Well that was worth getting out of bed for! (I imagine; thanks to the iPad and NASATV I didn't have to bother). I don't think I have much to add to the general yawps of pride, joy, excitement, relief and so on; it was an amazing achievement, and a real thrill. But there's something to be said for taking opportunities to refresh oneself on the basics, which are often forgotten. "It's sometimes a struggle to know what you know," as my friend Ken puts it; as Donald Rumsfeld might have said, there are knowns that sometimes somehow get unknown.
The cost pendulum has swung all the way over. In the days when my Mars interests were at their peak, NASA was in full-on faster-cheaper-better mode. The cheapness carried the can for the loss of the Mars Climate Orbiter, the Mars Polar Lander and the Deep Space Two microprobes. This was not, I think, fully deserved. As I remember the inquiry MCO was lost because of poor management; anomalies were noticed but not hunted down. The MPL case was more complex; more money might have caught the bug that probably did it in. Either way, faster-better-cheaper went out the door. Curiosity has cost roughly 10 times what MPL cost. Rather than being one of a series of landers which, pre-MPL, were intended to fly at every quasi-biennial launch opportunity, it will quite probably be the only Mars lander this decade.
One ought to assume that the pendulum will now swing back. If you want to continue exploring Mars, you have to find a way to do it cheaper. In practise this probably means do not do it through JPL. JPL, as the world saw this morning, is magnificent. But it is also very expensive. I've talked over the years to various people who have tried to put together cheaper Mars missions. None of them could go through JPL and fit inside budget caps. JPL needs big missions, and fights hard for big missions (cf the saga of SIM). For this reason alone, a Mars lander not conceived at JPL would be a great thing. The "Red Dragon" concept from SpaceX and NASA Ames is obviously of interest here, not least because there's always the chance that if all his other businesses do well Elon might undertake it off his own bat. But other people, such as APL, might also get into the game (I've pretty much given up on ESA as far as this is concerned, but would love to be wrong).
One complicating factor here: longevity. The Curiosity entry, descent and landing (EDL) telemetry came back through Mars Odyssey, which has been in orbit more than ten years. Mars Express and -- amazingly -- Opportunity have been there almost a decade. No one expected that those missions would last that long. If Curiosity can operate interestingly for a decade, then it can basically *be* the program as a big sample return mission slouches towards Bethlehem.
But redundancy would be better. More missions can drive down mission costs -- for example through the reuse of EDL systems. I have no idea how much of Curiosity's cost went on EDL, but I bet it was a lot. And currently there are no plans to reuse the system at all. Indeed none of the successful EDL systems demonstrated on Mars have ever been re-used after their initial success (the MER systems were meant to be a reuse of the Pathfinder system, but they were so extensively redesigned as to be more or less de novo). Every time people go to Mars they find a new way of doing it. Those who have already succeeded get better at it -- this report by Eric Hand argues that thanks to experience, better knowledge of Mars and better software Curiosity's EDL was a lot less risky than many, including me, assumed. But it would be even easier if the same system were used more than once. And the whole enterprise would be better if people could buy such a system of the shelf, rather than tring to recapitulate the EDL-development expertise that has built up at JPL over decades.
America still has true interplanetary pre-eminence. Spending billions of dollars, maintaining continuity and inspiring great engineers does bring results, as the EDL success makes clear. I think I heard John Holdren tell someone this morning that no other country had landed on another planet, which isn't quite true; the USSR landed on Venus. Also Europe, with American assistance, landed on Titan, which is pretty planetlike even if it is a satellite, Japan landed on an asteroid, and the USSR landed on the Moon a number of times. But it is definitely true that no other nation has chosen to develop the capability to do things like land Curiosity, or build and operate Curiosity, and it's a pretty open question as to how easily any other nation could. This is much more difficult than simply repeating the feats of the 1960s, as the Chinese space program looks set to do for the next decade. For the time being, the trans-lunar solar system is the province of the United States, with a few allies just about in the game. [Update: This doesn't, though, excuse ignoring international naming conventions.]
There could be fossils. This is, I think, widely downplayed, and probably reasonably. But the odds that Mars once had life are pretty good. Life on Earth started early, and that means both that a) early starts for life on terrestrial planets are plausible, perhaps (depending on how much anthropic principle you feel comfortable with) likely and that b) in its formative years the inner solar system was littered with Earth rocks that had bacteria in them, many of which will have landed on Mars innoculating it through what I (but not enough other people) call transpermia. This is because big impacts knock small rocks off planets, and there were a lot more big impacts early on than there are today. Bacteria can remain viable in space for quite a while, and though the flow of rocks from the surface of the Earth to the surface of Mars would be a lot slower than the flow the other way (it's uphill, not downhill) it would have been appreciable.
If there was life on Mars, wet sediments from 4 billion years or so ago would be a good place to find fossils of it. Sediments on Mars are likely not to have been anything like as heavily reworked as sediments on Earth are. Microbial colonies can leave quite large macrofossils. Identifying them is not without issues: as the "Knoll criterion" has it, anything being put forward as a fossil must not only look like something that was once alive, it must also not look like anything that can be made by non-biological means. So I don't think fossils are a sure thing, or even likely, and I don't think, if there are fossils, that it will be easy or indeed possible to establish definitively that that's what they are. But my feeling is that the chance of seeing fossils is not that low (in the realm of a few percent more than in the realm of a few chances per million) even if they are not incontrovertibly recognised as such.
Science won't get people to Mars. In the understandable enthusiasm people are talking of Curiosity as a pioneer for future human exploration. Not so much. Science has never been a driver for human spaceflight. Science was an add-on to Apollo (a great add-on, needless to say) and after that, well, the space station? Really? What's more, sending ever more capable rovers reduces, at the margin, the case for sending scientists (unless, perhaps, they find something both fascinating and flummoxing -- see above). Opportunity and Spirit took months to match the output of a lesiurely few hours of human field geology. Curiosity should be more impressive that way. I'm not remotely saying that there wouldn't be much more for well equipped human scientists to do; just that, at the margin, the case for them shrinks a bit.
There are, I think, two ways that people get to Mars. One is a big national/international prestige thing for which there is currently no driver. The other is that technology and continued virtual presence on Mars tips the question from "Why go to Mars?" to "Why *not* go to Mars". Wanting to know more about Mars will play, at best, a minor role, though it will benefit hugely from any such endeavour.
[Updated a little to correct some of the typos, lest neophyte blogger Geoff Brumfiel be set a bad example]