The surface of Mars is slowly becoming littered with spacecraft and scientific equipment. As a systems engineer at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., ASU alumnus Joel Rademacher will soon begin contributing to the clutter.

Rademacher is helping to build what’s known in NASA lingo as the Mars Environmental Compatibility Assessment experiment for the Mars 2001 Surveyor lander. He has already offered to clean up after himself.

“I wouldn’t mind going out and picking up MECA,” says Rademacher, who recently submitted his astronaut application to NASA. “I would love to go to Mars.”

If Rademacher gets to Mars in 20 years or so, he might want to pick up a few other discarded instruments built or used by ASU scientists on Mars Pathfinder, Mars Polar Lander, and the 2001 and 2003 Mars Surveyor landers. Never mind the others he could collect in orbit from Mars Global Surveyor, the Mars 2001 Surveyor orbiter, and the European Space Agency’s Mars Express orbiter.

Mars Global Surveyor began orbiting Mars in September 1997 equipped with geology Professor Philip Christensen’s $9.4 million thermal emission spectrometer. TES can identify the composition of Martian rocks and its atmosphere by measuring the distinctive wavelengths of thermal infrared energy, or heat, given off by the planet. To date, TES has beamed back such a mass of data that Christensen’s team recently submitted 13 papers to the Journal of Geophysical Research that describe the instrument’s various findings.

The most dramatic findings occurred last in 1998, when TES identified the mineral hematite near the Martian equator. “This is really the first evidence for some local process on Mars that involves lots of water,” Christensen says.

Phil Christensen and fellow researchers have spent years developing TES. Its versatility is demonstrated by this image. TES records varying intensitites of different wavelengths of infrared light. Researchers use this information to identify surface materials because particular types of minerals reflect characteristic amounts of infrared. TES collected data along the dark bands, with positions indicated on a composite photograph of the surface. The red areas show where hematite was identified. Hematite forms only in the presence of water.

In one of the JGR papers, Christensen and his team propose five possible explanations for the hematite deposit. His preferred explanation: the mineral precipitated from a large body of standing water, probably a frozen sea extending for hundreds of miles.

However, hydrothermal processes (hot springs of the type found at Yellowstone National Park), together with water percolating down through the soil, could also account for the mineral. Whatever the process, it surely involved lots of water. This fact prompted Christensen to propose the region as a potential landing site for future missions. Images of the area show flat-lying, layered rocks, the type of sediments geologists would expect to find deposited by a large body of water.

“If you wanted to go look for life or early life, this would be a pretty good place to start,” Christensen says.

Another JGR paper by the TES team will describe the first observations of the day-by-day growth and decay of a massive Martian dust storm. Covering as much surface area as the Atlantic Ocean, the storm raged for three months in the Martian southern hemisphere in late 1997.

These dust storms could influence atmospheric circulation by heating the atmosphere, Christensen explains. A key factor in understanding global circulation is the movement of air from warm regions to cold ones. According to TES measurements, the global nighttime temperature on Mars ranges from minus 149 to minus 248 degrees Fahrenheit.

Scientists already are using these temperature data, the topic of a third JGR paper, to refine computational circulation models that predict seasonal motion in the Martian atmosphere.

Martian circulation patterns are simpler than those found on Earth, but complicated enough. “I think that in a few years we will have fine-tuned the models to where we can in fact predict the weather on Mars,” Christensen says. “I think we’ll learn a lot in doing so and that it will eventually help us to better predict Earth’s circulation and weather.”

Regents Professor of Geology Ronald Greeley also studies Martian winds, the subject of two JGR papers by his research team. While examining images of the Mars Pathfinder landing site, his team found evidence for fossil wind features that could lead to new insights about previous climatic conditions on Mars.

The sand dunes and ripples and the way debris tails away from rocks point to prevailing northeasterly winds at the Pathfinder site today. This conclusion matches computer model predictions for the area, says graduate student Michael Kraft, a member of Greeley’s team. “Winds measured during the mission came from all directions, but were very mild and not strong enough to move particles on the surface,” Kraft says.

However, wind-eroded rocks at the Pathfinder site, as least those analyzed so far, indicate winds from the east or southeast. “When we look at orbital data over the site, we again see those two sets of features at a bigger scale,” Greeley adds.

According to the ASU researcher, scientists might be able to reconstruct former climatic conditions on Mars if they can use computer models to match the conditions that created the fossil wind features.

Wind velocity profiles collected by the ASU windsock experiment, meanwhile, could lead to a better understanding of modern Martian winds. The experiment, performed in connection with the Mars Pathfinder camera, collected wind speed and directional measurements at three heights ranging from approximately one to three feet. These measurements have enabled Greeley’s team to calculate for the first time a value for aerodynamic surface roughness on Mars.

