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How do they know what's under the surface of these asteroids?

• DanBC 14y ago
  (http://curious.astro.cornell.edu/question.php?number=13 http://curious.astro.cornell.edu/question.php?number=13) I don't want to do a TL;DR because I'd mess it up.
  • paulhodge 14y ago
    TL;DR - Science!
• gliese1337 14y ago
  They assume that it's probably pretty similar to the surface, which is a good assumption as long as the asteroid hasn't undergone geological processes to cause differentiation. If it's spherical, it has enough to gravity to have made itself that way, and stuff probably melted and floated and sank and it's probably not the same on the inside as the outside. If it's not spherical, it's probably a pretty uniform blob of stuff all the way through. They know what's on the surface by looking at IR and radio spectra. This is complicated by overlapping spectra from different minerals, but you can still get a pretty good idea of what range of minerals are there. And since we know the elemental compositions of the minerals on Earth that produce the same spectra, we can use that to predict how much of any particular element the asteroid contains.
  • phreeza 14y ago
    In addition mass and therefor density are known so they can probably be used to cross verify this?