Speaker
Description
Telescopic characterisation of asteroids and the study of meteorite geochemistry in the lab are fundamentally linked: they study the same objects. However the two disciplines have been mostly disjointed so far, if we exclude the handful of asteroid sample return missions. If we can detect and characterise an asteroid while it is in space, and recover meteoritic samples of it after it impacts, we can close this loop unambiguously.
Set to begin science observations in 2025, the Vera Rubin observatory with its 10-year Legacy Survey of Space and Time (LSST) is going to revolutionise many fields of astronomy. While increasing the number of known asteroids by nearly an order of magnitude, it will also detect 1-10 small asteroids just before they impact the Earth. The current generation of telescopes has so far detected 11 asteroids before impact, including 4 that have subsequently been observed as fireballs and for which meteorites have been recovered. This is just a taste of what is to come with LSST, starting end-2025.
Closing the astronomy/geology loop with impacting asteroids is not without challenges. With an imminent impactor typically detected only hours before impact, this leaves little time to bring to bear more specialised instruments than those that provide astrometry and photometry. Ideally spectroscopy and radar techniques will be required for adequate in-space characterisation. Spectroscopy has only been achieved once so far (2008 TC3), and spectro-photometry also once (2022 WJ1). For LSST targets, the facilities delivering these observations have to ideally be located in the Southern Hemisphere.
Unlike a typical meteor, a metre-size asteroid impacting our atmosphere creates a fireball that outshines the full moon, visible night or day. Imminent impactors are set to become focus events for the Planetary Defence community to communicate to the wider public, enabling large numbers of people, including residents of light polluted cities, to witness the spectacle.