Hey Ben and cariann, Thanks for another great show
I realise how much every show goes into. I also beleive that you guys could’ve acutually done the first few videos at home and when you uys had fixed all your glitches, you guys would have had more time to talk more on the set.
Coming on the Topic, I cannot imagine that a space elevator can be made because generally it’s too big, it’ll not work plus it’ll cost more than the shuttle, might be over 8 Trillion dollars. but if it does happen, it might be built at spaceport. and i bet there must be a building supporting it in order it to work.
but anyways thanks for another show
P.S: Next week, could you maybe do that “spacenews” singing and handshakes rather than that graphic thing, i just love that
Well Yucky, even if we did the first few shows at home, we would still have the glitches when we move to the new studio. When we see a problem we don’t notice it until it is show time. Then we fix it for next week. So we would have just delayed the inevitable.
Nice show this week. Looks like you are getting things figured out.
In regards to space elevators, you should probably discuss the advantages and disadvantages of the elevators as well as the advantages and disadvantages of what it would be competing with (chemically propelled rockets for now).
The main disadvantage of current rockets is that they have to carry not only the cargo and the vehicle structure but also the fuel and the oxidizer. That is very, very heavy and leads to an inefficient vehicle to get a payload into orbit. The main advantage of rockets is that they work and they work today (mostly).
A space elevator would theoretically not have to carry much weight beyond the cargo and the vehicle structure since the power could be transmitted from an external source. It would also not be based on a “controlled explosion” on top of the world’s largest “gas tank” with two freakin’ huge “firecrackers” attached for added excitement. It should be much safer and cheaper over time since it will be more efficient. The main disadvantage is that it does not exist and I am skeptical that they will find a material for the cable within say 50 years. I think it is worthwhile looking for that material since finding new materials that are stronger and lighter than anything we currently have is bound to have many uses.
Also, don’t get stuck on the word “elevator” there. As far as I know, the idea is basically that you have a cable attached to the ground with a counterweight out near geosynchronous orbit to hold the cable up. That cable is just there for support and doesn’t move or anything. Then they attach a vehicle that climbs up and down the cable to get things in and out of orbit. That vehicle would probably be more like a vertical train rather than what you typically would think of as an “elevator”.
Good points Flared, all. Although how fast can a train move on a cable that will probably also be moving a bit? Heck, even the tallest buildings in the world sway a bit, imagine what this thing would do!
But the main advantage is, cheap transport in to space. Once we’re in space we can then use a lot less fuel to break from our gravity and go to cool places that might be out of our reach today.
Then again, maybe we need to start looking at space in a two phased approach. One vehicle to get in to low Earth orbit and dock with a space station. A second vehicle to go from the space station to the moon or Mars.
How bout they build a docking station on the ISS for the privately funded x-cor and virgin galactic type spacecraft? Why can’t they send an unmanned one up there and park it? From there it could be refueled and sent on to the moon and back?
Guess they’d have to build a runway on the moon as well, haha. With every solution comes a new problem I guess.
Hi Ben and Cariann,
A little trivia for you. The idea for the space elevator was first introduced in Arthur C. Clarke’s novel “The Fountains of Paradise” in the late 1970s.
In answer to your question about the speed such an elevator would travel, most proposals site the 400 to 600 miles per hour range. For reasons relating to how the space elevator is constructed and the orbital mechanics involved, the only place where passengers would actually be in “orbit” would be at the altitude of geosynchronous orbit (approximately 22,300 miles up). If a passenger got off below that altitude, he would fall toward the Earth (rather than float in orbit) because he would not have enough lateral speed to be in orbit. If he gets off above geosynchronous orbit he would be slung out of Earth’s gravity well by centrifugal force! The latter effect would be great for launching interplanetary probes!
As you may have surmised, since the only orbit available is at 22,300 miles and the car only travels at around 400 miles per hour, it would take days to reach orbit on a space elevator.
