Satisfying our Curiosity: Studying Martian soils could help explain a lot about the red planet


When most people send a correspondence to a coworker, an email goes out to a neighboring office. When Doug Ming and Brad Sutter send a correspondence to a coworker, a message goes out to a neighboring planet. Their coworker is the Curiosity rover, and their correspondences have to travel millions of miles to reach it.

artist rendition of rover touching down

Ming and Sutter, planetary scientists with the National Aeronautics and Space Administration (NASA), are members of the team that is carrying out the Mars Science Laboratory Mission. The mission and its Curiosity rover are part of a long-term effort to explore Mars. Both scientists have backgrounds in soil science, and their knowledge is well suited for the project, which aims to study the Martian soils for signs of life.

Curiosity landed on Mars on August 6, 2012. The prime mission is planned to last one Mars year, the time it takes Mars to go around the sun once and the equivalent of 687 Earth days. Like other rovers, however, Curiosity could be in service well beyond that.

“The Opportunity rover has been on the surface since the end of January of 2004, so it has been going for over nine years of operation,” explains Ming. “I expect Curiosity to be doing analysis on the surface of Mars for some time.”

Sutter’s work with NASA began when he was a graduate student working with Ming on the Advanced Life Support (ALS) program. The ALS program develops technology that will make human space travel more self-sufficient and keep crews alive on long-duration missions. When funding for the ALS program was drastically cut, however, Sutter began studying the soils of Mars.

“I became involved in assessing water on silica surfaces under Mars temperatures and pressures,” says Sutter. “I also examined the hyper-arid Atacama Desert soils of northern Chile. Those soils were a model for how soils form under hyper-arid conditions on Mars.”

Ming began his work at NASA as a post-doctoral fellow and first studied lunar materials. He has since been a part of several previous Mars missions. He was on the science team for the Mars Exploration Rovers, Spirit and Opportunity, and he then joined the Mars Phoenix Scout mission, which was launched in 2007.

rover landing site

“The Phoenix mission was, in my view, the first real soil science mission on another planetary surface,” says Ming. “That was truly a soil science delight.”

Both researchers’ love of soil science will be fed by the Curiosity rover. While the Phoenix rover analyzed soil and ice in the arctic regions near Mar’s poles, the Curiosity rover landed in Gale Crater near the Mars equator. Curiosity will explore a larger area of Mars than any other rover.

Sutter’s role in the Mars Science Laboratory Mission is focused on data analysis, and he is a collaborator on the Sample Analysis at Mars (SAM) instrument team. SAM, a suite of instruments onboard the rover, heats samples using an oven and detects gases that are released when minerals break down. The instruments can measure different properties of the soils that Curiosity picks up on Mars. The team hopes that by testing the Mars soil, the rover will detect organic compounds, which are necessary ingredients for life. Sutter’s role is to use the data obtained by SAM to determine what types of minerals (such as carbonates, sulfates, and phyllosilicates) may be present in the Mars soil.

While Sutter works with the data sent back from SAM, Ming is busy planning the rover’s activities that lead to the collection of that data. He works with the scientists and engineers to make sure that everyone is part of the planning process and on the same page, including Curiosity.

“We have to make sure that plan is [sent] to Mars so that it’s up there when we’re starting the next day of activities,” explains Ming.

Advancing data collection through technology

The activities that the rover is capable of performing have led to high hopes for the knowledge that it will collect on Mars. The rover has been suited with the most advanced technology yet to be used on a Mars mission. Curiosity is about 10 feet long and five times as heavy as the Mars Exploration Rovers allowing it to roll over obstacles up to 2 feet high.

installing the SAM instruments

The equipment that is used to gather and analyze soil and rock samples is also more advanced than on earlier rovers. In addition to SAM, the suite of instruments from which Sutter obtains data, Curiosity holds several other technologies that can be used to characterize Mars. Onboard the rover are several cameras, an instrument that fires a laser and analyzes the elemental composition of vaporized minerals, a station that monitors temperature, winds, and other environmental conditions, and a radiation detector that will determine whether the planet would be suitable for further human exploration. Curiosity also has a device called the Chemistry and Mineralogy (CHEMIN) instrument that can provide complete characterization of the soil minerals for the first time on the surface of Mars.

Once Curiosity has gathered data with its collection of instruments, it has to send those pieces of information to scientists, such as Sutter and Ming, on Earth. The NASA Deep Space Network, a set of antennas, provides the necessary link between Earth and Mars. The Network is made up of three facilities placed strategically around the world – in California, Spain, and Australia – allowing for constant observation even as the Earth rotates.

