NASA planners have tentatively added an engine to its planned Ares V moon rocket, and increased the length of its shuttle-derived solid-rocket boosters to accommodate a larger hydrogen tank, as early work on lunar surface operations gets under way.
As now conceived, the Ares V will use six Pratt & Whitney Rocketdyne RS-68 engines to power its core stage, and twin five-and-a-half segment versions of the four-segment ATK shuttle solid boosters. Previous Ares V concepts had five RS-68s and twin five-segment boosters that basically matched the first stage of its Ares I crew launch vehicle.
That configuration was "a couple of tons short" of the throw weight needed to get the planned Altair lunar lander and an Orion crew exploration vehicle to the moon, so the agency's exploration launch vehicles office at Marshall Space Flight Center has been considering higher-powered options.
Exploration managers settled on the upgrade configuration during a three-day Lunar Capability Concept Review (LCCR) just concluded that sought to meld inputs on lunar exploration goals from the 14 other nations working with NASA on a "global exploration strategy."
"We confirmed that Constellation's conceptual designs for both Ares V and Altair will enable us to land astronauts and cargo anywhere on the moon and to build an outpost supporting widespread exploration of the lunar surface," said Constellation Program Manager Jeff Hanley. "This extensive review proves we are ready for the next phase: taking these concepts and moving forward to establish mature requirements."
If authorized by senior NASA management later this year, the Phase A work coming up next will define requirements for the vehicles and other elements needed to push human flight operations beyond the International Space Station in low-Earth orbit to an outpost, probably at one of the lunar poles. It will culminate in a systems requirements review tentatively set for 2010.
As currently conceived, the Ares V will be able to deliver more than 156,600 pounds to the moon, according to NASA. With its size limited by the height of the doors in the Vehicle Assembly Building at Kennedy Space Center, it will stand some 381 feet tall in the current concept. The J-2X engine in development to power the Ares I upper stage will also power the Ares V upper stage - known as the Earth Departure Stage - that will drive the Altair and a four-seat Orion to lunar orbit.
Although the extra half-segment on the solid-rocket boosters will add some lift to the Ares V, its main contribution will be to raise the structural pass-through that holds the solid boosters to the core stage. That, in turn, will allow a larger liquid hydrogen tank to fit under the pass-through to keep the RS-68B engines burning longer.