Debate Over NASA's Heavy Lift Space Launch System Heats Up

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In an apparent response to a Wall Street Journal op-ed piece calling for the cancellation of NASA's heavy lift Space Launch System, Alabama Sen. Richard Shelby vowed to defend funding for that project,according to

Call for Space Launch System cancellation in favor of more support for commercial space

The Wall Street Journal op-ed had called for the cancellation of the Space Launch System, the heavy lift rocket that NASA is developing to send human astronauts beyond low Earth orbit starting in the next decade. The authors, Robert Walker, a former representative, and Charles Miller, a former NASA adviser, suggested that commercial space companies could develop such rockets at a fraction of the cost of what it would take NASA to build them. The op-ed's asserted that the SLS was not needed.

Shelby pushes back

Shelby, in whose state NASA's Marshall Space Flight Center resides, vowed to fight to keep the Space Launch System funded, according to He suggested that the commercial options under NASA's commercial crew program are largely funded by taxpayers' money. He also stated that the SLS is needed to preserve American leadership in space. Shelby praised the work NASA employees and contractors are doing to build the SLS at Marshall.

Space Launch System compared to commercial options

According to NASA, the Space Launch System will be capable to taking 70 metric tons to low Earth orbit in its first version, to be flight tested in 2017. Eventually the SLS will be capable of flying 130 metric tons to LEO. By contrast, the most powerful rocket being developed by a commercial company is the SpaceX Falcon Heavy, which the company states will be capable of taking 53 metric tons to low Earth orbit.

Heavy lift vs. fuel depots

While the Wall Street Journal op-ed does not mention it, supporters of attempting to conduct space exploration with smaller, commercial craft tout the idea of using space-based fuel depots to compensate for the lack of a heavy lift launcher. The idea is that multiple launches of fuel to an orbiting fuel depot by smaller, commercial launchers would take place. Then an exploration spacecraft would be launched, would top fuel off at the depot, and then proceed on its way. Since the need to develop a heavy lift launcher would be eliminated, according to an article in the New York Times, the fuel depot architecture would result in cost savings, citing an internal NASA study. But because each mission would require many multiple launches, the missions would become more complex and risky.

Former NASA officials defend heavy lift

Former NASA Administrator Mike Griffin and former NASA Associate Administrator Scott Pace wrote a piece in Space News defending the Space Launch System and calling attention to what they view as technical and economic hurdles inherent in relying on fuel depots in the near term. They suggested that claims of low-cost launches by commercial space companies should be met with suspicion. They also cited the tendency of cryogenic fuel to "boil off" when stored in space. They did suggest, however, that heavy lift plus space based fuel sources (say, derived from lunar ice) would eventually become practical and desirable.

Mark R. Whittington is the author of Children of Apollo and The Last Moonwalker. He has written on space subjects for a variety of periodicals, including The Houston Chronicle, The Washington Post, USA Today, the L.A. Times, and The Weekly Standard.

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