I started on the Crew Exploration Vehicle program with the first proposal, building the Integrated Master Plan / Integrated Master Schedule. That proposal was replaced with a second RFP when the NASA Administrator changed. Again I worked the IMP/IMS.
The first proposal had a really nice "winged" vehicle, the Orbital Space Plane. Ignore that it had limited capabilities. The replacement was called FAST. With the new administrator, the name was changed and so was the vehicle to Orion.
For all the agilest, the notion of emerging requirements on any project you can imagine is trumped by the switch from a winged machine to a capsule and new launch vehicle and a general change in mission.
Our role in this mega-project is the program planning and controls for the avionics suit.
Here's a link to the Program Office, now that everyone is getting closer to a real flying machine. On the lower left side of the page is a weekly summary of progress.