“It’s a building block to understanding the interaction between the wind and the surface,” Greeley says

When Mars Polar Lander lands in December 1999, it will take similar wind measurements from yet another area of Mars.

“If we can characterize the landing sites and then link them to measurements made from orbit, we can extrapolate to the same orbital measurements for other areas,” Greeley explains.

Mars Polar Lander will be the first spacecraft to visit a Martian polar region, and the first specifically designed to look for water. But first, a descent imaging system will take a series of progressively higher resolution images as the lander puts down near the edge of the south polar ice cap.

“This will be the first descent imager that the United States has flown since the pre-Apollo days,” Greeley says.

Providing the descent imaging system will be former ASU geology Professor Michael Malin, a TES science team member and founder of Malin Space Science Systems in San Diego, Calif. Greeley serves as a member of the imaging team for a separate camera system that will operate on the surface.

Images of the landing area taken by the camera Malin provided for Mars Global Surveyor show what appear to be alternating layers of ice and dust. Scientists will study the layers with the lander’s robotic arm, which has a close-up camera and a scoop mounted on the end.

“The hope is we’ll be able to dig down into those layers and look for differences that might indicate changes in climate, just like the ice layers on the polar areas of Earth record the recent climate,” Greeley says.

Working with Greeley on Mars Polar Lander will be a former student, Laurie Leshin, a 1987 ASU chemistry graduate. As an undergraduate summer intern at the Lunar and Planetary Institute in Houston, Leshin worked with Mars data collected in the late 1970s by the Viking spacecraft’s infrared thermal mapper. A forerunner of TES, it was the same instrument that furnished Christensen the data for his doctoral research at the California Institute of Technology.

Now an ASU assistant professor of geology, Leshin is a science team member for the lander’s Mars Volatiles and Climate Surveyor payload. MVACS consists of four integrated instruments that will search for water in all its forms: in water-bearing minerals, in the soil, in the atmosphere, and locked in ice.

“It’s not directly measuring whether or not there are living critters in the soil, but understanding the current reservoir of water is a positive step in understanding Mars as an abode for life,” Leshin says.

Evidence already has emerged for water on Mars, including the hematite deposit identified by TES, and images of dry riverbeds taken by Malin’s camera. But how much water did Mars have historically, and where did it all go? A study of Martian hydrogen isotopes may help provide an answer.

Scientists think this image may depict the remnants of a pond that formed and evaporated in this impact crater basin. Channels on the crater wall suggest fluid seepage. The image is a tantalizing hint of the past presence of liquid water.

Responsibility for developing Polar Lander’s isotopic measurement capability fell to Leshin after NASA already had selected the mission’s other experiments. As originally proposed, Polar Lander’s Thermal and Evolved Gas Analyzer, a soil analysis instrument, would analyze water and carbon dioxide in the soil. A set of meteorological sensors would do likewise in the atmosphere. Then mission scientists realized they could use the same sensors to measure isotopes of hydrogen, carbon, and oxygen.

The lead scientist on the MVACS payload turned to Leshin for help. Leshin specializes in using isotopic measurements of meteorites to reconstruct the environmental histories of asteroids and planets. The Polar Lander’s soil analysis experiment will essentially duplicate with Martian soil the experiment that she conducted on Martian meteorites as a doctoral student at Caltech.

One key difference: Leshin used a conventional mass spectrometer to make her isotopic measurements at Caltech. On Mars Polar Lander, she will use tunable diode lasers about the size of a pinhead. It is an innovative experimental idea that scientists now are interested in using on Earth to better understand the dynamics of Earth’s upper atmosphere and their links to climate and weather.

On Mars, though, Leshin will use the method to trace processes that occurred in the atmosphere long ago. “We think a lot of water has been lost out the top of the Martian atmosphere. That would leave behind a significant isotopic signature,” she says.

Leshin estimates that the Martian reservoir is probably 90 percent gone. “There may still be some water left deep down. We don’t really know. The evidence from meteorites is that the interior of Mars is relatively dry,” she adds.

Isotopic measurements of two other key elements, carbon and oxygen, may provide insight into the Martian atmosphere and its climatic history. Today, the Martian atmosphere consists largely of carbon dioxide. If Mars ever had a warm, wet climate deep in its early history, as some scientists believe, it would have needed an even thicker carbon dioxide atmosphere than it has today.

