Friday, 12 February 2010

Mexican "impact" / fireball event is NOT due to Kosmos 2421 debris

News is doing the rounds of a spectacular fireball/sonic boom near Mexico city on 10 Feb, 18:30 local time (= 11 Feb, 00:30 UTC).

Initial reports talked about an actual impact with a 30 meter wide crater and damage to a bridge and road. That seems not to be the case.

Subsequent news releases suggested that it was a piece of Komsos 2421 debris impacting (06-026 HK, #33006).

For a summary, see Phil Plait's Bad Astronomy blog post here.

However, this event was certainly NOT due to the mentioned piece of space debris. The object in question was, contrary to apparent statements by a spokesman of the Mexican Space Agency (?), no way near passing over Mexico in a window of several hours around the reported time:

click image to enlarge

In addition, there are elements available with an epoch 0.75 days after the event, suggesting it indeed was still in orbit after that time. I used Alan Pickup's fine SatEvo software with the current F10.7 solar flux parameter (94) to predict a decay near 12 Feb 9h UTC, 1.25 days after the Mexican event.


Anonymous said...

Good work.

Since final orbits are a bit flakey and thus it is hard to rely upon any reentry software, is it possible that the object skipped or bounced in the atmosphere for any reason during the time period over Mexico?

Since the debris was only 8 cm by 8 cm, it does seem unlikely to cause a fireball and certainly not a crater.

SatTrackCam Leiden said...

Not likely (read: no way): as you can see from the map, the track of the object was over a completely different part of the globe around that time.

Anonymous said...

No doubt you are correct that the 33006 debris was not the cause of the impact, but regarding the Satevo software you used and whatever other software is out there to make such reentry predictions, they make a lot of assumptions for this software. Just look at the input data file. There is no way things can be as simple as that, the atmosphere is too complex! There is not enough data to design a really good model of the upper atmosphere. Fluctuations of the atmosphere such as gravity waves (not Einstein related, just giant "low frequency" pressure waves) can change the pressure and density as you go around the Earth. Also, the mass and aerodynamic coefficient of the debris is unknown. We have the radar crossection of it, but it could be oriented in one axis when passing through the NORAD radar, or be full of holes (a wire mesh/net). That is, is it a heavy, dense piece or a light wing-like object? So I think there is some room for uncertainty in this but I really don't know how much it affects anything during the final few orbits of a spacecraft.