Under the NASA Authorization Act of 2010 the Obama administration ordered the agency to build a heavy-lift launch vehicle (HLV), dubbed the “Space Launch System” or SLS. The goal is an initial capability of putting 70-100 tons in low Earth orbit (LEO), increased to 130 tons by the end of 2016. NASA was allotted $6.9 billion from 2011 to 2013 for development, and given 90 days from the date the legislation was enacted to provide a detailed report of the vehicle design. At the end of January NASA presented its report to the U.S. Congress, telling them their demands aren’t possible and that the agency needs more money and time.
The report states:
Guidance from the Administrator has established three principles for development of any future systems for exploration. These systems must be affordable, sustainable, and realistic. To date, trade studies performed by the Agency have yet to identify heavy-lift and capsule architectures that would both meet all SLS requirements and these goals. For example, a 2016 first flight of the SLS does not appear to be possible within projected FY 2011 and out year funding levels.
Currently, our SLS studies have shown that while cost is not a major discriminator among the design options studied, none of the design options studied thus far appeared to be affordable in our present fiscal conditions, based upon existing cost models, historical data, and traditional acquisition approaches.
The report summary did not gone down well with Congress. In response, Senate Commerce Committee members released a statement reminding NASA that the requirements put forth in the authorization act were not optional. “We appreciate NASA’s report and look forward to the additional material that was required but not submitted. In the meantime, the production of a heavy-lift rocket and capsule is not optional. It’s the law. NASA must use its decades of space know-how and billions of dollars in previous investments to come up with a concept that works. We believe it can be done affordably and efficiently - and, it must be a priority.”
Jeff Foust, editor and publisher of The Space Review reports,
The senators argued in their report that NASA should focus on existing, shuttle-derived technologies and focus more energies in refining the techniques they use to manage the program, rather than study new technologies—as NASA is currently doing with a series of trade studies awarded late last year to 13 companies.
The shuttle-derived technology that many believe NASA can build is called a Shuttle Side-Mount (SSM), which places the payload and the main engines on the side of the vehicle similar to how the space shuttle is mounted on the side of the external tank. This design would replace NASA’s original concept being built under the Constellation program, Ares V; the program was canceled by the Obama administration. Paul D. Spudis, a senior staff scientist at the Lunar and Planetary Institute, writes on the website of Air & Space magazine,
It resurrects an old concept of replacing the Shuttle orbiter on the existing stack with a payload fairing and engine pod. This configuration, called Shuttle Side-Mount (updated from the old “Shuttle-C” concept) was not considered by the HEFT study team, but meets the specific language of the new authorization. The advantage of SSM is that, as it is a minimal modification of the existing stack, it uses all of NASA’s existing launch and processing infrastructure - launch pads, mobile crawlers, scaffolding in the VAB and fabrication facilities in Michoud and Utah. SSM initially carries about 80 metric tons (70 (63.3 metric) to 100 (90.7 metric) tons) and can be stretched to meet the 130 ton (118 metric tons) legal requirement with minimal modification (for example, adding 5-segment (instead of 4-segment) Solid Rocket Boosters, 4 Shuttle Main Engines, extended External Tank). So in fact, SSM meets all the technical, budgetary, safety and schedule requirements set out in the NASA Authorization Act of 2010.
Yet, a larger issue that Spudis points out is that it’s a “fool’s errand to design architectures and new space vehicles if you do not know what your mission is.” He writes, “You can design and build a space system without an objective but as it must satisfy many different purposes, it tends to not satisfy any of them particularly well.”