The 2011 Draconid meteor shower

On 8 October 2011, the Earth will cross a stream of dust particles that have been ejected from the comet 21/P Giacobini-Zinner more than a century ago.

The Draconid meteor shower will start around 16:00 UT on Saturday, October 8th, and will last for approximately 6 hours. Maximum flux is expected around 19:55 UT, with a minor peak occuring earlier at around 17:30 UT (Fig. 1). The relative speed of the incoming meteoroids will be 20 km/s, relatively low when compared to other meteor showers (e.g. Leonids and Perseids with 71 and 59 km/s, respectively).

Predicted 1-mm meteoroid flux during the Draconid outburst on 8 October 2011
Fig. 1: Predicted 1-mm meteoroid flux during the Draconid outburst on 8 October 2011. Source: "The 2011 Meteor Shower Activity Forecast for Earth Orbit", Cooke & Moser (2010)
As a result of the Draconid meteoroid stream, the risk of spacecraft surfaces to be hit by sub-mm to millimetre-sized particles will increase considerably (a few tens or hundred times) over the normal background of sporadic meteoroids for a period of a few hours. In addition to the mechanical/structural damage, a hypervelocity impact of a microparticle on a spacecraft can cause electrical interference and is thought to trigger electrostatic discharges via the plasma cloud that is generated upon impact.

The prediction of periods of increased meteoroid fluxes is one the services that will be provided to spacecraft operators in the framework of the planned European Space Situational Awareness (SSA) programme. Warnings/alerts will inform about the enhanced impact risk and allow operators to take precautionary measures, e.g. by re-orienting solar arrays or shutting down high-power electrical subsystems.

On the ground, the 2011 Draconid meteor shower promises a be good show, though slightly spoilt by the near full moon. Zenith hourly rates between 500 and 750 have been predicted. Observers are advised to keep a long wish list ready...
A Perseid meteor recorded with ESA/RSSD's meteor camera system.
Fig. 2: A Perseid meteor recorded with ESA/RSSD's meteor camera system on 11 August 1997. Courtesy of D. Koschny (ESA/ESTEC).

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