Members of our solar system that were little more than points of light for decades or centuries have now become familiar family members, seen up close and personal by spacecraft. Here are introductions to three worlds that are no longer mere names in a catalog. Even the names of members in this trio may be unfamiliar to some. They’re worth getting to know.
Vesta: At long last, after its launch four years ago, the DAWN spacecraft is in orbit around Vesta – second largest of the asteroids. Having been in orbit now for 3 months (7/29/2011), DAWN has given scientists enough material to share initial science results (to say nothing of eye-popping images). In its Oct. 3 report, accompanied by a false-color image of the asteroid, Science Daily headlined the highlights as “Massive Mountains, Rough Surface, and Old-Young Dichotomy in Hemispheres.” Science Daily posted more information on Oct. 14, but the BBC News beat them by a day. JPL’s DAWN mission site is the place to look for official press releases and news.
Most amazing is a south polar mountain three times the height of Everest – one of the largest mountains in the solar system, here on a body smaller across than Texas. The mountain,13 miles higher than surrounding terrain, sits in a large impact basin named Rhea Silvia. It is just 3 miles shy of the record holder on Mars, Olympus Mons. National Geographic News posted an oblique view of the massive mountain. Sporting equatorial troughs and other large impact basins,Vesta had another surprise reminiscent of some of the outer-planet moons like Enceladus and Miranda: parts that look old (according to crater counts, see 4/13/2011), and parts that look young (see Astronomy Picture of the Day for August 2, 2011). Planetary scientists may have to concoct a new word like yold for this oxymoronic dichotomy. Vesta is rocky; Ceres, the largest asteroid, is icy. It will be interesting to compare these two giants among mini-worlds after DAWN arrives at Ceres in 2015.
Lutetia: The 21st asteroid discovered is named Lutetia. In July 2010, the European Space Agency’s Rosetta spacecraft, on its way to an epic landing on comet Churyumov-Gerasimenko in 2014, flew by the asteroid and took images and data. Three papers in Science this week (28 Oct 2011, doi:10.1126/science.1207325) provided the first anaylsis from the encounter. “Lutetia has a complex geology and one of the highest asteroid densities measured so far,” the papers said: some 3.4 grams per cubic centimeter….
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