The barren, dusty Red Planet was not always a lifeless mess. In fact, scientists have often theorized that Mars was once covered in vast waterways. There’s a lot of evidence to suggest that may be the case, too. However, new research involving that evidence suggests that it might not have been water that left those marks after all and that the chance of finding life on Mars is actually much slimmer than we hoped.

Mars is by far the planet that humanity has explored the most, with several rovers now having made their way across the barren surface of our neighboring planet. One of the key missions with those rovers has always been to find signs of life, or signs that life once existed on Mars. We’ve come close a couple of times, with some theorizing that NASA accidentally killed the only Martian life we’ve ever discovered on the planet.

Through it all, though, the hope that our chances to find life on Mars were high has relied on one key thing: the existence of water in Mars’s past. However, that watery past we believe the planet had may not have been as long or as extensive as we thought. New evidence suggests that places we thought had been carved out by water flowing through them could have actually been created by explosively evaporating carbon dioxide ice.