Meteoroids and meteors
Meteors are caused by the entry of meteoroids (rocks in the Solar System) into a planetary atmosphere. On Earth, they last on average 0.3 s. They are today the most efficient way to exchane matter in the Solar System. Meteoroids are ejected from comets (by outgasing process) or from asteroids (by collisions). As such, they can teach us a lot about the composition and history of the Solar System. However they are extremly hard to detect, because they are too small to be directly detected in a telescope, and too large to efficiently diffuse the Sun light. Infra-Red observations have revealed dense meteoroid stream before they collide with planets.
The work at Pegase is dedicated to understanding their origin and role in our planetary system. For this, unprecedent work on dynamics of meteoroid streams and observation tool development are currently going on.
Dynamics of meteoroid streams in the Solar System
To perform the prediction of meteor showers on Earth has haunted researchers since the public failure to predict the 1899 and 1998 Leonids. Since then, McNaught & Asher (1999) have pointed out the necessity to consider meteoroids on individual orbits, independent from the parent comet. We have taken one step forward by examining how the outgasing of the comet can tell us about the amount of meteoroids that will hit our planet (Vaubaillon et al. 2005). For this, heavy parallel numerical simulations are daily run on supercomputer at CINES. The prediction of meteor shower is now a regular task and is useful for science purpose (plan observation with regular or exceptional means, confront the predictions and the observations) as well as for space agencies (CNES, NASA, ESA) e.g. in order to protect artificial satellites.
Moreover, dynamical studies involve the role of non-gravitational forces is primordial for such tiny particles. Group behaviour can be described and studied. The role of planets (e.g. Jupiter) or the fragmentation or even explosion-like behaviour of comets can be established in order to explain past showers. Life time expectancy can be derived from "long term" studies (in the case of meteoroids, 50kyrs is already a long time, because of frequent close encounters with planets and Poynting-Robertson drag). The age of the stream can be derived thanks to the duration of a shower. The demonstration of the presence of three body resonance was performed for meteoroid streams. The definite proof that meteoroids might self-fragment in space was provided. Lost parent bodies can be recovered. Actually, out of more than 700 showers, only a few dozen have known parent bodies today. Our work deals with finding new methods to unveil new parents and understand the Earth meteoroid environment.
Meteoroids are actually not much different from small asteroids (the boundary is hard to define...), and we have participated to a study examining the ocurrence of Earth mini-moons by capture of small asteroids.
Meteor shower are not limited to the Earth. Any planet having an atmosphere with have meteors. This is of special interest for Mars or Venus, around which spacecraft might detect meteor showers. On Mars, the tiny atmosphere can hardly prevent even rather small asteroids (or let say large meteoroids) from hitting the ground. The InSight space mission aims to put seismometers on the Martian surface to study the interior of the planet. Planetary bodies without atmosphere reveal meteoroids thanks to flashes.
However, all these theoretical works need to be confronted to observation, which sometimes demends exceptional means.
Development of Observations tools
Meteor observation networks
The observation of meteoroids through e.g. meteor showers, with professional means was completely inexistant until 2010. The CAmera for BEtter Resolution NETwork (CABERNET) project aimed at measuring the most accurate meteroid orbit, in order to unveil their origin. For this, we developed the most accurate meteor camera, in terms of space and time reslution. A 40x27 deg^2 camera was developed, that provides us with a ~6 arcsec and 100Hz space-time accuracy. Today the only competing device is the Canadian CAMO system. Auriane Egal demonstrated the limits of today methods of trajectory and orbit computation, and proposed a new way to achieve a better reduction of any meteor observation.
The Fireball Recovery and InterPlanetary Observation Network (FRIPON) project was funded by ANR (2014-2017) to cover metropolitan France with 100 allsky cameras. The scientific goal is exactly orthogonal to CABERNET: to observe all fireball falling in France, and recover the associated meteorite. For this, Pegase people are currently in charge of the pipeline reduction to compute the trajectory and orbit, taking benefit from A. Egal's work on CABERNET. This project is on-going.
Unusual observation means
What is best to understand a phenomenon than to have it in a laboratory? With the university of Stuttgart (IRS), artificial meteor disintegration were performed.
After performing the prediction of the 2011 Draconids we realized this event would be exceptional, as it would not occur in the coming 50 years, and the last time it did was in 1946. For thus applied to use the INSU/MeteoFrance/CNES Falcon 20 research aircraft, and gathered an international team of meteor researchers to perform double station observations, thanks to a similar Falcon 20 (DLR). The shower appeared at the predicted time. This was the first time a double station meteor orbit was measured, and the first European airborne campaign to observe the meteors.
The 2008 Quadrantids airborne campaign (organized by P. Jenniskens, NASA) allowed us to observe this shower for a few hours, whereas it is visible for up to an hour at best.
The 2008-ATV reentry campaign (organized by ESAS and NASA) allowed us to be best positioned to observe the first European space cargo reenter the Earth. Our experience with meteor observation was precious to perform the task.
The 2007 Aurigids meteor airborne observation campaign was the first organized to witness the return of a meteoroid stream ejected by a long period comet.
The 2004 Genesis reentry campaign (organized by P. Jenniskens, NASA) was our first airborne observation campaign of an artificial meteor.
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Last update Wednesday 15 November 2017