Orion Redux

Or, “You don’t know what you’re talking about Snarky Boy.” that came from this and this.

That may be, after all I’m not a rocket scientist. However, I do have some experience scaling things, and while I might not know the correct rocket terminology, I think I’m correct when I stipulate that chemical rockets will never lift enough mass off the Earth to allow a meaningful human presence in space.

The Saturn V, the biggest thing we’ve ever launched (just go with me here) weighed in at 6,699,000 lbs, or 3,350 tons, and managed to put a measly 100,000 lbs (50 tons) into lunar orbit.

So lets pretend we want to build a classic L5 space colony.  How big does it have to be?

Well, I don’t know, but the Empire State Building weighs 365,000 tons and it’s only about a thousand feet tall.  Some of the L5 colony designs are several miles long.   But for the sake of argument, lets start small.

The Snarky L5 habitat will weigh 500,000 tons.  I suspect that’s too small but you’ll see it doesn’t matter for the sake of this thought experiment.

The Saturn 5 could lift 50 tons into Lunar orbit.  L5 is comparable to lunar orbit for our purposes so let’s start building Saturn Vs to launch material and start building the Snarky Space Colony.

We’ll need 10,000 Saturn Vs.    (NASA only ever launched 12, so we might have a problem or two.)

If we launched one a day, we’d be done in 28 years.  How likely is that?

Lets wave a magic wand and double the payload to L5.

That’s now 5,000 magical rockets.

Double it again.  The rocket gods have blessed us with a magical chemical rocket drive that can put 200 tons of payload at L5. (I’ll leave it to the real rocket scientists to explain how unlikely that really is.)

That’s 2,500 super magical rockets.

For one colony.

Oh.  Did you want more than one colony?

How about supplies and such?

Oh, you cry foul…   That’s cheating to insist on L5.  Build it closer, like in Low Earth Orbit.

OK, lets see, the Saturn V could put 130 tons into LEO.   It doesn’t help much.  The biggest step is getting the mass off Earth in the first place.

It’s just not going to happen with chemical rockets.

On the other hand, General Atomics figured they could launch a 400 meter diameter, 8,000,000 ton (Yes, that’s 8 million tons) payload at once.  And not just to Earth Orbit, but anywhere you wanted it.

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0 Responses to Orion Redux

  1. Pingback: SnarkyBytes » What’s Wrong With Orion?

  2. RocketSurgeon, MD says:

    Well, I was a rocket scientist (before med school) and your assumptions are in error.

    Why launch stuff from earth, that is available in space? Construction materials are plentiful – all we have to do is get them.

    The process would start with launching machines that can make other machines that can process extraterrestial materials (from asteroids, the moon, etc) and make any sort of habitat you want.

    Further, chemical rockets are very, very cheap to use. Not everything has to be man-rated and built by NASA, two guarantees of incredibly high costs. Leave the rocketsurgery to those qualified to comment on it.

  3. alan says:

    I’ll ignore the condescending bullshit like “Leave the rocketsurgery to those qualified to comment on it” and just assume you’re an asshole. That’s OK, I’m an asshole too sometimes.

    But I’d like an explanation of why my assumptions are wrong instead of just saying they are.

    My main assumption is that at some time in the future, we’ll want to move tens of thousands or even millions of people off Earth and into space. Earth is the only place I know of that has people, so they’ll have to come from here. Was that wrong?

    I want to ride in a man-rated vehicle if I go into space. I’ve seen too many satellite launches blow up to take a chance on a non-man-rated rocket. And by the way, even the man rated ones don’t have a very good track record. Nuclear space ships could be overbuilt and therefore much stronger and safer than fragile chemical rockets.

    Another assumption is that reusable multi-stage rockets won’t work for thousands of launches because the reassembly required slows the turn around too much to allow the number of flights needed.

    Reusable SSTOs might be doable but chemical SSTOs are very limited in payload capacity. Even I can work the rocket equation out to realize that.

    “Construction materials are plentiful – all we have to do is get them.” sounds nice but there’s a big ??? between “it’s there” and “go get them”. Maybe the underpants gnomes can help out with that.

    And von Neumann machines… Are you kidding me?

    A lot of people are saying things like “rockets work fine” but It’s pretty clear they don’t. We can’t reliably launch payloads onto LEO and we haven’t sent people beyond LEO in 36 years. I submit that not only are chemical rockets not able to do what’s required in the future, they can’t even do it today.

    The numbers just don’t work out. Even if we’re moving the mass in from the asteroid belt and don’t have to lift it from a gravity well, chemical rockets can’t supply enough delta v to move millions of tons of mass around the solar system.

    We’re going to need something else.

  4. Joe says:

    How many Orions do you think you get to launch, before people get upset, about the radiation?

  5. Ride Fast says:

    “Leave the rocketsurgery to those qualified” Hmmm.

    Orville and Wilbur (amateurs) built and flew the most successful, self propelled, heavier than air flying machine the world had ever seen (Wilbur built the engine, from scratch. He forged all the parts, from pig iron).

    Thousands of professionals built, launched and sank the Titanic.