Water-Rich History On Mars.
Ever since Galileo began looking at astronomical objects through telescopes, people have been able to observe the seasonal growth and decay of the Martian polar caps. Until recently, scientists assumed they were analogous to the ones on Earth. In 1877, Italian Giovanni Schiaparelli observed lined features on Mars which he called canali, meaning channels. Percival Lowell, observing from Flagstaff in 1894, believed they were man-made (or more accurately “alien-made”) canals and proposed they were the remnants of an ancient civilisation. It wasn’t until the first flybys of Mars by the Mariner missions in the 1960s that scientists got a good look at the surface and found ancient imprints of dry riverbeds, but there were no artificial canals.
The atmosphere was also very thin, suggesting that the seasonal caps are carbon dioxide ice, said Shane Byrne, associate professor at the University of Arizona’s Lunar and Planetary Laboratory. In the 1970s, scientists discovered the perennial caps are composed of water ice in the north and carbon dioxide in the south and that they both sit atop layered ice deposits containing dust. It wasn’t until 2008 when the radar instrument Sharad (SHAllow RADar) on the Mars Reconnaissance Orbiter observed the poles that they were confirmed to be mostly water ice. Liquid water on Mars, past or present, was still a possibility. It has been NASA’s motto to “follow the water” because — if we follow Earth-based logic — where there’s water, there should also be life. In the mid-’70s, the Viking 1 and 2 orbiters and landers captured images of the surface and ran soil samples for signs of microbial life. The results were inconclusive, according to NASA. More American robots were sent in starting in the mid-’90s through the early 2000s with missions to search for habitable conditions past or present. This included the Mars Global Surveyor orbiter, the Pathfinder lander and Sojourner rover, the 2001 Mars Odyssey orbiter, the Spirit and Opportunity rovers, the Mars Reconnaissance Orbiter (on which HiRISE is installed), and the Phoenix Mars lander — a mission headed by the University of Arizona.
The latest rover, Curiosity, landed in 2012 and is still exploring. The latest orbiter, MAVEN, continues to study the Martian atmosphere. The next mission, a lander named InSight, is planned for 2018 and will collect seismic data to reveal more about the interior of Mars. All missions inform scientists about the conditions on Mars in the past or present and whether such conditions were suitable for water and — by extension — life. Credit: Mikayla Mace for the Arizona Daily Star
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