In-situ detection of cometary dust

Astronomy Unit Seminars
Dr Simon Green (Open U.)
Iwan Williams
December 5th, 2014 at 14:30
GO Jones Room 610

Cometary dust is the solid component of comets, released by sublimation of volatiles and accelerated by gas drag to form the dust coma. Its subsequent dynamics are controlled by gravity and solar radiation pressure and it represents the dominant source of the interplanetary dust complex. Broad indications of the sizes and composition of cometary dust can be inferred from remote sensing of large-scale coma and dust tail properties, and IDPs (Interplanetary Dust Particles) collected from the stratosphere are ascribed a cometary origin. Greater insight into inner coma processes, ejection mechanisms from the nucleus and the role of dust in cometary evolution, can only be gained from in-situ measurements. Flyby missions have so far provided only brief snapshots of inner coma properties, but have still revealed remarkable variations in spatial density that have been controversially interpreted as the result of dust fragmentation on a range of scales. Samples of dust returned to Earth by the Stardust mission have shown unexpected compositions indicative of widespread early mixing of solar system material. I will review our current understanding of cometary dust comae through recent mission results and present the first results from Rosetta, which, for the first time, is providing long-term monitoring of cometary activity.