The Second Half of Life: Space Junk or Asteriod?

A side-light of the Trout Lake Star Party was that I picked up a bunch of objects going across my short (30s to 1min) images. In one case I actually had two different objects appear in two consecutive frames! Most of these seemed pretty ordinary and were confined to single frames. The tendency is to immediately discount them as shooting stars or man-made satellites. However, on this night, one of them stood out as special.

While I was taking a series of 30sec images of M17 (The Omega Nebula) I had four consecutive frames in which the same object drift across my FOV. Not only was this relatively slow speed interesting, the object showed up as a "dashed", as opposed to continuous line of light. As my friend Ed pointed out when I described this event to him, the object must have been tumbling and must have either an irregular shape or a varying reflectivity across its surface. The pattern suggests that it rotates approximately once in every 3.75 seconds. The four images of this object are shown below.

Of course I'm wondering what this is. Given that it is tumbling, it must either be space "junk", mankind's garbage-in-the-sky, or be an asteroid. Is there any way I can tell? What immediately occurred to me is to check the speed of the object by measuring its track in arc-seconds, calculating the distance with the assumption that it is in a circular orbit in a typical range of altitudes, and dividing by the exposure time. With orbits ranging from 125 miles to 10,000 miles, the calculated speed comes to the range of 23,500 mi/hr to 52,750 mi/hr. This is significant in that required orbital velocity for that range of altitudes is 17,500 mi/hr to 9,420 mi/hr... suggesting that it is traveling too fast to be in a circular orbit. This leaves the possibility that it is either traveling in an elliptical orbit and we are seeing it at is closest approach (where it travels faster) or we are seeing an object that is indeed traveling faster than orbital speed and not in orbit of Earth.

A little research shows that most space junk is in very close to circular orbits and only a very small fraction has high eccentricity (going as high as 0.75). I can't exclude this possibility.

If I had been able to track this object for a significant period of time I might have looked for evidence that the track length was changing, which might indicate that the object is not traveling parallel to my position... but it was traveling fast enough that this wasn't a possibility.

My ability to narrow this down at this point is running towards the end of the rope. My last check was on the Internet, to investigate whether any known object was passing across M17 at that moment. I found this link, which allowed me to make this check and alas, no such object was in the database. Unfortunately, it appears that the database for space junk is not online.

I'm left wondering...space junk or asteroid? ... but I'm spurred on now to start observing known asteroids and to further investigating the amateurs options when it comes to the NEO (Near-Earth-Object) search. At OSP, I'm going to try to look for asteroids named Klotho and Hippo.

The object enters my images and proceeds across M17 in the next three images. The date of observation was 07_11_2010 and the time on this image was 07:33:35.061 (UT).