Mars Exploration Rovers – Field Science on Mars October 2009

In the 18 century, about the time the United States was formed, scientists were voyaging around the earth in ships exploring the land, life, and people.

Today we are exploring Mars using MER – our first overland expedition on another planet.

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People have never been on Mars, but using computer tools sciensts can have the experience of seeing Mars and making measurements as if they were actually on a voyage. Traveling on a roboc vehicle, we have been exploring craters…Taking pictures…Brushing the soil with our wheels… And learning about what happened on Mars billions of years ago.

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Mars is about half the size of Earth, the 4th planet from the Sun. We are especially interested in Mars because it is the most likely place we could live after leaving the Earth. We believe Mars was wet and had a thicker atmosphere. We want to find out what happened: Did life form there? Why was the atmosphere lost? We are studying Mars using two robotic laboratories. Every day we send commands to the robot’s computer and get back more photographs and data.

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MER is a Mobile Robotic Laboratory Robotic => It is controlled by a computer that we program on Earth Mobile => we can program it to drive to and move around Laboratory => it has instruments for analyzing rocks and soil It is about the height of a person Below is the computer-controlled arm with the scraper, close-up camera, instruments for analyzing chemical composition. Up above is a panoramic camera and more instruments. Navcam below.

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The two rovers are named Spirit and Opportunity. We landed them near the Mars equator so there would be more sunlight to provide power. It is also warmer. We are looking for evidence of water, where life may have existed.

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Here is the first part of Opportunity’s voyage. The bottom photo is taken from a spacecraft that is orbiting Mars called “Mars Reconnaissance Orbiter” We took a Pancam image (top photo) of Eagle crater, then used that to drive closer.

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We took Navcam and Pancam images of the outcrop so we could see what we wanted to study in more detail.

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Here is the Pancam image of the outcrop (visible rocks) you see in the crater at the top.

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Then we moved in even closer to take a Micro-image of the soil. We discovered spherical, bluish deposits we called “blueberrries” (right).

On Earth such objects are formed by water, so this is evidence that there was water flowing on Mars. That means that the planet was once warmer and wetter.

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(Read the slide) We make inferences about Mars’ past by finding things similar to what we find on Earth. By identifying minerals we recognize from Earth, whose origin is known, we can infer what might have occurred on Mars.

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This spectrum, taken by Opportunity's Moessbauer spectrometer, shows the presence of an iron-bearing mineral called jarosite in the collection of rocks dubbed 'El Capitan.' El Capitan is located within the rock outcrop that lines the inner edge of the small crater where Opportunity landed. The pair of yellow peaks specifically indicates a jarosite phase, which contains water in the form of hydroxyl as a part of its structure. These data suggest water-driven processes existed on Mars.

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We found a high concentration of Sulfur in Magnesium, Iron, and other salts (using MER’s alpha particle X-ray spectrometer) This is evidence of Jarosite (Mössbauer spectrometer) 8-9% composition, found inside, not on the rock’s crust (more evidence it’s Jarosite). On Earth, rocks with as much salt either have formed in water or, after formation, have been highly altered by long exposures to water (e.g., acidic lake hot springs) Physical appearance provides yet more evidence: indentations called "vugs," spherules and crossbedding.

All the evidence fits: Composition, where the materials were found, and their appearance. This suggests that there were acid lakes on Mars.

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The part I just showed you is at the top. We continued for over two years to reach Victoria Crater, which we studied for about two years. Now we are driving to a much larger crater that will take several years to reach. So far in 5 ½ years we have driven 10 miles with Opportunity! Why does it take so long? Because we are continuously stopping to take pictures and analyze the rocks and soil with our instruments.

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The Mini-TES instrument provides information about the chemical composition of a broad area by showing temperature variations. The colors in the top image represent cooler (blue) and warmer (red) areas. By revealing properties of rock surfaces below the covering of dust, this instrument is useful for showing promising areas for further investigation.

The Mars rover Opportunity took the panorama of Burns Cliff (bottom image) with its mast-mounted panoramic camera between Nov. 13-20, 2004. The image is a composite of 46 separate images taken with different filters as Opportunity sat at the cliff's base in Endurance Crater

These are very old craters. We were able to go inside, but the rover slipped a lot on the steep rocky surface and in the sand. We used a model in Pasadena to understand how it would move on a slope (inset photo).

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We designed MER so we could do the same work geologists and other scientists would do in the field when they are exploring. We can climb, inspect, and explore using MER. But of course all of our analysis and writing occurs on Earth.