If you want more details of how such a structure would be constructed and what its capabilities and limitations are, I will be glad to discuss it with you on the phone. A full explanation of the principles involved are really very simple, but it would take too much time to explain all of the details in writing. I don’t think you want pages of explanation in a blog post!
As is often the case, the wiki is your friend for these matters:
This is a pretty comprehensive overview of space elevator concepts, what tensile strength is needed for the cables, and some interesting historical background going to the late 19th Century with some incredible visionaries that were thinking very far into the future.
What is frustrating about space elevators is that they are currently right at the bleeding edge of material science concepts in terms of what might be a reasonable material for the primary cable. Carbon nanotubes currently seem to be the hot ticket item, but there are some limitations to their use that I think will in the long run stop them from being used. If anything, I expect that any significant breakthroughs that will happen will come from a very unconventional source, sort of like how high-temperature super-conductor materials seem to come from very unexpected places. We just don’t know what will work, and trying to guess when or if some breakthrough will happen is purely speculation.
Space elevators certainly can’t be built with current materials, although unlike faster than light travel, it is at least something which is permissible with current understandings of physical science.
Robert, your misgivings are well founded and I would add one. Putting a craft into a low earth orbit would only be possible from the elevator by expending large amounts of extra energy. The accompanying need to lift a fairly large rocket to those low altitudes to provide the extra energy would be a serious drawback. Though the rocket would not need to be as large as if it was launched from the ground, it still might be too much mass to be hoisted on the elevator. There would also be a massive stress on the elevator cable from the sudden load reduction when the rocket separated from the cable. Also there would need to be some way of pushing the rocket away from the cable before the main engines fire; otherwise, the cable could be seriously damaged.
You could “launch” a satalite from somewhere higher than LEO, so when it falls down it “earns” the energy needed to stay in orbit.
You don’t get more energy out of a fall in a gravity well than is put into it to get to the altitude where the object is dropped. If it is not going at orbital speed for it trajectory heading when it is released, it will not orbit. Even after it hits its maximum fall speed, energy would have to be added to get it to orbit. The one exception to this is a spacecraft that is entering the Earth’s gravity well from elsewhere in the solar system at high speed at certain critical angles. This method is the famous “sling shot” effect used to boost the speed of spacecraft on interplanetary missions. The spacecraft gets the extra speed by “stealing” some of the energy from a planet’s orbital momentum, causing the planet to move inward toward the sun by a microscopic amount. But the physics of an object dropped at any point below geosynchronous orbit does not allow a free indefinite energy boost.
I think so many people are this optimistic about us going to mars for 2 reasons:
1. They brought out the rover for Obama’s inauguration.
2. It was on CNN?
Oh and I actually hope X-cor doesn’t fly this year. Planning a flight this early sounds pretty dangerous to me.
And as for the space elevator… The amount of tension you’d need to keep the top in orbit would be astronomically high. I think even if you got something to stretch out into space, it would either snap or fall back to earth.
Carbon nanotubes have more than enough tensile strength to handle the load. http://nextbigfuture.com/2009/01/cambridge-making-carbon-nanotubes.html
That is IF they can ever be made in long enough lengths, which is a BIG IF.
The length currently being made is measured in millimeters, not the tens of thousands of kilometers necessary for a space elevator cable. Millimeter-ength is the “extra long” version too!
One of the huge problems that this material faces is dealing with ionized Oxygen, Hydrogen, and other elements that exist in the Stratosphere, Exosphere, and other realms of the atmosphere that are both different from the low-earth orbit (LEO) environment as well as from the Troposphere that we are more used to. We are talking nearly pure carbon here, which not only can easily burn, but can react with a great many chemicals and elements.
Even assuming that you get these cables put up into space and that they can carry the weight required just to support itself, there are going to be erosion problems that will cause them to degrade…. in some places very quickly. This requires either extra cable to withstand the deterioration of the cable or a nearly constant process of replacing the cable in the area… and splicing the cable to make a “seamless” connection between old and new parts of the cable/ribbon. Making a splice stronger than the original material is something mariners have done for centuries, but this is something that will have to be done on nearly a molecular level with the full tension of the cable on the area needing to be spliced… something I normally wouldn’t even dream of trying with a rope or other cable.
