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We have some reasons to think that this object is potentially VERY
interesting: maybe a temporary captured object by the Earth.
The reasons are:
-no satellite reentry planed this day. If artificial, this object was
-very long path: only very large satellite would do: I think even the
ATV reentry in 2008 did not last for this long (in space). The only
object I can think of was the Columbia shuttle accident.
-temporary captured object are theoretically and practically real (see
Granvik et al 2012 study on this topic).
So, this might be a natural object. If proven, it would be a fantastic
news and the first atmospheric entry of a natural temporary Earth satellite!
SO, my question is the following: does anybody have a record (image or
better video) of this object?
Breaking News - UK Earth-hugging Asteroid Circled the Earth and Hit Again
According to the modeling done by Finnish mathematician Esko Lyytinen, the big UK fireball of the 21st of September was captured by Earth`s gravity.
After one circle around the Earth one of the remnants seems to have re-entered the skies over North America.
"It looks now that the fireball witnessed 155 minutes later in US and Canada, may have been one fragment of the British fireball, most probably the biggest one. This was its second entry into the Earth`s atmosphere", Lyytinen says. "If so, this is historical scientific observation, but it needs to be confirmed."
The large meteoroid entered the atmosphere with a very low speed of approximately 13 km/sec, only a little more than the escape velocity. Due to the low velocity and angle of entry the gravity of Earth pulled the meteoroid and curved its trajectory. This made the exceptionally long passage in atmosphere possible.
"I estimate that the fireball came to its closest point at 53 kilometers above the Earth", says Lyytinen.
The entry mass of the asteroid has been estimated to be in the range of tons of kg or tens of tons. Probably a significant portion of the mass was lost during the luminous-flight fireball phase. Videos taken of the UK event show that the fireball fragmented into multiple pieces.
According to Lyytinen, the deceleration during the fireball phase left the meteoroid at the speed of only 9.2 km/sec as it was leaving the atmosphere. Hence it remained travelling around the Earth until it re-entered the Earth's atmosphere.
"After leaving the atmosphere it probably made about a full revolution around the Earth before re-entering", Lyytinen says.
Lyytinen predicted two days ago, that the US/Canada fireball might be a part of the same event. The idea was studied yesterday by Dr. Robert Matson, an aerospace engineer and meteor expert. Matson found that the direction of fireball over Quebec seems to fit the prediction.
Moreover the required speed for this space rock according to Matson to show up at the observed times over UK and America is 9.08 km/sec, which is excitingly near Lyytinen`s value.
Matson in his study also had independently concluded that the UK fireball was starting to rise up at the end of the observed track.
Lyytinen estimates, that during the fireball`s long first flight over UK it was visible from the ground for almost a full three minutes.
"I have no information of a similar duration of a fireball ever being observed", Lyytinen admits. "Naturally it is theoretically possible, but this is so rare that I'm amazed that it really happened."
"The great daylight fireball of August 10, 1972 over North America was similarly magnificent, but it was notably faster and shorter in duration", he says. The Earth-grazing meteoroid of 1972 has been estimated to have lasted 100 seconds before returning to space and leaving the Earth's gravity.
Esko Lyytinen is a mathematician of the Finnish Fireball Working Group of the Ursa Astronomical Association. In this research he co-operated with Dirk Ross of Tokyo, Japan who operates a website, "The Latest Worldwide Meteor/Meteorite News", which continuously monitors meteor events worldwide.
More on the 21 September 2012 fireball: why it definitely was a meteor
Observers report durations between 20-60 seconds: most video's on the web suggest a 40+ seconds duration.
It would take a reentering satellite travelling at 8 km/s (the orbital speed at decay altitudes) about 138 seconds or roughly 2.25 minutes to travel this distance. While the reported fireball durations are long, none of the reports nor videos comes even remotely close to that value.
A meteoric fireball travelling at the lowest speed possible for such an object, 11.8 km/s, would take 93 seconds to travel that distance. This is still longer than almost all of the reports suggest, but clearly getting closer.
If we take an estimated duration of 60 seconds, the 1100 km trajectory length results in a speed of approximately 18 km/s.
18 km/s is a very reasonable speed for a slow, asteroidal origin fireball.
(it is, let me repeat, also way too fast for a satellite reentry).
Meteorite dropping fireballs typically have speeds between 11.8 and 27 km/s. A speed near 18 km/s sits squarely in the middle of that speed interval.
Almost all non-polar satellites move prograde, from west to east (or north-south and v.v. for a polar orbit). An east to west movement would necessitate the object to have a retrograde orbit (meaning that it moves counter to the earth's direction of rotation). Such objects are extremely rare: they literally amount to only a handful of objects (including the US FIA Radar satellites, and the Israeli Ofeq/Shavit satellites/rb). For this reason, it is extremely unlikely that this fireball was a reentering satellite.
Update 24 Sep: in the comments to this blog post, the issue was raised of the potential reentry of a classified object. However, the larger classified pieces are tracked by us amateurs. We have no likely decay candidates among the retrograde objects that we track. We can account for and hence exclude the FIA's for example (the rocket bodies of that launch were deliberately de-orbitted right after launch so are no candidates either). The Israeli Ofeq/Shavit are no candidates as their orbital inclinations never take them over the Netherlands and the British Isles. And there are simply no other suitable retrograde objects
There are moreover no unclassified reentry candidates for this date listed by USSTRATCOM on their space-track portal. Given the brightness of the fireball, this should have been a seizable chunk of space debris, that really would have been tracked (and predicted). Again, this makes it very unlikely that this fireball was a satellite reentry.
Big Meteoroid Boomerangs Around Earth
For the first time ever, a meteor has grazed in and out of Earth's atmosphere, slowing enough to become a temporary satellite that perhaps lasted a full orbit.
A second analysis of photos and videos of the European event, by aerospace engineer and meteor expert Robert Matson, likewise suggests that a big chunk of this Earth-grazer ended up in a temporary orbit with an inclination of about 54° (corresponding to the latitude of its "perigee" over Ireland). Its single looping orbit was highest, about 3,930 miles (6,330 km), somewhere south of Australia, before it boomeranged back to a fiery finale.
However, after a close look at the event over North America, Matson is now skeptical that it's related to the earlier graze seen across the Atlantic. "Using two all-sky videos from Ontario, Canada, I was able to roughly triangulate the location of the Québec fireball to a spot between Ottawa and Montréal," he says. "Unfortunately, I cannot dynamically link this location and timing with that of the U.K. fireball — it is too far west." Moreover, Matson adds, the videos show a fairly short-duration event and a much steeper trajectory than a UK remnant could have had.