Abstract

A meteor cluster is the occurrence of many (from 3 to a few dozen) meteors within a very short time span (a few sec). They are extremely rare (8 ever observed) and tell us about the lifetime expectancy of pristine cometary grains in the Solar System, before enriching the Earth atmosphere with their own atomic composition.

The goal of the whole project is to estimate the frequency of meteor clusters thanks to data mining in meteor databases. The outcome of the study will be the detection (or absence of) new meteor clusters. The generalization to cometary grain physical lifetime expectancy will be derived and compared to today’s consensus. Any deviation will have consequences on our current view on the interplanetary population.

The goal of the workshop is to bring together experts in the domain of meteor observation, modelling, data reduction and database construction and exploitation. Many have built their own meteor camera network and associated data reduction pipeline and database. The idea is to dig in those data to detect other possible meteor clusters. Thorough statistical analysis, implying the development of new tools must be performed. Comparison with past detected clusters and validation is another crucial aspect.

Scientific rationale

Several outcomes from the search for new meteor clusters in databases can happen. First : no new cluster is detected. Second : a handful are detected. Third : many (>10 are detected). In all cases, this will set an upper limit to the occurrence of clusters, from the 8 already known. The scientific consequences deal with the formation and destruction of planetesimals, especially those loosely bound involved in the composition of the most pristine material known in the Solar system : the comets. If more clusters are detected, the size frequency distribution of the fragments will tell us about the formation of the grains. If no other cluster is detected, this will put boundaries on the frequency of self-disruption of the large grains in the interplanetary space. Indeed, a suspicion of such a mechanism, with a search for the physical origin (by the partners in CZ) was performed recently. In either case (new detection or not), publications will be produced in referee journals. The consequence for the meteor scientific community lies in the interpretation of the data : to which extent what we detect reflects reality ? For the planetary science community, the physical structure of the planetesimals has a great influence on our understanding of planetary formation. In addition, the current interplanetary environment estimated from the Zodiacal light observations and dust impacts on spacecraft will find a new understanding, leading scientists to consider self-fragmentation frequency to better design interplanetary probes. The very practical application deals with the amount of protection (and weight and therefore cost) to put on spacecraft.
For the team, the data sharing will strengthen the already ongoing collaboration. Such endeavor is a crucial step towards a larger scientific program. For example, in the past, such collaboration allowed us to strengthen our proposal for a double-airborne observation campaign (which represents a huge effort to put in place).
Data and code sharing are one aspect, and student exchanges, which already happened in the past (Vaubaillon et al., 2021) through the collaboration, is yet another positive outcome of the proposal. It is worth mentioning that the different teams have access to unique instruments, developed by their own team, unequaled in the whole scientific community.
Young researchers will have an experience of international team work. In addition, they will start networking, which is a crucial step towards finding a stable position. Postdocs will also strengthen their networking contacts thanks to physical meetings with top researchers in their domains

Workshop program

Monday 18th :

• morning : arrival of participants
• afternoon : short presentation from each partner : observation network, pipeline, database (public/private) ; past works : established clusters and first results found by A. Ashimbekova during her M2 internship on the topic with publicly available databases.
• presentation of databases data, formats and accessibility

Tue 19th :

• database exploration : how to access ? Which data are needed ? Discussion about uncertainties.
• creation of sub-database as a basis for following work

Wed 20th :

• exploration of cluster search algorithms based on past experience (e.g. DBSCAN, used by A. Ashimbekova) : performances, limits ; need for additional CPU ?
• create a fist set of potential clusters

Thu 21st :

• discussion and development of statistical methods to decide whether or not a potential is statistically significant, based on past work and experience of the participants (CZ team)

Friday 22nd :

• morning : conclusion, ideally outline of a future paper
• afternoon : participants departure