Imagine trying to splice into the main cables of a suspension bridge like the Golden Gate in San Francisco…. during rush hour… to replace the cable that has been deteriorating due to the elements. I don’t think any such feat has ever been contemplated, much less attempted. And the tension on a suspension bridge is small potatoes compared to a space elevator. Encasing the cable can help to reduce this sort of damage, but it can’t be entirely eliminated… and that also reduces the overall tensile strength of the material.
“The length currently being made is measured in millimeters, not the tens of thousands of kilometers necessary for a space elevator cable. Millimeter-ength is the “extra long” version too!”
Exactly, which is what I meant when I said,”That is IF they can ever be made in long enough lengths, which is a BIG IF.”
I already knew about all of the other issues that you spoke of. There would also be the issue of orbital debris (pieces of old satellites, boosters, etc), that could potentially damage the cable. But as I said, I did not want to get into a long dissertation of all of the aspects of the problem.
I think the big question for me is once the technology is figured out, will it be too late? As we get better and better at putting objects in to sub orbital flight we will also get better at putting things in to LEO and on. So will we even need a space elevator in the future when we can already safely launch the moon just as we can today safely fly to Paris or Australia via airplane.
Or maybe we’ll never be able to travel in to space safely without a space elevator.
Reliability will go up and cost will go down as flight rate increases, just as it did with airplanes in the early twentieth century. The problem with manned rockets is there have never been enough vehicles and a high enough frequency of flights to accomplish this outcome. Hopefully, that situation is about to change. Unfortunately, until we have learned enough from frequent flights to make the vehicles safe, spaceflight will still be dangerous. Early commercial space flight will only be done by people willing to accept the risk. After a while, it will problably become about as safe as airliner flight.
I don’t think it is physically possible to make rocket transportation to GTO cheaper than elevator transportation pound per pound. The question is weather the original investment to build the elevator is to large to make financial sense. If the answer is no at any point in the future then they will be built, maybe even by Virgin Elevators. 😛
The reason we have the ISS today is because of the originally Russian building technique of assembling space stations from plug’n play modules. It would make more sense to just build space stations from larger, possibly non cylindrical pieces in order to reduce the outer surface which needs to be heavily shielded for anything beyond LEO because of micrometeorites and radiation and things we know nothing about yet. Lets face it: if people are to go to the Moon and Mars in large numbers they won’t do it in small deathtraps that were the original Moon landers or the new ones which kinda look a lot like them.
The show was great!
Yes, as I said, the one orbit it is practical to reach via elevator is Geostationary Transfer Orbit. Assuming such a structure could ever be built, it would be hard to beat pound per pound for that particular orbit. But the technology is currently beyond us (maybe for quite some time), and even then it does nothing for useful Low Earth Orbits.
Elon Musk has set a rather ambitious goal of eventually reaching $100 per pound to LEO. I will consider it great if he can do it for five times that price.
Finally, the best way to assemble a space station is the way Bigelow Aerospace is going to do it – using inflatable meteoroid resistant modules that can be made structurally rigid after inflation. They take up little payload space on a conventional launch vehicle (because they are deflated until they reach orbit) and also have much less mass per volume than the rigid materials that would be used if assembly was done one piece at a time. http://www.bigelowaerospace.com/
By the way, did you know that Bigelow has also successfully launched two large fully functioning prototype space station modules into orbit, both of which are still inflated and functioning? The first called Genesis I was launched two and one half years ago! Their first space station made for actual use by manned crews is called Sundancer and is due to be launched in the next few years. It will be three times larger than the currently orbiting Genesis modules.
