For the last several years, I've followed every meeting of the several Analysis Groups that provide NASA with feedback on it's planetary exploration plans. There's a group for Mars (MEPAG), the outer planets (OPAG), small bodies (SBAG), and Venus (VEXAG). When there's no major issues in the area of focus, the meetings can be status updates that might provide tidbits of news. When there's a hot issue, the meetings can provide first looks at those issues with meaty presentations.
The just completed VEXAG meeting had a focus I'd not seen before, that appeared to be asking NASA to explain the lack of missions planned for Venus:
- NASA SMD [Science Mission Directorate] View/Outlook for Venus
- SMD Competed Missions - NF & Discovery
- Discovery Program
These presentations haven't been posted yet, but the journal Nature has provided a summary of the concerns behind asking NASA to discuss these topics. According to the article, the Venus science community perceives, "an agency bias against Venus, a planet that hasn't seen a US mission since the Magellan probe radar-mapped its shrouded surface in the early 1990s, and which won't see one any time soon, after NASA this year rejected a bumper crop of Venus proposals."
The community has tried to get a mission prioritized by describing why Venus is worthy of exploration and listing priority investigations (for example, Venus Exploration Goals and Objectives). The SAGE Venus lander was proposed for the last New Frontiers competition, but was passed over and the OSIRIS-REx asteroid sample return mission was selected.
According to Nature, a quarter of the 28 Discovery proposals for the latest competition targeted Venus, but not one was selected as a finalist. Six of those received the lowest ranking, and only one that focused on atmospheric studies was judged competitive.
Nature reports that NASA's explanation for the low rankings is that, "Venus scientists need a clearer consensus on their goals and the measurements that they want to make." In the meantime, that community is seeing interest in Venus shrink among the larger planetary community as missions focus on other solar system targets.
Editorial Thoughts: I know from personal experience how tough proposal reviews are. The ones that hurt are those where the proposing team had a technical error (they should have caught those). Proposals for spacecraft missions also have to demonstrate that they can be developed with the program's mission cost cap. The Nature article doesn't mention any proposals rejected for technical or cost issues, but some may have been.
Usually, the bigger hurdle for proposers is developing a compelling scientific question to address. It's not enough to, for example, say that you will map x% of Venus' surface at 10x higher resolution than has been done before. You have to show what compelling question(s) will be answered. And your compelling questions have to be better than your competition's questions.
Given the low ranking for six of the Venus Discovery proposals, it appears that either the Venus community hasn't sharpened its priorities and questions sufficiently, or the best questions available for Venus that can be addressed within a Discovery budget aren't compelling compared to those for other solar system targets. It may be that previous missions have picked off the inexpensive low hanging fruit.
The European Venus science community has also proposed Venus missions to follow up on the Venus Express mission, but so far have had no luck. The Russians are defining a new mission, Venera-D, that would include a lander and possibly also an orbiter and balloon platforms. (I'm not sure that this is a formally approved mission or not. I'd appreciate it if any readers with a better understanding of this mission's status could leave a comment.) See this previous post on the European and Russian proposals: http://futureplanets.blogspot.com/2010/01/russian-and-european-venus-ambitions.html
Bonus: NASA generally doesn't reveal too much information on the Discovery mission proposals. The Nature article, though, gives the number of proposals by target for the competition in progress:
Venus - 7
Moon - 3
Mars and it's moons - 4
Asteroids - 8
Jupiter system - 1
Saturn system - 2
Comets - 3
The selected finalists were the Titan Mare Explorer (TiME), the GEMS Mars geophysical station, and the Comet Hopper.