder landed, the NASA Pathfinder Web site -- which carries the latest photos and "live from Mars" video and audio clips -- became the most popular place in cyberspace. At least 20 mirror sites had to be set up to handle the record amounts of web traffic. Between July 4 and July 6, the combined Pathfinder sites reportedly received over 100 million hits.
According to ABC News, "The Pathfinder mission is a defining moment for the internet, the way the JFK assassination was a defining moment for television."
As of July 18, CNI News found no difficulty accessing the Pathfinder sites, which are each designed to handle from 2 to 5 million hits a day.
A PLACE LIKE EARTH...
Though spacecraft had visited Mars before, none of the Pathfinder mission scientists seemed quite ready for the impression all were soon admitting -- that Mars is more similar to the earth in its composition than even the moon.
The exclamations began after Sojourner scanned a rock known as "Barnacle Bill" with its alpha proton X-ray spectrometer and found that it was probably one third quartz, judging by the amount of silica it contained.
"I was just floored when it came out silica, and I am still struggling with what the implications are. Our own moon... has no quartz on it,'' said Hap McSween of the University of Tennessee, a Pathfinder scientist.
He said the other two elements making up the rock were feldspar, the most common mineral in Earth's crust, and orthopyroxene, another mineral commonly found in Earth rocks.
Meanwhile, Pathfinder continued to return a torrent of startling images of the Martian terrain. As of Monday night, according to mission scientist Matthew Golombek, more than 1,175 images had been received. "I could only hope for this in my wildest dreams," he said.
A RUN-IN WITH YOGI...
After examining "Barnacle Bill," Sojourner was directed on July 9 to begin its approach to the second of the now-famous "rock stars," this one named Yogi.
However, rather than stoppping directly in front of the rock as intended, the rover collided with Yogi, wheeling part-way up the side of the rock and pointing its alpha proton X-ray spectrometer at the sky.
Mission controllers quickly assessed the problem and determined that the rover was unharmed in the mishap. They reprogrammed it to back down and reapproach Yogi on Thursday night.
Initial analysis of Yogi was announced the following Tuesday, July 15. Scientists said Yogi seemed much more primitive than its quartz-rich neighbor Barnacle Bill. It may have been volcanic in origin, but also could have resulted from a meteorite impact, they said.
A TRIUMPHANT FIRST WEEK ENDS...
Except for a recurring software glitch on the lander -- a problem that required frequent resetting of the spacecraft's computer -- the first week of Pathfinder's mission on Mars was virtually flawless, exceeding all expectations. Mission scientists were ecstatic not only about Pathfinder's performance, but about the astonishing new picture of Mars that is emerging.
"This mission has rewritten the history of Mars," said Deputy Project Director Brian Muirhead.
During the giddy first week, the press doted endlessly on Pathfinder. But Friday night, July 11, nearly all of the estimated 570 news reporters that had descended on NASA's Jet Propulsion Laboratory packed their bags and returned home.
But the story was hardly over. Though Sojourner's mission was nominally slated for only one week, it will continue to explore the rocks and soil of the landing site for weeks to come. The lander is expected to keep returning photos and atmospheric data for many months.
Asked to rank the most important achievement in a week of superlative achievements, Muirhead said the landing itself had to take the prize.
"Before you can do all these things you have to put a spacecraft on Mars," he said.
Muirhead said he believed the success of the Pathfinder mission could be the first step on the way to a manned expedition to Mars, adding that the lessons learned from Pathfinder would be extremely useful for a manned flight.
"I think we've shown that you can use innovative technology that hasn't been proved in space before, providing you test it thoroughly on Earth, taking every contingency into account," he said.
NEW MISSIONS AHEAD...
The great success of Pathfinder bodes well for the ambitious sequence of future Mars missions already planned by NASA.
The Mars Global Surveyor is scheduled to begin orbiting Mars this September, its mission to photograph every square meter of the planet's surface. UFO enthusiasts are hopeful that MGS will settle, once and for all, the mystery of the so-called "Face on Mars." NASA's chief administrator Daniel Goldin has publicly pledged to post MGS images of the "Face" on the internet as soon as they are acquired.
