No Space Elevators?

Maybe not:

Laboratory tests have shown that individual nanotubes can withstand an average of about 100 GPa, an unusual strength that comes courtesy of their crystalline structure. But if a nanotube is missing just one carbon atom, this can reduce its strength by as much as 30%. And a bulk material made from such tubes is even weaker. Most fibres made from nanotubes have so far had a strength much lower than 1 GPa.

Recent measurements of high-quality nanotubes have found them to be missing one carbon atom out of every 1012 bonds; that’s about one defect over 4 micrometres of nanotube length1. Defects of two or more missing atoms are much more rare, but Pugno points out that on the scale of the space elevator they become statistically probable.

Using a mathematical model that he has devised himself, and which has been tested by predicting the strength of materials such as nano-crystalline diamond, Pugno calculates that large defects will unavoidably bring a cable’s strength below about 30 GPa. His paper has been posted to arXiv2, and will appear in the July edition of the Journal of Physics: Condensed Matter.

Pugno adds that even if flawless nanotubes could be made for the space elevator, damage from micrometeorites and even erosion by oxygen atoms would render them weak. So can a space elevator be made? “With the technology available today? Never,” he says.

This seems like kind of an oxymoronic statement, because “never” implies the technology available any time, not just today. I would think that devices that continuously repaired redundant cables at a molecular level could solve this problem, though they’re not “technology available today.” In any event, I remain an agnostic.

Why I Didn’t Vote For Kerry

I have to say that I agree with almost every word of this (hint: it’s not because we think that Bush is a great president). For instance:

I didn’t vote for Kerry because in every domestic policy with which I disagreed with Bush, Kerry seemed to be worse. I deplore Bush’s immigration policy, his lack of commitment to free trade, his wishy-washy position on gun control, his big government spending, his unrealistic environmental policies, his generally anti-science positions, and so on and so forth. But in every way, whenever Kerry could actually be pegged down as having a position it was even worse than that of Bush.

Why I Didn’t Vote For Kerry

I have to say that I agree with almost every word of this (hint: it’s not because we think that Bush is a great president). For instance:

I didn’t vote for Kerry because in every domestic policy with which I disagreed with Bush, Kerry seemed to be worse. I deplore Bush’s immigration policy, his lack of commitment to free trade, his wishy-washy position on gun control, his big government spending, his unrealistic environmental policies, his generally anti-science positions, and so on and so forth. But in every way, whenever Kerry could actually be pegged down as having a position it was even worse than that of Bush.

Why I Didn’t Vote For Kerry

I have to say that I agree with almost every word of this (hint: it’s not because we think that Bush is a great president). For instance:

I didn’t vote for Kerry because in every domestic policy with which I disagreed with Bush, Kerry seemed to be worse. I deplore Bush’s immigration policy, his lack of commitment to free trade, his wishy-washy position on gun control, his big government spending, his unrealistic environmental policies, his generally anti-science positions, and so on and so forth. But in every way, whenever Kerry could actually be pegged down as having a position it was even worse than that of Bush.

Local Boosters

The Antelope Valley Press has a self-serving editorial on spaceports. Agenda revealed in last graf:

Right now, there is a serious and dangerous shortage of viable commercial airports. It would be far better to deal with that overwhelming present-day need than to try to compete for space tourism that will become a reality through the good works of Burt Rutan and Sir Richard Branson.

It’s certainly true that there are more spaceports being planned than are justified by current demand (or constraints of locale), and it’s also true that there’s a hard regulatory road ahead for many of them, given the issues that they’ll have with general aviation (something solvable with a more rational approach by AST). But to think that only Mojave will have a spaceport, and only Burt Rutan and Richard Branson will succeed or are even making any progress is, at the least, disingenuous. This was the line that Burt took in his luncheon speech in LA a couple weeks ago, and Stu Witt (manager of Mojave Airport) said the same thing when I met with him in Mojave last week (no confidences broken here, as far as I know–he’s happy to tell the same thing to anyone who asks).

I expect Burt and Stu to say those things, and I expect the Antelope Valley Press to stenograph them, but Oklahoma has a tenant with funds, developing vehicles, and we don’t know what Jeff Bezos is going to do out in the middle of Armadillo* Scrotum, Texas, where he’s not near either populated areas or military ranges, and may in fact have an easier time getting a site license than some of the more “conventional” choices. In any event, such editorials are to be taken with the prescribed amount of sodium chloride.

[* Update: Sorry, no slight to these guys intended]

Biting Commentary about Infinity…and Beyond!