E-type (enstatite achondrite–type) asteroids are thought to have enstatite (MgSiO3) achondrite surfaces. They form a large proportion of asteroids inward of the asteroid belt known as Hungaria asteroids,
Description
E-type asteroids have a high
albedo (0.3 or higher), which distinguishes them from the more common
M-type asteroid . Their spectrum is featureless flat to reddish. Probably because they originated from the edge of a larger parent body rather than a core, E-types are all small, with only three (44 Nysa, 55 Pandora, 64 Angelina) having diameters above 50 kilometres and no others above 25 kilometers (the biggest three also orbit atypically far, c. 3 AU, from the Sun).
(enstatite achondrite meteorites) are believed to come from E-type asteroids,
because Aubrites could be linked to the E-type asteroid 3103 Eger.
This grouping may be related to the X-type asteroid of the SMASS classification.
E-Belt
The E-type asteroids of the Hungaria family are thought to be the remains of the hypothetical
E-belt asteroids.
[ Late, Late Heavy Bombardment - Bill Bottke (SETI Talks) – Youtube.com] The dispersal of most of that hypothetical E-Belt might have been caused by the outward migration of the
of the
Solar System according to simulations done under the
Nice model – and these dispersed E-Belt asteroids might in turn have been the impactors of the Late Heavy Bombardment.
Exploration
On September 5, 2008, ESA's robotic spaceprobe Rosetta visited the E-type asteroid 2867 Šteins.
[ H. U. Keller, et al. - E-Type Asteroid (2867) Steins as Imaged by OSIRIS on Board Rosetta - Science 8 January 2010: Vol. 327. no. 5962, pp. 190 - 193 ] Spectral data from the spacecraft confirmed the asteroid was composed mainly of iron-poor minerals such as
enstatite (magnesium-rich pyroxene),
forsterite (magnesium-rich olivine) and
feldspar.
See also
