The Curious Case of Methane on Mars
Today NASA held a press conference to announce the results of two papers released in Science this week: One on atmospheric methane, and one on organics in the soil, both from Curiosity rover data.
The history of methane detections on Mars is a tumultuous one. In 2004, the European Space Agency announced that Mars Express had detected small amounts of methane in the martian atmosphere. This was exciting news because on Earth, 95% of methane comes from biological sources—mostly microbes and cows, but we’re pretty sure there are no cows on Mars.
Methane should break down in the martian atmosphere over the course of about 300 years. So, a source to replenish the methane is required. There also appeared to be geographic and temporal variability in the methane levels. Ground-based measurements from Earth by a team led by Michael Mumma of NASA Goddard in 2003 and 2006 also pointed to localized methane release that varied over time, although these results were not published until 2009. However, the results from both Mumma and Mars Express were somewhat controversial among the scientific community. Why would the methane not be equally mixed throughout the atmosphere? Where could it possibly be coming from? And were the spectroscopic detections of methane really strong enough to be distinguished from noise?
