Thermal infrared (8-13 μm) spectra of 29 asteroids: The Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) survey

Lucy F. Lim, Timothy H. McConnochie, James F. Bell, Thomas L. Hayward

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


We report the results of the Cornell Mid-IR Asteroid Spectroscopy (MIDAS) survey, a program of ground-based observations designed to characterize the 8-13 μm spectral properties of a statistically significant sample of asteroids from a wide variety of visible to near-IR spectral classes. MIDAS is conducted at Palomar Observatory using the Spectrocam-10 (SC-10) spectrograph on the 200-in Hale telescope. We have measured the mid-infrared spectra of twenty-nine asteroids and have derived temperature estimates from our data that are largely consistent with the predictions of the standard thermal model. We have also generated relative emissivity spectra for the target asteroids. On only one asteroid, 1 Ceres, have we found emissivity features with spectral contrast greater than 5%. Our spectrum of 4 Vesta suggests emissivity variation at the 2-3% level. Published spectra of several of the small number of asteroids observed with ISO (six of which are also included in our survey), which appeared to exhibit much stronger emissivity features, are difficult to reconcile with our measurements. Laboratory work on mineral and meteorite samples has shown that the contrast of mid-IR spectral features is greatly reduced at fine grain sizes. Moreover, the NEAR mission found that 433 Eros is covered by a relatively thick fine-grained regolith. If small bodies in general possess such regoliths, their mid-IR spectral features may be quite subtle. This may explain the evident absence of strong emissivity variation in the majority of the MIDAS spectra.

Original languageEnglish (US)
Pages (from-to)385-408
Number of pages24
Issue number2
StatePublished - Feb 2005
Externally publishedYes


  • Asteroids, Ceres
  • Asteroids, Vesta
  • Asteroids, surfaces
  • Infrared observations
  • Spectroscopy

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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