I have made it pretty clear how important I think that Space X and its rocketry developments are likely to be for Mars colonisation. Space X has entered into operation of the unmanned Dragon spacecraft using its Falcon 9 rocket. In the pipeline are both a manned version of Dragon and the Falcon Heavy rocket. The Falcon Heavy will essentially strap three Falcon 9 first stages together. Before these first stage rockets consume all their fuel, the two outside boosters will transfer their remaining fuel to the centre booster. This is a novel manoeuvre but if it works the outside rockets will be separated after the fuel transfer leaving a fully fueled single first stage booster to carry on accelerating the vehicle. Effectively the centre rocket will be acting like the second stage of the launch system. A Falcon Heavy is already slated for operational use in 2015. It is anticipated among other things that it will deliver a Bigelow space habitat to the international space station that year.
On its own, the Falcon Heavy will not be able to launch a manned Mars mission. It is conceivable that multiple launches could place the components of a Mars vehicle in Earth orbit for subsequent assembly and fueling. But this approach would be inefficient, would require a lot of launches, and could be very costly. Space X has, however, revealed that it is considering developing a Falcon Super Heavy rocket that could be larger than Apollo's Saturn V. It is suggested that such a rocket might be able to launch 150 ton payloads into orbit. This would be a real game changer for Mars settlement. A Falcon Super Heavy program has yet to be formally announced but some statement may come later this year, along with the expected development of Space X's Mars plans. What relationship the Super Heavy might have to the vague statements so far made about a Mars Colonial Transporter (MCT) it is hard to say at the moment. Perhaps an MCT will consist of some development of the Dragon spacecraft for delivering crews to the martian surface, together with a habitat for transit to Mars, and a cargo carrier/surface habitat for landing on Mars as well. We are likely to learn a good deal more in a few months time.
The Super Heavy launch system is what I think may make NASA's space launch system (SLS) redundant. Given Space X's track record so far, the SLS is going to look ruinously expensive alongside the Super Heavy, and probably under-powered as well. We shall see: most speculative illustrations of a possible Super Heavy seem to use much larger individual rocket stages than the Falcon 9. New rocket development is always costly, and although Space X appear particularly adept at keeping costs under control, I will be very interested to see projected time-lines and cost estimates for the Super Heavy. One crucial aspect of cost minimisation per launch is how far the lessons of the Grasshopper project can be built in to a Super Heavy launch system. Currently the test reusable rocket is using a Falcon 9 first stage. If the system can be made operational it will dramatically reduce Falcon 9 costs. But how readily the development can be up-scaled to a larger booster remains to be seen.
It is not clear how the Mars One proposals can fit into all this. It seems to me that given the head start Space X are developing, then Mars One would probably need to use Space X rockets and spacecraft technology. Would the Super Heavy be ready in time for Mars One's schedule? I am not sure. There might be an alternative of uprating the Falcon 9 further in the interim. Instead of strapping just three Falcon 9s together as the Falcon Heavy will do, a ring of six Falcon first stages could be built around the centre Falcon 9 rocket. These could use fuel transfer technology to keep the centre rocket topped up. Two of the outer ring of boosters could be exhausted and jettisoned at a time, refueling the remainder before breaking away. This might in effect produce an analogue of a three stage launch system and possibly propel a largely fueled Falcon 9 first stage into orbit, to power later a voyage to Mars. This interim idea is pure speculation on my part; however: I am not an engineer so I do not know if it might be practicable. Still, in for a penny, as they say; just thought I'd mention it!
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