Before it lost its atmosphere Mars was covered with liquid water. There is now evidence that certain areas of the red planet may still have free flowing water during certain times of the year. The results come from Alfred McEwen of the University of Arizona and were published in Nature Geosciences.

In 2011, NASA’s Mars Reconnaissance Orbiter (MRO) provided images that showed dark streaks in the soil in areas near the equator. Though they faded over time, the streaks return at the warmest part of each year. The most likely answer is that there could very well be liquid water flowing on the surface of Mars under certain circumstances; an unprecedented discovery, since the atmosphere is much too thin to retain liquid water for long periods of time.

The trouble is, researchers don’t know enough about Martian geology and composition to definitively say where the water could be coming from. There could be pockets of ice underneath the surface that liquify when warmed, but the emergence pattern of the dark streaks doesn’t seem to suggest that. There is also a possibility that the streaks are caused by water vapor being pulled from the atmosphere and condensed into the soil.

For life as we know it to exist, liquid water is a must. The fact that there is still liquid water on the surface of Mars is very exciting, but space agencies need to proceed carefully. Any probes that visit these potentially watery areas must be completely sterilized which is a complicated and expensive procedure. If there were any traces of Earth microbes on the probe, it could easily contaminate that which it was sent to study. The Committee on Space Research (COSPAR) is part of an international organization that defines good research practices in space and would shut down any mission that did not ensure the utmost of cleanliness for the spacecraft.

Of course, completely eliminating microbes is incredibly expensive. To completely prevent contamination, the probe would need to be heated using hydrogen peroxide vapor or ionized radiation to kill anything that might be stuck on the space craft. Similar treatments were performed on Voyager 1 & 2 and were about 10% of the entire budget that has spanned over 35 years. For a probe that would be able to land on Mars and analyze potential liquid water samples, the sterilization price tag could be too great to overcome for any one agency. Eventually, though, the mission will be done correctly, and having accurate and meaningful data will be well worth the investment.