Advances in determining asteroid chemistries and mineralogies

Abstract

Considerable progress has been made in the last few years in determining asteroid chemistries and mineralogies. Dedicated spacecraft missions have allowed mineralogical predictions based on ground-based data to be confirmed or refuted. These missions include NEAR-Shoemaker to (253) Mathilde and (433) Eros, Hayabusa to (25143) Itokawa, and Dawn to (4) Vesta and (1) Ceres, the upcoming Hayabusa2 to (162173) Ryugu, and the upcoming OSIRIS-Rex to (101955) Bennu. All of these missions have or will make significant advances that could not have been made through just Earth-based observations. The recovery of Almahata Sitta from 2008 TC 3 was a rare opportunity to recover meteorite samples from a spectrally observed body from a naturally occurring event. This review will discuss the importance of spacecraft missions to asteroids.

Visible-infrared spectroscopy of ungrouped and rare meteorites brings further constraints on meteorite-asteroid connections

“…Those missions have so far visited only a dozen asteroids: (1) Ceres and (4) Vesta (Dawn, Krohn et al, 2018), (253) Mathilde and ( 433) Eros (NEAR Shoemaker, Prockter et al, 2002), (243) Ida and ( 951) Gaspra (Galileo, Johnson et al, 1992), (21) Lutetia and (2867) Steins (Rosetta, Glassmeier et al, 2007), ( 4179) Toutatis (Chang'e 2, Huang et al, 2013), ( 5535) Annefrank (Stardust, Duxbury et al, 2004), ( 9969) Braille (Deep Space 1, Buratti et al, 2004), ( 25143) Itokawa (Hayabusa, Tsuda et al, 2013) and ( 486958) Arrokoth (New Horizons, Young et al, 2008). During these missions, detailed elemental composition has only been obtained for a few of these bodies ((1) Ceres, (4) Vesta, (433) Eros, (25143) Itokawa) (Burbine, 2016). A third approach to study small bodies is through sample return missions.…”

“…Although the spectral properties of the main meteorite groups have been studied in details (e.g. Burbine et al, 2002;Beck et al, 2013;Burbine 2016;Vernazza et al, 2017;Takir et al, 2019;Eschrig et al, 2020), the spectral properties of the ungrouped chondrites have received much less attention, even though they represent a large fraction of the diversity of the meteoritic material available for study. In addition, only a few studies have focused on connecting ungrouped chondrites to asteroids.…”

Vesta and Ceres

“…Detailed reviews concerning the compositional interpretation of asteroid taxonomic types and their distribution across the Main Belt can be found in Burbine (2014Burbine ( , 2016, DeMeo et al (2015), Reddy et al (2015), Vernazza et al (2015b), , and Greenwood et al (2020) and will not be repeated with the same level of detail in this chapter. Rather, we put the emphasis on the currently proposed connections between the various compositional classes present among the largest Main Belt asteroids and the two main classes of extra-terrestrial materials, namely meteorites and interplanetary dust particles (hereafter IDPs).…”

“…Their spectral properties have been measured in laboratories over an extended wavelength range (from the visible to the mid-infrared; e.g. Gaffey, 1976;Cloutis et al, 2010Cloutis et al, , 2011Cloutis et al, , 2012Cloutis et al, , 2013Beck et al, 2014) and used for direct comparison with those acquired for asteroids via telescopic observations (see Burbine, 2014Burbine, , 2016DeMeo et al, 2015;Reddy et al, 2015;Vernazza & Beck, 2017, and references therein). Because most minerals present in meteorites possess diagnostic features either in the near-or mid-infrared and because quality measurements in these ranges became available for a large number of asteroids in the late 1990s, we can say that the Golden Age of asteroid compositional studies really started toward the end of the second millennium.…”

Exploring the Bimodal Solar System via Sample Return from the Main Asteroid Belt: The Case for Revisiting Ceres

“…Isotopic measurements of presolar grains of one micron or smaller can routinely be made in the laboratory (e.g., Davis 2011). Only bulk elemental compositions and estimated silicate mineralogies have currently been determined remotely for main-belt asteroids using spacecrafts (Burbine 2016). The use of well-calibrated standards allows a wide range of high-precision measurements to be obtained in the laboratory that are simply impossible using spacecraft-based techniques.…”