Archive for June, 2006
This is the latest salvo from the Space Frontier group, urging Congress to take the money currently allocated towards finishing the Shuttle missions (approximately $20 billion, according to them) and redirect it towards commercial development of space.
It’s hard to argue with that logic. I was a fan of the shuttle for a long time, not so much because I thought the Shuttle was the be-all and end-all of space delivery systems, but it was SOMETHING that kept a US presence in space. But the Columbia disaster really changed my mind.
I wonder what LiftPort and/or Brad Edwards could do with $20 billion…
June 30th, 2006
Over at Tam-Bram, Thank You Ma’am!, Dishkyaon has posted a rather unique take on what a bored AI in charge of Space Elevator operations might do for kicks. It’s in the form of a short story and, IMHO, is well worth reading…
June 30th, 2006
This is from Andy Price’s email list;
As the editor for the American Astronautical Society’s bimonthly publication Space Times, and a regular recipient of the e-mail traffic you sponsor on carbon nanotubes and space elevators, I’d like to offer you and the members of your group the opportunity to submit an article/s for our magazine. This is an incredibly important subject, and I’d be willing to consider an entire issue dedicated to the topic if you or your associates had the interest.
I’ve attached a copy of our article submission guidelines as well as a PDF of our March/April issue. Thank you for your consideration, and best of luck in the continuing quest to turn “The Fountains of Paradise” into a reality!
I’ve attached their article submission guidelines here and a pdf (Bob Munck alert) of their March/April 2006 issue here.
A couple of people have already stepped up to volunteer articles and I’m trying to come up with a way that I can contribute as well. If anyone is interested in contributing, please contact Andy at aprice(AT)healthspace.ca.
June 28th, 2006
Dr. Bradley Edwards has recently set up a new personal webpage. You can find it here.
June 27th, 2006
Dr. Seth Shostak at SETI Institute Science Radio interviews Steve Jones and George Camps about their team’s (Team Snowstar, from British Columbia, Canada) entrance into this year’s Space Elevator Games. This interview is one of a number in this broadcast and begins at 45:24 into the recording.
June 23rd, 2006
Sorry there have been no posts lately - I came down with something which made me feel somewhat on the order of ”death warmed over.” I’m feeling nearly alive now and should be posting again soon…
June 21st, 2006
The third in the series of Interviews with the competitors in this year’s Space Elevator games is now available. I talk with Michael Fischer of Team Fischer28. Michael is a veteran of the 2005 Space Elevator games and his climber has a rather novel way of propelling its way up the tether. In addition, Michael presented a paper at this year’s 2006 ISDC conference on his method. You can find the paper here (Bob Munck alert - it’s in pdf format).
You can listen to the interview (an .mp3 file) here.
(Note that the sound quality is not that great; I’m not sure why - I’ll be working on cleaning it up and reposting it as soon as I can)
June 12th, 2006
Aviation Week & Space Technology has a recent article about On-Orbit Automation; efforts being made to robotically repair and refuel satellites. At the National Space Society’s Space Elevator Special Interest Chapter, they have a copy of the article. As they point out, this type of technology will play a significant role in Space Elevator development.
June 11th, 2006
Zhiping Xu, Lifeng Wang and Quanshui Zheng propose that “condensed multiwalled carbon nanotubes (CMWNTs) can greatly enhance intershell shear strengths by several orders, and can simultaneously generate higher tensile strengths and moduli respectively than those of ordinary CNTs…It is believed that CMWNTs featured with those properties can be taken as excellent candidates of super fibers for creating space elevators.” You can find the details here.
June 11th, 2006
In the June 10th-16th issue of The Economist (the issue with picture of Zarqawi on the cover), there is a fine article summarizing the current status of the space elevator project. This article is also available online here.
June 10th, 2006
The estimable Jim Dempsey (again, via Andy Price) weighs in on the Pugno controversy and Dr. Brad Edwards comments on it. Writes Mr. Dempsey;
Brad, your response was a good “well wait a minute” response. In particular, from my unfounded point of view, I key in on your statement:
- assumes that all CNTs will be damaged (it appears to be on a 100 nm length) and that
- none of them interact with each other in a supportive manner.
