Asteroids and Meteorites from Venus? Only the Earth Goddess Knows
Abstract
No meteorites from Venus have been found; indeed, some find their existence unlikely because of the perceived difficulty of launching rocks at speeds above 10 km/s and traversing the planet's 93 bar atmosphere. [1] Nonetheless, we keep hope alive, since cosmochemists say they can identify Cytherean meteorites, should candidates be found[2]. Gladman et al. [3] modeled the exchange of impact ejecta betweenthe terrestrial planets, but did not consider meteorites launched from Venus in any detail. At the time of Gladman's work, no asteroids that remained entirely within Earth's orbit were known. 14 such Earth-interior objects with good orbits have now been discovered, and are known as Atiras, for the Pawnee goddess of the Earth. The largestknown member of the class is 163693 Atira, a binary whose components have diameters of approximately 4.8 and 1 km. Discovery of Atiras is very incomplete because they can only be seen at small solar elongations [4]. Greenstreet et al. [5] modeled the orbital distribution of Atiras from main-belt asteroidal and cometary source regions, while Ribeiro et al. [6] mapped the stability region of hypothetical Atiras and integrated the orbits of clones of 12 real Atiras for 1 million years. 97% of the clones survived for 1 Myr impact with Venus was the most common fate of those that met their ends. We have performed orbital integrations of 1000 clones of each of the known Atiras, and of hypothetical ejecta that escape Venus after asteroid impacts, for 10-100 Myr. The latter calculations use techniques like those of Alvarellos et al. [7] and Zahnle et al. [8] for transfer amongst Jupiter's galilean satellites. Our goals are to estimate the fraction of Atiras that are ejecta launched from Venus,the time spent in space by hypothetical meteorites from Venus, and therate at which such meteorites strike the Earth.[1] Gilmore M., et al (2017). Space Sci. Rev. 212, 1511. [2] JourdanF., Eroglu E. (2017). MAPS 52, 884. [3] Gladman B.J., etal. (1996). Science 271, 1387. [4] Masi G. (2003). Icarus 163,389. [5] Greenstreet S., Ngo H., Gladman B. (2012). Icarus 217,355. [6] Ribeiro A.O., et al. (2016). MNRAS 458, 4471. [7] Alvarellos,J.L., et al. (2008). Icarus 194, 636. [8] Zahnle, K., etal. (2008). Icarus 194, 660.
- Publication:
-
AAS/Division of Dynamical Astronomy Meeting
- Pub Date:
- April 2018
- Bibcode:
- 2018DDA....4910202D