The rover landed on Mars in August 2012 to determine whether the planet most like Earth in the solar system has or ever had the chemistry and conditions to support microbial life.

Over the past decade, scientists using Mars orbiters and telescopes on Earth have reported plumes of methane in the Martian atmosphere.

The gas breaks down in sunlight so its presence on Mars indicated that either biological activity or a recent geologic event was responsible for its release. The gas which lasts about 300 years in Earth’s atmosphere, could be expected to stick around for 200 years on Mars. But curiosity’s findings, compiled over eight months indicate that the methane may have virtually disappeared in a matter of years. Based on the previous observations, scientists had expected to find about six times more methane in the atmosphere than the negligible amounts cusiosity found.

“There’s a discrepancy” lead research Christopher Webster, which NASA’s Jet Propulsion Laboratory in Pasadena, California told Reuters. “Suddenly the whole interpretation of earlier observation is stuck.”

Webster said it is possible but unlikely that the lack of methane  is particularly to curiosity’s landing site, a giant basin neat the planet’s equator. Once methane is released from the surface, scientists believe it would spread fairly quickly through the planet’s thin atmosphere.

“It’s disappointing of course” Webster said. “We would have liked to get there and find lots of methane.”

The search is not over. Curiosity will continue to take air samples and test for methane as it continues its geology mission.  Scientists also plan another round of observations with Earth based telescopes next year. This research appeared on journal Science.

Not that it’s been an easy journey. While Opportunity rover hasn’t experienced the same hardship as its twin rover, Spirit (whose abandonment was immortalized in this brilliant XKCD comic), it’s had its share of troubles. It spent a little over two months trapped in a sand dune before its operators were able to wriggle it free centimeter by centimeter, and it’s overcome mechanical problems aplenty. Not to mention the overwhelming loneliness.

Despite all that, Opportunity rover has spent the last 3449 days driving nearly 23 miles around the surface of another world. Its discoveries include the first meteorite found outside of Earth, a temperature profile of the Martian atmosphere, and tiny, iron-rich spheres known as “blueberries” that hint at a time when Mars had water. In fact, Opportunity’s most important discovery may have come just last month: A rock that proves that Martian water was once drinkable. Which in turn suggests strongly that life could once have thrived there.

Opportunity’s quest is far from over; the little rover that could will keep taking its measurements until it breaks, or gets stuck, or NASA loses its funding once and for all. Godspeed, little buddy. We can’t wait to see what the next 10 years holds for you—and for our understanding of the universe.

From: Gizmodo

Curiosity’s Radiation Assessment Detector (RAD) was able to measure the radiation of Mars from inside the spacecraft and found data that makes NASA reconsider the effectiveness of current radiation shielding. Specifically:

The findings, which are published in the May 31 edition of the journal Science, indicate radiation exposure for human explorers could exceed NASA’s career limit for astronauts if current propulsion systems are used.

Two forms of radiation pose potential health risks to astronauts in deep space. One is galactic cosmic rays (GCRs), particles caused by supernova explosions and other high-energy events outside the solar system. The other is solar energetic particles (SEPs) associated with solar flares and coronal mass ejections from the sun.

Right now, spacecrafts do a better job at shielding against SEPs than they do GCRs. GCRs are highly energetic and penetrate the shielding on current spacecrafts. In order to protect astronauts from being exposed to radiation, NASA might have to invent better shielding. Or invent better something.

Exposure to radiation, which is measured in units of Sievert (Sv), increases the risk of cancer. We know that. Exposure to 1 Sv over time is associated with a five percent increase in risk of developing cancer. NASA’s acceptable limit for its astronauts is a three percent increase in risk. Curiosity’s RAD instruments measured an average of 1.8milliSv per day on its trip to Mars. The accumulated dose of the trip, according to Cary Zeitlin, lead paper in the findings and a principal scientist at the Southwest Research Institute (SwRI) in San Antonio, would be equivalent to “getting a whole-body CT scan once every five or six days”. Yeah, that’s too much.

But knowing this doesn’t prevent a manned trip to Mars from ever happening. Knowing this helps protect the men and women who will take that manned trip to Mars. [NASA]