From top: The Mars Climate Orbiter, the Polar Lander, Deep Space 2, and Stardust.

(CNN) -- Over the next four months, NASA will launch a quartet of space probes that will open a new chapter in unmanned exploration -- including the first mission to bring back to Earth interstellar material from beyond the orbit of the moon.

All four missions will collect data that scientists hope may shed light on the origins of life on Earth and the possibility that it may exist elsewhere in the universe.

Mars Climate Orbiter

The first component of the three-pronged, $183.9 million Mars Surveyor 98 mission, the Mars Climate Orbiter will launch December 10 aboard a Delta 2 rocket.

Upon arrival at Mars 10 months later, the 629 kilogram (1,387 pound) spacecraft will carry out a series of aerobraking maneuvers, dipping into the upper reaches of the martian atmosphere, to achieve a stable orbit.

The orbiter will then use atmospheric instruments and cameras to provide detailed information about the surface and climate of Mars and provide command and data relay support for the forthcoming Mars Polar Lander. The orbiter will perform systematic daily global sounding and imaging of the Mars atmosphere for about one Mars year (687 days)

Mars Polar Lander

The Mars Polar Lander will launch in January, one month after the orbiter and will land near the southern polar cap on Mars. The lander is equipped with cameras, a robotic arm and instruments to measure the Martian soil composition.

Unlike Mars Pathfinder, the Mars Polar Lander will use thrusters to perform a controlled, propulsive landing, and will collect images of the martian surface during descent.

Its targeted landing site is an uncharted territory on the southern pole, where it will dig for traces of frozen, subsurface water.

Instruments used by the Lander on the surface will perform meteorology, imaging, and soil composition experiments. A robotic arm will dig a trench and collect soil samples for analysis. The Lander is expected to operate on the surface for about three months.

NASA scientists say new images of the landing zone for the Polar Lander, taken by the camera aboard NASA's Mars Global Surveyor, currently orbiting Mars, indicate that the strange, layered terrain in the south polar region represents a dramatic departure from the now-familiar Martian landscapes observed by the Viking landers and Mars Pathfinder. In December 1999.

"Despite ground fog that obscures part of the surface in these images, we can see much more surface detail than we've ever seen before, which suggests that the 75-degree south latitude landing zone is quite a bit more rugged and geologically diverse than we had previously thought," said Dr. Michael Malin of Malin Space Science Systems Inc., San Diego, California. Malin is principal investigator of the Global Surveyor camera.

Deep Space 2

In December 1999, two basketball-sized aeroshells will crash onto the Martian surface at a velocity of about 200 meters per second.

Each aeroshell will shatter on impact, releasing a miniature two-piece science probe that will punch into the soil to a depth of up to 2 meters.

The microprobes' primary science goal: to determine if water ice is present in the Martian subsurface -- an important clue in the puzzle of whether life exists or ever existed, on Mars.

The tiny science stations will piggyback on the Mar Polar Lander, and be released ding its descent. The probes will also measure temperature, monitor local Martian weather, and test key technologies NASA hopes to use in future missions.

Stardust

NASA's Stardust, launching in February, is the first U.S. mission dedicated solely to visiting a comet and represents the first attempt to return extraterrestrial material from outside the orbit of the moon.

The primary goal of the $199.6 million misssion is to collect comet dust and volatile samples during a planned close encounter with comet Wild 2 in January 2004. The Stardust spacecraft will bring back samples of interstellar dust, including the recently discovered dust streaming into the solar system from the direction of Sagittarius.

While in space, it will open like a clamshell, with the dust collector grid deployed into the dust stream. The spacecraft will make three loops around the sun. On the second loop, the trajectory of the spacecraft will intersect that of Wild 2.

During encounter the spacecraft will send back pictures of Wild 2, counts of comet particles striking the spacecraft, and real-time analyses of the compositions of the particles and volatile samples. Stardust is to return to Earth with its celestial bounty in January 2006.

Related stories: Engine stalls on NASA's Deep Space probe - November 12, 1998 Deep Space 1 soars - October 24, 1998

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