Key Blue Origin officials have begun to drop hints about the imminent hot-fire test of the company's new rocket engine, the BE-4. Jeff Bezos recently said to expect a full-scale engine test "in the coming weeks." And last Wednesday the company's director of business development, Brett Alexander, said during a Center for Strategic and International Studies panel discussion the test "was coming soon."

For many people, a rocket engine is just a rocket engine. But Blue Origin's new engine is a big deal for a number of reasons, not the least of which is its 550,000 pounds of thrust at sea level, more powerful than a space shuttle main engine, which had 418,000 pounds of thrust. Beyond the brawn, however, there are other reasons to anticipate a successful test.

A new kind of engine

During a tour of his rocket factory in Kent, Washington, last year Bezos explained the philosophy behind the BE-4 engine. "In principle, rocket engines are simple, but that’s the last place rocket engines are ever simple," he said. Nonetheless, Blue Origin sought to make an engine that was not too complex, nor one that required ultra-premium materials. The designers didn't want to create a work of art that pushed the limits of engineering—rather, they wanted a reliable workhorse that could be flown again and again, perhaps as many as 100 times as the company pushes the boundaries of reusable spaceflight.

Blue Origin began developing the engine in 2012 for its own purposes, but in 2014 the rocket company United Launch Alliance came to them about a replacement engine for its next-generation rocket, Vulcan. The company, which launches the majority of US military payloads with its Altas V rocket, needed to move on from its use of the Russian RD-180 engine, as the national security community was no longer comfortable buying from Russia during a time of rising tensions.

Blue Origin

Blue Origin

Blue Origin

Blue Origin

Blue Origin

Blue Origin

Blue Origin

Blue Origin

Blue Origin

The RD 180 is a very high-performance engine, operating at extreme temperatures and pressures. Higher pressures translate into marginally more performance but at a high cost of development time, money, and uncertain reusability. “Our strategy is, we like to choose a medium-performing version of a high-performance architecture," Bezos said. "The RD-180 is both—a high-performing version of a high-performance architecture. That’s a very challenging engine to develop, and it really complexifies everything. With a lower pressure, you can still get very high performance."

As a result of its design philosophy, Bezos said the BE-4 engine should cost about 30 to 40 percent less than the RD-180 engine. It should also, in theory, be more durable and capable of reuse without worrying about the failure of components due to the extreme pressures and temperatures inside an RD-180 engine, which is flown once and then discarded.

The BE-4 also uses a new kind of fuel for a first-stage engine, liquid methane. Whereas hydrogen has a higher specific impulse (which is good), it is difficult to work with and requires large and bulky tanks to store because it is not dense. In some ways, because of its ease of use and potential for harvest on worlds such as Mars, methane is the rocket fuel of the future. When Elon Musk sought to design his Raptor engines, for his rocket to transport humans to Mars, he settled on liquid methane-liquid oxygen fuel as well.

Prove doubters wrong

Earlier this month Ars first reported on efforts by some Congressmen to nudge United Launch Alliance away from the BE-4 engine toward a different engine being developed by Aerojet Rocketdyne, a traditional aerospace company with a legacy of developing large, powerful rocket engines. The BE-4 engine "is unproven at the required size and power," the letter stated. The Congressmen seemed to be pushing Aerojet because the company had promised to produce its AR-1 engine in Huntsville, Alabama, creating 100 new jobs near NASA's Marshall Space Flight Center.

This is the kind of bias that SpaceX has had to fight for the better part of a decade, as it sought funding from NASA, US military, and other government agencies for its lower-cost Falcon 9 rocket. Among some in Congress, there remains a general mistrust of "new space," a newer generation of aerospace firms whose express goal is to lower the cost of access to space, rather than to just win the next government contract.

The Center for Strategic & International Studies recently reported on five different options the US Department of Defense had as it seeks to transition away from the RD-180 rocket engine for national security launches to one made in the United States. If the highest priority factors are minimizing costs and supporting the long-term competitiveness of the US space launch industrial base, the report said the Air Force should pick either the BE-4 or AR-1 engine. Moreover, if the BE-4 hot fire tests are successful, the report stated, the Blue Origin engine seems the obvious choice because it would cost less, is almost fully paid for by the private sector, and will be ready sooner.

If successful, then...

Successfully testing the BE-4 engine would therefore, at a single stroke, both prove that "unproven" companies can get the job done in space and validate the use of a relatively untested new rocket fuel—methane—in a large engine. It would also lead to a blue-blood rocket company, United Launch Alliance, choosing the upstart BE-4 engine over that from a traditional aerospace company, Aerojet Rocketdyne.

A proven engine would also go a long way toward making Blue Origin's New Glenn rocket a reality. This reusable, heavy lift booster, powered by seven BE-4 engines, could fly by 2020 and become a major player in the global satellite launch industry—and may also eventually bring hundreds of human beings into orbit.

The promise of the upcoming test, then, is pretty straightforward. SpaceX has long stood alone as a new space outlier in the global launch community, running up against traditional aerospace companies and government launch businesses in Russia, China, and Europe. It is possible to dismiss one tech entrepreneur dreaming about reusable rockets as a naive optimist or rich, rocket boy pretender. But it is much harder to dismiss two of them who have both developed their own engines.