DATE: Thursday, July 3, 1997                TAG: 9707020015

SECTION: LOCAL                   PAGE: B10  EDITION: FINAL 

TYPE: Editorial 

                                            LENGTH:   56 lines

DIVING TO THE RED PLANET THE MISSION IS THE FIRST OF A SERIES OF LOW-COST EXPEDITIONS.

Mars will have this in common with the United States on the Fourth of July: Americans will fire rockets to celebrate the 221st anniversary of the Declaration of Independence. Rockets will be fired from the NASA Mars Pathfinder probe to slow the spacecraft's descent to the Martian surface.

More than two decades have passed since two unmanned Viking spacecraft orbited the Red Planet, relaying back images and other data that increased our knowledge of the planet in our solar system most like our own.

The Vikings, each of which cost many times more than the Mars Pathfinder, made a sloping entry into Mars' atmosphere. The Mars Pathfinder will plummet, its red-glowing heat shield partly disintegrating before being jettisoned.

Mars Pathfinder began its trip seven months ago. Its plunge could end in success or disappointment. Its lander, loaded with information-gathering technology (including an exotic camera and roving robot), could be disabled or destroyed.

The dramatic entry is supposed to take five minutes.

NASA's scenario says the probe will rip into Mars' atmosphere at 17,000 mph; friction will slow it to 900 mph; a parachute will pop out about two minutes before touchdown; the heat shield will fall away 20 seconds later; the lander, tethered to a 65-foot line, will tumble downward; the rockets will fire to further slow the descent; the lander will be cut loose to strike Mars going 50 mph.

Air cushions will soften the arrival of the lander, but also cause it to bounce perhaps 10 feet before settling.

A NASA Langley team developed the computer models that foretell Mars Pathfinder's descent.

If all goes as expected, the lander will unfold its three solar panels and unleash its rover to collect soil and rock information. Rock, soil and weather data and pictures will then be beamed to our blue planet.

A successful mission will hearten NASA. The Mars Pathfinder mission is the first of a series of comparatively low-cost expeditions designed to further human understanding of our closest neighbors in space.

Americans are the first humans to have walked on the moon, but manned flight to other worlds is on the back burner, awaiting development of futuristic fuels and other technological breakthroughs.

While NASA collaborates with Russia on development, deployment and operation of an orbiting space station more sophisticated than the decrepit Mir, the U.S. space agency is sensibly assigning the job of interplanetary exploration to cost-efficient robotic machines.

If something goes wrong with Mars Pathfinder, America loses the time and the money invested in it. If something goes wrong with a manned spacecraft, lives can be lost. Russian cosmonauts and American astronauts have perished in their nations' manned spacecraft. Two incidents - a fire on board and last month's crashing of a cargo rocket into a solar panel - endangered the personnel aboard Mir and spread fear for their safety. Better to risk only money and time on far-out space travel.

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