An Obstacle to Flying the Shuttle: A Shortage of Payloads

The Orlando Sentinel points to a problem that shuttle supporters face in attempting to extend flights beyond the four remaining ones that are scheduled:

When asked what they would fly aboard more shuttle missions, NASA officials shrug.

“Right now, we wouldn’t have a list of things to go fly,” said Mike Moses, shuttle-launch-integration manager. “The way we built the [shuttle-launch] manifest was to give station everything it needed to make to 2015 or 2020 without the shuttle flying.”

Despite that assessment, Florida lawmakers are pressuring President Barack Obama to add more shuttle flights as he prepares to host an April 15 space summit at or near KSC. They argue the shuttle is the only reliable U.S. vehicle now capable of launching crew or cargo to the station and are pushing NASA to study what the agency cut from its delivery manifest when the Bush administration announced its plans to retire the shuttle, hoping to find something else that can be taken into space.

“Any serious plan to keep us first in space must involve extending the life of the shuttle beyond 2011,” wrote U.S. Rep. Bill Posey, R-Rockledge, in a letter to Obama last week. “… [it] is more than able to meet our nation’s space demands for the next several years, until a successor is closer to coming online.”

It’s an interesting issue. Unless something radically changes, the plan for ISS servicing after the shuttle retires is as follows:

• Human crews will fly exclusively on the Russian Soyuz until the U.S. fields a shuttle successor;
• Supplies will be launched aboard the Russian Progress, European ATV, and Japanese HTV freighters;
• Resupply from American spaceports will be via SpaceX’s Dragon and Orbital Sciences Corporation’s Cygnus spacecraft, which are now under development;
• NASA will launch crews later in the decade aboard either the Orion spacecraft or commercial alternatives, depending upon whether Congress approves the Administration’s proposal to cancel the Constellation program;
• Russia will field a Soyuz replacement capable of carrying the station’s entire 6-person crew around 2017.

The issue of supply seems to be well in hand with the development of five separate freighter systems. None of these have the lifting capacity of the space shuttles, but between them they should be sufficient to supply the station. What ISS really needs is a return capsule that can carry experiments back to Earth. The Soyuz is far too cramped to carry much more than three astronauts home. The problem will be partially solved when Dragon comes online because SpaceX’s vehicle is designed with down-mass capability in mind.

So if the issue isn’t cargo, then what? It’s probably that the U.S. maintain the ability to fly humans into space independent of Russia. Having the shuttle as a backup for human access makes some sense. However, the Soyuz vehicles have flown for nearly 40 years without a fatality, so from a purely technical standpoint the risk appears manageable even if the solution is not ideal.

The benefits of keeping shuttle flying lie elsewhere. There’s the obvious matter of maintaining jobs. There’s also an issue of national pride. Being forced to rely on Russia for five years (or longer) is a bit embarrassing for a country that landed men on the moon. There’s also the question of what happens with ISS should relations between the United States and Russia turn sour over, say, a conflict in the Ukraine. Nobody says such things publicly, but it’s probably in the back of people’s minds.

The obvious question is how the U.S. could continue to fly the fragile and aging space shuttle fleet for another five to seven years while still being able to fund a replacement system. The cost alone would be daunting; it’s expensive to keep a large standing army employed for perhaps two flights annually. There’s another complication: NASA says that it could take two years before additional external tanks start rolling off the assembly line.

The programmatic risks involved are non-trivial. NASA would risk further delays in bringing the new system online by diverting financial resources to the shuttle program. The more the schedule slips, the longer you have to keep shuttle flying and the more that costs. That, in turn, could lead to more delays and increase the risk of another fatal accident befalling an aging orbiter.

XCOR CEO and Augustine Committee member Jeff Greason said recently that NASA doesn’t have any good options to escape its current predicament. “They all suck.  Tough.  Deal with it,” he said.   I’m not quite as pessimistic, but he’s not that far from the truth.