This might be an obscure one. As I understand it: Diamandis co-founded Microsat Launch Systems, which was renamed International MicroSpace, in 1989. (This is apparently not the Micro-Space of 1977 to 2011 founded by Richard Speck.) The launch vehicle they were developing was the Orbital Express, renamed the OrbEx after a competitor complained about name similarity (and it is apparently not the Orbex that is a British company, founded 2015, which is developing a launcher called the Prime). Diamandis's company got a $100 million Defense contract for "one launch plus nine options", as Wikipedia put it. But they didn't have the financing to develop the technology to complete it (Guthrie, 127). In 1993 they were bought, with contract, by CTA of Rockville. In 1997 CTA sold its satellite business to Orbital Sciences.
I haven't been able to find what happened to that $100 million contract or the hardware that it concerned. Did CTA complete it? Orbital? Was it cancelled?
Edit: I think I answered my own question. "CTA had a contract with BMDO for a launch on a small "ORBital EXpress" vehicle. However, that contract has been cancelled, and CTA put the project on indefinate hold because of a glut of small launchers. "
That seems to be a copy-paste from another source, I've seen that text in a few places. I don't know the original source. But there is a book that discusses it, The Orbital Express Project of Bristol Aerospace and MicroSat Launch Systems, Inc., by Hughes.
I'll see about an inter-library loan for that one. You still sometimes have to go outside of the internet for stuff.
Guthrie, Julian. (2016). How to make a spaceship. Penguin Press.
Micro-Space, Speck's company: https://en.wikipedia.org/wiki/Micro-Space
Orbex, the British company: https://en.wikipedia.org/wiki/Orbex
CTA sale to Orbital: https://www.baltimoresun.com/news/bs-xpm-1997-07-16-1997197001-story.html