I'm not the first person to suggest it. Most of the discussion about the theory revolves around the fact that the X-37 isn't in an ideal orbit to spy on the Tiangong-1. Something I rarely see mentioned, however, is that the X-37 has a payload bay and if you want to put a satellite in there, there's nothing stopping you. Let's take your dimensions, 'cuz I like 'em. 8' by what, 4' diameter? Obviously, you don't need to shove the entire third stage of a Thor-Agena in the payload bay of an X-37. But you could fit... lots of fun in a 4x8 payload bay, particularly if you're already in, you know, orbit. Frankly? I'd build a good'n'proper 2000mm f/2.8 telephoto lense and leave the rest of it for tracking. There's probably a million and one instruments you can hang off of a spying-on-satellites satellite, particularly if nobody knows it's there. Patent US5345238 You probably know more about this than I do, and frankly, if you can find a link you'd be doing me a favor. All mention of it appears to have dropped off the face of the earth. Used to be the Air Force published a "meteor flare database" or something; basically, a data dump of all the infrared hot spots that SBIRS detected. Then one fine day in 2008 or 2009, they classified the data. Then in 2010, the X-37 flew... and nobody could triangulate that wonderful public-domain infrared flare data to figure out where our buddy with the payload bay was going. Ring any bells?
Teal Ruby was a technology experiment to test new IR sensors for early warning satellites. Originally named P80-1 until December 1983 when it was renamed AFP-888 and its launch date became classified. It has essentially a rectangular parallelepiped shape and approximate dimensions 2.4 × 2.4 × 0.7 m. The spacecraft is three-axis stabilized to maintain one 2.4 × 2.4 m surface vector pointing at the nadir. The spacecraft serves as a stable platform reference for three experiment telescopes. The spacecraft telemetry capability is PCM and it uses onboard tape recorders with up to 6 hours storage.
I read what you posted, but the size did not register with me. HOLY SHIT. That is both amazing and sort of concerning that they can do that. Every launch of a missile/rocket is registered due to nukes and all, but year if you fake a problem and a reentry... There was something way back in 2008-2009 in either Sky&Telescope or Astronomy Magazine where the B612 Foundation was upset that they no longer had the raw data about meteor activity in the earth's atmosphere. This is when NASA set up the All Sky Camera network that is on the bottom of Spaceweather's page tracking fireballs.