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U.S. Senate-prescribed Heavy-lifter Looks Like Ares 5
WASHINGTON — The bill, S. 3729, was drafted and approved by the Senate Commerce, Science and Transportation Committee in July and passed by the full Senate Aug. 5.
In a report accompanying S. 3729 issued a few days later, senators state that regarding the heavy-lift rocket, “the most cost-effective and ‘evolvable’ design concept is likely to follow what is known as an ‘in-line’ vehicle design, with a large center tank structure with attached multiple liquid propulsion engines and, at a minimum, two solid rocket motors composed of at least four segments being attached to the tank structure to form the core, initial stage of the propulsion vehicle.”
The report notes that the committee “will closely monitor NASA’s early planning and design efforts to ensure compliance with the intent of this section” of the bill.
Viewed by many as a compromise between advocates of continuing NASA’s Moon-bound Constellation program and Obama’s plan to abandon that effort, the bill would extend the life of the international space station through 2020 and authorizes an additional space shuttle mission in 2011. The bill also supports the president’s desire to invest in private space taxis capable of one day transporting astronauts in low Earth orbit.
But whereas Obama seeks to spend the next five years studying options for a heavy-lift launcher with a kerosene-fueled main engine that could send astronauts to an asteroid around 2025, the Senate bill directs NASA to continue much of the work already under way on Constellation, which features the Ares rockets utilizing shuttle-heritage hardware and the Orion crew capsule. The bill — shaped largely by lawmakers whose states will lose jobs if the shuttle is retired with no government-owned follow-on in the pipeline — would require NASA to immediately begin work on the shuttle-derived heavy-lifter and crew capsule incorporating space shuttle technologies and Ares and Orion design work completed to date.
In addition, an amendment to the bill adopted on the Senate floor Aug. 5 would give NASA just 90 days to complete a comprehensive study detailing how it would meet the architectural requirements outlined by lawmakers, including supporting data and analysis of the new space launch system.
Doug Cooke, NASA associate administrator for exploration systems, said the agency would work within administration and congressional guidelines but would prefer to see more flexibility in a NASA authorization in terms of vehicle design.
“I think we would negotiate to broaden the trade space,” Cooke said Aug. 11 following a NASA-sponsored conference here on near-Earth object exploration. “We have done some very objective heavy-lift studies over the last number of months along those lines. We’ll operate within the constraints we’re given, but we will try to influence the conversation to make sure we don’t preclude possible answers that might be the optimum overall.”
Initially, the Senate-prescribed launcher would need to lift payloads weighing between 70 metric tons and 100 metric tons into low Earth orbit, “lift the multipurpose crew vehicle, and serve as a backup, if necessary, for [space station] cargo or crew transportation,” states the committee’s report, which also says the vehicle should be evolvable to handle even larger payloads. The Ares 5, in contrast, is designed to lift more than 180 metric tons.
Bill Adkins, a space industry consultant here, questioned whether the language in the report is backed by analysis.
“It’s very prescriptive in telling them what they want the performance and schedule of the rocket to be, and to a large degree how much it will cost, and it’s not clear there’s any in-depth work that’s been done to back up whether those things are realizable within those constraints,” Adkins said Aug. 11.
Adkins said the new space launch system could pose design issues for Orion, which is under development by Lockheed Martin Space Systems of Denver.
In addition to an emphasis on leveraging existing space shuttle infrastructure and Constellation work, the bill limits NASA’s ability to terminate existing contracts and urges the agency to retain critical skills and capabilities “in the fields of liquid and solid engines, large diameter fuel tanks, and other rocket propulsion hardware skills and capabilities.”