The possibility of life on Mars has long captured the imagination of earthlings, whether in the form of science fiction creations, the “canals” Percival Lowell thought he saw there, or the tantalizing hints provided by NASA’s Mars rovers. But was there, or is there, really life on Mars? This is not such a crazy question, as we’ve known for some time now that several billion years ago the red planet had an environment more conducive to life than it does now, with abundant water and a thicker atmosphere to keep it warm and shield it from radiation.
More recently, in Gale Crater, the Mars rover Curiosity discovered clays that form in water that would have been safe for humans to drink. These clays were found to contain the most important elements needed for life: hydrogen, oxygen, nitrogen, carbon and phosphorus. In addition, minerals such as sulfates and sulfides were found that could provide food, or an energy source, for primitive microbes.
We know that Mars currently has plenty of water in the form of ice, but recent photos taken by NASA’s Mars Reconnaissance Orbiter and Odyssey Orbiter have revealed dark streaks that may be evidence of liquid water flowing on Mars today. These flows are thought to contain iron-rich minerals that act as a kind of antifreeze, allowing the water to remain liquid despite temperatures below freezing. If it is indeed the case that Mars has some liquid water today, might there also be life?
One possible sign of life scientists look for is methane gas, an organic chemical that can be a waste product of certain living microbes. Just over a year ago there was much disappointment when Curiosity reported that it had found only a miniscule amount of methane (0.7 parts per billion) in the Martian atmosphere, dashing hopes that life might be found there today. However, more recently it was reported that the rover had detected a burst of methane gas ten times that amount that lasted for at least two months, and possibly longer. As methane gas does not remain in existence for very long, any found there now must have been created recently. According to Sushil Atreya, a member of the Curiosity science team, “This temporary increase in methane – sharply up and then back down – tells us there must be some relatively localized source.” Whether that source is some form of life remains to be seen, as methane and other organic molecules can also be a product of nonliving geological processes such as the interaction of heat, water and rock. Even if it were the result of geological processes, this would still be significant, as such processes require the presence of warm water, and any place on Mars with warm water would be a prime spot to search for life.
Apart from methane, Curiosity has detected other organic molecules in a powdered rock sample collected by the rover’s drill from a mudstone rock dubbed Cumberland. These were the first definitive carbon-based organics detected on surface materials on Mars, and were confirmed by the rover’s Sample Laboratory at Mars (SAM) to be of Martian origin.
Curiosity’s onboard laboratory has also analyzed water bound more than three billion years ago in lakebed minerals in the Cumberland rock, yielding information suggesting that Mars lost much of its water before the rock was formed, and continued to lose large amounts afterwards.
Unfortunately none of these findings tell us definitively whether Mars ever harbored living microbes, but they do indicate that the planet currently has an active chemistry, that conditions on ancient Mars would have been favorable for life, and that they might still be today. The good news is that NASA plans to send another rover to the red planet in 2020, with the goal of looking for signs of past life and collecting samples for future return to Earth. Perhaps this will bring us one step closer to answering the big question: Is there or was there ever life on Mars?
Join the Springfield Stars Club on Tuesday, February 24th at 7pm at the Springfield Science Museum for a talk by Richard Sanderson and Ed Faits on “The Future of Space Exploration: Human versus Robot.” Sanderson is curator of physical science at the Springfield Science Museum and manages the museum’s Seymour Planetarium and Observatory. He is an astronomy writer and past president of the Springfield Stars Club. Ed Faits, an avid astronomer, is a founding director and current president of the Arunah Hill Natural Science Center in Cummington, MA and a past president of the Springfield Stars Club. Refreshments will be served, and the public is welcome. The meeting is free of charge for members, with a suggested donation of $2 per non-member. For more information please visit the Stars Club – Massachusetts page on Facebook at https://www.facebook.com/groups/929125583765113/ or the Stars website, reflector.org.
Also, on Friday, March 6th at 7:30pm, the Stars Club and the Springfield Science Museum will host “Stars Over Springfield,” an astronomy adventure for the whole family. Ed Faits will speak on “Exploring the universe from your back yard: Five fun family projects you can do to observe the night sky without a telescope!” A fee of $3 for adults and $2 for children under 18 will be charged.
Copyright © Amanda Jermyn