May 25, 2019

09.06.10: H2O in the Solar Neighborhood.

Water, water, everywhere… over the past year or so, evidence for water in the solar system has been mounting in some unlikely places. The poles of our Moon. Ice geysers on Enceladus. Now add the denizens of our asteroid belt to the list; earlier this year, scientists at the Johns Hopkins University of Applied Physics in Laurel, Maryland have revealed findings that water ice may pervade the surface of asteroid 24 Themis. This comes from six years of careful study carried out by astronomers Andrew Rivkin and Joshua Emery using NASA’s Infrared Telescope Facility. By studying the asteroid of seven separate occasions, a definite signature pattern of water ice and carbonaceous organic materials has emerged. Much like the revelation of water hydroxyls on the Moon, this comes as something of a shocker; the asteroids bordering the inner solar were long suspected as being bone dry. 24 Themis orbits the Sun at a distance of 297 million miles, or about 3 A.U. “This is exciting because it provides us a better understanding about our past and our future,” stated Don Yeomans of NASA’s Near-Earth Object Program office at JPL. Clearly, the possibility of a “wet asteroid belt” may have further implications not only for space travel, but as to the origins of terrestrial water as well. Keep in mind, the ratios mentioned are often minuscule in an everyday sense; for example, the amount of water reckoned on the lunar surface during last years’ media blitz was on the order of one liter per ton of lunar regolith. Clearly, it will be a major technical feat to harvest such a small amount in useful quantities. Obviously, many sources of extraterrestrial water are still bone dry by the standards of the harshest terrestrial desert. Still, this tantalizing find may provide clues to fuel speculation as Dawn mission enroute to the asteroids Vesta and Ceres draws near; Vesta displays a curious reddish brown spectrum highly suggestive of a tarry surface, and Ceres has been proposed to perhaps harbor a subterranean ocean similar to what’s thought to exist beneath the surface of Jupiter’s large moon, Europa. This all begs for further exploration and could drive a new emphasis towards the President’s eluded to “Mission to an Asteroid” by 2030 or so… Apophis in 2029, anyone?

2009 UN3:A (Semi-) Bright Asteroid flyby.

This week, a brief cosmic interloper graces our skies. Tonight, 2009 UN3 will glide silently past Earth, at a distance of 0.03667 Astronomical Units, or about 3,400,000 miles. That equates to roughly 13 times the Earth-Moon distance. Not especially close, as Near Earth Asteroids go; 2009 UN3 isn’t considered a hazard on this pass, but has been classified as a Potentially Hazardous Asteroid, (PHA) or one that warrants watching. What is interesting about this particular asteroid is the fact that it is nearly a kilometer in size, and thus should appear moderately bright. At maximum approach, 2009 UN3 will be approximately +12 in apparent magnitude, bright enough for moderate (8” aperture or larger) scopes. Closest approach occurs at 4:48 Universal Time (UT) on the 9th, at which time the asteroid will be moving in a south to north direction through the constellation  Corvus into Virgo around Right Ascension 12h 23’ 26.0” and southern declination -08° 55’ 30”. Keep in mind, the coordinates mentioned are topocentric; with Near Earth Objects (NEOs), parallax as viewed from along the Earth’s surface comes into play.

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