Saturday, 15 June 2013

Fireball seen over Eastern Australia, 13 June 2013 6:05 pm AEST, was NOT the decay of Molniya 3-53

On June 13, 2013, near 6:05 pm local time (AEST - corresponding to 10:05 UTC), many people in Eastern Australia observed a bright fast light falling down in the sky. It was even recorded by one of those new-fangled dashboard-cams (one of these days, I must get me one for my bike).

The Australian news website "The Chronicle" claims it was a satellite decay - more exactly, that of the Russian Molniya platform Molniya 3-53 (2003-029A).

It was however most definitely not a satellite decay.

All descriptions talk about a fast object. The dashcam video shows a pretty fast fireball indeed.

It is much too fast to be a decaying satellite. The latter move at relatively slow speeds - 8.5 km/s. At that speed, it takes them several minutes to traverse your sky, not just a few seconds. As low over the horizon as the dashcam video shows it, it would have been very, very slow, taking several tens of seconds to traverse the distance it does in the video.

In addition to it being too fast to be a satellite decay, the proposed connection to Molniya 3-53 can be rejected right away.

First: Molniya 3-53 did not decay on June 13. Orbital data by Strategic Space Command ("NORAD") show it was still in orbit in the early hours of June 15 - two days after the Australian fireball. At the moment of writing (12 UTC, June 15), the last available orbit is for epoch 13166.42726929 ( = 15 June 2013, 10:15 UTC). The moment of decay is currently predicted as 15 June 14:04 UTC, with an uncertainty of 2 hours. [Update 22/6: SSC's final TIP-message issued 15 June 15:30 UTC gives 15 June, 14:10 UTC +/- 26 minutes for the moment of decay)

Now, given that the apogee of the satellite was at a very low altitude already, could it have been the case that it briefly started to burn but survived after it passed perigee?

The answer is "no" in this case and brings us to a second point against the identification with this satellite: Molniya 3-53 was not over Australia at June 13, 10:05 UTC. It was at very high altitude over Northern Europe at that time (see map below). It would not pass over (central) Australia untill 10:55 UTC (6:55 pm AEST), i.e. a full hour later than the fireball sighting.

So what was it then? Given the speed, it is very clear this was a meteoric fireball, a small piece of cosmic rock or ice (debris from a comet or an asteroid) entering the atmosphere.

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