Could it be evidence that there was once life on Mars?
NASA's Curiosity rover has found spikes of methane in the Martian atmosphere, a gas that on Earth is strongly tied to life.
The rover also found organic chemicals in a soil sample collected by a robotic drill. They are the latest findings as NASA hunts for clues about the possibility of extraterrestrial life.
Last week, scientists determined that billions of years ago, a lake filled the 96-mile-wide crater being explored by Curiosity.
The finding was another hint that Mars, the planet most like Earth in the solar system, was once suitable for microbial life.
The rover has traveled around 5 miles since landing on Mars in August of 2012.
It has been exploring an area where rocks have been found containing water-deposited sediments to learn if the life-friendly environments actually existed long enough for life to evolve.