Composition
Ida was classified as an S-type asteroid based on the similarity of its reflectance spectra with similar asteroids. S-types may share their composition with stony-iron or ordinary chondrite (OC) meteorites. The composition of the interior has not been directly analyzed, but is assumed to be similar to OC material based on observed surface color changes and Ida's bulk density of 2.27–3.10 g/cm3. OC meteorites contain varying amounts of the silicates olivine and pyroxene, iron, and feldspar. Olivine and pyroxene were detected on Ida by Galileo. The mineral content appears to be homogeneous throughout its extent. Galileo found minimal variations on the surface, and the asteroid's spin indicates a consistent density. Assuming that its composition is similar to OC meteorites, which range in density from 3.48 to 3.64 g/cm3, Ida would have a porosity of 11–42%.
Ida's interior probably contains some amount of impact-fractured rock, called megaregolith. The megaregolith layer of Ida extends between hundreds of meters below the surface to a few kilometers. Some rock in Ida's core may have been fractured below the large craters Mammoth, Lascaux, and Undara.
Read more about this topic: 243 Ida
Famous quotes containing the word composition:
“The composition of a tragedy requires testicles.”
—Voltaire [François Marie Arouet] (1694–1778)
“Give a scientist a problem and he will probably provide a solution; historians and sociologists, by contrast, can offer only opinions. Ask a dozen chemists the composition of an organic compound such as methane, and within a short time all twelve will have come up with the same solution of CH4. Ask, however, a dozen economists or sociologists to provide policies to reduce unemployment or the level of crime and twelve widely differing opinions are likely to be offered.”
—Derek Gjertsen, British scientist, author. Science and Philosophy: Past and Present, ch. 3, Penguin (1989)
“When I think of God, when I think of him as existent, and when I believe him to be existent, my idea of him neither increases nor diminishes. But as it is certain there is a great difference betwixt the simple conception of the existence of an object, and the belief of it, and as this difference lies not in the parts or composition of the idea which we conceive; it follows, that it must lie in the manner in which we conceive it.”
—David Hume (1711–1776)