Thursday, 12 November 2015

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:


Unknown said...

Could it be a panel or other part that was blown off when the oxygen tank of the Apollo 13 Command Module exploded?

Unknown said...

Good question M,
My guess would be no for several reasons. First, Apollo 13 was originally the first manned Moon mission to be in a "no return" trajectory. One of the first things they had to do was to get back on a "free return" course. That guaranteed that they would get back to Earth, either alive or dead, if you get my drift. (In other words,no one wanted a spacecraft out there that had three dead people aboard.) An interesting article I read recently was about someone calculating what would have happened to the spacecraft if this didn't work. It turns out that Apollo 13 would have hit the Earth's atmosphere a short few, weird orbits (I think two) after they had perished. Wow, thank the heavens (pun intended)that didn't happen, huh? Now, I suppose it could be argued that the explosion might have put the debris in this type of orbit, but I think it's unlikely just due to the many, many Moon missions there have been, manned and especially unmanned. But that's part of the problem. Nobody really sits down and plots out all the different orbits of all of this cis-lunar "stuff." Actually my first thought was one of those panels that opened like a four petal flower during transposition and docking just after leaving Earth orbit. There are 36 of those out there somewhere. But maybe that it a little unlikely too because of those S IV-B third stages that didn't crash into the Moon (Apollos 8, 10, 11, and 12), they are all in solar orbits similar to the Earth's. The panels might all be in that kind of orbit as well. I hope this helps.

Unknown said...

So, we've been tracking a 1-2 meter object for a couple of years and the animation above is showing movement of a 1-2 meter object in space? What rocket stage is only 1-2 meters long? I smell baloney or am I wrong?

SatTrackCam Leiden said...

Kathryn: yes, the images in my post show an approximately 1-2 meter large object, at that moment at a distance of about 178000 km (about half the earth-moon distance). As unbelievable as it sounds, it is truth!
You assume anything out there must be a rocket stage. But there are also adapter rings, payload fairings, and various other pieces of hardware. For example, a lunar ascend module from Apollo 10 that is only 4 meters in diameter is still out there somewhere (but probably has left the earth-moon system and is on an orbit around the sun, at too far a distance to be seen). There was some speculation whether WT1190F actually is that Apollo 10 Lunar ascend module (there is some leeway in the size estimate for WT1190F).
We track several pieces of space junk at this distance: for example, two rocket boosters from the Chinese Chang'e 2 and 3 Lunar missions. See my earlier post here:
Tracking these objects is not easy, certainly if they are as small as WT1190F was. They are faint and WT1190F needed a big research-grade telescope to image it. They move (due to repeated close Lunar encounters and the influence of solar radiation pressure) in chaotic orbits that cannot be predicted too long in advance.