Elon Musk, founder and CEO of SpaceX, says that the missions to Mars by his company will use rockets powered by methane, which can be manufactured on the Red Planet. The announcement came last as the South-African born entrepreneur was giving a lecture in November to the Royal Aeronautical Society in London, where he was presented with the Gold Medal – the society’s highest award.
In his talk, Musk said that he foresees the first Mars mission as a collaboration of private industry and government, but is prepared for the possibility that it will be just commercial. His vision is to see a manned landing on Mars within 15 years as the prelude to colonization. With this in mind, he said that the only way to make such a program economical is to keep transport costs as low as possible.
His target is to keep the price of passage at US$500,000, which he said is was within reach of people in developed countries. "Most people in their mid-forties could put together enough money to make the trip,” he said. “Half a million dollars, that's a normal middle-class couple in California."
Part of keeping these costs down is the choice of fuel. "The cheapest fuel is methane,” said Musk. “So it's going to be methane. Also, the great thing about methane is that you can create it on Mars because Mars has a CO2 atmosphere and there's a lot of water ice also. Conceivably, you could extract water vapor from the atmosphere. With water you've got H2O plus CO2 and bingo, you can replace propellant."
Musk was referring to the Sabatier reaction, which uses a nickel catalyst to convert water and carbon dioxide into methane gas and water. It has been proposed as a means of creating rocket propellants on Mars, with one possibility being to send automated factories to the Red Planet to process fuel in anticipation of a manned landing.
Musk also pointed out that methane performs almost as well or better than kerosene or hydrogen, but has certain advantages – especially over hydrogen. “Methane is much easier to deal with. It's not a cryogen and hydrogen likes to get into all sort of places, making metal brittle and creating invisible high-temperature fires and that sort of thing. Methane is just much easier to deal with."
As to kerosene, Musk said, “The energy cost of methane is the lowest and it has a slight (specific impulse) advantage over kerosene and it does not have the pain-in-the-ass factor that hydrogen has.”
Musk added that the Russians have made advances in methane-powered rockets, so the technology is there. Another factor he cited is that the Mars ship needs to be not only cheap, but large, since making the over two-year journey in Dragon would result in the astronauts “coming back mad, if at all.” This makes inexpensive propellant even more important.
As part of this long-term planning, SpaceX will be using methane in its future rockets, beginning with the Raptor upper-stage engine. The technology will then migrate through the rest of the flight systems as development proceeds.
The video below is of Musk's complete lecture and Q&A session.
Source: Royal Aeronautical Society via Flight Gobal