I did know about the Sundancer module and its predecessors. Here’s the thing:
We will have no problem putting things into LEO at an affordable price. But the orbit you need for missions beyond Earth for instance Moon, Mars… is GTO. The ‘TO’ stand for transfer orbit :). So while LEO is interesting now, the orbit which will have great significance for humanity is GTO. that’s where our interplanetary ships will be built and launched from and that’s where future space stations will be. We have to remember that in the grand scheme of things the ISS is just our proverbial foot in the water.
Remember what I said in an earlier post,”If he gets off (of the elevator) above geosynchronous orbit he would be slung out of Earth’s gravity well by centrifugal force! The latter effect would be great for launching interplanetary probes!” So I too know what the TO stands for. 🙂 Furthermore, I am in the process of finishing my Master’s degree in astrophysics and I would be in big trouble if I did not know the intricacies orbital mechanics.
Geostationary orbit is convenient as an interplanetary transfer orbit only if a low energy means of getting to that orbit (such as the elevator) exists. The amount of energy saved using GTO as the tranfer orbit versus using a lower orbit is not nearly as large as the amount of energy needed to get from the surface of the Earth to LEO. Most experts think that the use of an on-orbit fuel depot at LEO will be an economical way to give the spacecraft enough energy to have practical LEO transfer orbits. http://selenianboondocks.blogspot.com/2008/03/space-access-2008-propellant-depot.html
didn’t mean to say you don’t know what GTO is or anything of the sort. just wanted to ilustrate my point.
Sorry if I gave the wrong impression.
I think if we’re going to build a colony on the moon, first we need to send materials to the surface. There needs to be some autonomous construction robots that build the first bio dome. It should be completely constructed before the first people land and stock it full of plants and animals.
Otherwise, steady shipments of food and oxygen would be way too costly.
That Challenger photo always makes me queasy… and I wasn’t even born yet!
It certainly is iconic at this point. I know I personally hold my breath every time I hear “Go at throttle up” for any shuttle mission.
I thought I was the only one who did that…
Its go and throttle up!
Really? It always sounds like “and” to me.
Really?!? I always thought it was “at” too! LOL!
Hey, the space elevator is very doable. The problem is not cost, but technical manufacturing issues. They are using carbon buckeyballs to get the tensile strength. Unfortunately they need a purity level of 80% or better, but can only get 15-20% with today’s manufacturing processes. And it won’t cost 8 trillion dollars because it’s mostly carbon and air. Once they solve the manufacturing purity issue, then they can setup the line and just do it. Probably they need to manufacture in a vacuum. Let’s get started…
Buuuut… Doesn’t solving the manufacturing problem take time, equipment, know how and as such lots and lots and lots of money?
Think of it like developping a pill (the medical kind). It costs a lot of money to develop but it provides a solution which increases the quality of life for many many people.
The problem here is up and down transport which is at this point very difficult and dangerous. This sort of transport will be the main focus of any space business untill such time as we have all moved into space or something… To me at least it makes sense but in the interest of full disclosure, I have no idea what the numbers in terms of investment capital or anything like that would look like.
I am going to MARSSS!!!!!!!!!!!!!!!!
haha Jan 30th is my Birthday!!!!!
OMG!! Did she just call the orbiter Enceladus and Excalibur!!!!
I was told about this site but, WOW… it is so unprofessional.
Not dressed well at all. Not sure which camera is on. Giggling and cackling over birthdays. Wsting MINUTES on not eating meat!!
I thought this was space related.
It took you over 5 minutes to get to anything newsworthy. I never heard anything on space elevators.. even after FIFTEEN minutes. I couldn’t listen to this trivial rambling anymore.
Well, not 100% sure how to reply to this. We like to keep the show open, casual and fun. We’re not a TV station by any stretch of the imagination and do this as a side hobby. So if you don’t really like it, I am open to ideas on how to improve while keeping it light, fun and with real-time communication open between us and our viewers.
So if we cant or dont have materials that are not light enough why dont we make the materials lighter… for example, if we have the worlds lightest/strongest maerial and next to it we have tubes or baloons of compressed nitrogen…???
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