For many of us, the notion that life exists elsewhere in the universe is an exciting prospect. As such, discovering even microscopic life on Mars would be a breakthrough in understanding our place in the universe and furthering mankind’s knowledge about nature. To understand how Earth might have once looked before it was home to living organisms, scientists can look at other bodies in our solar system. In recent years, missions have been sent to Mars and asteroids to study their surface compositions as well as an interior structure through remote sensing techniques (remote sensing involves collecting data from afar). Here is what we know about Mars till now.
1. Mars has two moons – Phobos and Deimos. They were discovered by Asaph Hall in 1877 and are named after the characters from Greek mythology who were sons of Ares (Mars).
They’re small, potato-shaped objects that orbit very close to the planet, which is about 1/3rd of what our moon orbits at. Deimos has a 3-hour orbit, while Phobos takes only 9 hours to make its single round around Mars. Phobos is just one of several thousand asteroids that are trapped in synchronous rotation and will likely break up within the next billion years.
2. Mars’ mantle does not undergo an internal heat engine like Earth’s or Jupiter’s for plate tectonics to occur, but instead features localized heat sources (volcanoes) that cause significant periodic changes in crustal stress and volcanic eruptions every 200 million years or so (the last one was ~800 MY ago). It has very distinct polar ice caps – they’re made of frozen CO2 and methane gas, which sublimate when warmed.
3. Mars has two small, irregularly shaped moons which are heavily cratered like the rest of the Martian surface. The ice caps at the north and south poles consist primarily (about 90%) of frozen water and have significant amounts of CO2 and Methane. There is no evidence of life on Mars at this time.
4. As mentioned above, Mars has polar ice caps made up primarily of carbon dioxide (CO2) and large quantities of frozen water ice. It does not have active plate tectonics like Earth does – instead it has localized areas where heat from the mantle causes volcanism. These eruptions result in massive changes to the planet’s surface every 200 million years or so – the last one was about 800 million years ago.
5. Mars has two small moons but no rings (rings would get ripped apart by its atmosphere). Its gravity is only 38% of that on Earth, which means you’d feel like you weigh about the same as if you were in a pool at the bottom of your house (yes, it’s possible to go swimming without drowning!) It also means getting up and walking around is challenging because there isn’t much air to breathe – thus spacesuits are required for significant amounts of time outside the ship.
6. The first spacecraft was Mariner 4 in 1965-66 which transmitted 21 images. The next one was Mariner 9 in 1971-72 which took 6,209 images from orbit and sent back the first close-up pictures of Mars’ surface. It also revealed its moons and showed volcanoes and channels that were previously unknown. Pathfinder landed in 1997 (the first U.S. mission to land on Mars), as did the MER rovers Spirit & Opportunity in 2004, which spent over a decade exploring the planet’s surface until communication was lost with both spacecraft in 2010. They sent back evidence for past water, volcanic activity, and ancient lakes on Martian terrain.
Seeking signs of life (past or present) has been the main focus of several missions since 1976 when NASA launched two Viking probes equipped with biology experiments designed to detect chemical evidence for life: soil analysis (for amino acids, nucleic acids, organic compounds), gas exchange (for methane and other gases), and meteorology (for trace gasses). Both landed in 1976, but their biology experiments failed to find any evidence for life. In 2004-2005, the European Space Agency launched two more landers: Beagle 2, which was never heard from again after landing on Mars; and the Mars Express probe. NASA also launched two rovers: Spirit & Opportunity in 2003 as part of its Mars Exploration Rover program. So far, this is what we know about it:
Some Facts About Mars
1) It’s quite difficult to get there – travel time can be years depending on where Earth and Mars are relative to each other.
2) Mars has a very little atmosphere (it’s essentially a vacuum) so landing there is very difficult – a spacesuit and oxygen supply is required for significant amounts of time outside the ship.
3) Temperatures can reach as high as 20-30 degrees celsius during the summer but drop to below minus 100 degrees Celsius during winter.
4) While Mars has large amounts of frozen water at its poles, it has an extremely thin atmosphere that’s only able to hold very small amounts of liquid – if temperatures are too low for liquid water to exist, it freezes directly to the ground. This means that on Mars, a lake or river will freeze over in the winter and evaporate completely during the summer.
5) Only about 38% as strong as Earth’s gravity
Visit Crawford Portal for more content!