Earthlings launch their most ambitious invasion of Mars this week, with the planned liftoff of the first in a 10-year series of robotic explorers to the Red Planet.
NASA's Mars Global Surveyor is set to blast off from Cape Canaveral, Fla., just after noon tomorrow. It should begin orbiting Mars on Sept. 11 for a two-year study of the planet's atmosphere, its surface geology and interior physics.
Two more spacecraft -- NASA's Mars Pathfinder and Russia's Mars '96 mission -- will join the Mars-bound squadron during the next four weeks.
Between them, they are packing 28 instruments, two missile-like surface "penetrators," three landers and a six-wheel surface rover, all designed to study Mars' rocks, weather and its capacity to support life -- past or present.
Although planning began years ago, the Mars missions are setting off just as scientific interest in Mars, and the possibility of life elsewhere in the solar system, is surging.
Two teams of scientists in recent months have reported that meteorites blasted from Mars by collisions eons ago appear to hold "strong" mineral and fossil evidence of ancient microbial life on Mars.
The Pathfinder mission will land first, on July 4. And soon after that, anyone with Internet access should be able to dial up the mission's home page via computer for the latest scenery and weather from the landing site.
"By sitting in your home and looking at the video screen in almost real time, you will be able to see it," said NASA Administrator Daniel S. Goldin. "I can't think of anymore exciting mission we've had in the last few decades."
If they make it, the three spacecraft will be the first to study Mars since NASA's two Viking landers touched down in 1976, when Gerald R. Ford was president.
Viking's instruments scratched the Martian dirt and sniffed inconclusively for signs of life. They also sent back the first red-hued TV images and frigid weather reports from the planet's surface.
The last Viking radio went dead in 1983.
Scientists also hope their 1996 missions will redeem the failures of NASA's $1 billion Mars Observer spacecraft, destroyed by a fuel explosion as it approached Mars in 1993; and the Soviet Union's twin 1989 Mars/Phobos missions, which failed in Martian orbit.
This year's missions are just the first wave of the new Mars explorers. NASA plans to send spacecraft to Mars four more times between now and 2005 -- each time the Earth and Mars are properly aligned for an attempt.
The next two robotic missions to Mars are scheduled for 1998 -- one orbiter and one lander. Another orbiter and lander are planned for 2001.
Two more missions are tentatively scheduled for 2003 and 2005. The latter may include a round trip to bring a sample of Martian soil back to Earth.
NASA's new, aggressive assault on Mars is the product of several forces at work in the space agency.
At the start of the Clinton administration, Goldin challenged NASA engineers to find "better, faster, cheaper" ways to do space science. There would be no more missions that required a decade of planning and billions of dollars -- like Viking, Voyager and Galileo.
The agency's new Discovery spacecraft, for example, must be developed and launched in less than three years, with a price tag for the spacecraft capped at $150 million in 1992 dollars. Mars Pathfinder is a Discovery mission.
Faster development gives scientists more opportunities to use lessons learned on past missions to redesign the next wave of experiments and spacecraft.
Mission designers are also reaping cost savings made possible by recent advances in technology: new, lightweight materials, more efficient power supplies and sensitive, reliable, miniaturized instruments.
The Mars Global Surveyor spacecraft set for launch this week was developed in 25 months and will cost $250 million, including launch and two years of operations. Yet it is expected to gather 80 percent of the scientific information the $1 billion Mars Observer mission would have collected.
December's Mars Pathfinder mission, with its lander and rover, will cost $270 million by the time it is finished. That compares with $3.7 billion (in today's dollars) spent on the Viking lander missions in 1976.
NASA's invasion plans do not include a manned landing.
Before that can happen, Goldin said, scientists must show the American people there is a scientific reason for humans to make the trip. They must also learn "how to go to Mars at a reasonable price and in a reasonable time, and how to live in space."
But "it is within our grasp to solve all of these issues in the next decade," he said. After that, if a decision is made to attempt a manned mission, "we ought to be able to do it in eight years."