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Steve Squyres, the science team’s leader said, “The whole idea behind MER is that these tools work together. Look at the silica discovery. The mobility system, which we use as a soil physical processes tool, trenches up some soil. We notice it with Pancam, we hit with mini-TES; it looks interesting, and we go over and we figure out what it’s made of with APXS. Everything works together.”

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Here we see Spirit’s path in Gusev Crater -- over the Columbia Hills and to the Home Plate area where we found almost pure silica.

Consider how the scientists traveled together during these four years. It’s like being a ship. You can’t go off by yourself, you can only reach out from the rover so far. It’s like we’re all huddled together moving up those hills, slipping in the sand, going this way and that around Home Plate…

Just as on a ship, we all need to agree where we are going in the long term, when we should stay a little longer at one place, and what we should do tomorrow. We need to talk to each other about what we are learning -- chemists and geologists, relating atmosphere and climatology. The scientists and engineers are all moving together…. If I could draw it, I’d show all 150 people on a huge skateboard, all standing together, leaning off the sides, moving at a snails pace through this terrain…

That is very strange compared to being a field scientist outside working alone or in a small group, maybe covering that same territory in a day or two, with different people perhaps heading off in different directions sharing what they have learned. You can’t do that on a ship, you voyage together and need each other if you’re going to survive.

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It took about one Earth year to reach the top of the Columbia Hills. We were studying the rocks all along the way. At the top we looked around and took this great panorama.

Spirit's Amazing Trek Continues This view from where NASA's Mars Exploration Rover Spirit stood on the rover's 149th martian day, or sol (June 3, 2004), shows terrain the rover has crossed since then. The yellow line traces the path Spirit has taken since arriving at the "Columbia Hills." Labels show the informal names of rocks the rover has studied along the way. Spirit is currently headed east, traversing the flanks of the hills en route to an overlook above a steep valley that is out of view from this perspective. Scientists hope to find more layered rocks that will tell a story of ancient water on Mars. Spirit has traveled 498 meters (more than one-quarter of a mile) and ascended 20 meters (66 feet) above the plains since arriving at the "Columbia Hills" on sol 156 (June 11, 2004). It covered much of that distance driving on only five of its six wheels. The images used to make this approximately true- color mosaic were taken with Spirit's panoramic camera from about 300 meters (984 feet) away from the base of the hills, using filters centered at wavelengths of 600, 530 and 480 nanometers.

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Here is a 3-D photo based on images taken from orbit. We came down off the Columbia Hills and have been studying this area called Home plate for about 3 years. We found almost pure silicon (looks like white sand in the picture), which occurs on Earth when a hot spring evaporates.

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Here is another 3-D photo based on images taken from orbit using the Mars Reconnaissance Orbiter. Maybe Home Plate was a hot spring like we find in Yellowstone National Park.

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Scientists feel like they are on Mars as if they were moving around the in the body of the rover…. << read quote >>

Through Visualization tools, we can experience touching and manipulating Mars…. They say, “now I take a close up and roll forward.” Such visualizations are essential for operating the rover.

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The rovers are on opposite sides of Mars controlled by two teams. Team includes scientists and engineers: The scientists decide what to do; the engineers program the rover The scientists do most of their work by looking at photographs, analyzing the data, and discussing in meetings what they have learned and want to do next.

Why do we operate MER during the day? So we can see, have power, and it is warm enough to move the arm, masts, and wheels of the rover.

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Here is a photograph from Eagle Crater marked up by the scientsts. They open the photograph in a computer program called Science Activity Planner (SAP). They then indicate what they want to photograph or where they want to apply instruments (called “targets” – in red) (SAP then creates a sequence of “observations” that can be converted into a computer program.

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At about 6 PM each Mars day, the team operating a particular rover meets and the scientists present their tentative plan for the next sol to the engineers. Together they examine the power, timing, memory, communication requirements and juggle priorities to create a final sequence. Here is a summary of a typical day on Mars for a rover… Another shift of engineers comes in during the night to complete the program for the rover and to send it to Mars the next morning.

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Block Island is a meteorite we stumbled upon during summer 2009 when driving Opportunity on the Meridiani plains. Opportunity is heading for Endeavor crater and might arrive during 2010…

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For more information… most of the photographs and facts in this presentation come from the JPL Mars Exploration Rover mission web site. You can also learn more about my work at my home page. It includes photographs and my blogs from expeditions in the Canadian Arctic and Utah, as we have been studying how field scientists explore and experimented with prototype computer systems they might use on the moon or Mars.

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