Q: What is the Falcon 9 intended for?
A: The Falcon 9 is intended for three missions:
Q: Why has SpaceX announced Falcon 9 now?
A: SpaceX wants to stick a crowbar into the public debate over NASA's two new boost vehicles. I'm sure the competing camps at NASA have been fully aware of SpaceX's Falcon 9 plans for a while, and probably driving them to some extent. But NASA's decisionmaking is not entirely internal -- they have to convince policymakers to fund their plans, and quite a lot of that convincing is done by attempting to frame the public's perception of those plans.
The ATK/Morton Thiokol lobbyists, and their camp within NASA, have been pushing two new mostly expendable launch vehicles, one to launch a 21 - 26 metric ton crew capsule and resupply ship to the International Space Station, and one to launch Very Heavy Things (110 metric tons) needed for manned lunar or Mars expeditions. Both would use solid rockets derived from the Shuttle SRBs. The big launcher might throw away four reusable SSME engines per launch, which is expensive.
The push isn't going well right now. Developing two vehicles will cost more than NASA is spending now, and that looks very bad to legislators spending hard-won tax dollars on the non-pork-barrel Iraq war and the $700 million/day cleanup of Katrina.
Jumping into the fray now lets SpaceX grab some of the public's mindset before it gets solidified by the ATK camp. They have a launch coming up soon. If it succeeds, John Q Public is going to wonder why NASA can't use the reliable SpaceX booster instead of developing a nearly brand-new launcher.
NASA's designs for a Shuttle-derived Shuttle replacement center around the idea that the technology development, supply chains, and infrastructure it has developed for the Space Shuttle are valuable in their own right. Because the Shuttle is nearing retirement, all three of these things are in danger. For instance, if there is no future vehicle to use a Shuttle/SRB-like solid rocket booster, ATK will have to shutter its plant for assembling these monsters. NASA is absolutely right in realizing that a unique capability that only exists within the U.S. will vanish if that happens.
But the hard question is: are those capabilities actually useful? The ATK boosters, for instance, produce 3.3 million pounds of thrust each, and cost about $40 million per launch. A simplistic analysis of SpaceX's launch prices put an end-user cost of $2.25 million per launch on each Merlin engine, each of which produces 85,000 pounds of thrust. The solid rockets are a much better deal for straight liftoff thrust, at $12.12/pound rather than the $26.47/pound of the Merlins. (The price difference is mitigated significantly but not reversed by the better Isp of the Merlins.) The as-yet-unfulfilled promise of SpaceX is that they are going to recover their engines or even most of the vehicle after each launch, and then will reduce their prices. And, of course, prices in the launch market are flimsy: I read wildly different estimates for costs and have not done my own accounting of NASA's costs, which I assume are public record.
I think the SpaceX entry is great for SpaceX. I had lamented earlier that the Falcon V was just not big enough for ISS resupply. Falcon 9 solves that. This gives SpaceX an obvious and fairly large launch market (I'm guessing three-plus launches a year), which should give them an operating profit with which to fund future development. It should also give them a launch history. It's up to them, of course, to make that launch history one to be proud of.
One hopes that launch market is also an elastic market: since SpaceX's prices are quite low, NASA might get to eventually rotate more of its astronauts through the ISS and actually do some science up there.
I think the SpaceX entry is great for NASA. It gives them the excuse to retire the Shuttle early. It gives them a cost-effective way to assemble the ISS without the Shuttle. With some foresight, they may be able to focus on the in-space aspects of putting people on the Moon or Mars instead of spending all their money on ground handling of launchers.
Lingering problem #1: How does NASA kill off the Shuttle-derived Heavy Launcher? NASA's standing army can't be dismissed until that thing is dead, gone, and maybe replaced. Or perhaps, the folks at NASA will let go of the need for big heavy launchers. I can see this happening for missions with large fuel requirements (launch the fuel seperately).
Lingering problem #2: SpaceX needs to launch a bunch of Falcon 9s before anyone should be confident that they are safe enough for people. What are they going to launch? Possible answer: ISS cargo-only resupply missions. Stretch goal: launch astronauts on Soyuz, and launch ISS sections on big Falcons. It might take a lot longer to assemble the ISS with just 4 people on board, but it might still be doable.
Finally, SpaceX's F9-S9 launcher has no less than 27 2.25-million-dollar engines at the bottom, and their launch prices are about $3000/kg to LEO. Maybe those engines are going to get cheaper if they start cranking them off the production line. But it seems to me SpaceX needs a bigger engine (and a larger diameter standard fuselage), because the current scheme isn't going to scale up much larger. Elon Musk promised that such an engine is in development, but it must not be well enough developed to enter into the current debate, as SpaceX is going to have enough difficulty getting credibility for even the Falcon 9. SpaceX development is late, and they are starting to reap the costs of being late.