Small unusual artificial object WT1190F will impact in a few hours [UPDATED with imagery of actual impact]

click image to enlarge

(for an update with imagery of the actual impact of this object from a research plane, see bottom of post)

The animated GIF above was made from images which I took just a few hours ago with the 0.61-m Cassegrain telescope of MPC G68 Sierra Stars Observatory in Markleeville, California.

The moving object is WT1190F, discovered on October 3 this year by the Catalina Sky Survey. This small peculiar object will impact in a few hours from now (near 6:18 UT, Friday 13 November 2015) just south of Sri Lanka.

It is an unusual object that is not a Near Earth Asteroid but almost certainly a small (1-2 meter) artificial object. It is moving in the Earth-Moon system (i.e. in a very elliptic orbit around earth) and its orbit is under influence of Solar Radiation Pressure, which shows that it is very light weight for its size. This fact, and the geocentric rather than Heliocentric orbit with apogee at twice the distance to the Moon, suggests it is some piece of hardware from a past Lunar mission.

image credit: Bill Gray, Project Pluto

It is not clear from which Lunar mission this object is a relic: it could be from one of the American missions, but also Russian or Chinese. The object in question turns out to have been sporadically observed since 2009, as it is probably the same object earlier designated 9U01FF6 in 2009 and UDA34A3 and UW8551D in 2013.

Shortly after its (re-) discovery on October 3, Bill Gray noted that the orbit yielded impact solutions on November 13 near 6:18 UT. The predicted impact point is over the Indian Ocean, just south of Sri Lanka. Bill Gray has put up a FAQ for this object with maps of the orbit and impact location here.

image credit: Bill Gray, project Pluto

As this is a small, 1-2 meter sized and lightweight object, the impact is harmless. It will burn up in the atmosphere and likely nothing will reach the water surface. It provides scientists with a good opportunity though to observe what happens during a small asteroid impact, as the speed and entry angle of this object is quite similar (see also the project page here).

The astrometry obtained from my images makes, along with data by many other observers, a modest contribution to  establishing the impact point and time as good as possible.

1st UPDATE, 13 Nov 2015, 09 UT:  WT1190F is now toast for a few hours. South Sri Lanka seems to have been clouded out, but there are reports on Twitter of sonic booms from the re-entry heard in Sri Lanka. 

In response to some of the comments, I want to point out that WT1190F is/was not the only artificial object in a trans-Lunar orbit which we were/are tracking. Here you can find an earlier post (out of several) on tracking 2010-050B and 2013-070B, two rocket boosters in trans-Lunar orbits from the Chinese Chang'e 2 and Chang'e 3 Lunar missions.

2nd UPDATE,  13 Nov 2015, 13 UT:  The first imagery (below, three stills and the video) has just appeared of the actual impact near Sri Lanka, shot from a research aircraft organized by IAC / UAE Space Agency / NASA / ESA:

Movie: Why the Russian Super Meteor was not related to asteroid 2012 DA14 - explained with the help of an orange

Dutch note: een Nederlandstalige versie van deze video is eerder hier gepost.



Added Note: the reality is slightly more complex than I present it in the video, as objects that graze just past the earth limb are slightly deflected by earth gravitation and can end up on (low) northern latitudes. Latitude 55 N is out of the question though, and as this added detail might make the story too complex I decided to leave it out.

Filmpje: waarom de supermeteoor boven Rusland niets te maken heeft met planetoide 2012 DA14 - uitgelegd met behulp van een sinaasappel

Note to English readers: an English version of the Dutch language video below is posted in a separate post here.




Toegevoegde noot: Het is in werkelijkheid iéts complexer dan ik hier doe voorkomen, omdat een langs de rand van de aarde scherend object door de aardse zwaartekracht iets wordt afgebogen en er zo dus wel fragmenten op (lage) noordelijke breedtegraden terecht kunnen komen. Maar 55 Noord is echt buiten de mogelijkheid, en ik heb dit er daarom maar uit gelaten omdat het anders misschien te complex werd.

[updated] HUGE fireball over Russia this morning! Not 2012 DA14 related.

A HUGE fireball has appeared over Chelyabinsk, Russia, this morning. And with HUGE I mean: HUGE. Apparent brightness rivalling the sun, and very strong sonic booms leading to glass damage and people being wounded by flying glass. This must have been a seizable object entering the atmosphere.

Phil Plait, the "Bad Astronomer" has very good coverage including some amazing videos here, so I will refer to him for imagery and the general story (apart from two I include below: one showing the meteor, the other one the arrival of the shock wave).





Below, I will briefly explain why this fireball cannot have been a fragment of 2012 DA14, the ~50 meter wide asteroid that will pass very close to earth coming evening (Feb 15, 2013).

First of all (and Phil Plait points this out as well), the fireball in Russia came from the wrong direction. Several of the videos show it appearing in the east near the rising sun, coming from a N-NE direction. That is the wrong direction: fragments of 2012 DA14 are on a south-north trajectory.

What is even more important: fragments of 2012 DA14 could never enter the atmosphere as far north as latitude 55 N (Chelyabinsk). Fragments in orbits similar to that of the asteroid, have a theoretical geocentric radiant at declination -81 degrees, i.e. almost at the southern celestial pole. They hence approach earth from due south. This means that the northern hemisphere is out of reach of these fragments: the northern hemisphere represents (as seen from these approaching fragments) the "far side" of the earth.

