Thursday, October 14, 2010
This is an update to this and many previous posts tracking the distance of the Dawn spacecraft in relation to 4 Vesta, where it will arrive in July. Apparently visual tracking will begin around May, but it would still be interesting to see a photograph or two before then, tiny or not. The comparison used in these posts is this image of 21 Lutetia taken at 900,000 km by the Rosetta spacecraft before its arrival:
and since 21 Lutetia is 100 km in diameter while Vesta has a much greater diameter of 540 km, we can show the distance and size of these two objects to scale along with the probe, which is to scale in terms of distance but not size. The distance between the two is now as follows:
So the area from the grey image at the bottom to the current location is the distance covered in between 22 September and now, 5 million km.
In other news, there is an interesting article here today on an object originally thought to be a comet which has turned out to be an asteroid that recently collided with another one, and it was not until the collision that we even knew it existed. The tinier asteroid that collided with it was likely completely destroyed. Since even two asteroids that collide with each other are difficult to spot, that means there are a lot of other collisions out there that we are unaware of and the more asteroids we discover the easier it will be to predict when the next collision will occur. You may remember this video showing the number of asteroids discovered from 1980 to 2010:
WISE has and is doing a great job in adding to this, and Pan-STARRS is another one that will also make a massive contribution once all four telescopes are in operation, which is expected to lead to an extra 100,000 asteroids and at least 20,000 Kuiper Belt objects. The chance of a collision will still remain extremely low, but if we had known about the two objects that collided to form P/2010 A2 beforehand, we could have arranged to observe them at the moment of impact as well.
The most exciting idea from all this is perhaps the prospect of knowing about a collision well enough in advance that a probe could be sent out to observe it from close up (though it a safe enough distance) as it happens and during the months and years after. That would be a phenomenal event to see up close.