The flight schedule planned for this year's Mars missions includes: TOMORROW: NASA's Mars Global Surveyor, set for liftoff from Cape Canaveral at 12: 11 p.m. aboard an unmanned Delta rocket. There will be more chances to launch each day through Nov. 25. The circuitous, 430 million-mile trip to Mars will take 300 days at an average speed of 66,000 mph.
Arriving Sept. 11 (assuming a launch tomorrow), the spacecraft will use repeated brushes with the Martian atmosphere to slow down and drop gradually into a circular orbit 234 miles above the surface. This "aerobraking" saves NASA the weight and cost of carrying extra rocket fuel for braking.
From a two-hour, north-south orbit over Mars' poles, Global Surveyor will scan the planet as it rotates below, accumulating a geographical portrait through all seasons of the 687-day Martian year. The mapping will begin in March 1998 and end in January 2000.
To save money, NASA loaded Global Surveyor with spare instruments built for the 1993 Mars Observer mission. Wide-angle and telephoto cameras will record the planet's surface, dust storms, clouds and seasonal changes in its polar ice caps, resolving objects as small as 4.6 feet across.
"We may even be able to photograph the Viking spacecraft and Pathfinder as they sit on the surface of Mars," said project scientist Dr. Arden Albee.
A thermal emissions spectrometer will analyze surface chemistry and search for sites with water and the highest probability of harboring past or present life.
The first laser altimeter ever sent to another planet will measure Mars' towering volcanoes and gaping canyons. Clues to Mars' interior structure and natural history may come from a magnetometer that will map any magnetic field it finds. Tiny distortions in the craft's radio signals can reveal dense regions of Mars' interior and the temperature and pressure of its atmosphere.
Russia's Mars '96 spacecraft is scheduled for launch Nov. 16 in Kazakstan atop a Proton rocket. If all goes well, it should arrive at Mars on Sept. 12, a day after Global Surveyor.
The Russian orbiter will carry 24 instruments and devices (including two U.S. experiments) for studying the planet's surface, atmosphere, interior and space environment.
Two 110-pound surface stations detached just before the orbiter's arrival will enter the Martian atmosphere at 12,600 mph, braked first by friction, then by parachutes before landing on air bags.
On the surface, an international array of instruments will study the environment.
Mars '96 will also release two 15-foot surface penetrators that will slam up to 20 feet into the planet at nearly 200 mph and send back data on weather and soil chemistry.
NASA's Mars Pathfinder is set for launch Dec. 2, arriving at Mars on July 4. Its 2,000-pound lander will shed its heat shields and parachute close to the surface. It will bounce the last few yards to the ground in a pillow of air bags, roll to a stop and then open like a three-petal flower.
Opened, the solar-powered lander is 9 feet across, about the size of a large kiddie pool. Its color stereo camera, on a 4-foot, pop-up mast, can send back snapshots every two seconds. Filtered images of the sun and Mars' moons will reveal the amount of dust and water vapor in the Martian atmosphere. Sensors and wind socks on a mast will reveal temperature, wind speed and direction. Views of the rover's wheels and tracks will hint at the consistency of the soil.
The agile, six-wheeled rover was named Sojourner, after black abolitionist Sojourner Truth. It is the size of a child's tricycle. It has a top speed of 2 feet per minute, but can scale a 10-inch rock and keep going.
It carries a camera, laser sensors and an Alpha Proton X-Ray Spectrometer. Geologists monitoring pictures from the lander and the rover itself will be able to send the "22-pound geologist" to any interesting rocks they see. Pressed onto the rocks, the spectrometer will collect and relay data on the rocks' chemical makeup.
"By understanding the mineralogy and rock type, a geologist can tell you how it formed and what the environment was like at the time it formed," said Pathfinder scientist Dr. Matthew Golombek.
The lander could operate for up to a year. The rover, with a range about the size of a football field, could last a week to several months, depending on how long its electronics and power reserves survive the bitter Martian cold.
Pub Date: 11/05/96