Expending Reusable Engines: A Good Thing?

One More to Go
Credit: NASA

There were three newsworthy developments regarding reusable engines this week.

First, SpaceX announced something close to firm pricing regarding what flights aboard a Falcon 9-R might cost in the near future. For the record, the reduction, enabled by 9 reusable Merlin 1-d engines that power the vehicle’s first stage, is 30% off the already low published cost.

Second, Blue Origin opened up its facilities to reporters for the first time, mainly to tout progress on the equally reusable BE-4 LNG engine that is at the heart of its booster development plans. If it also happens to lock down the role of providing the power for ULA’s Vulcan roccket, the detachable BE-4 may very well make history as it is plucked from the air over the Atlantic as part of ULA’s rather unique approach to partial reusability.

And then there is NASA, which proudly announced on Thursday that it completed a 500 second test firing of an equally reusable RS-25, (former Space Shuttle Main Engine) which in an odd show of thanks for long service to its country, will be summarily be discarded into the Atlantic Ocean after its flight. Like everything else, it is all a part of the “Journey to Mars.”

As the old saying goes, one of these things is not like the others.

There was of course, a fully expendable and decidedly cheaper to manufacture alternative to RS-25 already in use. That engine is the RS-68 and 68-A which power the ULA Delta IV and Delta Heavy. At one time the RS-68 was penciled in as the powerplant for NASA’s predecessor to SLS, Project Constellation’s Ares V.

What happened?

While the RS-68 has never been “human rated,” Project Constellation got around that issue by sagely following the Columbia Accident Investigation Board’s advice that to the greatest extent practical, crew and cargo should be separated. Thus, crews would launch to orbit on the Ares-1, where they would rendezvous with larger payloads lofted by the Ares V.

Oddly enough, as originally envisioned that booster would have used a fully expendable SSME as well, this time as the second stage engine. When it turned out to be harder to air-start the SSME than cocktail napkin engineering suggested it would, the RS-25 was dropped in favor of the J-2X. Soon enough the whole thing was dropped altogether as the Obama Administration sought to change the nation’s space policy. The SSME won a stay of execution. It was however, all too brief.

The NASA Authorization Act of 2010 saw Congress enthusiastically take on the role of rocket designers par excellence.

From the act:

(a) IN GENERAL.—In developing the Space Launch System pursuant to section 302 and the multi-purpose crew vehicle pursuant to section 303, the Administrator shall, to the extent practicable utilize

— (1) existing contracts, investments, workforce, industrial base, and capabilities from the Space Shuttle and Orion and Ares 1 projects, including

— (A) space-suit development activities for application to, and coordinated development of, a multi-purpose crew vehicle suit and associated life-support requirements with potential development of standard NASA-certified suit and life support systems for use in alternative commercially developed crew transportation systems; and

(B) Space Shuttle-derived components and Ares 1 components that use existing United States propulsion systems, including liquid fuel engines, (emphasis added)  external tank or tank related capability, and solid rocket motor engines; and

(2) associated testing facilities, either in being or under construction as of the date of enactment of this Act.

For the RS-25, the fix was in. In the final analysis, the Space Launch System got an entirely new tank, newly upgraded and now fully expendable solid rocket boosters, and the nation’s remaining supply of flight proven RS-25’s.

Perhaps the NASA hype is right, and use of the remaining SSME’s on SLS is good and worthy thing.

It sure doesn’t feel that way.

Here is the NASA release:

“NASA successfully tested the first deep space RS-25 rocket engine for 500 seconds March 10, clearing a major milestone toward the next great era of space exploration. The next time rocket engine No. 2059 fires for that length of time, it will be carrying humans on their first deep-space mission in more than 45 years.

“What a great moment for NASA and Stennis,” said Rick Gilbrech, director of NASA’s Stennis Space Center in Bay St. Louis, Mississippi. “We have exciting days ahead with a return to deep space and a journey to Mars, and this test is a very big step in that direction.”

The hot fire marked the first test of an RS-25 flight engine for NASA’s new Space Launch System (SLS), being built to carry humans on future deep-space missions, including an asteroid and Mars. Four RS-25 engines will help power the SLS core stage.

The engines used on initial SLS missions are flight engines remaining from the Space Shuttle Program, workhorse engines that are among the most proven in the world, having powered 135 space shuttle missions from 1981 to 2011. For the SLS vehicle, the engines will fire at 109 percent thrust level and provide a combined two million pounds of thrust.

“Not only does this test mark an important step towards proving our existing design for SLS’s first flight,” said Steve Wofford, engines manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama, where the SLS Program is managed for the agency, “but it’s also a great feeling that this engine that has carried so many astronauts into space before is being prepared to take astronauts to space once again on SLS’s first crewed flight.”

NASA and Aerojet Rocketdyne, the prime contractor for RS-25 engine work, conducted a series of developmental tests on the RS-25 engine last year at Stennis, primarily to validate the capabilities of a new controller – or, “brain” – for the engine and to verify the different operating conditions needed for the SLS vehicle. Following today’s firing, Stennis and Aerojet Rocketdyne will conduct a development engine series to test new flight engine controllers and will continue to test RS-25 flight engines.

In addition, the agency is preparing the B-2 Test Stand at Stennis to test the SLS core stage that will be used on the rocket’s first flight, Exploration Mission-1. Testing will involve installing the flight core stage on the B-2 stand and firing its four RS-25 rocket engines simultaneously.

“One more powerful step forward accomplished on the SLS journey,” said Ronnie Rigney, RS-25 project manager at Stennis. “It really feels great to be part of such an important program in our nation.”

End release.

What do you think?