credit: spaceX
Speaking to journalists after his speech at the Royal Aeronautical Society in London on 3 July, Space Exporation Technologies chief executive Elon Musk talked about his ideas for a circumlunar flight service
At an overall cost of $80 million the BBC journalist, asking Musk about this, noted that with seven crew in the Dragon that could be $11 million per passenger. Musk did talk about a Falcon 9 (F9) heavy launching such a flight as it has a low Earth orbit payload capability of 60,000lb, which is just over 27,000kg
Personally I am sceptical about this briefest of descriptions as you are not going to want to be strapped in to a capsule for what would have to be at least a week long trip there and back and so you need a habitation module, you need an Earth departure stage to get the hab and capsule out to the Moon, and you would need a number of changes to the Dragon spacecraft such as a larger heatshield for the higher speed reentry into the Earth’s atmosphere.
I also asked Musk if for such a mission he had a roadmap for F9 Heavy development and he looked a bit blank, which may have been the jetlag as he had just got off a plane from California
But anyway, those minor points to one side, Musk also spoke about, a first customer for a particular mission being offered a discount (suggesting that his UK HYLAS satellite customer Avanti Communications got that just that as SpaceX’s first geo mission); government regulations adding up to 25% to his cost base; there being two sizes of seat for Dragon, one for tall people and one for “medium sized” people; and he talked about the F9 heavy version using three first-stages, one core and two “strap-on” giving a total number of 27 engines. His launch pad, pad 40 at Canaveral, is being designed for such a wide base and the flame trench it requires
Some people claim that there is an issue with so many engines. Musk claims the Soyuz rocket has a similar number and that if the F9 loses two or there engines then it can still reach orbit – but is it the right one? I am more relaxed about having lots of engines. At the end of the day it is a reliability issue. And that is a function of good design and testing (easier said than done I admit). But if you decide on that many engines then you must have reconciled yourself to that additional work and, in particular, the expense, or you’re mad
Before the media interviews Musk was asked if he was concerned about turbopumps exploding and he said he wasn’t as such an explosion was not expected to cause catastrophic damage and that they had only seen a gas generator explosion during development work
During the question and answer session after his speech, Musk described Falcon 1 as a technology test bed; said that for every 7lb (3.1kg) of first-stage mass you lose 17lb of payload capability; explained that his chocie of thermal protection material, Phenolic Impregnated Carbon Ablative, could cope with 2kW/cm2; that you could use a folded wing that snapped out for glide back stages; that the Dragon’s launch abort profile would see crew experience up to 16g (ouch!!);
As his speech was about extending life beyond Earth he talked about a Mars colony, only briefly, and not in any depth. He talked about a one-way ticket costing $2 million
On F9 he said they had wind tunnel tested a scale-model but all that did was prove that their Stanford University/NASA Ames Research Center produced computationl fluid dynamics code was very, very accuate
The reviews he does with NASA involve up to 400 people. They provide the documentation a month before the review meeting. Those 400 send in questions and over time the queries are resolved. At review meetings SpaceX deals with up to 30 NASA personnel (some of whom can be on the phone) and there are usually outstanding issues
He talked about how the second stage of F9 would be recovered. He was coy as he said he was concerned about the ever present US technology export laws but he did say they are looking to use “stabilising aerostructures” for controlling the second stage’s reentry
