Increased tension between the U.S. and Russia following last week’s shootdown of a Malaysia Airlines 777 is adding fuel to U.S. efforts to consider an alternative to the Russian-made RD-180 rocket engine, the U.S. Air Force’s top space officer says.

The RD-180 helps launch national security space assets into orbit by powering the first stage of the United Launch Alliance (ULA) Atlas V rocket.

"There is no indication right now that the supply will be interrupted," notes Gen. William Shelton, head of Air Force Space Command. "It’s been business as usual. It’s been relatively calm. The events of the last couple of weeks, however, give us even more pause and certainly call into question the possibility of continued supply of RD-180 engines. Whether this turns into a new engine development that’s a government program, or a public-private partnership or a technology maturation program, it is not yet clear."

Still, Shelton is seriously investigating possibilities, including accelerating production of ULA’s other rocket for launching national security payloads – the Delta IV Heavy. Shelton says he asked the Space and Missile Systems Center on July 21 what would be required to increase production of the Delta IV from a contractual perspective. "It may be time to start thinking seriously about that," Shelton says.

If the supply of RD-180 engines is disrupted, the U.S. has already looked at adjusting the current manifest of space launches. The U.S. has 15 RD-180s in its inventory, expects two more will be delivered in August and is waiting for another three in October.

At a minimum, the effect of mitigating restrictions on the use of RD-180s would cost $1.5 billion to $5 billion, depending on how the Russians might restrict the use of the engines.

"It is really about launch storage costs," Shelton says. "It is very expensive to store a satellite longer than anticipated."

All along, the U.S. was looking for a way to mitigate reliance on the RD-180, from co-production of the engine to its eventual strategy of stockpiling a two-year supply.

"Here we are at what appears to be a rainy day – at least potentially. So now, what’s our mitigation strategy beyond stockpiling," Shelton asks. "For our industrial base, for our leadership in liquid rocket propulsion, it would be interesting to do a national program on a new engine to regain what I think is required world leadership in liquid rocket propulsion."