Along with its later arriving twin, the robotic Vikings gulped down scoops of dirt, digesting the material in a kind of exotic microbial game of feast or famine.
All these years later, the answer to the top priority question the Viking twins were assigned to ask remains an arguable outcome.
For a cadre of scientists, the expensive probes may well have crackled back to Earth clear and definitive data to a $1 billion inquiry: "Is there life on Mars?" But to others, the Viking landers appear to have coughed up a simple response: "Can you repeat the question?"
The Viking 1 touchdown on July 20, 1976, came seven years to the day after Apollo 11 astronauts made the first footfalls on the Moon.
Picking up where Viking left off
Scientific teams are now readying experiments that do repeat the question -- this time looking for unequivocal answers, not wishy-washy appraisals.
The European Space Agency's (ESA) Mars Express is targeted for a June 2003 liftoff. Once in Mars orbit, the ESA spacecraft -- chock full of its own science gear to peruse the planet from high altitude -- casts off the British-built Beagle 2 lander.
On the surface, Beagle 2 is designed to open up like a giant pocket watch. After four solar panels are deployed by the lander to power itself, work begins.
"Beagle 2 will return to Mars in 2003 to carry on where Viking left off," said Colin Pillinger, lead scientist for the lander and professor at The Open University's Planetary and Space Sciences Research Institute in the United Kingdom.
Viking experimenters tried to generate a clear-cut verdict concerning life on the Red Planet, Pillinger told SPACE.com. In a sense, some scientists feel that what Viking likely detected was a "chemical practical joker" in the soil that mimicked life.
"To discover life, even dead life, you have to find a body," he says. Viking failed to turn up a body, in essence.
"Now Beagle 2 will go back to Mars with an analytical method which detects every atom of carbon in all its forms. This time we should be able to find a body if it existseven if organic matter has been degraded by processing in the hostile environment of Mars," Pillinger said.
Packed with science
Beagle 2 is packed with exquisite science gear, said Everett Gibson, an adjunct scientist on the lander. "It has the highest percentage of science payload of any spacecraft delivered anywhere," he said.
Gibson is also senior scientist at the NASA Johnson Space Center in Houston, Texas. He's no stranger to unraveling the life-on-Mars question. He is part of the team that discovered evidence for Martian biology in the famed pet rock from space, Mars meteorite ALH 84001.
Outfitted with the most sophisticated analysis system built to date, "Beagle 2 far exceeds what Viking was doing," Gibson said. Among its abilities, equipment on the lander can spot the presence of methane. Detecting methane would point to what amount to a Martian organism's "exhalations," a product of metabolism, he said.
"Beagle 2 has the potential of answering the life on Mars question," Gibson said.
Finding that methane signature would also shore up the notion that Mars may harbor a subsurface biota, Gibson said.
Up next and joining Beagle on Mars is NASA's launch of twin geology-laboratory rovers. Capable of exploring like a field geologist, the Mars Exploration Rovers are concentrating not on current life and organics, but the Mars of long ago.
"It's a different, complementary approach," said Steven Squyres, Cornell University professor of astronomy, and principal investigator for the Athena science payload to be hauled by each of the rovers.
"Mars is complicated. There are all kinds of ways that Mars can surprise us," Squyres said. "Because we understand Mars so badly, there are many possible approaches to how you can explore the planet. Mars is a tough place, no matter how you cut it."
Next page: Change in paradigm
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