Relevé de déclarations de Space X

Ci-dessous des extraits parmi les plus éclairants d’articles et de déclarations au sujet du MCT. Au-delà des informations sur la conception, l’insistante communication sur ce projet, clairement présenté comme la véritable raison d’être (l’objet) de la société SpaceX, démontre l’importance qu’y attache Elon Musk. La déclaration de Juillet 2013 indique d’ailleurs bien qu’à ses yeux l’activité sur le marché des lancements est avant tout un moyen de le promouvoir, à travers les développements techniques qu’elle autorise mais aussi en vertu de la croissance du poids financier de l’entreprise qu’elle entraîne.

Novembre 2012

(source : space.com)

Accompanying the founders of the new Mars colony would be large amounts of equipment, including machines to produce fertilizer, methane and oxygen from Mars’ atmospheric nitrogen and carbon dioxide and the planet’s subsurface water ice. The Red Planet pioneers would also take construction materials to build transparent domes, which when pressurized with Mars’ atmospheric CO2 could grow Earth crops in Martian soil. As the Mars colony became more self-sufficient, the big rocket would start to transport more people and fewer supplies and equipment.

Musk’s architecture for this human Mars exploration effort does not employ cyclers, reusable spacecraft that would travel back and forth constantly between the Red Planet and Earth — at least not at first. « Probably not a Mars cycler; the thing with the cyclers is, you need a lot of them, » Musk told SPACE.com. « You have to have propellant to keep things aligned as [Mars and Earth’s] orbits aren’t [always] in the same plane. In the beginning you won’t have cyclers. »

Musk also ruled out SpaceX’s Dragon capsule, which the company is developing to ferry astronauts to and from low-Earth orbit, as the spacecraft that would land colonists on the Red Planet.

When asked by SPACE.com what vehicle would be used, he said, « I think you just land the entire thing. »

Asked if the « entire thing » is the huge new reusable rocket — which is rumored to bear the acronymic name MCT, short for Mass Cargo Transport or Mars Colony Transport — Musk said, « Maybe. » Musk has been thinking about what his colonist-carrying spacecraft would need, whatever it ends up being. He reckons the oxygen concentration inside should be 30 to 40 percent, and he envisions using the spacecraft’s liquid water store as a barrier between the Mars pioneers and the sun.

The fully reusable rocket that Musk wants to take colonists to Mars is an evolution of SpaceX’s Falcon 9 booster, which launches Dragon. « It’s going to be much bigger [than Falcon 9], but I don’t think we’re quite ready to state the payload. We’ll speak about that next year, » Musk said, emphasizing that only fully reusable rockets and spacecraft would keep the ticket price for Mars migration as low as $500,000. The Falcon Heavy is still much smaller than Musk’s fully reusable Mars rocket, which will also employ a new engine.

While Musk declines to state what the Mars rocket’s payload capability will be, he does say it will use a new staged combustion cycle engine called Raptor. Because Raptor is a staged combustion engine — like the main engines of NASA’s now-retired space shuttle fleet — it is expected to be far more efficient than the open-cycle Merlin engines used by the Falcon 9.

While the Falcon 9’s engines use liquid oxygen (LOX) and kerosene, Raptor will use LOX and methane. Musk explained that « the energy cost of methane is the lowest, and it has a slight ISP [specific impulse] advantage over kerosene and doesn’t have any of the bad aspects of hydrogen. » (Hydrogen is difficult to store at cryogenic temperatures, makes metal brittle and is very flammable.)

Juillet 2013

(source : The Guardian)

Of course we must pay the bills along the way. So that means serving important customers like NASA, launching commercial broadcasting communication satellites, GPS satellites, mapping, science experiments.

Février 2014

(source : The Daily Caller)

“We need to develop a much larger vehicle, which would be a sort of Mars colonial transport system, and this would be, we’re talking about rockets on a bigger scale than has ever been done before,” Musk explained. “It will make the Apollo moon rocket look small.” And they would have to launch very frequently as well. [reusable]

Mars 2014

(source : NASA Space Flight)

Tom Mueller, head of SpaceX rocket engine development, has his main focus being the development of the reusable Raptor engine. It will use liquid methane and oxygen to achieve 1 million pounds of thrust.

Methane is related to the facts that:

• it could be sourced from Mars;
• it is easier to store and handle than liquid hydrogen;
• at just a 27% more volumetric than the RP-1/LOX combination (the tank and T/W of the engine could be kept at optimal sizes);
• it also holds much better reusability properties on the engine, whereas Kerosene tends to polymerize (coke) and thus requires oxidizer rich combustion, which is quite corrosive and aggressive to the turbopump system. Kerosene also leaves more residues throughout the engine, which might require expensive cleaning and even rebuilding;
• it can be run by preburning the fuel;
• it has basically no coking problems;
• it has much better cooling characteristic;
• and if used in the form of LNG, is the cheapest and most abundant fuel.

Current turbopumps rotate on balls or rolling elements, with the rotation producing heat and wear and tear due to material contact. Hydrostatic bearings use the turbopump’s own fluid to actually float the pump on high pressure liquid. The advantage is the reduction of wear being suffered only during start up, in turn significantly increasing useful life and enabling very long mission duration. However, if you run the turbine with hot gas of the other propellant element (i.e. oxidizer gas with fuel liquid or the other way around), you have a perfectly explosive device. Thus, this technology is best used on engines that have completely separate oxidizer and fuel turbopump systems, in turn eliminating a failure mode by not requiring an interseal.

The breakthrough characteristic is that since each turbine is effectively fed by its own propellant mass, it can have a lot more turbine power. Such power could be used to increase the main combustion chamber pressure and increase the overall performance, or by using cooler gases, providing the same performance as a staged combustion engine but with much less stress on materials and thus significantly reduce material fatigue or weight.

As an added bonus, lower pressures are required through the pumping system, which not only increases the life span, but reduces the risk and effects of a catastrophic failure.

Raptor’s current design is to have 1Mlbf (4,500kN) gas-gas (full flow) liquid methane and oxygen engine, with an isp of 321s at sea level 363s at vacuum.

• Mr. Mueller confirmed nine of these engines would power each 10 meter diameter core of the notional MCT (Mars Colonization Transport). The 9 million pounds of thrust would be more than the first stage of the Saturn V (7.68 million pounds).

SpaceX Co-Founder and Vice President of Propulsion Development Tom Mueller has revealed the company is deep into the development of the first “full flow methane-liquid oxygen” rocket engine. Known as the Raptor, nine of these immensely powerful engines – on one or three cores – will be utilized to send SpaceX’s Super Heavy Lift Launch Vehicle (SHLV) uphill on missions to Mars.