Heavy Development
marginal mission capture for NEO missions.”
also is playing in the ongoing heavy-lift options studies.
Although it listed only cost-comparisons rather than
That test, in turn, could inform a final configuration
absolute figures, preliminary estimates in the Marshall
decision and, if the J-2X is selected for the upper stage,
report identify a side-mounted shuttle-derived carrier as
could be followed with more tests under the new heavy-
the fastest and cheapest option, but also the most
lifter program, Cooke says.
dangerous for a crew and the least capable. Of the four options selected for additional study, “the total cost for the [initial human flight] for the large RP vehicles and the LOX/[liquid hydrogen] vehicles are approximately equivalent,” the study found. “However, if a flight rate of four per year is assumed, there is a small recurring costsavings for the RP vehicles. Above four flights per year, LOX/[liquid hydrogen] plus solids compare more favorably than most RP configurations.” Development costs were lowest for the variant using the RS-65E and five-segment solid-fuel boosters, while the RP-fueled variant had the lowest ground operations costs. For schedule, the study found initial flights possible in the 2017-18 time frame. Flight rates for human missions could be increased and costs lowered if the heavy-lifter were used for science and national security missions, as well. Based on the work so far, no variant stands out as a clear best solution for all missions. The Marshall planning office must work through how the options stack up against the directions included in the authorization bill. And it remains to be seen what the congressional committees that appropriate the necessary funds within the $19-billion topline will do. While those committees in general have said they will follow the authorization language, which represents a compromise with represents a compromise with the White House on the original NASA budget request that would not have started heavy-lift development until 2015, the exact way forward in unclear, with lawmakers in recess. Until there is a Fiscal 2011 appropriations bill for NASA, the agency is bound by Fiscal 2010 appropriations language requiring it to continue to work on the Constellation program. Cooke says there is a good chance that will enable a first test early next year of the Saturn-heritage J-2X upper-stage engine being developed for the Ares I and Ares V upper stages, which
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Flight Safety Quarterly, Winter 2010
Feom Aviation Week & Space Technology Oct 11, 2010