NASA's Cassini spacecraft has returned the first images from its Monday flyby of Saturn's moon Enceladus, revealing a deeply fissured surface littered with blocks of ice but no sign yet of the source of the moon's active geysers.
The first images NASA revealed were taken from the moon's south pole, an area of particular interest because geysers of water-ice and vapour shoot forth from fissures and supply material that ends up in orbit around Saturn, in one of the planet's rings.
The geysers have attracted broad interest in the scientific community since they were discovered in 2005, with a number of astronomers suggesting they pointed to both volcanic activity and the possibility of liquid water on the moon, both considered important preconditions for the development of life on Earth.
The first images have yet to reveal exactly where those jets of water-ice are coming from, Cassini imaging team leader Carolyn Porco wrote on Tuesday.
"The first images … are clearly littered, completely, with blocks of ice ... not surprising given that we saw such things in our first very high res [four-metre]/pixel resolution images taken back in 2005, and not surprising for a very fractured environment," she wrote on the Cassini mission blog.
"Now we have to figure out if we indeed have captured the sites where the jets are emerging, so there’s a lot more to do," she wrote.
It was the second time Cassini has flown to within 50 kilometres of the distant moon. During the first such manoeuvre, in March 2008, Cassini flew through the icy geyser plumes and was able to detect the presence of water vapour as well as trace amounts of methane and simple organic compounds.
Two more Enceladus flybys are planned for October, NASA said. The first of those will bring the spacecraft to within 25 kilometres of the moon's surface.