Jeffrey LewisSTP-R1

In May 2004, I blogged that the Air Force “exercised an option order for a Minotaur space launch vehicle … to launch a classified payload in 2005.”

Given that the Minotaur’s other payloads include XSS-11 and NFIRE, I was pretty eager to find out some details about this classified payload.

A new detail has emerged: The payload is called STP-R1.

“STP” is a reference to the Space Test Program. The Space Test Program provides Space Flight to the DoD space Research and Development (R&D) community.

Although the Space Test Program has flown “over 400 experiments on more than 150 missions” since its inception in 1966, DOD has begun renumbering the Space Test Program sequence with STP-1. The STP-1 mission will see an Atlas V launch the Orbital Express demonstration program, along with four secondary payloads (MidSTAR-1, FalconSat-3, NPSAT1, STPSat-1).

That is STP-1. STP-R1, however, is something entirely different.

I presume, the R is for research. So what could it be?

It isn’t the Microsatellite Propulsion Experiment (MPX), or at least not entirely. An MDA official told Jeremy Singer that MPX will be a secondary payload on some other mission.

STP-R1 simply tells us what we already knew—that the payload is classified. The new information is that the satellite appears to be on schedule for a launch this summer.

I don’t know, at this point, where to dig next. Even if the STP-R1 payload was in the unclassified budget, it would be buried somplace other than the STP budget item (PE 0605864F). Orbital Express, for instance, is a distinct item and its inclusion in the STP-1 mission was only mentioned in passing last year.

Thoughts are appreciated.


  1. Felix Deutsch (History)

    Nothing serious (at least no more than the STP logo), but fun nonetheless.

  2. just passing

    much more in the way of details on this page

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