Bethany Ehlmann spoke to the University of Massachusetts community on Wednesday evening about the history of water on Mars. Ehlmann is a participating scientist of NASA Mars Rover Curiosity mission, a research scientist and the Jet Propulsion Laboratory, and assistant professor of planetary science at Caltech.
According to Ehlmann Mars and Earth have similar day lengths (Mars has a 24 hour and 40 minute day), and Mars has roughly four seasons. The discovery of water on Mars is a huge breakthrough.
To better explore the surface of Mars, NASA created the Curiosity Rover. “Curiosity’s primary scientific goal is to explore and quantitatively assess a local region on Mars’ surface as a potential habitat for life, past or present,” said Ehlmann. It is also calculating Mars’ chemical building blocks, isotopic, and mineralogical composition, geological processes, and surface radiation.
The rover weighs about one ton, and has a movable arm that weighs 50 kilograms. It has a laser that can shoot at rocks up to seven meters away and get elemental composition readings from the laser.
Curiosity’s ChemCam laser shoots beams that are 500 microns in size, and penetrate the rock anywhere from a millimeter deep to just barely getting below the surface. The ChemCam laser is used to see if rocks and soils have traces of minerals or components necessary for life.
It also has a camera, instruments that monitor weather and neutrons, and interior instruments that calculate mineralogy and chemistry. Over the decade of 2004-2014, Curiosity has cost billions of dollars.
Curiosity was launched from Cape Canaveral in 2011 for an anticipated landing in 2012. It took seven months for it to reach Mars. In order to land the rover, several procedures had to take place. Because of the heavy weight of the rover, it couldn’t be parachuted right away once it was in Mars’ atmosphere. Instead, it had to be lowered like crane from the back shell, before it could be parachuted down to the ground.
Curiosity landed on the Gale Crater, which sits at the dichotomy boundary. The crater was about 3.7 billion years old and is composed of a mountain of sediments that has a record of the formation of Mars. It is about the size of Mount McKinley in Alaska. Curiosity’s destination is Mount Sharp, which lies about 12 kilometers from Gale Crater. Since landing, it has only traveled four kilometers.
At Gale Crater, the data that Curiosity gathered showed that at one point in time there was water there. The rover was able to gather the data from minerals found in the sand.
There is also a drill attached to the rover, which was used in Gale Crater to create a dime-sized hole. Veins in the hole showed probable water related minerals. X-ray diffraction was then used to detect clay minerals in the crater. The data showed that the rocks contained 25 percent clay mineral, which is the only mineral formed in the presence of water.
Ehlmann said, “Water is heading down the crater walls, down into this valley, and then lake water and groundwater created these sediments.”
Curiosity was then sent to the rock bed, Rocknest, where it scooped windblown sand for samples. Using X-ray diffraction, the rover detected basaltic, a mineral that was expected to be found. The crystalline component of the data was similar to the components that can be found in desert areas of the United States. However, 27 percent of the minerals in the crystalline sample are unknown..
As Curiosity has travelled over Mars’ surface, five minerals related to water have been discovered. Gale Crater was an obvious area of periodic fluxations of water.
“There was water there at one time,” Ehlmann said. “It did flow.”
