NASA Mission for Burrowing Under Skin of Mars Studied

Projectiles twice the size of garbage cans would drop off a spacecraft and burrow beneath the surface of Mars during a little-known mission being considered by NASA.

The devices, called penetrators, “would just crash right into the ground. They’ll penetrate through rock,” said Rocco Mancinelli, a microbial ecologist at the National Aeronautics and Space Administration’s Ames Research Center in Mountain View, Calif.

“We want to know what the subsurface of Mars is like. Beneath that surface could be an entire warehouse of knowledge,” he said.

The Mars Network/Penetrator Mission is among many possible but unfinanced unmanned solar system explorations in the early planning stage at NASA.

It would occur after the Mars Observer Mission, a spacecraft that once was scheduled to orbit Mars in 1992, and before the Mars Sample Return, in which spacecraft would scoop up a bit of Mars and bring it to Earth, perhaps near the turn of the century. NASA scheduling is in doubt because of the space shuttle Challenger disaster.

Penetrators are viewed officially by NASA as a network of unmanned stations on Martian soil that would study the planet’s weather, detect any seismological movements and study other geology and internal heat flow.

A NASA advisory panel said in 1983 that the mission would cost roughly $200 million for six penetrators deployed and serviced by a simple orbiter, adding that more development work was needed.

Mancinelli and some other NASA biologists and chemists believe that the mission should also study Martian soil and rock for signs of subsurface permafrost and chemical evolution--the process of increasingly complex reactions of organic chemicals that most scientists believe led to life on Earth.

Hopes to Drop 15

In 1976, the Viking 1 and 2 landers failed to detect any existing life or organic chemicals in soil at two locations on Mars. But the soil had unusual chemical properties that in some ways mimic some reactions in living things.

Although the penetrators would not be able to detect any fossils of life that once might have existed on Mars, they would “give us an indication of whether there were any biologically formed molecules; it will give us information on which to speculate about whether life ever existed on Mars,” Mancinelli said.

The penetrators’ design remains undecided, but they would be roughly the size “of two garbage cans on end,” Mancinelli said, adding that he hopes 15 will be dropped on Mars by an orbiter in the late 1990s.

“Wherever a site has been selected, which hasn’t been done yet, the orbiter will shoot down a projectile” using gravity but no propulsion, Mancinelli said.

“Upon penetration, it separates into two pieces. There’s a portion that stays on the surface and a portion that penetrates (about six feet) down into the soil. The two portions are connected by an ‘umbilical cord,’ which is a communications cord.”

Both parts will have instruments to collect information. The surface portion will transmit the data to either the Mars orbiter or to a satellite above Earth for relay back to Mission Control.

He acknowledged that some scientists think NASA should skip the Network/Penetrator Mission and go directly from Mars Observer to the Sample Return spacecraft.

But NASA-Ames chemist Sherwood Chang said penetrators make sense “as an intermediate step between the (Mars Observer’s) identification of sites for future study and any more detailed study through the return of samples.”