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NASA intends to use Delta 4 upper stage on moon flights

Posted: May 15, 2012

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NASA says Boeing is best equipped to provide two cryogenic upper stages derived from the Delta 4 rocket to power the agency's Orion capsule on a test flight around the moon in 2017 and send astronauts on a voyage to lunar orbit in 2021, according to documents posted on a federal government procurement website.

Artist's concept of the Space Launch System. Credit: NASA
The space agency issued a sole-source award to Boeing on April 27 for a feasibility study on the compatibility of the Delta Cryogenic Second Stage, or DCSS, with the Space Launch System, a heavy-lift rocket designed to dispatch astronaut crews on expeditions to the moon, asteroids, Mars, and other deep space destinations.

The $2.4 million contract also covers an evaluation of the upper stage against NASA's human-rating requirements. Boeing will also determine what modifications are needed for the Delta 4 second stage to fly with the Space Launch System.

The Delta 4's hydrogen-fueled upper stage includes an RL10B-2 engine built by Pratt & Whitney Rocketdyne, or PWR. The engine generates 24,750 pounds of thrust and has flawlessly flown on all 19 Delta 4 missions to date.

Space agency officials declined comment on the upper stage acquisition until they formally select a procurement strategy.

But NASA released a justification document for the sole-source study award to Boeing, outlining internal market research and a public request for information solicitation which indicated the Delta 4 second stage is the only propulsion system available to meet NASA requirements.

"The DCSS appears to be the only solution mature enough to meet the requirements of the government within the timeframe needed to support the government's need date for initial delivery," NASA officials wrote in the justification document.

In a presolicitation notice posted May 3 on the Federal Business Opportunities website, NASA wrote it "determined that the DCSS is the only means available to support the immediate in-space propulsion needs of the SLS."

Boeing maintains the design data and manufacturing skills to modify the Delta 4 upper stage for the Space Launch System, according to NASA. United Launch Alliance, a partnership between Boeing and Lockheed Martin, currently builds the Delta 4 and Atlas 5 rocket fleets.

NASA is accepting proposals and quotes from other rocket contractors through May 18, and the agency will use the data to determine whether to conduct a competitive procurement for the SLS upper stage.

File photo of a Delta 4 second stage. Credit: NASA
The interim cryogenic propulsion stage for the first Space Launch System flight must be delivered to the Kennedy Space Center by the end of 2016 for an unmanned test launch of the mega-rocket and 26.5-ton Orion spacecraft in 2017. The flight will send the Orion capsule on a free return trajectory around the moon and back to Earth for a splashdown landing in the ocean.

"We're in a very constrained budget environment, so it's going to have to come in on mark and show up in time for that first flight," said Todd May, NASA's Space Launch System program manager.

NASA's proposed budget for the SLS program calls for nearly $1.4 billion per year through fiscal year 2017.

The second mission of the SLS and Orion vehicle, tentatively scheduled for 2021, will launch an astronaut crew into orbit around the moon for three or four days, according to current plans.

The RL10B-2 engine on the first two SLS flights would inject the Orion spacecraft into low Earth orbit, then accelerate the capsule on a course toward the moon. NASA says the upper stage engine must be capable of igniting three times on each SLS mission.

The J-2X engine will ultimately fly on the upper stage on future missions of NASA's Space Launch System.

But NASA has put development of the J-2X engine on the back burner while engineers race to ready the Space Launch System for its initial test launch before the end of 2017.

The launches in 2017 and 2021 will use a version of the Space Launch System designed to lift at least 70 metric tons, or 154,000 pounds, into low Earth orbit. The earliest flights will feature a rocket standing up to 320 feet tall powered by a 27.5-foot diameter core stage and twin solid rocket motors derived from motors flown on the space shuttle.

The colossal rocket's cryogenic core stage will be propelled by four space shuttle main engines, known as RS-25D/E engines, provided by PWR. The engines are left over from the space shuttle program.