Rosetta flyby of Asteroid Lutetia Options

[Stu]

I don't believe it is. IIRC, Lutetia is expected to be mostly just black-and-white.

I just said that.



The posts are both marked 12:30, so your post was probably posted while Hungry was typing.

[Hungry4info]

Haha yep

[Phil Stooke]

A composite of the last two approach images, the 'Saturn' image and the first of the high resolution set (thank you ESA and the OSIRIS team!)

It reveals an interesting fact... the last (top) image can only be made to match the others if it is flipped left to right - NOT a 180 rotation but a flip. One sequence or the other is reversed. I don't know which. I have these arranged north-up, assuming the approach images are not flipped. If they were flipped these are all south-up. The landslide crater is visible as a bright patch in the last few approach images and the Saturn image.

Phil

[ugordan]

It reveals an interesting fact... the last (top) image can only be made to match the others if it is flipped left to right - NOT a 180 rotation but a flip.

I don't understand why they don't take care of this automatically in their calibration pipeline. It's not the first time this happened, either - recall the Earth flyby image with Australia mirrored left-right.

[cotopaxi]

I admit this is kind of a lame excuse, but the reason is most likely that the spacecraft was flipped 4 hours before closest approach (between the relevant images if I understand Phil correctly) and some of the early release images are taken from early processing levels. Normally those are then rotated and flipped "manually". Apparently we forgot that here......

[ElkGroveDan]

The similarities with Phobos are striking, the photos clearly show two families of roughly parallel grooves, in two different planes. But the grooves seem to have been obliterated over most of the surface by later big impacts.

Not just impacts, but massive impacts creating craters a significant portion of the diameter(s) of the objects. In both cases, the largest impacts probably approach the threshold for completely breaking up their respective bodies. It would make sense to suppose the massive impacts are somehow related to the grooves.

Why are Phobos' so much more apparent?

It's a matter of perspective. Because Phobos is so much smaller, you have to get a lot closer relatively to see the grooves. It's why the hairs on a flea seem more defined than the hairs on a rabbit.

[helvick]

Lutetia's grooves certainly make it more likely that such features have an origin that does not rely on interactions with a planet, either from ring impacts or debris from large impacts on the surface of the planet. That's not to say they rule it out completely but I'm a lot less convinced about them now that we have evidence of very similar features on a body that almost certainly has never been near a planet. Shock effects from impacts, or (far less likely I think) tidal effects from passing near other bodies, seems much more likely now. The similarity with Phobos is quite spooky too.

I'm sure there will be many other interesting findings from this flyby but it's fantastic to see data come back immediately that should help develop better ideas about a really intriguing structural feature on small bodies that seems to be common and not understood.

[Stu]

http://webservices.esa.int/blog/post/5/1248

[kenny]

Very nice indeed... poetically rhythmic in measured time, even with the absence of normal rhyme.

[Hungry4info]

I found a couple craters that seemed a bit strange. They have what look like crevaces jutting out of them.

These are the only two craters I've identified with this feature. Anyone have any idea as to what caused this?

Attached thumbnail(s)

 

[Phil Stooke]

Emily mentioned these squiggly features in her blog. I think they are secondary craters from a fresh impact outside the image. Yes, I think you can have secondaries on Lutetia.

Phil

[Guest_cassioli_*]

I found a couple craters that seemed a bit strange. They have what look like crevaces jutting out of them.

These are the only two craters I've identified with this feature. Anyone have any idea as to what caused this?

I noticed them at a first glance.
Just rolling stones, I suppose. Not FROM but TOWARD the craters.

[AndyG]

Yes, I think you can have secondaries on Lutetia.

Naturally these secondaries would have to have impact velocities less than Lutetia's escape velocity of ~80 m/s.

That's very low. Most (?) rocky impactors would survive the event. If any were visible in a crater for a mass estimate, then it might be possible to come to some estimates with regards to the surface's strength and structure.

Job for Dawn at Ceres and Vesta?

Andy

[tanjent]

"Just rolling stones, I suppose. Not FROM but TOWARD the craters."

I like this idea, but then where are the stones? If they had rolled away again, they should've left tracks in that direction too.

[Guest_cassioli_*]

no new images yet?

"Just rolling stones, I suppose. Not FROM but TOWARD the craters."

I like this idea, but then where are the stones?

nice question.
buried?

Once again I have to say they look like the tracks of intersection with rings

Some grooves are perpendicular to others...