We recently examined how and why the planet Venus could answer the longstanding question: Are we alone? Despite its harsh environment on the surface, its atmosphere could be hospitable for life as we know it. Here, we will examine the planet Mars, aka the Red Planet and the fourth planet in our solar system, which has been marveling sky watchers from ancient times to the present day.
In terms of space exploration, no planetary body has been visited more times than Mars, with NASA’s Mariner 4 becoming the first spacecraft to image the Red Planet in 1965. Today, there are 3 rovers and 1 lander currently exploring Mars, along with over a dozen orbiters teaching us something new about this mysterious world every day. But what makes Mars so fascinating to study?
“Mars fascinates me in many ways,” said Dr. Antonio Paris, who is the Chief Research Scientist with The Center for Planetary Science, and author of Mars: Your Personal 3D Journey to the Red Planet. “From science fiction to science, the Red Planet can serve as a lifelong research interest to unravel the mysteries of the Solar System, such as how did life on Earth begin and will our planet meet the same fate as Mars?”
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Today, Mars is both a cold and dry world, with average surface temperatures ranging from -140 degrees to 21 degrees Celsius (-220 degrees to 70 degrees Fahrenheit), and not a drop liquid water on the surface. This lack of water is explained by the lack of atmospheric pressure, which is a paltry one percent of Earth’s. Much like Venus, this doesn’t bode well for life as we know it. So, what makes Mars so intriguing for astrobiology and finding life beyond Earth?
“Mars used to look a lot more like Earth,” said Dr. Mackenzie Day, who is an Assistant Professor in the Department of Earth, Planetary, and Space Sciences at UCLA. “It had liquid water flowing across the surface that carved river valleys and filled craters to form lakes. Lakes in particular are great places to find life on Earth, so Mars is an intriguing astrobiology target because it used to have so many lakes. The Mars 2020 rover, Perseverance, is currently exploring a dry paleo-lake with a delta deposit in its interior. Deltas on Earth naturally organize sand, mud, and gravel by size, and we know that the best place to find signs of life are in the smallest grains. Taking advantage of what we know about deltas on Earth (like the Nile River Delta or Mississippi River Delta) will improve the rover’s chances of making particularly exciting discoveries.”
Evidence suggests that billions of years ago, Mars was a much warmer and wetter place, and the current Mars missions are attempting to figure out if life once existed on the surface, or even just beneath it. While we’ve learned a ton of science about the Red Planet in just the last few decades, humans can’t study Mars directly because we don’t have any samples back on Earth. But that could all change with NASA’s Mars Sample Return mission that is slated to launch in the late 2020s. In the meantime, NASA’s Perseverance rover is currently preparing samples that will later be returned to Earth sometime next decade. But how could these returned samples help improve our understanding of Mars’ habitability?
“There are so many questions that could be answered with an actual piece of Mars and the suite of samples that the rover is collecting is being carefully selected to get a little bit of everything,” explains Dr. Day. “With actual samples we can use many laboratory tools and methods that the rover doesn’t have onboard. The samples will give us a much clearer picture of what was happening on ancient Mars and where or how life might have survived.”
Was Mars capable of supporting life, even for even a short time? What will the current missions continue to uncover about the Red Planet, and what will we learn from the samples returned to Earth? These questions could very well be answered in just the next few years.
“There is much speculation as to whether or not life existed on Mars,” said Dr. Paris. “If I could make a bet, I would choose lava tubes as the locations to search for life on Mars. Many of the lava tubes on Mars remain closed off, which can serve as important locations for direct observation and study of Martian geology and geomorphology, as well as potentially uncovering any evidence for the development of microbial life early in the natural history of Mars.”
And with this, we wonder if Mars will finally answer, “Are we alone?”
As always, keep doing science & keep looking up!
Featured Image: True-color image of the Red Planet taken on October 10, 2014, by India’s Mars Orbiter mission from 76,000 kilometers (47,224 miles) away. (Credit: ISRO/ISSDC/Justin Cowart) (This file is licensed under the Creative Commons Attribution 2.0 Generic license.)