Rep. Dana Rohrabacher, R-California, has called on NASA to release analysis on the use of orbital fuel depots as an aid for space exploration. He has sent a letter to former NASA administrator Mike Griffin asking him for help in this.
The idea behind orbital fuel depots is that fuel tanks would be sent into low Earth orbit by commercial space launchers. Then an exploration ship, such as the planned Orion Multi Purpose Crew Vehicle, would be launched separately by another commercial launcher, would dock with a fuel depot, top off its fuel, and then blast out of low Earth orbit to the moon, an asteroid, or some other destination in deep space. The theory is that this architecture would make building a heavy lift launcher such as the Space Launch System unnecessary. Rohrabacher, a support of commercial space, is also a supporter of this approach.
NASA has chosen to go with the heavy lift launcher, something which Rohrabacher would like to find out why. His enlisting Griffin's aid in this undertaking is curious, as the former NASA administrator has rejected the notion of fuel depots as a replacement for heavy lift. He made this very clear in recent congressional testimony. He found the architecture using fuel depots to be inefficient, costly, and overly complex. He also had this to say:
"What is ignored by proponents of propellant depots is that the remaining one-third of the total mass consists of large, complex, heavy, tightly integrated systems whose design and development benefits enormously if they can be launched in one piece, with those pieces as large as possible. This can only be done with a true heavy-lift vehicle, preferably one with the largest possible payload volume as well as payload mass. It is simply the case that in some fields of human endeavor, size does matter. Human space exploration is one of those.
"Finally, a fuel depot requires a presently non-existent technology - the ability to maintain cryogenic fuels in the necessary thermodynamic state for very long periods in space without expending excessive amounts of propellant due to heating and subsequent "boil off". This technology is the holy grail of deep-space exploration, because it is necessary for both chemical- and nuclear-powered upper stages. We should by all means pursue it. But to embrace an architectural approach that requires a non-existent technology at the very beginning of beyond-LEO operations is unwise in the extreme."
Rohrabacher is proposing a curious alliance. The congressman would like to see the NASA fuel depot study because he thinks it might vindicate his view that using smaller rockets in combination with fuel depots would be cheaper and quicker than building a large, heavy lift rocket. Griffin would want to see the study, in the theory goes, because he would feel that the study would support his opinion that fuel depots and smaller rockets would be more expensive and more complex than developing the big rocket.
Griffin's view would seem to be supported by the conclusions of the Augustine Committee which, while suggesting that fuel depots should be tested for future use, also advised that the technology of storing cryogenic fuels in space was too undeveloped to be placed in the critical path for a space exploration program.
There is one other point to consider. NASA delayed the rollout of the Space Launch System design many people suspect because it wanted to sabotage the project, probably on the behalf of the White House. What better way to attack the case for the SLS if it had a favorable report on fuel depots and was able to leak it?
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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