In addition to direct-to-Earth transmission, the rover also communicates with orbiters. The orbiters have bigger antennas and can “see” Earth for longer periods each day, allowing more data to be sent. This means that data transmission to Earth through the orbiters is faster than transmission directly to Earth. An orbiter is in the vicinity of the rover for about eight minutes per day, and in that time, up to 250 megabits of data can be sent to the orbiter. That same amount of data would take up to 20 hours to be transmitted directly to Earth.

Evidence of life beyond Earth?

Scientists hope that the technological advances of Curiosity will help to answer some of the most interesting questions in planetary soil science today. For Sutter and Ming, those questions are focused around one central unknown.

“The big question that Curiosity is asking is could something beyond Earth support life?” posits Ming. “Are there places out there where life could have existed and maybe does exist today?”

scoop marks in Martian soil

Sutter also hopes to uncover evidence of biological life, and understanding the soils of Mars is an important step toward that discovery. True soils are modified and supplemented by living organisms and consist of minerals, air, moisture, and organic materials. It is possible that the soils of Mars are not true soils – that they instead were formed strictly from wind erosion or processes without biological or chemical activity. Sutter hopes that the data they receive from Curiosity will give clues about Martian soil formation.

“Evidence of soil formation on Mars may provide better indicators of past climates and if conditions were suitable for biology,” explains Sutter. “Also, Mars soils have been found to be both acidic and alkaline. Those characteristics can affect whether ancient microorganisms were able to live there.”

The future of planetary research will likely be driven by this search for life beyond Earth. The Kepler program, another NASA initiative, is looking for planets that are orbiting other stars at the same distance as Earth orbits the sun. These “habitable zones” may contain planets that are similar in size to Earth and would provide conditions that could support life.

Other missions will also dig deeper into the question of life back on Mars. NASA plans to launch a Curiosity-like rover in 2020, and in 2018, the European Space Agency will send a rover to the red planet. That rover, called ExoMars, will be fitted with a drill that can dig six and a half feet into the surface of the planet, through several soil types.

“The goal of ExoMars is to evaluate soil chemistry and mineralogy as a function of depth,” says Sutter. “Perhaps organics are better preserved at greater depths.”

Additionally, the data from Curiosity will continue to come in, and evaluating that data will be a significant project. If the mission were to end today, says Sutter, there would still be years of interpretation and laboratory work to do to fully understand the data already collected.

Future of planetary research faces hurdles

While the idea of life on other planets is exciting and Curiosity is a technological achievement, further planetary research faces some hurdles. One of the biggest issues that many scientists are currently dealing with is a lack of funding, and NASA scientists are facing the same tightening budgets.

Doug Ming looking at data

One of Sutter’s main concerns is the lack of trained soil scientists actually doing planetary science. Instead, he says, the community is dominated by geologists, which can make it a challenge for soil scientists to obtain some of the limited funding and make their voices heard in the field.

“Soil science doesn’t stop at Mars – there are other places, like the Moon and asteroids, that have unconsolidated surface materials,” says Sutter. “While these may not be considered soils in the traditional sense, soil science still has a lot to offer in studying these materials.” Sutter also notes that clay minerals in meteorites may be interesting to those researching clay mineral formation in soil.

Despite the obstacles planetary soil scientists can face, both researchers find great rewards in the work that they do. Ming finds one of the most interesting parts of his job to be the unexpected.

“Every day I go to work, and I can expect the unexpected,” comments Ming. “Every time we get a data set, I think, ‘Now what in the world is that about?’ The data is often totally unexpected – something we wouldn’t have planned for, and here Mars throws this result at us. There is always something new.”

While specifics of Curiosity’s findings so far have not been released, NASA held a press conference in December of 2012 to explain preliminary results. They stated that the rover was working successfully, and it had detected water, sulfur, and chlorinated methane gas, which contains carbon. However, scientists cautioned that the carbon-containing gas may not be from Martian soils – it could have been created in the analysis or may have been carried from Earth. NASA scientists urged people to be patient as more data is collected and analyzed.

In addition to the exciting findings that Curiosity will continue to uncover, Ming says there is another benefit of his work on the project: “There are few people who can say they go to work on Mars. And there’s nothing like going to work on Mars every day of my life.”

This story appears in the March-April issue of Soil Horizons.



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