Where did the missing carbon dioxide go? Perhaps a comet or an asteroid impact blew it out of the atmosphere. Or maybe the atmosphere collapsed and the carbon dioxide became trapped in the Martian crust.

A lot of Earth’s carbon dioxide is trapped in carbonate rock, which, incidentally, is commonly associated with biological processes. To date, scientists have been unable to identify carbonates in any significant quantity on Mars, Leshin says. Then again, they have never before had Mars Polar Lander’s capability to look for them.

Philip Christensen’s Thermal Emission Imaging System, a part of the Mars Surveyor 2001 orbiter, will look for carbonate minerals too. Scheduled to reach Mars in December 2001, THEMIS will be able to detect all the known major minerals, including volcanic minerals and salts. It also will measure atmospheric temperatures.

An $11.2 million instrument, THEMIS was inspired by some mapping projects that Christensen conducted in Scottsdale and elsewhere in Arizona with an airborne Thermal Infrared Multispectral Scanner. TES operates in 143 wavelengths at a resolution of 1.8 miles, TIMS in only three wavelengths but at a resolution of a football field.

The TIMS work in Arizona demonstrated to Christensen that he could obtain a lot of valuable data using fewer wavelengths—THEMIS will have 10—at higher resolution.

NASA will send both THEMIS and a TES to Mars in 2001. The 2001 lander will have on deck a mini-TES about the size of a soda can. The $4.5 million mini-TES will look straight up into the atmosphere with a little telescope, or view the entire landing site through a swiveling periscope. Exactly what it will see depends on the landing site, which NASA will select later in 1999.

Engineering constraints dictate that the lander put down somewhere near the Martian equator. Christensen is a member of the landing site selection advisory committee that began debating the possibilities at a NASA workshop in June 1999.

“There are two camps in the landing site community. One wants to go to a place that has the most interesting rocks but might have boring scenery. This hematite zone that TES discovered probably falls in that category,” Christensen says. “The other camp says let’s go land at the bottom of Valles Marineris.”

Extending for more than 3,000 miles roughly parallel to the Martian equator, Valles Marineris is a vast canyon system that would stretch from coast to coast if superimposed on the United States. If Valles Marineris becomes the target, mini-TES would identify the minerals that make up the various rock layers in the canyon wall. It would be like viewing the rock layers of the Grand Canyon, only on a much larger scale.

NASA engineers would need to nestle the Surveyor lander up against the cliff without hitting the cliff itself. No easy feat considering that Mars Pathfinder’s landing site could only be narrowed to an area measuring 62 by 124 miles.

“They think they can land in a 10-kilometer (6.2-mile) spot,” Christensen says. “If you’re 10 kilometers away from the wall of Valles Marineris, you’d have a pretty nice view. That wall is seven kilometers (4.3 miles) high.”

Either way, mini-TES, mounted on the lander, will support the activities of the 2001 Marie Curie rover, a twin of the Mars Pathfinder Sojourner rover. Another mini-TES will fly on the Surveyor 2003 lander, but will be attached to Athena, a new, more capable rover. Mini-TES will help Athena select rock and soil samples for return to Earth during the Surveyor 2005 mission.

“Out of all these instruments, mini-TES will be fun because it’ll be on the surface,” Christensen says. “But I think that THEMIS is going to be the most interesting. We’ll take really neat infrared pictures that could very well change how people look at Mars.”

Flying with Christensen’s mini-TES on the 2001 lander will be the $5.2 million MECA experiment that aspiring astronaut Joel Rademacher is building. Rademacher, a 1996 ASU master’s degree recipient in aerospace engineering, has been promoted six times in three years at the Jet Propulsion Laboratory.

Rademacher’s contributions to the space program began during his undergraduate days at the University of Colorado. As a CU aerospace engineering major, he worked as the structures team leader for the Get Away Special experiment launched on the space shuttle Discovery in April 1993. Students entirely designed and built the experiment to measure the sun’s ultraviolet radiation.

As a graduate student in aerospace engineering at ASU, he co-founded a satellite program in October 1993, and served as ASUSat 1’s first program manager. A 10-pound satellite equipped with infrared and visible-light imagers, ASUSat 1 was scheduled for launch in October 1999. With funding from the U.S. Air Force, plans are under way for ASUSat 2.

“Small satellite programs are becoming more popular all over the U.S.,” Rademacher says. “More and more companies are getting involved with several universities and each branch of the armed forces is expressing more interest and taking action.”

Today, Rademacher oversees MECA’s basic design as well as the six engineers who work on its mechanical, electrical and software systems, among other duties. The size of a shoebox, MECA’s instruments will identify hazardous substances that may emanate from the Martian soil when exposed to water in a human habitat.