[video added 18/02/2013]


[added 18/02/2013] In the above video I explain this more visually, with the help of an orange. In reality, it is slightly more complicated than I present it in the video, as objects grazing the earth's limb are actually slightly attracted by earths gravity and can end up a little bit over the line between "front" and "far" side of the earth. Ending up at latitude 55 N is nevertheless out of the question.

The funny thing is that the latitude of Chelyabinsk and the approach direction of 2012 DA14 (and fragments in a swarm around it) are well established facts, even if the trajectory of the Russian fireball is less so at the moment. So it is quite nice that from the encounter geometry with the 2012 DA14 orbit and the latitude of the Russian meteor alone, we can actualy already exclude a connection between the two with a quite strong certainty.

Fragments in 2012 DA14-like orbits and the Russian fireball itself are also too fast to be temporarily captured in earth-orbit, so that is no explanation either.

This fireball was not man-made space junk either. Besides coming from an unlikely direction, it is too fast and much too bright for that.

These are amazing times: the reentry of a Russian rocket stage seen from NW Europe on the evening of the 13th, then this hughe meteoric fireball over Russia this morning, and a close pass of asteroid 2012 DA14 tonight. Wow!

Space debris lands in Brazil village

Through Carlos Bella on the satobs mailing list, news broke today that an object which almost certainly is space-debris crashed in the Brazilian village of Anapurus on February 22, 2012, near 6 am local time (9 UTC). It landed about 6 yards from a house and damaged trees upon impact.

Photo's of the object can be see here.They show a spherical object that strongly resembles a spherical rocket fuel cell (tank) or a Helium pressurization tank. These are the most resistent objects among space debris and often involved in reported cases of space-debris reaching earth surface.

Ted Molczan quickly noted that date, time and location correspond well to the re-entry of 1997-016C, an Ariane 44L rocket stage from the launch of two geostationary satellites, Thaicom 3 and Bsat-1A, on 17 April 1997.

The Ariane 44L r/b in question re-entered at 9:09 UTC +/- 1 min on 22 February 2012, near 4 S, 312 E. This corresponds well with the time and location of the Anapurus event (3.7 S, 317 E). Anapurus is located right on the re-entry track and was passed within a minute of the estimated re-entry time (movement of the r/b was from West to East, i.e. to the right in the map):

click map to enlarge

OT - 1883 Zacatecas observation of objects before sun were not 12P/Pons-Brooks fragments [updated]

A rather weird story has been posted here on the Technology Review website, based on this paper posted on Arxiv.org.

In it, Manterola et al. discuss an observation from 1883 by Jose A. y Bonilla from the Astronomical Observatory of Zacatecas, Mexico. On August 12th and 13th, he observed objects passing in front of the sun during telescopic solar observations. These objects were "misty" (= unsharp?) and crossed the sun in about 1 to 1/3 seconds of time. They were not seen during simultanious observations from other Mexican observatories. The observations were published in L'Astronomy in 1886, and the editors put it down to dust in the telescope system, birds or insects crossing the FOV.

Manterola et al. now make an argument that it were cometary fragments passing as close as 800 to 6000 kilometers (!) from earth, suggesting Earth narrowly escaped a shower of cometary fragment impacts. They also argue that it were fragments of comet 12P/Pons-Brooks.

The latter theory can be quickly falsified (and so can be the suggestion that it were comet fragments passing close by earth). The 1883 nodes of the orbit of comet 12P/Pons-Brooks were at solar longitude 255.8 deg (ascending node) and 75.9 deg (descending node), corresponding to December 6 and June 5. The latter (descending node) is far away from earth, beyond Saturn's orbit. The ascending node is closer, but still closer to the orbit of Venus than to the orbit of Earth.

This means that the earth only comes (not particularly) close to the cometary orbit near this date, and hence any fragments in similar orbits can only come close to earth on this date: December 6. Not on August 12-13, the date of  Bonilla's observations.

The diagrams below show how the earth is nowhere near 12P/Pons-Brooks' orbit on August 12-13, passing closest on December 5-7 instead (with the comet orbit at 0.2 AU minimum distance from Earth orbit: closer to Venus than to Earth):

click diagrams to enlarge

It should also be noted that the MOID between the Earth orbit and the comet's orbit is not particularly close (minimum 0.2 AU). Hence, it does not tally. These cannot realistically have been 12P/Pons-Brooks fragments.

The whole story seems far-fetched and very unlikely.

The "fuzzy" character of what Bonilla describes to me suggest out-of-focus objects, i.e. close by (with the telecope focussed on the sun), well within the Earth atmosphere and most likely within the telescope system. The "dark before sun disc, bright outside disc" is very odd, especially the latter - objects need to be very bright to outshine the sun and (presumably) a solar filter so close by the sun.

Moreover, the non-observation by other observatories (e.g. Mexico City) conducting solar observation that same day, is deadly to the hypothesis. Manterola et al. try to explain this by parallax, arguing that this must mean the fragments crossed very close to earth. However, the total observation time of the objects was 3h25m. Earth moves about 6150 km 370 000 km (about one Earth radius one earth-lunar distance) in it's orbit during that time, and the earth's surface rotates a considerable distance in this timespan too. This is deadly for the "restricted visibility area through parallax" argument. The area of visibility should be thousands of km wide, otherwise Zacatecas could not have had visibility for over 3 hours. The objects therefore really should have been seen from other places as well.