The surface of Mars is a tough place to survive, but researchers at the German Aerospace Center (DLR) found some lichens and cyanobacteria tough enough to handle those conditions.

How tough is it on Mars? Pretty tough. First, the Martian surface pressure of 6 millibars is pretty much a vacuum compared to Earth’s surface pressure of 1000. 6 millibars of pressure corresponds to a point waaay up in Earth’s middle stratosphere about 35 kilometers above the surface. This is an altitude almost 5 times taller than Mount Everest and right about where altitude records for air-breathing jet airplanes are set. Next, you’ve got the harsh radiation from the Sun. On gentle Earth, much of the dangerous photon radiation from the sun is filtered out by Earth’s thick atmosphere. But on atmospherically-challenged Mars, energetic ultraviolet rays blast the surface. These rays could plow through an unprotected biological cell and wreak havoc on the critical information-carrying genetic material in the cell. If that weren’t bad enough, the rays can also smack constituents of the martian rocks and dirt and make some really nasty reactive chemical species that could chew up any cellular biological membranes not tough enough to resist. Finally, Mars is very dry and cold, dryer than the driest deserts on Earth. Any water might come in a brief morning dew that quickly evaporates as the temperature rapidly fluctuates. Life would have to struggle getting water quickly during these transient events then survive being freeze-dried for long periods of time.

To see if they could find terrestrial life tough enough for Mars, the researchers collected specimens of organisms that were found in some of the most extreme and inhospitable places on Earth. They collected organisms from inside rocks, on mountain tops, and in the polar regions. These are places that might come closest to the environment on Mars. The researchers then created an environmental chamber that simulated conditions on Mars: ultraviolet radiation, infrared radiation, martian soil, low pressure, atmospheric mix, temperature ranging from -50 C to 23 C, the whole bit. They threw the collected specimens in the chamber to see if any could survive.