When SpaceX (News - Alert) CEO and chief rocket designer Elon Musk talks, space geeks listen. And ask questions. Lots of questions. And so it was when Musk gave a keynote to a roomful of aerospace engineers at the AIAA/AMSE/SAE/ASEE Joint Propulsion Conference in San Diego on August; his talk was webcast as well.

True to SpaceX’s modus operandi, Musk first played a video highlighting the company’s achievements in rocketry and spaceflight, then started dropping hints on what’s next.    But SpaceX’s first two priorities are to have a successful Dragon docking with the International Space Station (ISS) in December, followed by “convincing NRO and the Air Force we’re a good thing.”

Both priorities are important for securing revenue streams to fund future hardware development. Later this year or early next year, Musk expected to unveil a “super high efficiency” staged combustion engine – just the sort of red meat teaser attendees at the conference will be looking for.

Why is SpaceX doing this? Not strictly for the Benjamins.

“We want to take significant amounts of cargo and people to Mars,” Musk said. “Are we on a path to become a multi-planet species or not? If not, that’s not a very bright future. We’ll be hanging out on Earth until some calamity claims us.”

In order to do that, SpaceX needs to develop and operate “fully reusable, rapidly reusable space transport,” Musk stated. “It wouldn’t be a good car if you had to change the tires on it every time you drove it or could only drive it once a week.”

Only 0.3 percent of the cost of a Falcon 9 launch is propellant. Being able to fully reuse all the parts of the launch system could significantly drive down the cost of launches. 

What success has SpaceX had in reusability? “It’s sucked,” Musk stated bluntly. “It’s super damn hard. SpaceX has learned a lot by flying and recovering Dragon, but the engineers can’t give that level of protecting to the first and second stages of the Falcon 9.” 

Constructing a “suit of armor” even for the first stage has been harder than anticipated. “It comes in at a pretty steep angle, the forces are very high,” Musk said. “It’s belly flopping on the atmosphere, something has to be done to shed velocity.”

One solution being looked at is restarting the engines to slow down the first stage, but the fuel to do that has to be weighed against payload loss to orbit, increased structural margins for recovery, and better thermal shielding. “It’s a tough trade,” he said. “We have something on paper that closes. We’ll have to see if that is a reality as well.”

In response to questions from the audience, Musk said SpaceX has a general architecture planned out for Mars trips and “know what the ingredients are.” The company’s Falcon Heavy rocket, to be flight demonstrated in late 2012 or early 2013, could deliver 10 to 15 metric tons to Mars, but Musk wants a vehicle capable of 50 metric tons and fully reusable.   If Falcon Heavy could be made fully reusable, costs to LEO could be low as $50 to $100 a pound. 

Musk stated that the company has had discussions with NASA to use Falcon Heavy for “big missions” to Mars and the outer solar system, with one notational mission going out 150 to 200 astronomical units (AU) “past Pluto and stuff.”

Two technology areas Musk didn’t like were lifting bodies/wings and nuclear rockets. On the former, he said he was a “vertical takeoff, vertical landing” type guy and eschewed wings since they had to be tailored for each planet’s atmosphere and were useless on airless bodies such as the Moon.

Drawbacks to nuclear power included the need for shielding (heavy), water (heavy), and public objections against launching nuclear fuel on a rocket. “It’s a tricky thing getting a reactor up there with a ton of uranium,” Musk said and went on to say while nuclear power would be useful for Mars or lunar operations, he implied that some assembly (i.e., mining and processing fuel off planet) would be required.

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