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The Planetary Society BlogBy Emily LakdawallaHow does Lutetia compare to the other asteroids and comets visited by spacecraft?Jul. 15, 2010 | 14:33 PDT | 21:33 UTC
Almost a week after Rosetta flew past Lutetia, the asteroid is now a distant pinprick of light to the spacecraft, and the science team is getting down to the business of analyzing their data. To help them place things in context, I've prepared a new version of my "asteroids and comets to scale" image, laid out to be easy to drop into your slide presentation software of choice:
A word on the Lutetia image: I wanted to use one of the two highest-resolution views captured near closest approach, but both of those views were truncated at the edges because the spacecraft was so close to the asteroid; the asteroid grew too large to fit within OSIRIS' field of view. I used the next-to-last image in the series released by ESA, taken two minutes prior to closest approach, and borrowed a bit of the image taken about three minutes earlier to fill in the truncated bit. It's not a perfect reconstruction because Lutetia's motion past the asteroid made it appear to rotate between the two images; but it's close enough for this montage. I was aided in this endeavour by Daniel Muller, who was able to calculate range information for me for those four images. With that and OSIRIS' angular resolution of 18.6 microrad per pixel, I figured out the approximate pixel scale of the images (at the center of the visible disk). In case this information will be helpful to anybody else playing around with the photos, here it is:
When's the next time the montage will need to be updated? Not very long from now! On November 4, 2010, Deep Impact will fly past 103P/Hartley 2, and we'll have another comet nucleus to add to the lineup. It shouldn't affect the layout much, though, because Hartley 2 will be one of the smaller bodies visited by a spacecraft; its nucleus is estimated to be only a bit over a kilometer across, about the size of Dactyl. Next year, on February 14, Stardust will fly past Tempel 1 again, hopefully giving us a view of the comet nucleus with its new crater, but since Stardust's camera is not as good as Deep Impact's I think it's likely I'll choose not to update the photo. But next summer, about exactly a year from now, Dawn will arrive at Vesta, the asteroid belt's second-largest resident. And while Vesta is technically an asteroid, it won't make a whole heck of a lot of sense to include it with this montage. To get a sense of how Vesta compares to all the things that we've visited before, here is Vesta and the same montage as above, presented at the same scale of two kilometers per pixel:
Of course, Dawn's going to go on to visit Ceres in 2015...here's that one, again at 2 km/pixel...
They're just not in the same class, are they?
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Though I confess my first (rather tired at the end of a long day) thought on reading the title was "Golly! She's analysed those grooves, compared impact histories and surface compositions and worked out whether it's a rubble pile already?"
But why save those images as png? That seems a heavy choice. The larger one as a jpeg, 10/12 high quality (almost no visible difference) weighs only little above 3 MB.
creo que los resultados son buenos
http://estereocosas.webs.com/lutetia.htm
saludos.
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I got two of the images to form a stereo pair.
I think the results are good
greetings.
I'd read that Lutetia was the largest asteroid we've yet visited but I hadn't realised just *how* much larger than the others it was nor how tiny Itokawa is.
Thanks again, much appreciated.
- Messier Tidy Upper aka. StevoR
@Karl: No, there was no attempt to compare albedos; the original images are not calibrated properly for doing that. They're all stretched. And I think there's quite a lot of albedo variation among these bodies.
@Martin: cool!
[Sigh]. You know this is going to happen. Just wait a few more days until it hits Fox News.
Where i can find database of all registered asteroids? Thanks by aftermath!
It's so cool to see all of these images together in a single figure.
Gerhard: It was produced by Ted Stryk, who is one of the amazing amateurs who work on archived mission data, employing modern computing power and Photoshop techniques to old data. Do a Google search on "site:planetary.org stryk" and you'll see I feature his work often. Here's where I originally posted that one. http://www.planetary.org/blog/article/00001611/ He doesn't post all his stuff to any particular website, but some of it is at planetimages.blogspot.com.
Thank you.
Cheers,
Erik and the asteroid people at UCSC