When a Russian spaceship bound for Mars plunged into the Pacific Ocean last weekend, having failed to escape from Earth’s gravity, the hopes of scientists from a score of nations crashed with it.
Among the most disappointed were a group of University of Chicago researchers who had four instruments aboard the 13,200-pound, unmanned spacecraft, Mars ’96. It marked the third failure by Russia since 1989 to get the Chicago gear, designed to analyze Martian rock and soil, to the Red Planet.
“It’s a big disappointment for us,” said Anthony Turkevich, an emeritus professor of chemistry who designed the instruments in the early 1960s to analyze the moon’s surface before NASA sent men to walk there.
With interest in Mars at an all-time high, however, the Chicago scientists won’t have to wait long for another attempt to put their device on Mars. One is scheduled to be launched Dec. 2 on a NASA spaceship heading for a soft landing on the Martian surface scheduled for next July 4. The device is the key component on a little robot called Sojourner that will roam the Martian landscape and pick up samples.
The Pathfinder mission will be the first American attempt ever to get the Chicago instrument to Mars, though Russia on three occasions tried and failed to put them there, including last weekend’s mishap. Two other Russian Mars-bound vehicles disappeared in space in 1989, each of them carrying the Chicago device on board.
“It’s a real setback for the Russian space program, which is struggling even more than ours for money and national support,” said Turkevich of last weekend’s failed mission.
Ever since Turkevich’s instrument, called an Alpha Proton X-ray Spectrometer (APXS), landed on three different moon missions in 1967 and 1968, he has wanted to see it get to Mars.
The NASA mission on Dec. 2 may well be the best opportunity so far to get it there.
The 1,250-pound spacecraft will be the third launched this autumn to Mars. Besides the failed Russian launch, NASA early in November successfully launched the Mars Global Surveyor, a 2,300-pound mapping satellite designed to orbit Mars. Surveyor already is making its way, scheduled to arrive next September.
Pathfinder, taking a shorter route, will arrive earlier and is designed to land safely and softly on the Martian surface. Once on the ground, it will release the plucky little robot to explore independently of the landing vehicle. The rover is named Sojourner after the African-American Civil War heroine Sojourner Truth who traveled “up and down the land” advocating freedom.
The information the spectrometer sends back may provide long-sought answers about the history of Mars and help set the stage for a day when humans may tread the surface of the Red Planet.
“We will find out the elemental composition of Mars,” says U. of C. physicist Thanasis “Tom” Economou. Since Turkevich’s retirement, Economou, a senior research associate at the university’s Enrico Fermi Institute, oversees design refinement and building of the spectrometers there.
“Our instrument does not determine molecular structure, so it does not distinguish organic (i.e. living) matter from inorganic matter. It can only say which elements are there (on Mars).
“But it can detect carbonates and nitrates, which would strongly suggest organic material being present.”
As Pathfinder plunges into the thin Martian atmosphere, its descent will be gentled and slowed by a billowing parachute, then a cocoon of inflating airbags, and finally a burst from deceleration rockets.
Upon landing, it would be the first Earth visitor to Mars since America’s Viking 1 and 2 landers sent back some 50,000 photos of the planet in 1976.
The robot aboard Pathfinder resembles a 2-foot-long toy wagon on six wheels. This Sojourner is equipped with artificial intelligence enabling it to think for itself to avoid hazards and barriers while scooting and snooping up and down the Martian landscape.
The spectrometer is a snoutlike 2-inch disk that will extend from one end of the robot wagon on a movable arm. As it “sniffs” rocks and soils, it will be determining what elements and chemicals are present, looking for clues as to whether life ever did–or still does–exist on Mars.
After a week of conducting the mission’s primary experiments, NASA hopes to at times put American schoolchildren in command of Sojourner. They will pilot the foot-high robot by viewing Mars from its navigation cameras, choosing paths and destinations for it via computer linkups.
All of the launches toward Mars this year were planned and OKd long before last summer’s NASA disclosure of possible evidence of primitive life within a meteorite from Mars.
Those announcements, however, have spurred interest in the new spate of Mars exploration, both scientific and emotional.
All of the new Mars explorations revolve around trying to find evidence of minerals that would tip off where water might have been or still be on the planet.
In the process, they will be preparing the way for a planned mission in 2005 that will scoop up carefully chosen rock and soil samples robotically and return them to Earth. Such hands-on molecular analysis of actual material from Mars is the only way science will unequivocally answer the question of Martian life.
And, ultimately, the present slate of robotic Mars exploration was planned to gauge the lay of the land for an eventual manned mission there, possibly in the second decade of the new century.
“We will have to learn how to live off the land, like early American explorers, if we send humans out there,” says Economou.
The economies of space travel now dictate that such explorers probably will have to replenish their stores of fuel, water and oxygen on Mars to outfit their eventual return to Earth. They would also have to find building materials out there to construct a base to shelter them for a year’s Martian stay.
To test how feasible those plans might be, scientists will rely, at least initially, on the tried and true spectrometer that Turkevich, Economou and their staff have been designing and refining in Chicago for the last 35 years.
The compact instrument can analyze the chemical composition of materials placed in front of it by bombarding them with subatomic alpha particles.
Turkevich led the development of the robot rock and soil analyzer in the 1960s, when Economou, now 59, was his principal assistant.
If the Pathfinder spaceship reaches Mars, it is expected to bounce softly on the darkened ground about four hours before the Martian sunrise, cushioned by the airbags that helped break its fall.
It is targeted to land on an ancient, rocky flood plain called Ares Vallis. Many eons ago rampaging Martian rivers deposited many different kinds of rocks and soils scientists want to examine.
Once down, the flying saucer-shaped spacecraft will unfold into three petal-like appendages, one bearing the Sojourner robot.
Solar cells on the main lander will begin to power up with the rising sun, and a camera will begin sending to Earth images of the surrounding terrain. Consulting those pictures, scientists will power up Sojourner and guide it off the lander.
Once free, Sojourner, on six cleated wheels, will begin its mission, grasping and climbing over soil and rock until it stops at something scientists wish it to examine.
“We will try to involve schoolchildren, who will have the chance after the primary, two-week scientific mission is completed, letting them try to navigate the rover from Earth by computer command,” he says.
“Kids are very good at this. The signal takes 14 minutes to travel out to Mars from Earth, and 14 more minutes for a response to come back. You send a command, and by the time you get to see what happened, you will be in a completely different place.
“You have to work in virtual reality and try to imagine and predict your path.”
