Thursday, April 29, 2010
Asteroid 24 Themis is back in the news again (first time was last October) due to having water ice on its surface, as in addition to the discovery made last October another team has confirmed the same findings, and this time organic compounds have been found as well. The post I wrote in October also goes over suitability of the asteroid as a destination for a manned mission, and it does quite well due to orbiting along the same orbital plane as the rest of the planets in the Solar System; most asteroids are off by at least a few and sometimes many degrees, making reaching them a much more three-dimensional task than reaching a planet, requiring much more fuel than if their orbit had been more similar to ours.
At the same time, 24 Themis is still quite large with a diameter of 198 km, a surface gravity 1.6% that of the Earth, and an escape velocity of 633 kph (176 metres per second), so it's more like a small planet than an asteroid. The surface area is also 123,000 km2, almost the same as Greece and somewhat larger than Bulgaria.