NROL-129 payloads located on-orbit

click image to enlarge

On July 15, 2020, at 13:46 UT, the NRO launched NROL-129 from the Mid-Atlantic Regional Spaceport at Wallops, using a Minotaur IV rocket (a modified Peacekeeper ICBM). This launch delivered four Classified payloads to Low Earth Orbit: USA 305, USA 306, USA 307 and USA 308.

The payloads and the Orion 38 Minotaur upper stage were located on orbit by amateur trackers last week. They are in 54-degree inclined, ~570 x 580 km orbits (see image above).

The payloads are bright, reaching magnitude +3 (naked eye) on a good pass. A fifth object which we believe to be the Minotaur's Orion 38 upper stage is about 2 magnitudes fainter and variable in brightness.

The images below, which I made in evening twilight of August 3 with a Canon EOS 80D and EF 2.5/50 mm lens, show two of the four payloads, USA 307 and USA 308, crossing Corona Borealis about a minute behind each other:

click image to enlarge

click image to enlarge

The four payloads seem to be grouped in two pairs, the two objects in each pair about 1 minute apart in pass-time at zenith. The two groups itself are about 8 minutes separated. We'll have to see what happens with the payload configuration over the next few weeks, but satellites operating in close pairs suggest to me that NROL-129 might be a SIGINT mission aimed at geolocating radio signals, similar to the French ESSAIM constellation.

The two payload pairs might be represented by the two mission patches (first two patches below), one showing a male warrior, the other a female warrior. Or maybe they represent the satellites making up each pair instead, as in a 'couple'.

The launch patch (third patch below) shows the Minotaur logo, and four stars in top which might represent the four payloads. In addition, it shows 7 stars at the left side, which probably represent that this was the 7th Minotaur IV launch. The single star at lower right might symbolize that this launch was the first Minotaur IV launch for the NRO.

The image below shows the position of the four objects when the orbits are propagated backwards to a few minutes after launch. The position and track matches a launch from Wallops well:

The moment of payload separation is unknown, but media sources suggest this was after a prolonged coasting phase. A coincidence analysis that I performed is hampered by the fact that the payloads probably manoeuvered several times, but does suggest that payload separation was somewhere between 14:10 and 14:40 UT, near the first apogee pass in the southern apex of the orbit. As Ted Molczan noted, release was probably in two directions (the upper stage rotating 180 degrees inbetween releasing the D/E and A/B pair)) to create the two pairs, the D and E objects released first, and then the A and B objects.

The video below is a compilation of 5 video segments I shot over 10 minutes near local midnight of 2/3 August, showing the objects pass in order of appearance: USA 305, USA 306, the Orion 38 Minotaur R/B, USA 307 and USA 308:

The first observation of one of the payloads, as a UNID, was done by Russell Eberst in Scotland on 27 July. Ted Molczan first suggested it was one of the NROL-129 payloads. A new observation of two of the objects was done by Leo Barhorst in Germany on July 29. One night later, Cees Bassa in the Netherlands performed a planar search and observed all five objects. I followed with observations the next night, and have now imaged them a couple of times.

A sixth object was initially reported by Cees Bassa. It was very faint and seen only once. It appeared to be in a somewhat differently inclined orbit than the other objects. It was not seen during later plane searches, including a plane search by me. We now believe this mystery object to be a chance sighting of a cubesat unrelated to the NROL-129 launch.