It’s often said that NASA needs to develop a superheavy lift rocket, such as the Congressionally-mandated Space Launch System, to avoid orbital assembly costs.

An unspoken (and unproven) assumption is that orbital assembly costs will exceed the development costs of a new rocket.

Assuming that assumption is actually true, there’s another question that planners should ask themselves: “Do we believe it will never be necessary to do orbital assembly, of anything?”

If the answer is “No, we will need to do orbital assembly someday,” then the amount of money we spend on orbital assembly now should properly be considered a research-and-development expense, which is helping to build capabilities for future missions.

If the answer is “We will never need to do orbital assembly,” well, that’s pretty depressing, because it implies we will never have anything in space larger than what we can launch on a single vehicle. In other words, a dead-end space program. Does anyone really want to go that route?

But wait a minute, you might ask, didn’t we already learn how to do orbital assembly with the International Space Station? Well, yes, we learned how to do orbital assembly, but we certainly didn’t learn how to do orbital assembly well (cheaply and efficiently).

The question then becomes, is it reasonable to spend money now developing capabilities for future missions that haven’t been approved yet? To do “undirected technology development,” as former NASA Administrator Mike Griffin once put it? That’s a reasonable question. Some would argue that advanced technology development is what NASA’s all about, but others would disagree. On the other hand, “undirected technology development” is pretty much what NASA’s doing with the Space Launch System, which has no defined missions at the moment. The difference is that the capabilities we develop by learning to do cheap, efficient orbital assembly will be useful forever, while a superheavy lift rocket will only be useful until the payloads outgrow the rocket (as they inevitably will).

Written by Astro1 on May 24th, 2012 , Space Exploration (General)

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