Cassini has completed another close reconnaissance pass of one of Saturn’s most intriguing moons; Enceladus. On November 2nd at 7:40 AM UTC, Cassini passed 62 miles above the icy surface of the south polar region, completing a carefully timed plunge through one of its liquid plumes. This was one of its most comprehensive passes of the moon out of the seven completed so far, enabling the spacecraft to utilize its array of infrared and ultraviolet detectors to analyze speed and particle size. Cassini itself is whizzing along at 5 miles per second. Sodium, water, and carbon dioxide have been detected in the out-gassing, tantalizing evidence that more complex organic chemistry may exist below the surface. Enceladus is heated from tidal flexing caused by Saturn’s gravity squeezing it like a rubber ball. Along with Jupiter’s moon, Europa, Enceladus has been proposed as deserving of future scrutiny as a possible abode of life. Enceladus is a tiny world, about 310 miles in diameter, or about 15% the diameter of our Moon. Two subsurface oceans in one solar system also poses the intriguing question; are environments like Enceladus and Europa more common throughout the universe than Earth? Cassini has phoned home after the recent pass and is reported in good health. Scientists are currently poring over the results; watch for another pass of Enceladus on April 28th of next year. What ever the outcome, Enceladus is proving to be a dynamic place, worthy of future study!
Scientists at NASA have announced the candidate target crater for the LCROSS impactor on October 9th; Cabeus A, a 11km wide polar crater thought to contain the ever- elusive water ice. The Centaur upper stage will slam into the carter floor at 7:30 AM EDT, at which time the Moon will be waning gibbous, and about 70% illuminated, and favoring viewers in the Americas (including Astroguyz HQ!). Contrary to earlier fears, LCROSS has enough fuel to make final maneuvers for impact. Both Keck observatories and LCROSS’s twin, the Lunar Reconnaissance Orbiter, as well as a multitude of eager amateur observers will be on hand to witness this rare event!
In a stunning press conference on Thursday, NASA revealed conclusive proof for what has been suspected for decades; evidence for water-ice mixed into the lunar surface! The evidence comes from multiple sources over the past decade;
Lunar Prospector, which measured a “flux drop” with its neutron spectrometer during its operational phase of 1998-9.
The “M-cubed” instrument NASA sent aboard India’s Chandrayaan-1 measured tell tale infrared signatures during its recent lunar mission;
Cassini (yes, that Cassini!) and Deep Impact both measured signatures highly suggestive of water during their respective outbound passes. Cassini with the VIMS (the Visible Mapping Infrared Spectrometer) and Deep Impact in its extended EPOXY (Extrasolar Planet Observation and Deep Impact Extended Investigation) role.
Clementine, which operated in 1994 produced data that also backed up these findings.
Perhaps what was most astounding was the fact that water signatures were found not only at the poles, which has been long suspected, but in the lunar equatorial regions as well! Apparently, water exists in some degree at all latitudes… quantities quoted were of the magnitude of one quart per ton near the poles to a tablespoon per ton of lunar material at the equator. Keep in mind, much of this is mixed in as hydroxyl compound as well as lunar ice. Think a clay-like material. Scientists also pointed out that this is still “drier than the driest terrestrial desert…” clearly, future settlers will have to move tons of lunar regolith to exact a useable amount of H2O… another stunning mechanism discussed for the existence of equatorial water was the possibility of a pseudo “hydrological cycle” on the Moon! This would be driven by gravity, heating, and hydrogen ions from the solar winds bombarding the surface throughout the lunar day. The layer is perhaps a few millimeters thick. Three separate papers were published formalizing these findings yesterday. This will undoubtedly spur on lunar exploration, as well as put all eyes on the Moon for the LCROSS impact on October 9th!