by Jeff Foust
|SpaceX has approached the “last mile” problem of station operations—the issue regarding how to allow spacecraft to safely approach and dock with the station—by allowing the ISS crew to manage the docking.|
The crewed version of Dragon would be able to carry up to seven people; Musk did not specify how much cargo the uncrewed version of Dragon could carry. The crew/cargo compartment will be made of an advanced aluminum-lithium alloy similar to the one used on the shuttle’s external tank, but developed just in the last several years. The propulsion module, located below the crew/cargo compartment, is a donut-shaped module that contains the reaction control system, avionics, and recovery systems. The “trunk” of Dragon, an adaptor for mating the spacecraft to the top of its Falcon 9 launcher, can also be used to carry unpressurized cargo to the station.
Dragon would be able to remain in orbit for up to six months before returning to Earth. Current plans call for Dragon to splash down, although Musk said “it wouldn’t be too hard” to modify the spacecraft to support a ground landing as well. Musk said that the lagoon at Kwajalein Atoll would be an ideal location for a Dragon splashdown. “It’s warm, there are no man-eating sharks, and you can jump out and swim to an island if you want,” he joked. That last option shouldn’t be necessary: Musk said they have a high-speed catamaran that can reach any point in the lagoon in about an hour.
While SpaceX is developing Dragon, is it also working on the Falcon 9 rocket that will be used to launch it. The rocket will be powered by a new version of the company’s Merlin engine, the Merlin 1C. Unlike the existing Merlin 1A engine, which is ablatively cooled, the Merlin 1C will be regeneratively cooled. “It’s a little higher thrust, a little higher efficiency,” Musk said. A “vacuum” version of the Merlin 1C, with a larger bell nozzle and some additional redundancy features, will be used on the Falcon 9’s upper stage.
The Falcon 9 is so named because it will use nine of those Merlin engines in its first stage. That has raised some eyebrows in the space industry, where the trend has been for smaller numbers of more powerful engines, like the single RS-68 engine that powers the first stage of the Delta 4. Musk noted, though, that some very reliable rockets have had large numbers of engines (which he defined as the number of thrust chambers): the Saturn 1 first stage had eight while the workhorse Soyuz rocket has 32. “If there’s any vehicle I’d like to fly on today,” he said, “it’s Soyuz.”
The large number of engines needed for the Falcon 9 will provide SpaceX with notable economies of scale, Musk believes. “Next year SpaceX will manufacture more rocket booster engines than the entire rest of the US industry combined,” he claimed. He estimated they will manufacture 25–30 engines in 2007, when Falcon 9 tests are scheduled to begin, growing to 40–50 engines in 2008.
|“Next year SpaceX will manufacture more rocket booster engines than the entire rest of the US industry combined,” Musk claimed.|
The complete Dragon program, including the development of the Falcon 9, will take about five years, he estimated, although it could be squeezed into four. “It’s too hard to say exactly, because there are some elements of that where our control is limited,” he said. After his presentation he did reiterate that he would continue to develop Dragon even if the company doesn’t win any COTS funding. In that case, though, Dragon wouldn’t be developed as quickly, and some ISS-specific hardware, like the Common Berthing Mechanism, would be dropped.
Musk made it clear in his talk that his long-term vision doesn’t end with launching spacecraft to the ISS. While SpaceX develops the Merlin 1C, a kerosene/liquid oxygen engine, Musk said the company was also considering developing a liquid hydrogen/liquid oxygen upper stage engine. Such an engine would be “really critical for going beyond Earth orbit,” he said. Such an engine used on the largest version of the Falcon 9 would be able to place nearly 50 tonnes into low Earth orbit.
At the same time, Musk is dismissive of some of the proposed applications that could take advantage of such a powerful rocket. “I don’t believe in the mining of stuff in space. The transportation costs are so horrendously high that I don’t think there’s anything… if there were packages of purified crack cocaine in orbit right now, I’m not sure it would be financially viable to go and retrieve them,” he said, to gales of laughter from the audience.
He was similarly dismissive of another popular proposed application, space solar power. “I know a lot about solar power,” he said, “and trust me, space solar power is not a good option.”
|“I think it’s really incumbent upon us to extend life beyond Earth,” he said. “Basically, to help make that happen is why I started SpaceX.”|
So what might be the “killer app” for space? Musk has an unconventional answer. “I think there’s some number of people in the US and other countries that would pay to move to Mars,” he claimed. “They would sell everything that they’ve got, and they would move to Mars.” If the cost of a one-way journey to Mars could be lowered to the “single-digit millions” of dollars, he said, “I think enough people would pay that to actually make the business plan quite viable. I think thousands of people a year would pay that.” Needless to say, that got a loud round of applause from the Mars Society conference attendees.
That concept might seem way of out left field for an industry that is only now accepting space tourism as a realistic market, but it also fits into Musk’s personal philosophy. Early in his presentation he spoke of the importance of becoming a multiplanet species, calling it “one of the most important things we could possibly aspire to”. “I think it’s really incumbent upon us to extend life beyond Earth,” he said. “Basically, to help make that happen is why I started SpaceX.”
He admitted later in the talk, though, that to some people such a vision “sort of sounds like a ludicrous aspiration. So, if we can lay a few stones on that road, then I’ll be pretty happy.”