NASA’s Cassini spacecraft has begun returning its best-ever views of the northern extremes of Saturn’s icy, ocean-bearing moon Enceladus. The spacecraft obtained the images during its 14 October flyby, passing 1,839 kilometres (1,142 miles) above the moon’s surface. Mission controllers say the spacecraft will continue transmitting images and other data from the encounter for the next several days.
Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts. “The northern regions are criss-crossed by a spidery network of gossamer-thin cracks that slice through the craters,” says Paul Helfenstein, a member of the Cassini imaging team at Cornell University, Ithaca, New York. “These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well.”
Cassini’s next encounter with Enceladus is planned for 28 October, when the spacecraft will come within 49 kilometres (30 miles) of the moon’s south polar region. During the encounter, Cassini will make its deepest-ever dive through the moon’s plume of icy spray, sampling the chemistry of the extraterrestrial ocean beneath the ice. Mission scientists are hopeful data from that flyby will provide evidence of how much hydrothermal activity is occurring in the moon’s ocean, along with more detailed insights about the ocean’s chemistry – both of which relate to the potential habitability of Enceladus.
Cassini’s final close Enceladus flyby will take place on 19 December, when the spacecraft will measure the amount of heat coming from the moon’s interior. The flyby will be at an altitude of 4,999 kilometres (3,106 miles).