August 31, 2005


Space Program: Looking Up (Glenn Harlan Reynolds, TCS, 8/24/05)

As I noted earlier, NASA was offering prizes for space elevator research. That's still going on, but there are some new studies suggesting that space elevators may be closer to practicality than previously thought. A cover story in the IEE Spectrum reports:
"A space elevator would be amazingly expensive or absurdly cheap -- depending on how you look at it. It would cost about $6 billion in today's dollars just to complete the structure itself, according to my study. Costs associated with legal, regulatory, and political aspects could easily add another $4 billion, but these expenses are much harder to estimate. Building such an enormous structure would probably require treaty-level negotiations with the international community, for example. A $10 billion price tag, however, isn't really extraordinary in the economics of space exploration. NASA's budget is about $15 billion a year, and a single shuttle launch costs about half a billion dollars.

"The construction schedule could conceivably be as short as 10 years, but 15 years is a more realistic estimate when technology development, budget cycles, competitive selection, and other factors are accounted for."

The first one is the hardest to build, which has an important strategic implication:
"The second elevator would be much easier and cheaper to build than the first, not only because it could make use of the first elevator but because all the R&D and much of the supporting infrastructure would already be complete. With these savings, I estimate that a second elevator would cost a fraction of the first one-as little as $3 billion dollars for parts and construction.
If it were that cheap, why would we need the government?

Posted by David Cohen at August 31, 2005 2:57 PM

Convince me you can do it for $10B, and I'll wait in line for the IPO.

Posted by: Mike Earl at August 31, 2005 3:37 PM

Ditto. No need for government funding.

Posted by: Bret at August 31, 2005 4:21 PM

Exactly. The space program is full of wide-eyed dreamers, if they are taking this guy seriously. Don't state-of-the-art chip fab plants cost a couple of billion now? Intel & Motorola don't have any problem drumming up investors.

President Bush (#41) proposed a budget for a trip to Mars that was IIRC about $450 Billion. It was a 'gaffe' in the sense that he accidentally told the truth.

Posted by: Bruce Cleaver at August 31, 2005 4:52 PM

Um - don't investors usually expect profit in return? Is there any tenable profit in the near future of space exploration? Intel and Motorola don't have any problem fishing up investors because they are making a profitable product to sell. Human achievement (and ultimately the survival of the human race) is worth far more than a disposable cell phone.

Posted by: Shelton at August 31, 2005 5:05 PM

A space elevator would allow pretty cheap rates for getting stuff into orbit. Given the going rate now (about $11,000 per pound), an elevator could certainly cover its operating costs. The question has been (besides whether such a thing is even possible) whether you could ever recover the capital costs, but at 10-15 billion you should be able to.

Posted by: David Cohen at August 31, 2005 6:14 PM

The *real* question is, who wants to get a significant amount of stuff into orbit? I mean, I'm a starry-eyed dreamer about space stuff---but where's the payback?

Posted by: ray at August 31, 2005 9:16 PM


There's an endless number of profit mechanisms, once you have cheap access to space, but I'll just sketch three.

1) Satellites. Imagine what you could do for, say, global cell networks if your launch costs per satellite were $100/lb instead of $10,000/lb. Not only could you launch far more satellites but they'd be enormously cheaper, since the major cost driver to day is that the satellite cannot fail because it's so hard to get a new one up. If launching is cheap you can build cheap satellites and go with redunancy across satellites instead of massive reliablity in just one.

2) Materials processing. Zero gravity environments are excellent for producing many of the high value manufactured substances we use (such as pure silicon for chip manufacturing). You could also do far more dangerous experiments with biologicals or other hazardous materials if your processing facility was separated by vacuum from everything else.

3) Energy production. Solar power is cheap and easy in space. And with a space elevator, you've got a good way of getting it down to the planet.

Posted by: Annoying Old Guy at August 31, 2005 10:02 PM

There are a few problems. The elevator station must be at geosynchronous altitude (~35,000 km) which means the tether must be about 100,000 km long with a large counterweight at the end so the center of mass is at geosynchronous altitude. It must be built from orbit in both directions, which means all the mass must first be taken to geosychronous orbit. Finally, the base must be somewhere on the equator, but there are few stable countries along this line. Ideally, the base shound be movable to permit dampening of oscillations.

As an engineer, I suspect the first one will fail due to unforeseen destructive oscillations. This is a common failure mode on large construction projects, and unfortunately engineers only seem to learn by such failures. There are also unknown potential problems from storms, the jet stream, and damage from micrometeorite impacts.

AOG: One of the advantages of using carbon nanotubes for the tether is that they are relatively nonconductive. When you incorporate conductors in the tether, you have large induced currents due to variations in the earth's magnetic field and solar storms.

Posted by: jd watson [TypeKey Profile Page] at September 1, 2005 5:24 AM

JD: Doesn't the space anchor more or less have to be a captured asteroid? And shouldn't the Earth anchor be a floating platform.

Posted by: David Cohen at September 1, 2005 9:20 AM

The longer the cable, the lighter the anchor needs to be; you might be able to start with a small one and gradually haul more up in increasing loads. Does the center of mass actually have to be geosynchronous, or below that to keep a slight tension on the cable?

Also, for solar power satellites, beaming the power down via microwaves is actually quite straightforward. Getting them built economically is the hard part, and a space elevator solves 95% of that problem.

Posted by: Mike Earl at September 1, 2005 11:20 AM


4) Military. Consider a 1000 pound tungsten pole with a small rocket motor and a JDAM GPS guidance package. A space elevator could put these in place at about

Posted by: Mike Earl at September 1, 2005 11:27 AM

"Does the center of mass actually have to be geosynchronous, or below that to keep a slight tension on the cable?"

Slightly above, to keep tension on the cable.

Posted by: Bill Woods at September 1, 2005 2:49 PM


I think we can accurately predict that the most lucractive businesses based on cheap launch costs are ones that no one has yet thought of but will seem obvious after the fact (like over-night package delivery).


Yes, it's quite the engineering challenge, although all the designs I've read at least consider the issues you raised (especially oscillations). I was simply addressing the question of why one would want to try in the first place. I'm not saying it will work, but if it did it'd be worth a whole lot of money.

Posted by: Annoying Old Guy at September 1, 2005 5:22 PM

Hi - found this thread via an icerocket blog search, pardon my drive-by (as it were) posting.

Mike Earl "Convince me you can do it for $10B, and I'll wait in line for the IPO."

Shelton: " don't investors usually expect profit in return? Is there any tenable profit in the near future of space exploration? "

Depends? There won't be any profit in sending (say) a Mars expedition but there will be profit sending their supplies. Most serious proposals call for seeding the future base of operations there with automated shipments of supplies. The Edwrards design for an SE dispenses with (most) of a counterweight at GEO in favor of a long tail - replacing mass with momentum. The upside of having more ribbon is that you get a flinger for cargo like that.

Ray "The *real* question is, who wants to get a significant amount of stuff into orbit? "

There have been studies for various price points - the one Boeing did in 2001 (?) comes to mind - all kinds of nifty things happen when the price drops below a threshold.

More stuff doesn't happen up there because it's too expensive to get there.

Something to add to the list - multiplexing satellite signals to maximize bandwidth. You can't do that now - the gear is too expensive.

JD, the osscilation problem has been worked on by some smart guys in the community - I am not one of them. They seem to think it can be dealt with. More study is needed of course.

Posted by: bdunbar [TypeKey Profile Page] at September 4, 2005 9:07 PM