Sunday, July 11, 2010

Rosetta spacecraft flies by asteroid Lutetia

The Rosetta spacecraft aquired several images of asteroid Lutetia. Rosetta is headed towards comet Churyumov-Gerasimenko, and will go into orbit about that comet in 2014. But this spacecraft also made a close pass at asteroid Lutetia while en route. Additional images are also posted at the European Space Agency's website. Lutetia might be a C type asteroid, ie a carbonaceous chondrite, which is a fairly common rocky asteroid that is also rich in organic molecules. Or else it is an M type asteroid, which is rich in metallic nickel-iron. M-types must have once resided deep inside the core of a much larger asteroid that likely fragmented early in the Solar System's history. These observations by Rosetta should resolve this asteroid's composition, and may provide clues about its origin.

5 comments:

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Anonymous said...

this is a very bizarre suggestion that has nothing to do with this news, I had a dream last night that an asteroid hitting the Earth, before it follows the rain meteors. during sleep i realised name of the astreroid.It was Proteus. Name that I have never heard of the asteroid, but i google later when I saw this name to the asteroid still exists. I'm not crazy. apologize for the comment. I had to tell somebodey

Anonymous said...

I have difficulty understanding why the impactors always seem to strike perpendicular to the surface, regardless of the orientation of the surface. Surely some impactors would come in at an angle that would leave an elongated crater, or maybe even bounce off, just leaving a trench or scrape. Also, if the surface is so thick with dust, does that mean there should be intact impactors buried deep, and if so, could they be detected by the on-board instruments?

Joe Hahn said...

Good question, and I'm not sure I know the answer. Impacts onto a small body will often be oblique, rather than purely vertical. But most of the craters seen here appear circular rather than elongated. I suspect that this is due to subsequent ageing of the crater. Impacts elsewhere should result in seismic shaking of the asteroid, which can cause landslides along craters rims, which may (I'm guessing) give the crater or more circular appearance.

And yes, this asteroid is clearly covered in a thick layer of dusty regolith. This is especially true for all the large craters, which are necessarily old (since big impacts occur less frequently), and are quite indistinct because they are blanked with regolith.

-JH

Anonymous said...

Thanks for that JH, but I'm not sure I can imagine a landslide in such low gravity.
You may not have an answer for this question either, I seem to have a lot of 'awkward' questions! I noticed the dense concentration of craters at the lunar south pole, and wondered why there would be more impacts at the poles?

http://yolearnchinese.com/wp-content/uploads/2008/12/change_moon_south_pole.jpg

The hexagonal craters are now thought to be due to acoustic fluidization. Would you concur?