Launcher developer SpaceX is designing a new engine for a new rocket, larger than the Falcon 9 that NASA expects to become a mainstay of its Earth orbit operations.

Elon Musk, the Silicon Valley entrepreneur who successfully parlayed the fortune he earned founding PayPal into launch systems developer SpaceX, said the new engine would not be based on the 160,000lb-thrust (712kN) Merlin 1 series that powers Falcon 9.

Musk said the new rocket, which he calls MCT, will be "several times" as powerful as the 1 Merlin series, and won't use Merlin's RP-1 fuel. Beyond adding that it will have "a very big core size", he declined to elaborate, promising more details in "between one and three years".

Musk declined to say what 'MCT' stands for, and declined to answer further questions on the project.

During an April interview, SpaceX president Gwynne Shotwell discussed a project with similar characteristics, describing engines with "more than 1.5 million pounds" of thrust.

"We've looked at a number of different architectures, we haven't honed in on one just yet," said Shotwell. "I think we're still considering vehicle diameter. But the vehicle diameter is large, 7m minimum, multiple engines. These are big rockets."

She further noted that the company was examining grouping several of the engines together, as SpaceX has done with the current Falcon 9 rocket.

Falcon 9 has nine Merlin 1 engines grouped together into a single core. Falcon 9 Heavy, three cores bolted together, is scheduled for launch in early 2013 and designed to lift 53t to low-Earth orbit - twice the payload of the Boeing Delta IV Heavy that is currently the most powerful rocket flying.

Shotwell said a possible payload range of the new rocket is 150-200t to low Earth orbit (LEO). A vehicle of that size would easily eclipse NASA's proposed Space Launch System, which will eventually be capable of launching 130t to LEO, making SpaceX's potential vehicle the most capable ever built by a wide margin.

Source: Flight International