One of the major factors in building suitable SE tether material is in obtaining adequate supportive interaction without the expense of unwieldy excess mass. Anyone familiar with traditional cordage understands that supportive interaction is the key element in constructing a reliable defect tolerant cord (tether in this case).
As a thought experiment assume one were to produce 100,000KM long SWNT. Assume you were to somehow clamp only the ends of the bundles. Given this scenario (and excluding Van der Vaal’s or electrostatic interaction) any defect subsequently introduced into a given SWNT in the bundle would weaken the bundle by one SWNT capacity. It is a virtual certainty that given the length of each SWNT this unsupportive bundle would quickly degrade. By the introduction of a suitable supportive interaction mechanism, the load bearing capacity of a damaged SWNT can bypass the local of the defect. In reading Pugno’s paper there appears to be no anticipation that a suitable supportive interaction mechanism could be found any time soon.
I am optimistic. I believe the problem is solvable, I believe it will be solved; I believe it will be solved within 5 years. But what would I know; I am not a molecular chemist.
If I “were” a molecular chemist, I would be a brash molecular chemist, I would buck the establishment, I would not be afraid to say “why not”.
I would take what little I do know, and inject this knowledge into an unrestricted pool of properties and characteristics, then draw upon this to produce subsequent precursor knowledge which goes back in the knowledge pool, and repeat the process until the solution is found.
Our current problem of finding the ideal (an acceptable) supportive interaction mechanism could potentially be an ideal candidate for genetic programming (see: http://www.genetic-programming.com/johnkoza.html).
What we know is:
Using an Atomic Force Microscope you can place and move about individual atoms on a flat crystalline surface.
We know that a supposedly flat crystalline surface at the atomic scale is bumpy.
We know that given different specimen atoms for a given surface will have different affinities to “stick” within depressions of the bumpy surface.
Given this knowledge:
I would begin experimentation with a graphene planar surface. The experimentation preferably could be performed by way of genetic programming as it would be much faster and more comprehensive than physical lab work.
The elusive prey would be that which causes good “stiction”. Something that “falls” deep into the surface but does not penetrate the surface. The test subjects need not be limited to atomic (ionic or charge neutral) selections but would also include molecular forms.
Next, with this reasonably large collection of potential candidates, reconfigure the simulation (or lab tests).
Then experiment with “dusting” the SWNT and bundling the SWNT to determine an optimal candidate and dusting density which produces good protection against slippage between SWNT and who’s dusting density is commensurate for the anticipated probability of environmental damage to the SWNT.
Added to the mix I would experiment with collecting various numbers of said dusted SWNT bundled and held together with a cladding. The purpose of this cladding is not to add tensile strength but to ensure a tight binding of the SWNT bundles such that the stiction from the dusting can do its work.
The said above dusted, bundled and cladded SWNT’s would be produced in large quantities and would exhibit the mechanical and processing properties of micro fibers. Call these DBCSWNT (Dusted, Bundled, Cladded SWNT).
The above DBCSWNT would be placed en mass into a binding mixture of PET or PET-like agent and drawn many times to ensure good alignment and packing density of the DBCSWNT. Then after evaporation of solvent and curing of binder the end result is a thread of any desired length and diameter. The cross section of which need not be circular. Hexagonal cross section might be a better choice.
These threads would then be twisted or braided into larger diameter cordage (fractional mm) which is finally incorporated into the ribbon.
To date, and without being privy to what is being done, experimentation is being performed by placing the SWNT directly into the PET or PET-like agent, i.e. the stiction dusting and cladding steps above are omitted. It is my gut feel that the key to or breakthrough to manufacturing suitable tether material is in the stiction dusting and cladding components of the above mentioned process. But then, what to I know, I am not a molecular chemist.
June 9th, 2006
Michael Laine, Founder and President of the LiftPort Group, will address the Bay Area Future Salon on June 22nd. Details can be found here.
June 9th, 2006
At The Oklahoman, Jim Stafford tells his readers about the Space Elevator.
