It's already 9:00 and I've hardly begun assimilating my 16 pages of notes, so I am going to have to just post a short summary with some highlights from today's meeting of the Outer Planets Assessment Group, or OPAG. This group has the same basic charter as VEXAG, which I attended on Monday and Tuesday, but as you'll see the issues with outer planets exploration are substantially more complicated than they are with Venus exploration. Today's agenda included updates on the status of the Cassini and Juno missions; a couple of science talks; presentations on plans for Europa, including a mission study from JPL, and also one on a Titan balloon mission from JPL; presentations on the status of programs to build radioisotope power sources and on the Deep Space Network; and some other future tech stuff.
The overarching message from today seems to be that outer planet exploration really requires a whole lot of things besides mission planning, and that without a coherent programmatic plan from NASA, the outer planets program is kind of in trouble. You can do inner planets missions on the cheap; and doing them relatively cheaply and frequently establishes a good skill and infrastructure base for continuing to do them frequently and cheaply, allowing you to have constant improvement in capability through incremental steps. But most outer planets missions, speaking realistically, cost a lot more, take a lot longer, happen more rarely, have longer gaps between them, and require a lot more investment in stuff back on Earth that is independent of the (often high) cost of the missions.
In addition to missions, you need, first of all, communications. All deep space communications go through the Deep Space Network, and outer planets missions rely very heavily on the very largest telescopes in that network, the 70-meter dishes, which turned 40 years old this year. I'll cover my notes from this presentation in more detail later, but here's a couple of numbers to make you think: over the last 15 years, the number of spacecraft tracked by the DSN has grown 450%, while the number of antennas in the DSN has grown by 30%.
Second of all, you need power. The Juno mission will manage at Jupiter on solar power, because it is avoiding the worst of Jupiter's radiation environment. But no mission to a Jovian moon, nor any mission to any target more distant than Jupiter, can get by with solar power; we need RTGs, radioisotope thermoelectric generators. Right now, the US has 15 kilos of plutonium-238 left for future RTGs, and 10 of those are earmarked for Mars Science Laboratory (MSL). We cannot do another outer planets mission without more plutonium. Even if we started this year, we couldn't start producing more until 2013 -- it would take that long to get our systems back online to turn our limited remaining supply of 300 kilos of neptunium-237 into plutonium-238 (at a production rate of only 2.5 kilos per year). But there are no funds in the budget to restart production this year, and in fact the program at NASA that develops more advanced technology -- including the new multi-mission RTG that MSL (and all future RTG-powered missions) will depend on -- had its budget cut by 30% this year because no future missions were being planned that needed the plutonium power supplies. It's a catch-22. Even if the funding were restored right now for starting a Europa mission, there's no guarantee that there would be plutonium available to power it when they need it.
Third of all, you need scientists around who can analyze the data once you get it back. They haven't talked about this yet at OPAG, but they will first thing tomorrow: outer planets scientists more than any other planetary group depend upon funding from NASA in between missions to keep them alive professionally until the next mission comes along. Cassini is the only game in town right now; if you didn't get on Cassini, your only other source of funding is NASA's research and analysis funding. Which has been cut dramatically in the FY 2007 budget.
The message has repeatedly been stated in the meeting room today that OPAG needs to come up with strong, clear, consensus messages to NASA about the need for investments in the DSN, investments in new power supplies, and, above all, plans for future missions. And I hope that OPAG produces all those things. In the end, though, it's not OPAG that leads NASA exploration of the outer solar system, it's NASA. And it looks as though we're beginning to see a program that is suffering from a failure by NASA to plan for the future. The present is extremely good, with Cassini in orbit and New Horizons on the way to Pluto. But there is only a single mission actually in the works for the future, and it's on the smaller side for outer planets: Juno. There has been a lot of talk over the years about going to Europa, going to Titan, and going to Neptune; there was even a presentation today about a Ganymede orbiter with a powerful enough camera to study Europa and Callisto too. But none of those things is actually being planned for future implementation by NASA, which means that nobody is planning for their power supplies or their data return capability or the scientists to support them.
I'm afraid I'm going to have to leave you with that cheery message because I have to get some food and get some sleep. If you want to read more about what The Planetary Society -- and the public -- thinks about this situation, read our press release from today on our "Save Our Science" campaign. I hate ending on a negative note though, so please do check out my previous post with all the terrific new stuff that came out of Cassini-Huygens and Hubble today; and when I can I will post my notes from some of today's interesting presentations.
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