News Services
University of Arizona

Dec 2, 1999

All systems go to land Mars probe tomorrow

By Lori Stiles

LOS ANGELES -- "We are ready," University of Arizona planetary scientist Peter Smith said Dec. 1, speaking for a team of scientists who built cameras arriving Dec. 3 at Mars.

"The camera is functioning. It's healthy. The team is trained. The software is working. We are ready for pictures. Now all we have to do is dock. "

Smith and a dozen other co-investigators for the Mars Volatiles and Climate Surveyor (MVACS) yesterday gave a news briefing at the UCLA Mars Science Operations Center. MVACS, headed by UCLA's David Paige, is the main package of science instruments on Mars Polar Lander.

Landing is to be at 12:15 p.m. Pacific Standard Time. The first opportunity for a signal that says the lander arrived safely at Mars' south pole is 12:39 p.m. PST. Landing initiates the first martian day of the mission, or "sol 0." That will begin the first-ever studies of climate, atmosphere, geology, and water at the southern region of the planet.

Smith said that a major part of mission success for his team's Stereo Surface Imager (SSI) will be taking a full-color, stereoscopic, 360-degree panorama. The panorama will be compiled from pictures taken on sol 1, sol 2 and sol 3. The imaging team might have the complete panorama by Dec. 7, he added.

Other SSI tasks include taking pictures of clouds, dust, and other phenomena in Mars' sky, imaging the geological features on the frozen polar surface, taking pictures of dust that clings to magnets in another MVACS experiment, and using SSI's 12-filter system for pictures that will show what kinds of minerals may be present or are not apparent in surface layers of Mars. Expect the best pictures from SSI later in the mission, when there will be time to send down higher quality data.

H. Uwe Keller of the Max Planck Institute of Aeronomy and Smith developed the Robotic Arm Camera in the MVACS payload. RAC will see features as fine as a human hair, Keller said. RAC is, in fact, the first microscope to land on another planet. RAC is also able to take wide panoramic views. RAC's big science contribution will be to photograph different colored layers of soil as the robotic arm digs a half-meter deep trench. Scientists will use RAC images to choose samples to be analyzed in TEGA.

TEGA, or the Thermal and Evolved Gas Analyzer, is headed by University of Arizona planetary sciences professor William V. Boynton. This instrument was designed, built and tested at the UA Lunar and Planetary Laboratory.

TEGA is basically designed to yield information on the history of water on Mars, said TEGA scientist Don Musselwhite, research associate with the University of Arizona's Lunar and Planetary Lab.

It is the first instrument that will directly measure water in the soil of Mars. It uses electric current to heat soil samples, which are then analyzed by laser spectrometry for water and carbon dioxide content. TEGA will measure how much of these volatiles are locked in ice and how much are locked in minerals.

TEGA will get its first sample within about a week of landing, according to current plans, Musselwhite said.

NASA Jet Propulsion Lab mission managers won't have a firm schedule of when pictures and data will be returned until they know the condition of the spacecraft after landing.

Each sample will be heated just hot enough for any water and carbon dioxide ice to melt. On the following day, the scientists will then more quickly bring the sample to maximum temperature, around 950 degrees Celsius (1,750 degrees Fahrenheit). This will release any water and carbon dioxide gases locked in minerals.

"We hope to get a sample once a week or so, depending on how the mission goes," Musselwhite said.

Musslewhite and other researchers used a mock demonstration site at the news briefing to explain the mission.

Just as SSI, RAC and robotic arm are part of TEGA science, they are integrated with the MVACS magnetics experiment, too, said Morten Bo Madsen of the University of Copenhagen.

He and his colleagues will study the magnetic properties of atmospheric dust particles, just as they did in 1997 on Mars Pathfinder. A magnetic array on the lander deck and another magnet near the SSI eye are designed to catch airborne dust.

But on this mission, the Danish scientists also will study magnetic properties of dust in the surface and subsurface martian soil, thanks to the robotic arm and extra close-up imaging camera capability.

"This dust in the soil may be something quite different from the airborne dust," Madsen said.

The scientists have mounted three magnets just beneath the mesh screen that feeds finer dirt particles into TEGA. As the robotic arm scoops a dirt sample into TEGA, particles that don't pass through the mesh screen run off onto the surface of the magnets. The idea is to sample magnetic properties of dust at the surface, then partway, then all the way to the bottom of the trench.

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