June 8th, 2006
Further thoughts from Dr. Edwards (again via Andy Price) on the Pugno study:
“The supportive interaction between the CNTs already exists in several forms:
1) van de Walls forces
2) physical “knotting” or twisting like cotton or any other fiber and
3) functionalized nanotubes
Any one of these could be used to cross link CNTs and effectively transfer loads and greatly reduce the overall strength reduction of any weak CNT. There are a couple other options as well, but these have been shown to work. By not including this in a discussion of a macroscopic material, Pugno is insuring that the material will fall apart. Compare a raw mat of cotton to a spun cotton thread - the performance is a little different. I can assure everyone that raw cotton fibers are not perfect throughout their length (much less so than quality CNTs) but strong threads can still be made from them.”
June 8th, 2006
Forwarded from Andy Price, and with the kind permission of Dr. Edwards, following are his initial thoughts on the Pugno study;
“The paper by Pugno has been beaten around a bit. I just read the paper, very interesting. Let me run through a few thoughts on it.
I start off worrying when someone creates his own theory and simulation to model everything from nanoscale to megascale (nanotubes to Earth) especially when there are plenty of molecular models out there. But having said that, let me assume his simulation is perfect for a nanotube. He appears to have scripted the paper to claim the cable will break (he repeats this claim at least four times throughout the paper often with the note that it is his opinion) – a second worry when an author appears to be trying to prove a conclusion. Here are a few notes I made on his discussion:
- references and then ignores coatings to eliminate atomic oxygen erosion.
- states radiation damage will cause defects but doesn’t discuss the amount. Damage seen in experiments is minimal for carbon fibers in the radiation fields around Earth.
- I may be wrong but it appeared to me that Pugno was using a macroscopic model to represent a damaged nanotube as a solid tube with a physical hole in it. He certainly discusses this and then discusses missing bonds so I would be curious to know which one he went with. I will need to look at this again.
- uses an erroneous theoretical maximum of 100GPa for the tensile strength of CNTs. CNTs have been measured at strengths from 150GPa to 200 GPa and he references one that is at 109GPa. His final 30GPa is directly related to this.
- uses the strength of long CNT bundles to prove his arguments. CNT bundles are not a valid comparison because they can have very short CNTs and limited interaction.
- assumes that all CNTs will be damaged (it appears to be on a 100 nm length) and that none of them interact with each other in a supportive manner.
This is from a quick read of the paper but essentially as far as I understand, Pugno makes some poor assumptions to argue that there will be damage to all the CNTs in a ribbon, calculates that each CNT will degrade 70% and then jumps to the conclusion that the ribbon will degrade 70%. As far as I can tell he doesn’t look at or consider the structure of the CNT threads, the interactions of the CNTs, real defect type and frequency, techniques to reduce defects in production, the real defect production rates in space, the maximum measured CNT strengths, … The paper didn’t strike me as very good scientific work.
Having said all of this, people will view my remarks as biased – a reasonable assumption. I have attempted to be objective because I would like to know the answers as well. I would like to request that others examine this material as well.
I applaud the attempt to examine the materials issue, but don’t think Pugno has provided a good analysis in this paper.”
Thank you Andy and Dr. Edwards.
June 8th, 2006
Once a Space Elevator goes into operation, there will be lifters traveling both up and down the ribbon. If we don’t want to have them travel in an asynchronous manner, we’ll have to figure out some way to have lifters pass each other (one going up and the other going down) while both are on the ribbon. Lifters designed now cannot do this - they clamp to the ribbon, enveloping both sides of it (or all four sides of it, if you want to count the ribbon edges). I’ve toyed with the idea of suggesting this as one of the challenges to be met in future Space Elevator games; i.e. you have to have two lifters on the tether simultaneously, one going up and one going down, and they have to be able to pass each other without causing problems.
Today I came across a video of another kind of climber, one that could, perhaps, crawl up on just one side of the ribbon. You can find a video of it in action here. It’s battery powered (I think), and doesn’t seem to be designed to carry anything, but it’s a step in the right direction. Funding for this is being provided by DARPA.
