Constraining the source family of mission-targeted S-type Near-Earth Asteroids

Since 2000, numerous missions have been targeting near-earth asteroids, either by flyby or by orbiting, with a significant number scheduled over the coming years. Identifying the source families of these objects is essential to contextualize the scientific results of these missions.

This talk will focus on S-type objects only:

-  Eros (433), the first NEA visited by a probe, NASA's mission NEAR Shoemaker. It entered orbit in February 2000. 
- Toutatis (4179), visited in December 2012 by CNSA's Chang'e 2 probe.
- Didymos (65803), the target of NASA's DART mission and scheduled to be visited by ESA's HERA mission by the end of 2026.
- Torifume (98943), a high-speed flyby target for the extended mission of JAXA's Hayabusa2.
- Apophis (99942), a designated target of NASA's OSIRIS-APEX mission and ESA's proposed RAMSES mission.

This presentation proposes an approach that combines a mineralogical and an orbital dynamical modelling to constrain it.
Visible and near-infrared spectra are used to compare each asteroid's surface composition with H, L and LL chondrite meteorites. This comparison follows the methodology of Marsset et al. 2024 [1], applying a space-weathering correction using the de-reddening function from  Brunetto 2006 [2] and finding the best match through chi-squared minimisation.

For Didymos, we reduced and analysed mid-infrared spectrum obtained with JWST/MIRI (Cycle 1, Program 1245, PI: A. Thomas)  (Rivkin et al. 2023 [3]) and compared the asteroid's emissivity with laboratory reflectance spectra of meteorites with varying porosities (Vernazza et al. 2012 [4]). 

On the dynamical side, numerical tools from Brož (2024a [5]  ; 2024b [6]) are used.  They implement a forward dynamical model that simulates the long-term orbital evolution of source family asteroids. By comparing the current orbital parameters of the target asteroid with those of the modeled population, the probability of a family origin can be estimated.

By integrating both compositional and dynamical constraints, this approach aims to more accurately identify the likely source families of these mission targets.

 

References:

[1] M. Marsset, et al 2024, The Massalia asteroid family as the origin of ordinary L chondrites. Nature, 634(8034):561–565, 2024.

[2] R. Brunetto et al. 2006, Modeling asteroid surfaces from observations and irradiation experiments: The case of 832 Karin. Icarus, 184(2):327–337, 2006.

[3] A. S. Rivkin et al. 2023, Near to Mid-infrared Spectroscopy of (65803) Didymos as Observed by JWST: Characterization Observations Supporting the Double Asteroid Redirection Test. The Planetary Science Journal, 4(11):214, nov 2023.

[4] Vernazza et al. 2012 High surface porosity as the origin of emissivity features in asteroid spectra. Icarus 221(2):1162–1172, 2012.

[5] Brož et al. 2024a, Source regions of carbonaceous meteorites and near-Earth objects. A & A, 689:A183, 2024.

[6] Brož et al. 2024b,Young asteroid families as the primary source of meteorites. Nature, 634(8034):566–571, Oct 2024.