Study suggests space probes can directly sample an extraterrestrial ocean
The seas of Saturn’s moon Enceladus are blasting into space.
Saltwater-spewing geysers on Enceladus’ icy surface — 101 of them — appear to connect to the moon’s warm subsurface ocean, scientists report July 28 in two new studies in the Astronomical Journal. The results suggest that these geysers offer an unprecedented chance to collect samples of a potentially habitable reservoir of liquid water away from Earth.
Over the last decade, Enceladus has become a tantalizing spot for finding extraterrestrial life because of discoveries of a deep underground ocean (SN: 5/3/14, p. 11) and ice erupting from the moon’s south pole (SN: 8/27/05, p. 141). Researchers have wondered whether the geysers’ spray originates in that ocean or at the icy surface, where friction along cracks could create hot spots that melt the ice.
The new findings, based on over six years of data from NASA’s Cassini spacecraft, reveal that hot spots around each geyser — regions that are slightly warmer than the surrounding ice — are too small to fuel the jets. Instead, the researchers suggest, Saturn’s gravity opens fractures in the ice, causing water from the ocean to get drawn up into the vacuum of space.
C. Porco, D. DiNino and F. Nimmo. How the geysers, tidal stresses, and thermal emission across the south polar terrain of Enceladus are related. Astronomical Journal. Published online July 28, 2014. doi:10.1088/0004-6256/148/3/45.
F. Nimmo, C. Porco and C. Mitchell. Tidally modulated eruptions on Enceladus: Cassini ISS observations and models. Astronomical Journal. Published online July 28, 2014.doi:10.1088/0004-6256/148/3/46.
C. Crockett. Subsurface sea hides below ice of Saturn moon. Science News. Vol. 185, May 3, 2014, p. 11.
J. Shugart. Saturn's tides drive icy moon's plumes. Science News Online, July 31, 2013.
R. Cowen. Saturn's moon may host an ocean. Science News. Vol. 174, August 30, 2008, p. 10.
R. Cowen. Enceladus: small but feisty. Science News. Vol. 168, August 27, 2005, p. 141.