Another orbiter will be launched in December 1998, followed by the launch of a second lander, the Mars Explorer, in 1999.
In 2001 an orbiter and lander, complete with a rover about four times the size of Sojourner, will be sent to Mars. As a prelude to eventual manned expeditions, the lander will carry out an experiment to try to generate rocket propellant from material at the landing site.
By 2005, if current plans hold, an unmanned spacecraft that arrives on Mars in 2003 could return a sample of Martian rock and soil to the earth.
WHEN WILL PEOPLE GO?...
It goes without saying that Pathfinder's success has rekindled enthusiasm for manned exploration of Mars.
"It's within reach," said Doug Cooke, manager of the Exploration Office at NASA's Johnson Space Center in Houston. "Technically it's something that can be done."
Such a mission could happen as soon as 2010, Cooke believes.
With their new commitment to "smarter, faster, cheaper" missions, NASA planners have embraced some radical ideas on how to get humans to Mars and home again in a time of shrinking budgets.
Robert Zubrin, a scientist with Pioneer Astronautics in Lakewood, Colorado, has demonstrated a way to generate fuel on Mars. His vision of the ideal Mars mission, dubbed "Mars Direct" in his 1996 book "The Case for Mars," involves sending an unmanned vehicle to Mars a year or more ahead of a manned craft. The unmanned craft refuels itself on arrival, extracting oxygen and synthesizing methane from the Martian environment. It then serves as the return vehicle for the astronauts.
On Wednesday, July 16, Doug Cooke presented an overall plan for a 2-1/2 year manned Mars expedition to NASA chief Goldin.
In Cooke's plan, a variation on what Zubrin calls "Mars semi-direct," two unmanned spacecraft would be launched. One would land on Mars and generate fuel for the return trip. The other would remain in Mars orbit.
Astronauts would head out two years later, spend 18 months on Mars, depart in the fueled spaceship, dock with the orbiter and head back to Earth.
Goldin has insisted that planners figure out a way to send people to Mars for no more than $25 billion. The latest estimate was about twice that. But even that represents great progress over plans that were generated when former President George Bush called for an aggressive push to Mars in 1989. Bush's blue-ribbon panel of space experts outlined a plan that would cost about $450 billion. That plan (Zubrin terms it the "Battlestar Galactica" approach) quickly died, along with Bush's Mars initiative.
But the engineers still need to resolve many other issues. Cooke's associate Kent Joosten ticks off nagging questions: "How can we make air? What's the radiation level for people? Is the dust toxic?"
Indeed, despite widespread enthusiasm for a human mission to Mars, the National Research Council on July 15 issued a report saying current human technology is incapable of making the trip.
"Today's technologies would not be able to sustain crews affordably on these types of missions," the report stated. Basic problems of air, food and water on a completely closed-cycle, two to three year trip were emphasized.
The NRC criticized NASA, saying the space agency "has not directed research and development to address, specific, long-term goals in human space exploration."
Currently, NASA allocates less than $20 million a year for R & D on human support systems for space travel. The NRC recommended NASA focus on developing a self-contained, onboard life-support system to control the atmosphere, manage wastes and provide food and water as well as a reliable method for monitoring the air, water and food supplies for contaminants.
Further, they urged NASA to design lighter and more mobile spacesuits for human activity in planetary surface gravity. Current spacesuits are designed for weightless environments.
ONWARD AND UPWARD...
Robert Zubrin, though agreeing that much remains to be learned, insists that humans are far more ready to go to Mars today than they were prepared in 1961 to achieve President Kennedy's vision of going to the moon. Back then, "We had 15 minutes of human space flight experience," Zubrin said.
In any case, the Pathfinder mission is far from over. Already it has taught us astonishing and unexpected things about the red planet some space scientists are now calling earth's "solar twin;" and its discoveries will continue for months to come.
Just as importantly, it has re-energized the passion for space exploration not only in the United States, but around the world. And, if the optimists have their way, Pathfinder will be seen in retrospect as a pivotal step toward the eventual human exploration of Mars.
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