ASU Geologists Excited by the Possibilities and Mysteries of Upcoming Mars Landing
30 Nov 1999
(Source: Arizona State University)
Arizona State University
James Hathaway, firstname.lastname@example.org, (480) 965-6375
Ronald Greeley, email@example.com
Laurie Leshin, firstname.lastname@example.org
(Both sources are currently in Pasadena and may be contacted via e-mail)
If all goes well on December 3, three Arizona State University geologists will find themselves sitting (albeit robotically through a NASA lander) on a dynamic and mysterious part of Mars that no lander has visited before and where no one, not even these mission scientists, knows exactly what to expect. One thing they do know - there is a chance to do planetary geology here unlike any that has been done before.
When the Mars Polar Lander touches down at the edge of the Martian South Polar Cap about 800 miles from the Martian South Pole, ASU's Ronald Greeley, Laurie Leshin and Marsha Presley - geologists on several of the mission's science teams - should find themselves in a novel landscape with many of the essential tools at hand that a geologist needs to really explore and understand.
"The payload for the lander is geared towards looking at Mars' climate history," said Greeley, who is on the science team for the lander's cameras. "The landing site was selected in the south polar area because, like the polar deposits on earth, they may record the climatic record of Mars."
Greeley is particularly excited by the possibilities offered by the lander's 2-meter-long robotic arm, which will be able to dig into the surface of the planet and scoop up samples for analysis. The arm is f
itted with a special close-up camera, a "microscopic imager." "Just as we look at the ice deposits in Antarctica and the Arctic, so we'll be able to examine the history of Mars when the arm digs down into the soil," said Greeley. "One of the things that the Mars Pathfinder camera and the camera on the rover were not able to do was to look at rocks and soils up close. If you are around any geologist, you know they always carry a hand lens - essentially, that's what this is. We want to be able to look at rock texture and to look at soils under magnification. That's what the arm camera is going to do for us."
Leshin, a "cosmochemist," (a geochemist who studies cosmic chemistry) is even more interested in the samples that the arm will dig up. "We will dig in the dirt looking for ground ice, which is predicted to be present at these southerly latitudes," she said. "We are testing this hypothesis with our mission. The robot arm will also deliver soil samples to the Thermal and Evolved Gas Analyzer which heats them up looking for ice, water- bearing minerals (like clays), and carbonates."
"I am a Co-Investigator on the Mars Volatiles and Climate Surveyor (MVACS). MVACS comprises 4 instruments that will work together on the Martian surface to form a sort of 'robotic geologist.' My specific interest is in using two tunable diode laser spectrometers on board to measure water and CO2 in the soil and atmosphere. These TDL spectrometers use highly tunable, tiny (head of a pin size) lasers to measure the absorption of water and CO2 in the atmosphere and that are released from the soil upon heating."
Presley is an expert on Martian thermal conductivity and is on the microprobe science team, which is a separate soil analysis effort. Before the landing, two basketball-sized aeroshells carrying the microprobes will deploy from the spacecraft, crash into the South Polar Region (at 400 miles per hour) and shatter on impact. The microprobes will be driven into the planet's surface.
The microprobes are less than 18 centimeters in length. After insertion, they will extend one component up to six feet beneath the planet's surface. A second component, tethered to the first, will remain at the surface. The microprobes are designed to operate for 50 hours in temperatures as low as -180 degrees Celsius (-292 Fahrenheit). The devices will search for evidence of subsurface water ice. They also will provide data that should allow scientists to characterize both the thermal and physical properties of the soil they are in. Presley's job is to translate that data into meaningful information.
All the instrumentation should provide a bonanza of information. Even with all the high tech tools NASA has already used on Mars, the projected landing site still holds some deep mystery. Remote sensing from orbit - which has a resolution of about two meters - has shown the scientists some features that the scientists still cannot fully explain.
"This is a part of Mars we've never been to before," said Leshin. "It's as if all three previous landers visited North America, and we're going to Antarctica! We honestly have no idea what the terrain will look like at a human scale. So when we wake up on the afternoon of Dec. 3 (it will be early morning on Mars) and look around, it will be very exciting to see what is there."
"This is a completely new terrain and the things that we do see in the high resolution pictures from orbit are very bizarre," said Greeley. "Those of us who have worked in geology and remote sensing for a while are really scratching our heads over what we're looking at. It's strange.
"There are dark and bright spots, maybe 20 to 30 feet across. We can't tell very well if they are hills or holes. This is a region where the seasonal ice cap is retreating, the carbon dioxide frost is ablating. Some of these things are related to the retreat of that frost. The bright areas are probably patches of frost that are left behind in areas that are a little more protected. The dark things are probably places where the frost is all gone and it's just dirt. But there are also dark patterns that radiate from some of these spots. Here we have a spot and then we have these dark, sinuous patterns forming out from them. Other places we see networks of dark patterns.
"There are patterns that we just don't understand. It's going to be interesting, whatever it is and to relate what we see on the ground to what we see from orbit... that's going to be really scientifically exciting," he said.