Digging Mars

By Jeffrey Kluger

On the whole, NASA has always treated Mars with respect. American spacecraft have flown by, orbited and even landed on the Red Planet. What they've never done is wound it. If scientists ever hope to understand Mars fully, however, they are going to have to puncture the dry Martian rind to sample the planetary pulp below. Next week NASA will launch a ship that will begin that process.

The upcoming mission is a two-spacecraft extravaganza. The first ship--set to fly Dec. 10--is the workmanlike Mars Climate Orbiter. Arriving in September 1999, the spacecraft will enter an orbit of the planet that traces a path over the Martian poles, allowing it to study the local atmosphere. Its orbit will position it perfectly to act as a relay satellite for any later ship that may land on the surface. That's a good thing, since three weeks or so after the orbiter leaves Earth, NASA will launch another spacecraft, the more ambitious Mars Polar Lander.

A spindly machine standing 3.5 ft. tall, the lander is set to arrive in December 1999, aiming to touch down near Mars' south pole, one of the few spots on the freeze-dried planet that is likely to contain some water. Just before reaching the Martian atmosphere, the lander will release a pair of tapered pods, each about the size of a basketball, made of brittle silica. Plunging ahead of the ship, the projectiles will free-fall to the surface and strike the ground at 400 m.p.h.

The pods are designed to shatter on impact, releasing a pair of 7-in. probes. Slamming into the surface, the probes are supposed to drive themselves 4 ft. into the Martian crust. Once buried, they will deploy tiny drills and begin sampling the chemical makeup of the soil around them. Scientists believe that chemistry could be remarkably rich. "The surface of Mars has been pretty well sterilized by ultraviolet radiation," says Sam Thurman, the mission's flight-operations manager. The subsurface has been spared that scrubbing.

Only minutes after the probes hit the ground, the lander will follow, descending by parachute and braking engine. Bristling with cameras and sensors, it will study Mars' terrain and weather, snapping pictures both during its descent and on the surface. It will also carry a microphone to record for the first time the sound of the Martian wind. More important, the ship will be equipped with a robotic arm and scoop, much like the arms carried aboard the Viking landers in the 1970s. Unlike the Vikings, though, which were able to paw just a few feeble inches into the Martian topsoil, the new ship will gouge out a trench nearly 3 ft. deep.

How long all this otherworldly hardware will operate is uncertain. The probes, powered by batteries, should wink out within three days. The lander, with robust solar panels to keep it humming, could last three months. But even if the systems do not survive that long, their work could be profound. After all, scientists have spent years studying just the Martian skin; this will be their first chance to dig a little deeper.