The RD-180 engine powers ULA's workhorse Atlas 5 rocket. Credit: NASA

The U.S. Air Force and United Launch Alliance have a problem with the timetable for enforcing the congressionally imposed ban on the future use of Russian-made engines in launches of U.S. national security space missions.

The ban, enacted following Russia’s annexation of Crimea last year, will effectively shut ULA’s most competitive rocket, the Atlas 5, out of what soon will become a hotly contested military market with the arrival of SpaceX’s Falcon 9.

The question is not whether the Atlas 5’s Russian-built main engine, the RD-180, must go, but when.

ULA and the Air Force argue that as currently written, or at least interpreted by the service’s lawyers, the legislation leaves the company with just five RD-180s for upcoming competitive rounds of the Evolved Expendable Launch Vehicle program. The two are asking for legislative relief to keep Atlas 5 in the game until ULA’s planned replacement becomes available in 2020 or 2021.

Congress appears for the moment to be standing firm, although some members are sympathetic to ULA. Lawmakers appropriated $220 million in 2015 to develop an RD-180 replacement to be ready by 2019, but the Air Force doesn’t seem to be in any rush to spend the money.

Meanwhile, ULA has teamed with the secretive Blue Origin venture bankrolled by founder Jeff Bezos to develop the BE-4, a new liquid-methane-fueled engine for an Atlas 5 replacement dubbed Vulcan. It is unclear whether Blue Origin or ULA intend to compete for a share of the government funding.

Aerojet Rocketdyne, on the other hand, has made no bones about its need for government funding to develop its own proposed RD-180 replacement, the AR-1, which the company says can be flight ready by 2019. AR-1 is ULA’s backup choice.

SpaceX argues, correctly, that ULA does in fact have a rocket eligible to launch military payloads in the Delta 4, which is powered by the Aerojet Rocketdyne-built RS-68 main engine. But it’s also true that the Delta 4, which costs some 30 percent more than the Atlas 5, cannot match the Falcon 9 on price, and ULA says it plans to phase out all but the heavy-lift variant of that vehicle over the next few years.

There are several competing interests at play in this extremely complex matter, but the needs of the U.S. military and taxpayer should come first. Which is why some modification of the RD-180 ban is warranted.

It’s true that ULA and its parent companies, Boeing and Lockheed Martin, are largely responsible for ULA’s predicament. They waited far too long to take SpaceX’s competitive threat seriously and ULA now finds itself in the unlikely role of underdog playing catchup. Boeing and Lockheed Martin have treated ULA as a cash cow, profiting handsomely from the venture even as some of its most important customers complained loudly about the high cost of launch.

And of course it’s not SpaceX’s fault that the Delta 4 cannot compete with Falcon 9.

But it’s not the American taxpayers’ fault either.

The ULA experience has painfully demonstrated why monopolies are problematic, and the Air Force is right when it says that forcing the company to compete with the Delta 4 will effectively trade one monopoly for another. Moreover, there are satellites in the Air Force portfolio that would have to launch on a triple-core heavy-lift rocket — either the Delta 4 Heavy or SpaceX’s soon-to-debut Falcon Heavy — if Atlas 5 becomes unavailable.

To be sure, there are many questions swirling around Vulcan. For openers, ULA says the rocket can be developed and built without government funding.

We’ll see.

Also unclear is whether the commercial launch market is big enough to justify what likely would be at least a $2 billion investment in Vulcan. Winning future commercial business is an integral part of ULA’s strategy, because government demand tends to be cyclical and may not be sufficient by itself. Remember, the ULA monopoly had to be created in the first place because Boeing, Lockheed Martin and the Air Force badly overestimated the size of the commercial launch market, funding two new rockets when there was barely room for one.

Finally, going with the BE-4-powered Vulcan appears on the surface to be a gamble. Relatively little is known about Blue Origin — the privately held company prefers it that way — and Congress is ready to fund a new engine whose likely builder, Aerojet Rocketdyne, is a known quantity with a more than 50-year heritage in this business.

But this is the path ULA has chosen and, as Lt. Gen. Ellen Pawlikowski, military deputy to the assistant secretary of the Air Force for acquisition, put it, the government has little to gain by rushing ahead with a new engine that nobody wants. This is especially true when the private sector appears willing to take on this investment.

Gen. Pawlikowski says the Air Force wants two launchers at its disposal, notwithstanding the fact that it has lived for years with monopolies for its different payload classes. The Air Force plans to use the engine funding it has available to do some technology work, to be followed by public-private partnerships for rocket development, ultimately leading to the award of two production contracts that would help the providers amortize their development costs over a large number of missions, both government and commercial.

This idea has risks, no doubt about it. In addition to those already mentioned, Russia has threatened to ban RD-180 exports for U.S. military launches. Moreover, lawmakers are legitimately concerned about feeding Russia’s military industrial complex, and some worry that a relaxation of the current RD-180 phaseout timetable will erode U.S. resolve to stop using the hardware.

But it might be riskier still to prematurely force the Atlas 5 out of the national security market. The rocket’s availability ensures competition in the near term, which gives ULA a fighting chance to preserve competition in the long term. Congress absolutely should phase out the RD-180, but on a schedule that does not foreclose this possibility.