Bennu's Natural Sample Delivery Mechanism: Estimating the Flux of Bennuid Meteors at Earth

Abstract

NASA's OSIRIS-REx asteroid sample return mission observed coin-sized rock fragments launching from the surface of the near-Earth asteroid Bennu. Although many of these particles fall back down to the surface of Bennu, about 30% escape the gravitational influence of this small celestial body and enter orbits around the Sun. By simulating the motion of small particles ejected from Bennu over the years 1780-2200, we test whether they eventually encounter Earth's atmosphere. The predicted particle flux ranges from undetectable to E 1 meteor per 10 h, a rate which is comparable with the weakest known meteor showers. We find that ejected particles spread out along Bennu's orbit and occupy positions around the entire circle within 80 years. For the 420 years simulated, the particles can be easily associated with Bennu by the similarities in their orbits. Particles we simulated being ejected from Bennu are not found to impact Earth until 2101. We predict a maximum flux in the year 2182, with around 161 intersecting meteors potentially visible as shooting stars. Our methods can be used to investigate the possibility of meteoroid streams from other near-Earth asteroids to identify sources of known meteoroid streams and meteor showers. MELIKYAN ET AL.

An observing campaign to search for meteoroids of Bennu at Earth

“…Given the now more reliable estimates of the present asteroid's particle production rate of ~8 × 10 − 8 kg/s by Hergenrother et al (2020) and Melikyan et al (2021), the past activity of Bennu would need to have been 7 orders of magnitude higher to have been detected by the current video camera network, with Ye's initial estimate of 0.15 kg/s providing a 1.5 kg/s upper limit to the asteroid's particle production rate during 1500-1800 CE.…”

“…More recent estimates of flux density by Melikyan et al (2021) put the anticipated rates orders of magnitude lower. Melikyan et al integrated 1.8 million particles during the years 1780-2135 when the orbit of Bennu is precisely known, and took into account that, unlike cometary ejection, particles are produced along the entire orbit of the asteroid (Hergenrother et al, 2020).…”

Dynamical study of Geminid formation assuming a rotational instability scenario

“…Therefore, even if the simulation particle does not directly contact Earth, if its MOID is small enough, then there will be a corresponding dust particle in reality that collides with Earth. Similar approaches to identify interactions between Earth and meteors have been used in studies such as Melikyan et al (2021) and Ryabova (2021). We set two MOID criteria, namely, Earth's radius (∼4.26 × 10 −5 au) and the semi-major axis of the lunar orbit (∼2.57 × 10 −3 au), because the meteor observations have been conducted either from Earth's surface or the lunar orbit.…”