By Hamish Johnston
A very long time ago, a large amount of water is thought to have flowed on the surface of Mars – and the above image shows what scientists think is an ancient Martian river channel that has been buried by volcanic material.
The river was probably created by a massive release of groundwater and the image shows the main channel as well as islands that have been shaped by the flow. The river is part of the 1000 km-long Marte Vallis channel system, which is believed to have been carved out less than 500 million years ago.
The image was created using the SHARAD radar sounder on the Mars Reconnaissance Orbiter. The former was built by the Italian Space Agency and the latter was launched by NASA in 2005. Gareth Morgan and colleagues at the Smithsonian Institution, NASA, Jet Propulsion Laboratory and the Southwest Research Institute analysed the radar data.
A key finding of the study is that the channel is about twice as deep as previously expected. Indeed, at about 100 m the channel is comparable to the deepest known “megaflood” channel on Earth.
The research is reported in the journal Science.