The Opportunity rover has just celebrated the 12th anniversary of its touchdown on Mars—a remarkable feat considering it was only supposed to last 90 days on the planet. Along with its twin the Spirit (now declared defunct), and joined by younger sibling Curiosity in August 2012, the Opportunity has barreled along for years and gone on to explore more terrain than any other off-world robot has managed to date. It’s fair to say that these remarkable machines have far outlasted their expected lifespans, and their findings offer incredible insight into the terrain, environment and history of Mars. So what have been the most important discoveries made by the Mars rovers to date? Here are just a handful:
Mars Was Once Habitable
Shortly after landing in 2004, Opportunity stumbled upon evidence of hematite and jarosite, which are minerals generally formed in the presence of water. On further examination, NASA concluded that the rover had landed in an area that was once drenched in water, possibly the coastline of a sea. It also discovered cross beds, which are small layers of rock that overlap each other and indicate that water once flowed through the area. These and other discoveries have helped us build a picture of what Mars was like in the distant past—warm, wet, and certainly capable of supporting life.
Possible Signs of Alien Life
Back in 2006, Spirit relayed images of strange cauliflower-like formations inside Mars’ Gusev crater, which may have hosted geysers or hot springs in the past. The deposits are comprised of a mineral called opaline silica, and look remarkably like formations found here on Earth—which are sculpted by microbes. If microbes created these structures here on Earth, it stands to reason that some form of alien microbial life could have been responsible for the ones on Mars. It will be difficult to prove the viability of this theory remotely, but if it holds, it will go down as one of the greatest discoveries in the history of astronomy.
The First Atmospheric Temperature Profile
Before the Mars rovers landed, we had only ever observed the planet from orbit. This made it difficult to get an accurate picture of Mars’ atmosphere, with orbiting instruments relaying wildly different measurements of important elements and gases, like methane. Operating from the ground, the rovers have been able to assist in creating the first temperature profile which shows how warm each layer of the atmosphere is at a particular location. But why is all this important, I hear you ask? Because now we have an excellent snapshot of Mars’ global weather, which will assist future landings and pave the way for…
Perhaps the Mars rovers’ most important legacy is that they have performed important practical reconnaissance, giving the first humans to touch down on the Red Planet a good idea of what to expect. Even setting aside their discoveries, we can harness valuable operational data from just the rovers themselves. How do solar panels perform on the surface of Mars? What happens to wheels in Martian soil? How do fluids and lubricants behave in the cold temperatures? The rovers have answered many important questions like these, and their insight will be crucial when preparing for the first manned mission to one of our closest neighbours.
Q: What might be left for the Mars rovers to discover? Let’s hear your thoughts in the comments below.