In its report to Congress earlier this week, NASA concluded that its “Reference Vehicle Design” for a heavy-lift vehicle, using five-segment SRBs and five SSMEs on the external tank based core stage, would not fit into the cost and schedule requirements of the NASA authorization bill. The report, though, did not indicate by how much that proposed design misses the mark, something Sens. Kay Bailey Hutchison and Bill Nelson criticized a letter to NASA administrator Charles Bolden on Thursday. Just how much would that HLV cost to build?
In a post on his blog at Air & Space magazine, Paul Spudis finds some answers in the form of a preliminary cost and schedule assessment performed by NASA last year. A 100-metric ton HLV like the one mentioned in the NASA report this week, with five-segment SRBs and five SSMEs, would cost $14.9 billion to develop; tacking on an upper stage to increase its lift to 130 metric tons would add $2 billion to the development cost. The 100MT version would be ready by the beginning of 2018, one year past the authorization bill’s deadline, while the 130MT version would not be available until three years after that.
Spudis uses his post to advocate for an alternative concept also studied last year: a shuttle-derived sidemount vehicle. That vehicle could lift 70-100 metric tons, according to the NASA study, but cost only $7.6 billion to develop and be ready by the authorization act’s deadline of the end of 2016. That cost estimate would appear to fit easily within the authorization act’s budget profile as well, which provides $6.9 billion through FY2013. Spudis adds that a sidemount vehicle could be upgraded to meet the ultimate goal of 130 tons through the use of five-segment SRBs, four SSMEs, and an extended tank.
“Curiously, the new NASA Authorization Act of 2010 was remarkably specific about the requirements of a new heavy lift vehicle the agency had been directed to build,” Spudis writes. However, the report language accompanying the bill was also very specific, in such a way that works against a sidemount concept. As noted here back in August, the report accompanying the Senate version of the authorization bill–the version passed by the House and signed into law in the fall–was very specific about the kind of HLV they were looking for: (emphasis added)
> The Committee anticipates that in order to meet the specified vehicle capabilities and requirements, 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 Committee will closely monitor NASA’s early planning and design efforts to ensure compliance with the intent of this section.
The HEFT concepts included in the NASA report, as well as the Jupiter designs proposed by the DIRECT team, would satisfy that language. A sidemount concept, though, not being inline, would violate that language. Report language does not contain the force of law, but not being responsive to it would likely raise questions among those in Congress who got that section into the report (as noted by the “closely monitor” language in the same section). So what exactly did members who inserted that language in the bill have in mind, if at least the existing NASA HEFT HLV concepts technically satisfy the report language but fall short on cost and schedule?