Bad Astronomy

Dawn approaches

The spacecraft Dawn is now just one day away from entering orbit around the asteroid Vesta, the second-largest in the main belt between Mars and Jupiter. On July 9th, it snapped this photo of the rock, from just over 40,000 km (24,000 miles) away:

As far as I can tell, this is the highest resolution image of Vesta ever taken! Vesta is a slightly flattened mildly-lumpy spheroid with a diameter of about 530 km (260 miles), and you can see it’s peppered with impact craters, as expected. It may just be the lighting, but they look shallower than I would’ve thought. Sometimes that happens when the impacted body is soft, like ice or loosely packed material – though we know the surface is rocky. Maybe it’s powdery, like the Moon’s surface? There are grooves, too, possibly cracks in the surface. Stress fractures from an impact?


It’s too early for me to speculate much, and I’m no expert, but this certainly whets my appetite to see what happens when Dawn slips into orbit and starts taking high-res images of the surface!

That will happen tomorrow, when I am at The Amaz!ng Meeting 9 in Las Vegas. I’ll be pretty busy with that (and trying to blog and tweet about it too) but I’ll do what I can to report on what I hear about Dawn and Vesta. In the meantime, keep your eyes on the Dawn mission homepage and The Planetary Society blog for info.

Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Related posts:

- On approach to Vesta
- Asteroid comparison chart, Part II
- Hubble spins an asteroid