Planets

Curiosity's Recent Hard Work Produces Slew of Science

NASA scientists have had a busy summer releasing results from the six-wheeled robot concerning everything from details about Mars' atmosphere and dunes to some cool laser science. Here are some of the highlights.

<p>NASA/JPL-Caltech/MSSS</p>

Curiosity is now on the road again as the NASA Mars rover begins its two-year mission extension that started Oct. 1. The rover -- which has been on the surface for more than four Earth years -- is now plowing uphill on Mount Sharp (Aeolis Mons) to learn more about the Red Planet's ancient history. It is particularly looking for signs of water in the ancient past, and one of its targets is a ridge of hematite -- a mineral likely formed in water. As Curiosity leaves the geologically interesting region of "Murray Buttes" let's see what science the hard-working rover has produced in recent months on the slopes of Mount Sharp:

It's amazing how a little analysis on the surface can show you changes in the Martian atmosphere. The Curiosity rover has made progress towards figuring out why there is more xenon and krypton than expected. (These two gases are important as they can help scientists understand how the Martian atmosphere changed, and also lost its mass over time.) Using Curiosity's Sample Analysis (SAM) at Mars instrument suite, the researchers determined that a process called neutron capture (which happens when neutrons transfer between chemical elements) may explain the difference in isotopes or types of xenon and krypton. "These isotopes could have been released into the atmosphere by impacts on the surface and by gas escaping from the regolith, which is the soil and broken rocks of the surface," NASA wrote in a statement.

Image: Xenon (Xe) and krypton (Kr) is more abundant in Mars' atmosphere than expected because of transfers from barium (Ba) or bromine (Br), according to observations from NASA's Curiosity rover. Credit: NASA/GSFC/JPL-Caltech

Turns out that layers of rock have quite the story to tell. While it will take several months at the least to analyze all the data from Murray Buttes, early observations by Curiosity in September shows scientists more information about how the old sand dunes in that region evolved over the eons. "Studying these buttes up close has given us a better understanding of ancient sand dunes that formed and were buried, chemically changed by groundwater, exhumed and eroded to form the landscape that we see today," said Curiosity project scientist Ashwin Vasavada, who is with NASA's Jet Propulsion Laboratory in California, in a statement.

Image: Some finely layered rocks at Murray Buttes, observed by the Curiosity rover in early September. Credit: NASA/JPL-Caltech/MSSS

Who doesn't like a laser-shooting robot? Especially one that can choose targets on its own? Curiosity's Chemistry and Camera (ChemCam) instrument has captured the imagination of the public ever since it landed on Mars in 2012. A few months ago, NASA discussed the positive results of authorizing the rover to start selecting rock targets on its own to learn more about their composition. "This autonomy is particularly useful at times when getting the science team in the loop is difficult or impossible -- in the middle of a long drive, perhaps, or when the schedules of Earth, Mars and spacecraft activities lead to delays in sharing information between the planets," said robotics engineer Tara Estlin, the leader of the rover's autonomous software development at NASA's Jet Propulsion Laboratory in California, in a statement.

Image: The Curiosity rover can now select targets on its own (image at left, yellow dot) to perform laser and image analysis (image at right). Credit: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes

In an example of older science paying off with newer study, Curiosity discovered that some sand ripple types on Mars come from a different process from similar dune types on Earth. While studying "Bagnold Dunes" in late 2015, Curiosity imaged types of ripples on the northwestern area of Mount Sharp (Aeolis Mons). An example: Meter-sized ripples on the Martian dunes show similarities with underwater dunes on Earth. On Mars, the researchers said they believe the wind drags sand particles to create the dune shape, similar to how water moves around sand particles on Earth. "The size of these ripples is related to the density of the fluid moving the grains, and that fluid is the Martian atmosphere," said Mathieu Lapotre, a graduate student at the California Institute of Technology who works on the Curiosity mission, in a statement. "We think Mars had a thicker atmosphere in the past that might have formed smaller wind-drag ripples or even have prevented their formation altogether. Thus, the size of preserved wind-drag ripples, where found in Martian sandstones, may have recorded the thinning of the atmosphere."

Image: Curiosity imaged two sizes of ripples in the Bagnold Dune Field. Credit: NASA/JPL-Caltech/MSSS

This is another example of older observations yielding new information. When Curiosty was looking at a location called "Buckskin" in July 2015, it found a silica mineral called tridymite. Usually this is seen on Earth with silicic volcanism. It's known to exist on Earth, but this type of volcanism was not believed to happen on Mars. "On Earth, tridymite is formed at high temperatures in an explosive process called silicic volcanism. Mount St. Helens, the active volcano in Washington State, and the Satsuma-Iwojima volcano in Japan are examples of such volcanoes. The combination of high silica content and extremely high temperatures in the volcanoes creates tridymite," said Richard Morris, a planetary scientist at NASA's Johnson Space Center and lead author of the research, in a statement.

Image: This August 2015 image of Curiosity shows the rover at the site where it drilled into a rock target called "Buckskin" and found an unexpected mineral: tridymite. Credit: NASA/JPL-Caltech/MSSS