Based on recent reports sent back by the Curiosity rover on Mars, scientists have come to the conclusion that Mars most certainly does not have any martian cows, or any other organic organisms for that matter.
The Curiosity rover landed on Mars in October of 2012, and from then until June made 6 different analyses of the atmosphere. The goal was to hopefully find the presence of methane. On Earth, methane is produced by almost all living organisms. (Especially cows, hence the earlier lame attempt at a joke.) Thus, if Curiosity would have found presence of methane on Mars, proof of life existing on Mars would have almost undeniable.
Scientists were looking for methane due to earlier reports from observations here on Earth in 2003 that there were huge plumes of the gas in Mars's atmosphere. When building Curiosity, scientists made sure to equip it with the best methane detector available to man - the Tunable Laser Spectrometer (TLS). This device can search for methane through 2 different means: One laser looks exclusively for the spectral lines of methane, and the other can detect methane, water, carbon, and oxygen. Because of the sophistication of the equipment, scientists are 95% sure that there are no methane producing organisms on the planet.
Despite those overwhelming statistics, the findings do not completely dissolve hope for life on Mars. While scientists still have no real answers for the discrepancies between the methane readings from Earth and the ones made by the Curiosity rover, they are still holding out hope for life on the red planet: “If it had found methane, that would have been killer. Yes, it’s disappointing in that we didn’t get a pony for Christmas. But it doesn’t mean there aren’t ponies out there,” stated Dr. Zurbin, president of the nonprofit Mars Society. (But once again, we definitely know there are no cows.)
Even Curiosity herself (Are rovers called girls like cars?) has not given up hope for life on Mars:
Lack of methane doesn't mean Mars never supported life. Plenty of Earth organisms don't produce the gas.
— Curiosity Rover (@MarsCuriosity) September 19, 2013
So where to search next? Considering scientists have had no luck searching the surface of the planet for life-forms, the next stop seems to be underground. All evidence points to the fact that Mars was once a hot and wet planet (Now would be the time for an inappropriate joke about red-heads, but I'll let that one slide). If there is no water on the surface, odds are that there is some below the surface. Also, the equipment Curiosity has to measure methane levels is about the best money can buy, but that doesn't mean it is perfect. The readings could be wrong. And if they are, there is still hope for Martian cows.
Image via Twitter