IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021B027 PROGRAM_TITLE Finding and characterizing asteroids related to the most primitive carbonaceous chondrites II PROGRAM_INV1 Margaret McAdam PROGRAM_INV2 Cristina Thomas PROGRAM_INV3 Annika Gustafsson PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG We propose a continuation of a pilot study to identify and characterize asteroids related to the most primitive carbonaceous chondrite meteorites. Primitive carbonaceous chondrites are characterized [among other indicators] by large abundances of amorphous iron-bearing silicates. These amorphous materials are spectrally active in the near-infrared, exhibiting at 1.4-um feature with 3-7% depth. This feature has been observed on asteroid [93] Minerva previously. Primitive meteorites are found in multiple groups of meteorites indicating they likely originate from multiple parent asteroids or classes of asteroids. We propose to search for additional asteroids that may be related to these primitive meteorites by obtaining rotationally resolved spectroscopy of two groups of asteroids: those with data in the PDS-SBN with a similar near-infrared spectrum to Minerva [determined by visual comparison] and members of the inner main belt primordial family [Delbo et al., 2017, Science 357, 1026]. One key question about primitive meteorites is how they are preserved on asteroids since the primitive materials [amorphous phases and others like presolar grains] are easily destroyed through parent body processing. Using rotationally resolved spectroscopy, we can determine if the candidate asteroids have the 1.4-um feature characteristic of amorphous materials and whether it appears over the whole surface or only in localized regions. If a heterogeneous surface is identified this may indicate an 'outer shell' model in which the asteroid preserves primitive materials in a thin shell of material while the interior experiences processing. If the asteroids have a homogeneous composition, this would indicate a late accretion scenario. Here the asteroid likely accreted after the peak heat flux from short-lived radioactive nuclei thus not experiencing processing at all. Using the IRTF+SpeX in prism mode, we can identify, characterize, and place constraints on the composition, timing and potentially the geophysics of primitive asteroids. PROGRAM_ABSTRACT_END