Meteoroids, not Space Debris

Posted by jns on 16 February 2009

SpaceWeather.com (operated by NOAA) reports that people all over the US are seeing meteors and are concerned that it’s space debris from that dramatic orbital collision between Iridium 33 and Kosmos 2251. Apparently there was also a large meteor seen over Italy that led to similar thoughts.

I’ve also seen reports that the FAA has warned pilots to be on the lookout for space debris, although it’s not clear to me what they’re supposed to do if they see some streaking by except get hysterical.

It’s easy to understand why people will have this reaction, so it’s also useful to note that meteoroids and space debris enter the atmosphere in different–and distinguishable–ways.

Anyway, here is what Spaceweather (for 16 February 2009) had to say about those fireballs:

WEEKEND FIREBALLS: A daylight fireball over Texas on Sunday, Feb. 15th, triggered widespread reports that debris from a recent satellite collision was falling to Earth. Those reports were premature. Researchers have studied video of the event and concluded that the object was more likely a natural meteoroid about one meter wide traveling more than 20 km/s–much faster than orbital debris. Meteoroids hit Earth every day, and the Texas fireball was apparently one of them.

There’s more: On Friday, Feb. 13th, people in central Kentucky heard loud booms, felt their houses shake, and saw a fireball streaking through the sky. This occurred scant hours after another fireball at least 10 times brighter than a full Moon lit up the sky over Italy. Although it is tempting to attribute these events to debris from the Feb. 10th collision of the Iridium 33 and Kosmos 2251 satellites, the Kentucky and Italy fireballs also seem to be meteoroids, not manmade objects. Italian scientists are studying the ground track of their fireball, which was recorded by multiple cameras, and they will soon begin to hunt for meteorites.

Videos, eye-witness reports and more information about these events may be found at http://spaceweather.com.