It’s confirmed. Dawn is finally in orbit around Vesta! She’s pretty close too, at the moment at about 6,500 miles and that’ll decrease down to about 3,000 miles over the next few days. Eventually Dawn could get down to within 200km of the surface during it’s year in orbit.
And now, fresh off the press, new pictures of Vesta!
Dawn – The journey to the beginning of the Solar System! It’s a fairly ambitious mission, as are most of NASA’s missions at the moment. Firstly the spacecraft uses ion propulsion, a technology tested on Deep Space 1 but never before used for a dedicated science mission. Secondly Dawn has not one but two targets. The large asteroid or even protoplanet, Vesta and then the dwarf planet Ceres. The spacecraft will go into orbit around Vesta, happily do some science for a while, break orbit and then go to orbit Ceres!
Launch of Dawn on a Delta II Rocket
Dawn launched back in September 2007 atop a Delta II rocket. It’s been in the cruise ever since, giving short bursts of ion propulsion to refine it’s orbit. Now after nearly 4 years she’s almost arrived, ready to hop into orbit.
Vesta is the largest asteroid in the Solar System (Ceres is larger but is termed a dwarf planet) it’s about 530km across and is estimated to contain 9% of the mass of the asteroid belt, so it’s a pretty hefty object. It’s thought to be differentiated, that is it’s so big so that heavier elements, like iron, fall towards the centre and lighter elements are found nearer the surface. This is the same way that Earth’s core formed.
We already know a fair bit about Vesta surprisingly. About 1 billion years ago Vesta was hit by an asteroid that’s left a small crater. This threw out lots and lots of debris, and quite a bit of this has fallen to the Earth. These meteorites have the fancy name of Howardite-Eucrite-Diogenite (HED) meteorites. Evidence from these meteorites show that Vesta is between 4.43 and 4.55 billion years old and reveals that Vesta has a history of extensive igneous processes. Infact the meteorites are very similar to magmatic rocks found on the Earth.
The mission at Vesta is to develop our understanding of how the Solar System formed and in particular what role water played in planetary evolution. Vesta and Ceres both reflect what the early Solar System was like, something we can’t figure out here on Earth because of all the geological activity the Earth is still going through. Continue reading →
It’s only ever short notice with these things – Near Earth Asteroids. The asteroid 2011MD is going to pass teeth-chatteringly close by on Monday 27th June, a mere 7,500 miles above the Earth’s atmosphere in fact.
This thing is so small (between 6 and 14 meters) so that we’re only able to see it when it’s very close. A bit of a problem if an object was actually going to hit the Earth! But thankfully this one’s only passing close by. Even if it did enter the atmosphere the majority of it would likely break up and the remaining bits to hit the ground would have minimal impact. Nonetheless still an exciting event.
It’ll only be viewable from the Southern hemisphere through a moderately powerful telescope, which is a shame. Here are some graphics of the objects predicted path however from NASA’s Near Earth Object Program
The next two are really cool animations, the second one showing you the Earth from the perspective of the asteroid which is really amazing stuff!