June 6th, 2006
I was at the Skeptics Conference this past weekend - the subject was Global Warming. One of the presenters was Dr. Gregory Benford (Physicist and prolific SF writer) and his topic was “things that we could DO to solve the Global Warming problem.”
During his talk, he dismissed fusion as a “solution that is 50 years off and always will be.” Another possibility he mentioned, but dismissed as being too expensive, was space-based, solar power panels. During the Q&A period after his presentation, I asked him why the solar power solution was too expensive - was it the lift cost to get the hardware into orbit or was it the cost of the hardware itself? He replied that it was the lift cost. I then asked him that if there was a much cheaper way to get this stuff up to orbit, would that change the equation; i.e., would this be now a viable solution - he readily agreed. I asked him what he thought about the idea of a Space Elevator. He replied that it would be developed ”after fusion power”, getting a nice laugh from the audience. Sigh.
After his presentation, I spoke to him and asked what he specifically thought was unrealistic about the possibility of a Space Elevator. He replied that it was “tension” and “stability”, but did acknowledge that some work was being done with “carbon fibers.” I didn’t have a chance to speak with him anymore - people wanted to talk to him about his solution to global warming and I didn’t want to monopolize his time with my pet subject.
Dr. Benford is a physicist and I respect him tremendously. He has a reputation for thinking outside the box and I was disappointed in his dismissal of the Space Elevator idea. On the plane ride back (the conference was in Pasadena, California and I live near Chicago) I spent some time thinking about what to do about this. I think what I’ll do is send him a copy of Dr. Edwards book and the new LiftPort book. I have no idea if he’ll look at them or not, but I think it’s worth a shot…
June 5th, 2006
There have been a lot of blogger posts about the Nicola Pugno study. Rather than continue to put each one in a separate entry, I’m going to combine them in this one.
At Advanced Technology, David Louisa is optimistic…
At Space.QJ.Net, they’re concentrating on which channel of Muzak should be playing.
Space.com’s take on it…
Over at The End of the Universe, Captain Xerox (copy that) is all doom-and-gloom…
Eric Zorn is a columnist at the Chicago Tribune and he’s one of my favorite reads. In his blog “Change of Subject“, he wrote this: “The idea of a space elevator was popularized in science fiction, where writers envisioned a 100,000-kilometre-long cable stretching straight up from the Earth’s surface and fixed in a geosynchronous orbit. Payloads, or tourists, would simply ascend the cable into low-Earth orbit, eliminating the need for rocket launches.” Nature.com discusses the latest research. (via Digg)“. The Nature.com story is, of course, the negative one saying that a carbon nanotubes won’t work because of their “inherent defects.” It’s nice to have the Space Elevator mentioned by someone with such a large audience, but anyone looking at only this story will not see the other side of the story. I left a comment directing people to my blog - others may wish to point his readers to other information.
At sciscoop.com, Chad quotes Clarke’s First Law in response.
At Instapundit, Glenn Reynolds is not discouraged.
Neither is Brent Kearney.
Bill Christensen at Technovelgy.com weighs in…
The Slashdot crowd weighs in with several hunred comments in their thread on the subject…
Skeptipundit says “…does seem that there are some new challenges to overcome.”
Colony Worlds opines that it’s much too soon to draw conclusions.
Tom Nugent at LiftPort is not discouraged.
At the Velcro City Tourist Board (cool name, that), he’s disappointed but not discouraged. He also weighs in on the Space Pier option.
futurismic’s Armchair Anarchist says we’ve created a blogstorm.
LiftPort’s Brian Dunbar says that nothing has really changed.
At My Corner of the Universe, blogger Cameron Peters hopes that despite the objections of Nicola Pugno, he’ll still be able to take a ride in a Space Elevator.
At advanced nanotechnology, blogger Brian Wang weighs in with his opinion, that the Space Pier is a superior concept and can be built with today’s materials.
At Pop Philosophy, Daniel Moore comments.
Hyperion Court weighs in on Space Elevators, including the latest controversy. As always, Brian was there ahead of me.
June 2nd, 2006