As the Dawn Spacecraft readies for orbit insertion only a week from now, the images coming in are getting sharper and sharper. Once the craft is fully in orbit its first task will be to map the surface of the planet in high definition. Even on the last few weeks of the journey to Ceres, we have seen increasingly clear images, and have already started asking ‘What the heck is that?’
This week’s ‘what the heck are we looking at?’ involves this apparent double bright spot on Ceres, imaged on February 19th from a distance of 46,000 Km, about an eighth the distance from the Earth to the Moon. What is the bright spot? Why are there two of them? Why are they so much brighter than the rest of Ceres’ surface?
There can be a lot of speculation about it, but the reality is that we won’t know until we get a closer look. If I had to guess I would say that because it’s in the middle of a very large crater, it’s likely reflective subsurface material revealed by the impact, ice of some sort (water or Carbon Dioxide), or reformed rock that was once molten due to the meteorite that made that giant crater.
Answers are coming, we just have to be patient. Still, its difficult to contain excitement about visiting a new world. It’s the explorer’s spirit present in us all. It’s like sailing across an ocean and spotting land and slowly moving toward it, seeing all kinds of mountains and trees appear as you approach. On that note, if we look at the images of Ceres from the past few months we see a similar progression.
Note the distances for each image. Its clear that Dawn has been slowing down, which it needs to in order to insert itself into orbit around such a small body (Ceres is about a quarter the diameter of the Moon). Compare those distances to the Hubble Space Telescope too. Hubble is about 1000 times further away for an image of comparable resolution. It shows how incredible Hubble is, but we also leave Hubble in orbit, so it can have a bit more power. It gives us an idea of how amazing JWST will be.
See you next week for the big orbit insertion of Dawn!