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Comment by jsprogrammer | Hacker News Reader

I believe the barreled design to be fatally flawed. An earthquake or other disruption during launch could be catastrophic to the vehicle. Much better for the vehicle to ride next to the track; in failure scenarios, the vehicle can simply detach and glide back to earth.

Yes, it means you have to go through the atmosphere, but it doesn't take far to clear. That will effect the calculations some, but not much. What will really effect the calculations though, is the cost of electricity. Generation costs will surely drop below $0.04.

Further, transmission loss can be almost entirely mitigated by generating and supplying the required power on-track.

Launches in favorable conditions (moon and/or planet alignments) would probably make some launches even cheaper. Of course, if the launcher were operating continuously, the savings would be used up during unfavorable conditions.

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You're suggesting that we should magnetically levitate the launch vehicle in free air above a track running along the ground? That seems like it makes the problem a lot harder — instead of having to push it through just the air between here and space, which is about ten tonnes per cross-sectional square meter, you're pushing it through another two or three hundred kilometers of air, which is about another 200 tonnes of air per square meter. You know that shroud of plasma surrounding a re-entering spacecraft? That's the power required to push an orbital-speed object through air — but in that case without even maintaining velocity, let alone rapidly accelerating, and in that case it's the rarefied air of the stratosphere. You're proposing to do that for the majority of the track. That seems like a bad idea.

Yes, generation costs will likely drop significantly below US$0.04/kWh eventually. But that's a Kardashev-Type-1 kind of event. Generating the power on-track may not turn out to be less expensive than long-distance transmission, because it depends on things like sunlight availability. Of the few suitable sites, most are pretty cloudy on one side.

No moon or planet alignments significantly reduce the energy barrier to get to orbit.

The track would not run along the ground. You'd want to get height as quickly as possible to minimize atmosphere and track length.

Originating somewhere around Mojave and launching towards Las Vegas could work.

Alternatively, you may want to launch over the ocean for safety reasons, but it seems like you may be subject to more weather concerns.

You don't want to run the track along the ground? Where then, on a dirigible at the mesopause as suggested in http://postbiota.org/pipermail/tt/2011-August/009613.html?

Bouyant structures could be used, as well as wings, to suspend the track.

You can't run along the ground because you don't want to go too fast through atmosphere.

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