No solid plans yet exist for a human mission to Mars. But any such mission would involve a stay of several hundred days because of the time it would take for Mars to move into a favorable orbital position for Earth return. In the meantime, astronauts would have to live with lots of dust. As NASA learned during the Apollo lunar missions, “dust does take quite a toll on spacesuits after a couple of days,” Rademacher says.

If breathed or ingested by astronauts when brought into crew cabins on spacesuits, it could become poisonous or cause disease. Martian dust adhering to machinery could clog filters, seize bearings, and short circuit electronics. Particles of quartz are the biggest concern, both for humans and machinery on Mars, Rademacher says.

MECA’s microscopy station will measure the size, shape, hardness, texture, and adhesion properties of Martian soil and dust particles. As a precaution against potential shock hazards, an electrometer on the heel of the robot arm will measure electricity buildup during digging operations and electrical charge in the atmosphere. A wet chemistry lab will evaluate samples of the Martian soil in water for hazardous elements, gases, and corrosive potential.

Two patch plates, each mounted with 72 fingernail-sized samples of spacesuit and other equipment materials, will be exposed to blowing Martian dust or digging action by the robot arm. Visual inspection via the robot arm camera will provide data on particle adhesion, soil hardness, and their affect on the various materials.

Rademacher has until June 2000 to deliver MECA to the Surveyor lander contractor, Lockheed Martin in Denver. There he will oversee the integration of MECA to the spacecraft. Following launch in April 2001, Rademacher will move on to other projects. A dazzling array of possibilities await as the result of his pioneering work in a secondary payload feasibility study that evolved into what’s now known as the Mars Micromissions.

Rademacher and another proponent of small satellites at JPL, Kim Leschly, are constantly looking for ways to promote low-cost secondary payload activities. In January 1997, they proposed launching a secondary payload aboard a French Ariane rocket into Earth orbit. From there they would use a small propulsion system to boost the payload into a planetary access trajectory.

The project originally involved an instrument to detect gamma-ray bursts. After Rademacher left the project to work on MECA, Leschly continued to push the concept with support from the French space agency. Then JPL’s Mars Program got involved, and the project took on a new life as the Mars Micromissions.

“I am proud to say that I was one of the pioneers who helped get it rolling,” Rademacher says.

The Mars Micromissions will be independent spacecraft and payloads weighing no more than 440 pounds launched aboard Ariane 5 rockets.

“One of these micromission payloads, to be flown in 2005, is envisioned as a propeller-driven airplane flying through the Martian atmosphere,” Rademacher explains. The first micromission payload will likely be a communication satellite arriving at Mars in 2003.

Rademacher will miss out on the 2003 Mars Micromission in order to see MECA through. Nevertheless, JPL has promised him a key role in development of the 2005 Mars Micromission.

The Mars Surveyor 2003 and 2005 missions also offer tempting assignments. The latter, a sample-return mission, will be the first to launch a spacecraft from the Martian surface.

But for now, he said, “I just want to leave my options open.”

As the Mars Micromissions demonstrate, international cooperation continues to be an important element of space exploration. Such cooperation led to Greeley’s participation in the German camera experiment of the European Space Agency’s Mars Express mission that will launch in 2003.

Originally developed for the Russian Mars ’94 mission that plunged back to Earth shortly after launch, the German camera will take stereoscopic color images from Martian orbit in 10- to 15-meter (33 to 49.5 feet) resolution. Greeley will coordinate imaging related to volcanism, wind features, and extraterrestrial biology.

The camera will augment the early notable success of Mars Global Surveyor, Greeley says, because only a small fraction of the planet has been imaged in high resolution.

“Even with later U.S. missions, huge areas will remain unseen in high resolution,” he says. “The U.S. program can’t do it all.” Perhaps it is this sense of incompleteness that keeps drawing humans to Mars. The planet does, after all, have something that Earth lacks: really old rock that may contain the secrets to the origin of life.

Earth has no rocks as old as the planet itself because it keeps renewing its surface through plate tectonics and seafloor spreading. The oldest Earth rocks that do exist—dating back 3.5 billion years—contain evidence for microbial life.

But having access to the first 500 million years of the history of a planet that had water, an energy source, and organic matter offers the possibility of studying the steps that lead to life.

“This is one of the gems of Mars,” Leshin adds.—Steve Koppes

The Mars Project and other planetary geology research at ASU is supported by NASA, the National Science Foundation, and other funding agencies. For more information about specific projects, call the Department of Geology at (480) 965-5081. Send e-mail to geology@asu.edu

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