All the photos streaming back from space (and there are a lot of them these days) continue to amaze us back on Earth.

A photo from Nasa’s Cassini spacecraft shows red streaks on Saturn’s moon Tethys’ surface. These look like narrow lines and would not be more than a few miles thick, but could be several hundred miles long. Nasa has been observing these images since April, but has only now made a public announcement. The area covered by the visible red streaks is approximately 305x258 miles (490x415 km) across.

“The origin of the features and their reddish colour is currently a mystery to Cassini scientists. Possibilities being studied include ideas that the reddish material is exposed ice with chemical impurities, or the result of outgassing from inside Tethys. The streaks could also be associated with features like fractures that are below the resolution of the available images," Nasa said in its official statement.

The Cassini mission is a joint effort of Nasa, the ESA (European Space Agency) and the Italian Space Agency.

Just a few days back, Nasa scientists turned around the Curiosity Rover to investigate a rather unusual rocky surface, which caught their eye. Dubbed “Elk", the bedrock, scientists say, has surprisingly high levels of silica. Silica is a rock-forming compound containing silicon and oxygen, commonly found on Earth as quartz. This suggests that this bedrock may provide conducive conditions for preserving the ancient carbon-containing organic molecules, if any exist.

Elk has been spotted on the lower reaches of the 5.5 kilometres-high Mount Sharp, in a region called Marias Pass. This region is what scientists call the “geological contact zone", where dark sandstone meets lighter mudstone.

The Curiosity rover has been driving around the surface of the planet Mars, since August 2012. Its mission has been specific to the 154-km-wide Gale crater.

If this indeed is a region that once supported microbial life, all eyes will be on the future missions to Mars—European Space Agency’s ExoMars (scheduled to land on Mars in 2016) and Nasa’s Curiosity follow-up, the Mars 2020 Rover (which will start in the year 2020).