"NASA issued a Broad Agency Announcement (BAA) seeking proposals for mission concept studies of a solar electric propulsion system demonstration to test and validate key capabilities and technologies for future exploration missions. ... For more information about the announcement, visit: http://nspires.nasaprs.com"
Keith's 20 June note: This press release was issued last Friday. The BAA that this release announces is still not online at http://nspires.nasaprs.com. I asked PAO about it last week and they said there was some sort of procurement disconnect. One would think that a procurement activity announced in a press release as being available would actually be "available" before that release is issued.
Keith's 21 June update: NASA finally got around to actually issuing the BAA that they announced as having been released 4 days ago.