Well, that was FAST! It can take months (or longer) to get an asteroid name approved via the process at the IAU – this one however, happened in less than a month!
NASA wowed the world on Nov. 2nd with image from the flyby of asteroid (152830) Dinkinesh, revealing that it has a companion! NASA wowed the world again on Nov. 7th with an image of the companion from a different angle showing it to be a contact-binary asteroid!
I was surprised to see a citation for this companion asteroid in the latest IAU WGSBN Bulletin – which hit my inbox on Nov. 27th:
(152830) Dinkinesh I = Selam
Discovery: 2023-11-01 / NASA / Lucy mission
Selam is the name given to the fossil remains of a 3-year old Australopithecus afarensis female, the same species as the Lucy fossil. It was found in Dikika, Ethiopia, in 2000 by paleoanthropologist Zeresenay Alemseged. The name is an Ethiopian word meaning ‘peace’ and was suggested for Dinkinesh’s satellite by Swiss planetary scientist Raphael Marschall.
The “Discovery” line was actually missing from the citation – which I can’t recall having seen before.
Dr. Raphael Marschall
Dr. Raphael Marschall is a planetary physicist working as a post-doctoral researcher at the Laboratoire J.-L. Lagrange of the Observatoire de la Côte d’Azur in Nice (France). He has previously worked at the Southwest Research Institute in Boulder, and the International Space Science Institute (ISSI) in Bern, Switzerland after completing his PhD at the University of Bern in the Planetary Imaging Group.
Raphael’s primary scientific interest is in small bodies of our Solar System. He also focuses on understanding how planetesimals form in the early protoplanetary disk.
Raphael is a collaborator on NASA’s Lucy mission. Roughly one and a half years ago, he did a set of calculations to look for additional asteroid observation opportunities for Lucy during its cruise. He found that Dinkinesh came within roughly 65,000 km of Lucy (15% of the Earth-Moon distance). This is, of course, very close in an astronomical sense. NASA and the mission decided to slightly alter the trajectory of Lucy and add this encounter – ultimately at a closest approach of only 430 km! The name Dinkinesh was given to the asteroid after it was assigned as a target.
Once the Lucy team saw the data, and realized that there was a satellite, the question of naming came up. The team was looking for something that matched the theme of the mission, and that of Dinkinesh – being the name of the Lucy fossil found in Ethiopia. After some searching, Raphael found that there was a fossil of a 3-year old child of the same species as Lucy; this fossil had been given the name “Selam,” and was also referred to as the “Lucy baby.” (The latter nickname is somewhat misleading, as Selam actually lived more than 100,000 years before Lucy.) There were a few other names that Raphael considered, but none had such a nice story as Selam, and so in the end it was quite an easy choice.
NASA’s Lucy Mission
NASA’s Lucy mission will explore a record-breaking number of asteroids, flying by three asteroids in the solar system’s main asteroid belt, and by eight Trojan asteroids that share an orbit around the Sun with Jupiter.
Lucy on NASA’s Eyes on the Solar System Web App
Asteroid Dinkinesh Citation
Discovered 1999-Nov-04 by LINEAR at Socorro
Dinkinesh is an Ethiopian appellation for the Australopithecus afarensis skeleton AL 288-1, also known as “Lucy”, that was discovered in 1974 at Hadar, in the Awash Valley of Ethiopia. The nickname means “you are marvelous”.
NOTE: An entry for asteroid Selam does not appear in the JPL Small Body Database, at the time of this writing.
Cover image: Binary asteroid companion Dinkinesh I, “Selam” enhanced in Paint.Net by Bob Trembley. Original image credit: NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab.