Archive for December, 2008
Markus Klettner, Executive Director of EuroSpaceward, has kindly sent me several documents resulting from or relating to the recent EuroSpaceward Conference.
This first document is an interview of Markus by BBC New Journalist Jason Palmer. Markus hastens to add that the views he expresses in this interview are his own and are not necessarily representative of EuroSpaceward. This document is in pdf format.
The next document is the Conference presentation by Professor Nicola Pugno entitled “The role of defects in the design of Space Elevator cable” and is in Microsoft Powerpoint format.
Finally, Markus has kindly provided us with 8 other documents/presentations authored or co-authored by the same Professor Pugno relating to his studies of defects in carbon nanotubes. All of these documents are in pdf format.
So, if you need some reading material - here it is!
These documents are particularly relevant as I have recently presented a series of posts (here, here and here) on Ben Shelef’s (CEO of Spaceward) view of how strong a carbon nanotube ribbon has to be to make a useful Space Elevator. From my own reading of Prof. Pugno’s papers, it appears that there are some differences of opinion (or at least differences in the way things are stated) between Prof. Pugno and Ben on this issue. Hopefully in the not-too-distant future, ISEC can explore these differences in more detail.
December 29th, 2008
OK, OK, OK already!!!
Michael Laine (of LiftPort fame) has been pestering me for the past few weeks to ‘get with it’ and start using some of the web tools out there to post all of the Space Elevator photos I’ve taken over the past 2+ years. So, I’ve set up a Flickr account (’Space Elevator Blogger’) and am beginning to post the many photos I’ve taken. I’m starting with the 2007 Space Elevator Games. Once those are done, I’ll move onto the 2006 Space Elevator Games and, hopefully, I’ll finish that before the 2009 Space Elevator Games begin
Michael has also convinced me to start a Twitter account. And, if that’s not enough, he’s now trying to convince me to take a look at del.icio.us.
I’m such a dinosaur, truly I am. I’m pretty computer-savvy, having spent my entire professional career in the computer software business, but I’m old-school - my language of choice was COBOL. And, for kicks, I’d like to enter machine instructions via the toggle switches on an IBM 360. Mr. Laine, however, is trying to upgrade me to Web 2.0 stuff. Oh, the humanity…
OK Michael, if my head explodes, it’s all your fault…
December 27th, 2008
This morning, the International Space Elevator Consortium (ISEC) sent out it’s first press release, basically saying “Hey world - we’re here!”. The real fun is going to start over the next several weeks. We’ve been working hard behind the scenes to set up our plans for 2009. I don’t want to prematurely mention anything specific now - but rest assured that we will be doing concrete work to further efforts in getting a Space Elevator built and we’re going to have fun along the way. Stay tuned!
I encourage all of you to visit the ISEC web site (http://www.isec.info) to sign up for our newsletter.
Here is the press release:
Leading Players in the Space Elevator Movement Join Together to Form New International Consortium
New Independent Group to Foster Global Research, Develop International Standards and Serve as a Worldwide Information Exchange on the Space Elevator
Rancho Santa Margarita, Calif. (December 22, 2008) – A coalition of leaders in the Space Elevator movement today announced the formation of The International Space Elevator Consortium (ISEC), a new independent group designed to promote standards and foster research relating to the construction of an Elevator to Space at the global level.
Founding members of ISEC include the Spaceward Foundation, the Space Elevator Reference, the Space Elevator Blog, EuroSpaceward and the Japan Space Elevator Association. Heading the new organization is Ted Semon of the Space Elevator Blog, who will serve as president.
According to the Consortium, the goal of ISEC is to promote the development, construction and operation of the Space Elevator as a revolutionary and efficient way to space for all humanity. The group will accomplish this through these key areas:
- Development of a unified plan and roadmap for the Space Elevator and the coordinated assignment of specific research topics
- Funding of research on technologies relevant to the Space Elevator
- Development of the international legal framework necessary for the operation of the Space Elevator
- Global public outreach and central information exchange on Space Elevator activities
“The Space Elevator is a project whose time has come,” said Semon. “With the challenges facing today’s global economy, it is clear that new industries and new ideas are needed to help our planet in the 21st Century. The Space Elevator can be a key positive contributor, from providing inexpensive nanotechnology material science breakthroughs that will make your car stronger and lighter, to the creation of new industries that offer opportunities for investment and job creation. The International Space Elevator Consortium devoted to its development can make this happen.”
ISEC will be unveiling additional plans and details in the upcoming weeks, including a board of directors, technical journals, university and industry relationships, research opportunities and scholarships. Memberships will be available on the individual, corporate, academic and governmental levels.
Headquartered in the greater Los Angeles area, center of the aerospace industry, the International Space Elevator Consortium (ISEC) is a non-profit organization devoted to the research and construction of an Elevator to Space. For more information please visit www.isec.info.
For more information please contact:
ted [at] spaceelevatorblog.com
byoung [at] bypr.com
December 22nd, 2008
Here’s a pilot for a new web series, Tranquility Dome. There is a Space Elevator and already it’s been destroyed!!
I hope this turns into a real series as something about this grabbed me - it’s actually well done IMHO. But they have to do something about the teeth…
(Image of the “NorthPac Elevator” is a screen capture from the video - click on it for a larger version)
December 21st, 2008
Yesterday, December 16th, would have been Sir Arthur C. Clarke’s 91st birthday. Jerome Pearson kindly sent me this picture of Sir Arthur and Yuri Artsutanov taken during Sir Arthur’s visit to Russia in 1980.
(Click on the picture for a larger version)
December 17th, 2008
We’ll take a short break from posting about tethers and tether strength to let everyone know the latest news from the KC Space Pirates;
We still are waiting for a venue and date for the competition. It is currently slated for Feb-March 2009 and I know that Spaceward and others are working hard to get it nailed down.
A film crew was in town this weekend to get an overview of the space elevator and catch some of our testing. This is for a show called “Space Pioneers” that is supposed to air around June 2009 on the Science Channel. The presenter was Dr. Basil Singer from “Project Earth” http://dsc.discovery.com/tv/project-earth/task-force/task-force.html. It was nice chatting with Basil about our system without the veil of secrecy that we usually have. If the competition gets delayed past June then we might be in trouble.
Just to make it more interesting I accidentally crashed the climber while demonstrating for the team members on the day before the video shoot. It fell about 15 ft to our concrete driveway and damaged the motor among other things. We repaired the motor and bench tested it. When someone asked me if I wanted to do a climb test with it, I answered no because I did not want to crash it again that late in the day. We can add this to the long line of bad calls that I have made as captain. The next day, with the cameras rolling and a dozen or so crew members watching, the motor just grunted pathetically instead of climbing for the sky. At this point we only have various speeds and sizes of motors and not any direct spares. But in about 20 min we were able to swap out most of the drive system and get it running pretty good. We will see if they are merciful in the editing.
The exercise let us capture a lot of performance data that will help us tune the climber for the competition. Other parts of our system are progressing well enough. We have only one critical issue that is looking to be expensive to fix. It also will take time so we can’t let up now.
KC Space Pirates
Thanks for the update Brian. It’s true that Spaceward is working very hard to nail down the venue and time. It IS getting closer to being finalized and we’re hoping for March (I think you can forget about February). I know it’s been a real PITA (for everyone), but there has been progress…
And yes, everyone, I haven’t been posting much lately - and I’m sorry for that. I do have several posts nearly ready to go, so the output should increase over the next several days…
December 16th, 2008
On December 14th, 1972, at 5:55pm Eastern Standard Time, Challenger lifted off the moon to rendezvous with the craft that would take mankind’s last moon walkers home.
Yes, it’s been 36 years since any human has been to the moon (or gone anywhere outside of LEO, for that matter). Apollo 17 marked the apogee of our manned space exploration efforts and we just have to hope that it won’t mark the end of them. Yes, yes, I know about NASA’s plans to return to the moon and to travel to Mars, but one just has to hope that the intense political lobbying and infighting going on about and within NASA won’t (again) cripple such efforts…
And, lets just say that a NASA web site showing ‘full resolution photos’ of the new moon visit is just going to give the conspiracy theorists new fodder in their claim that the original moon landings were hoaxes
(Apollo 17 logo from here - click on it for a larger version)
December 14th, 2008
In ‘Part 2′ of this series on Space Elevator tether strength, I referred to Ben Shelef’s document (The Space Elevator Feasibility Equation) on how strong a Space Elevator tether really has to be and explained how stronger power systems can increase the amount of material a Space Elevator can carry at any one time.
Are these stronger power systems a luxury? Can we start out with a weaker power system and then, at some point in the future, increase its power? After all, isn’t everything a Space Elevator is going to carry to space useful payload – i.e., satellites, tourists, manufacturing plants/capabilities, etc.? Wouldn’t a weaker power system mean that we carry just less useful stuff into space?
The answer to that is a resounding “No”. In addition to being able to support its own weight, there are other ‘housekeeping’ requirements which a Space Elevator tether HAS to satisfy before it can start hauling useful payload.
The Space Elevator tether is going to degrade over time. Micro-meteorites, atomic oxygen, radiation, physical wear and tear from Climber runs, etc., are all going to cause damage to the tether. This means that the tether material is going to have to be periodically replaced. How quickly this has to happen is one of the key, unanswered questions which must be addressed before a Space Elevator is built, but obviously the material has to be replaced faster than it wears out. So, in addition to holding its own weight, the first housekeeping requirement is that a space elevator must be able to replace itself faster than it wears out.
In addition, to being able to periodically replace itself, the space elevator must also be able to increase its carrying capacity. When the initial space elevator is launched and deployed, it will not be strong enough to carry much payload; launching a fully-fledged space elevator capable of supporting, say, a 20 ton climber, would be prohibitively heavy and prohibitively expensive. So the current plan is to launch a ‘seed ribbon’ and, once that is in place, to send up climbers on that seed ribbon with additional material which is spliced to the tether. As more climbers add more material, the more payload the space elevator can carry. Incidentally, this highlights the chief advantage of a Space Elevator over other methods of carrying payload to/from space, its scalability. There really is no practical limit on how big a Space Elevator can be. You can make a Space Elevator which will carry hundreds, even thousands of tons of cargo into space every day; all you have to do is just keep adding tether material to the space elevator ribbon. Of course there’s a price to pay for that; payload dedicated to additional tether material is payload capacity which cannot be used for other things. You do not have to continually increase the capability of the Space Elevator, of course, you can stop when it can handle, say, a one hundred ton climber, but it will take many years for this to happen. The upshot of this is that this second housekeeping requirement says that a space elevator must also be able to carry a ‘doubling capacity’ in addition to carrying normal payload.
Finally, prudence dictates that a spare seed ribbon should be carried by the space elevator up to and stored at GEO (or perhaps beyond, to act as counterweight material) to facilitate making a new space elevator in the case of a ribbon break (or other catastrophic failure). Yes, one could hope that there would be rocket capability to launch another seed ribbon if necessary, but it would be foolish to plan on it. So, this third housekeeping requirement says that the Space Elevator must also be able to carry this spare seed ribbon into space.
So, we have three housekeeping functions that a space elevator MUST be able to perform before it can carry useful payload into space; replacement material to handle tether degradation, additional material to increase the tether’s carrying capacity and a spare seed ribbon.
If the Space Elevator cannot, at a minimum, carry all of this material within the required time frame, then there is no point in even trying to build one – it HAS to be able to do this to succeed. As I discussed in the previous post, the stronger your power system is, the faster, in general, the climbers will be able to ascend the ribbon. And they have to be able to ascend fast enough to allow the Space Elevator to handle BOTH the housekeeping requirements and hauling useful payload into space.
In his paper The Space Elevator Feasibility Condition, Spaceward CEO Ben Shelef converts these housekeeping requirements into mathematical variables which he then matches against possible tether strength scenarios and possible power system scenarios.
There is one other Space Elevator requirement which must be discussed and that is its safety margin. How ‘safe’ does a Space Elevator have to be? Nothing is 100% safe, everything can fail under certain conditions. So how safe do we want a Space Elevator to be?
In my next post, I’ll discuss this in more detail.
(Picture of competition tether from 2006 Space Elevator Games - click on it for a larger version)
December 11th, 2008
I’m interrupting my posts on tether strength as I, today, received this email from Markus Klettner of EuroSpaceward;
Find enclosed the Book of Abstracts (2 parts) on our Luxembourg conference on Dec 6-7 FYI.
The gathering has been highly constructive. Excellent presentation were given, notably by Prof. Vesselin Shanov UC (unexpected stop of growth of pure nanotube arrays at approx 2 cm length that is inexplicable at the moment…hopes are there that it may be overcome), Prof. Nicola Pugno (thermodynamical limits for a mega cable, the impacts of holes and cracks and 3 proposed approaches to eventually push the limits), Brad
on manned space elevator, latest achievements on fibre strength and production at CRRP Bordeaux and Cambridge held by Prof. Cécile Zakri resp. Marcelo Motta. Highlights were also the lectures of Akira on Japanese activities and of Prof. Cockell on saving our world by seeking others!
Presentations will be soon online on EuroSpaceward’s member website and a detailed summary will be posted in the news part.
The two (pdf) abstracts are available here and here.
Thank you Markus!
December 8th, 2008
In my previous post, I referred to Spaceward CEO Ben Shelef’s document (The Space Elevator Feasibility Equation) as a basis for discussing how strong a Space Elevator tether really has to be and I wrote this; “The answer to this question relates to how strong the climber power system is. The stronger the power system is, the weaker the tether can be (and vice-versa).”
Why is this so? Well, let’s look at an example.
Say you have a tether which is rated at 30 tons. What this means is that you can have up to 30 tons of Climber/Payload weight on the tether at any one time. Does this mean that you can only have one 30-ton Climber (or three 10-ton Climbers or six 5-ton Climbers) on the tether at one time?
The answer is no – you can have more than 30 tons of mass on the Climber at one time and the reason for this is the Climber, as it ascends, weighs less and less (though its mass, of course, never changes). This is due to the force of gravity weakening as you get farther and farther away from earth. So, a Climber which weighs 30 tons at ground zero will only weigh only half as much (15 tons) when it gets to 2,624 kilometers in height (where the force of gravity is one-half that at ground level). When the Climber ascends to 6,400 kilometers, the Climber will weigh only one quarter as much (7.5 tons) and so on. So this means that when a 30 ton Climber ascends to 6,400 kilometers (and weighs only 7.5 tons), you can then launch another Climber weighing 22.5 tons. When that Climber gets to 6,400 kilometers (and the first one launched is now at 12,800 kilometers), the total Climber weight on the tether is now 10.8 tons (1/4 of 30 tons plus 1/9 of 30 tons) which means you can launch another 19.2 ton Climber (note that the Climbers will weigh even less than I’ve indicated as they ascend due to centrifugal force, but that factor doesn’t become significant until you get close to GEO and so I’ve ignored it here).
As you can see, one can play with these numbers in several different ways to get different launch schedules, but the bottom line is this; you can launch any number of Climbers you want to on this 30-ton rated tether as long as the total weight of these Climbers (as opposed to the total mass of these Climbers) does not exceed 30 tons.
From this, it should be pretty clear that it is advantageous to have the Climbers ascend as rapidly as possible. The higher they ascend and the quicker they do so, the sooner you can launch another significant Climber. And this brings us back to the statement; “The stronger the power system is, the weaker the tether can be”.
The stronger your power system is (with all other things being equal), the faster your climbers can ascend (up to a limit, of course). So, if your goal is to get 20 tons to GEO every day, you need, say, a 30 ton rated tether with a power system strong enough to propel a 20 ton Climber at least 2,624 kilometers per day, or, you can have, say, a 60 ton rated tether with a weaker power system just able to propel a 20 ton Climber at least 1,312 kilometers per day. Both tethers will do the job, but it’s certainly going to be easier (and faster) to build a 30-ton rated tether than a 60-ton rated one. And what if a 60-ton rated tether is just not possible?
“The stronger the power system is, the weaker the tether can be”.
Not only would we LIKE to lift the maximum amount possible on any specific tether, it is also going to be NECESSARY to lift the maximum amount possible on any specific tether. This is because there are ‘housekeeping chores’ which will consume a very significant fraction of a Space Elevator’s capabilities, housekeeping chores which, if not done, will mean a Space Elevator will simply not be viable. I will talk about these housekeeping chores in my next post.
(Picture of Stone-Wales defect from here - click on it for a slightly larger version)
December 5th, 2008
How strong does a tether really have to be in order to make a working, useful Space Elevator? This is a question that Ben Shelef, CEO of the Spaceward Foundation, has been exploring in some detail.
The answer to this question relates to how strong the climber power system is. The stronger the power system is, the weaker the tether can be (and vice-versa). There is no absolute minimum number, but there is an equation which Ben has created, The Space Elevator Feasibility Condition, which answers this question.
According to Ben’s calculations, for example, a tether which has a tensile strength of 30 GPa-cc/g would be strong enough to create a useful Space Elevator provided the Climber power system can generate at least 1.5 kWatt/kg. If the tensile strength of the tether is only 25 GPa-cc/g, the power system needs to generate at least 3.5 kWatt/kg.
How does climber power relate to tether strength? Ben documents all of this in a new paper; The Space Elevator Feasibility Condition, available (in html and pdf formats) in the Library section of the Spaceward website.
Over the next few days, I’m going to be looking at and writing about this paper in more detail.
This paper is very important for all of us in the Space Elevator community to read and understand. We need to be able to pose realistic scenarios and give justifiable answers to questions when they are presented to us. The Space Elevator Feasibility Condition will help us do that.
(Picture of spontaneous formation of Stone-Wales Defect in a nanotube under tension from the Spaceward website - click on it for a slightly larger version)
December 1st, 2008