March 26th: Day 1 in the Mojave
On my first day in the Mojave, we took a geologic tour of the region looking at Mars and Lunar analogs. Our first stop was at some stromatolite deposits. This deposit was about 1.6 billion years old and is some of the earliest evidence of life on Earth. Stromatolites are dome–like structures formed by algae. The algae build up in layers over time, forming domes in the shallow seas. Evidence suggests that similar shallow seas may have existed on Mars. A robotic expedition to one of these areas on Mars would be looking for similar dome-like structures ifor evidence of life. At this site, we also learned about desert varnish. Desert varnish is a dark shiny layer that forms on the surface of rocks in desert environments. The layers are usually made of manganese or iron oxides. These layers do not form from the rocks themselves but are deposited on them. The question is by what? Bacteria are present in the desert varnish and some evidence suggests that the bacteria are depositing the oxides as part of their biological processes. This is important because similar varnishes may occur on Mars. If desert varnishes on Earth are biological, then that could be evidence for life on Mars.
Our next stop was the Cima lava flows. These flows range from 500,000 years old to 10,000 years old. What we were observing was their structure and similarities to flows on the moon and Mars. On Earth, over time, gaps in the rock that forms the lava flows fill in with wind blown deposits forming a layer on them that looks like pavement. The older lava flows look very much like the surface of Mars except for the occasional plant. Standing on a lava field, you can easily imagine yourself looking at the surface of Mars.
We then drove up closer to the cinder cones that formed during the same period as the lava flows. Cinder cones are also seen on the moon and Mars. Near the cone was a collapsed lava tube. Lava tubes form by the surface of the lava hardening into a crust, as the lava continues to flow below the surface. Once the lava flows out from under the crust, a hollow tube is left. Sometimes these tubes collapse forming snake-like valleys. These valleys are also known as rills, and can be seen on the moon and Mars. Sometimes just small amounts of the lava tube ceiling collapse forming skylights to the surface above and providing some light within the lava tube.
Lava tubes are important for space exploration for several reasons. The may provide protection for life from ionizing radiation and could also be used as habitats on the moon and Mars to protect astronauts. Instead of transporting heavy protective habitats to the moon and Mars, astronauts could take advantage of the protection provided by the lava tubes.
One of the experiments conducted was to locate lava tubes by remote sensing. Using an IR camera in a hot air balloon, scientists looked for the temperature differences between openings to the lava tubes and the surrounding rock. In the morning the openings were warmer than the surrounding rock giving distinct differences on the camera. In the afternoon the cave openings were cooler than the surrounding rock making them visible on the camera. Probes orbiting Mars could use similar techniques to identify lava tubes and caves. Later, robots designed to enter the caves could explore them for scientists. We tested some robots in the lava tubes to get ideas for future designs