I know, I know, it looks mainly like they just unfocused the image. It turns out that many of the images in the "after" sequence have a crappy focus, but there are enough of them here to prove that it really happened.
NASA's Stardust spacecraft returned new images of a comet showing a scar resulting from the 2005 Deep Impact mission. The images also showed the comet has a fragile and weak nucleus.
The spacecraft made its closest approach to comet Tempel 1 on Monday, Feb. 14, at 8:40 p.m. PST (11:40 p.m. EST) at a distance of approximately 178 kilometers (111 miles). Stardust took 72 high-resolution images of the comet. It also accumulated 468 kilobytes of data about the dust in its coma, the cloud that is a comet's atmosphere. The craft is on its second mission of exploration called Stardust-NExT, having completed its prime mission collecting cometary particles and returning them to Earth in 2006.
The Stardust-NExT mission met its goals, which included observing surface features that changed in areas previously seen during the 2005 Deep Impact mission; imaging new terrain; and viewing the crater generated when the 2005 mission propelled an impactor at the comet.
"This mission is 100 percent successful," said Joe Veverka, Stardust-NExT principal investigator of Cornell University, Ithaca, N.Y. "We saw a lot of new things that we didn't expect, and we'll be working hard to figure out what Tempel 1 is trying to tell us."
Read the rest here.
I don't think it's a lack of focus in the later images, as much as the fact that the images were taken from much farther away, and hence have lower resolution when magnified to match the scale i
of the previous image.
Yeah! This is why I don't mind paying taxes. Now we know more about asteroids and when one comes near, how to deal with it.
John, yes, that is exactly what it is. I was using the term "focus" in what must be an incorrect technical sense. The images are blurry because of relative lack of resolution. But nicely focused blurryness.
Actually, it's amazing that Stardust is able to take these pictures at all. It was launched in 1999, so it's way past its warranty (and incidentally, there's a stuck filter wheel on that camera that it has to contend with, reducing resolution further) but it's not even 1999 tech. The camera is a spare from the freakin' Voyager program! (They did rip out the old vidicon tube and replace it with something a tad more modern, though, and also added shielding specifically to the camera since it wouldn't be protected by the spacecraft's main Whipple shields.)
Stardust was one of the triumphs of the "faster, better, cheaper" movement within NASA, and this awesome encounter was icing on the cake. It's simply spectacular.
BTW, part of the reason it looks softer in places in the Stardust images isn't just down to resolution -- some of it is changes in the actual asteroid! A crater chain in another part of the asteroid has slumped into sort of an ellipse-shaped depression, for instance. Most of it's the fact that Stardust's camera just isn't as good, though. (Also, Deep Impact was a heck of a lot closer; that left image was taken by the impactor, not the mothership, while on its suicide dive.)