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Tethers Unlimited's ultimate plan is to be able to launch rockets higher into orbit while already in space

Researchers are prepared to launch several satellites satellites which will travel up and down a 1-kilometer tether in space. The launch will take place on April 17, and is designed to allow researchers to test technologies that would be able to hopefully one day launch satellites higher into orbit. Rob Hoylt, chief executive officer of Tethers Unlimited, said the launch on April 17 will allow researchers to see how a spacecraft and tether operate and interact while in orbit.

If a long tether is moving lengthwise, researchers believe that it could possibly catch satellites and launch them higher into space. One of the advantages would be that rockets would require less fuel since they would be launched to lower altitudes.

Hoyt and his team will use three "picosatellites" that will work in sync to do the majority of the work. The satellites will separate once they reach 750 kilometers in altitude, while pulling the 1-kilometer-long tether to its proper position.  Two of the satellites will be anchors, with the "inspector" satellite in the middle called Gadget. 

The thermos-flask-sized Gadget will use a digital camera to look in the surrounding area for space junk, radiation, and other harmful objects while moving along the tether.  Gadget is solar-powered, its motor expected to last at least three months.   The estimated trip from one end satellite to the other satellite around seven days.

There has been a recent emphasis put on tethers and other types of devices that could effectively be used in space.

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Or..
By TimberJon on 3/30/2007 3:57:31 PM , Rating: 2
We save our dough for the research and development needed to engineer and manufacture spacecraft of various sizes once the fusion reactor projects reach stable plasma. THEN we will need money to R&D the fusion rocket that will be sending ships up out of the atmosphere under their own power.

We will have to be collecting all those expensive satellites once we get a spacecraft up there.

We need a better space station..




RE: Or..
By osalcido on 3/30/2007 4:00:24 PM , Rating: 2
what fusion rocket? as far as i know the only fusion project is ITER and its mammoth.....


RE: Or..
By masher2 (blog) on 3/30/2007 4:27:30 PM , Rating: 5
A fusion-based spacecraft isn't even close to the horizon; its a considerably more difficult task than commercial power generation via fusion...and we aren't even close to that.

However, fission-based spacecraft are viable today, and would be vastly more efficient than chemical rockets. NASA drew up plans for nuclear-powered rockets as far back as the 1960s, and even did initial testing. Had it not been for the nuclear test ban treaty, our first trip to the moon might have been conducted under nuclear power.


RE: Or..
By novacthall on 3/30/2007 4:31:22 PM , Rating: 2
Haven't we also played with some more exotic propulsions methods in the past? I seem to recall an ion-propelled probe being launched sometime a few years ago.


RE: Or..
By johnsonx on 3/30/2007 4:36:51 PM , Rating: 3
Ion drives are of no use for lift vehicles. They can provide slow-n-steady propulsion for a space craft once it's beyond the gravity well of any planet or moon.


RE: Or..
By codeThug on 3/30/2007 6:52:44 PM , Rating: 2
thank you....

You saved me the trouble of replying.


RE: Or..
By herrdoktor330 on 3/30/2007 8:52:11 PM , Rating: 2
I was reading this expecting to hear something about the idea of a "Space Elevator" to carry things into space. How much of a pipe dream is it to lift things into space that way?


RE: Or..
By masher2 (blog) on 3/30/2007 9:18:15 PM , Rating: 2
Well, we need to solve a dozen different engineering and materials-science problems before we could build one on Earth...but the technology we develop from rotating tethers could easily segue into a true space elevator. The big problem is of course the tether itself...it needs to be built from a material at least 20 times as strong as steel, and yet significantly lighter. So far, the only thing that comes close is carbon nanotubes. And once you solve the problem of building a 40,000 km long nanotube-cable and hoisting it into space, you have to deal with wind and weather in the lower atmosphere, damage from micrometeorites and a whole host of other problems.


RE: Or..
By Visual on 4/2/2007 5:56:35 AM , Rating: 2
sufficiently strong carbon nanotubes have been announced for a few years already. there's still the technical challenge of producing enough of them and combining them to form a ribbon, but i think the biggest problem before the space elevator idea right now is fundings. neither nasa nor any other governmental organization is taking this idea seriously, it's all up to private researchers, and they just don't have the resources necessary.


RE: Or..
By masher2 (blog) on 4/2/2007 9:12:08 AM , Rating: 2
> "sufficiently strong carbon nanotubes have been announced for a few years already.."

No. You need a material with a Young's modulus considerably above 100 gigapascals. The strongest carbon nanotubes made so far are about half the required value.


RE: Or..
By Visual on 4/10/2007 8:00:46 AM , Rating: 2
I can't be bothered to search for references now, but I've seen articles stating requirements of about 50-60GPa for the tensile strength of the fibers, and such carbon nanotubes (although as just very short fragments) have existed since 2001.

I've never seen anything about the Young's modulus requirements though, and you might be right that we've not created a suitable material yet. Your quoted figure of just 100GPa doesn't make sense to me though as there are many materials with higher values, and wikipedia lists single-walled carbon nanotubes at more than ten times that figure.


RE: Or..
By Grast on 3/30/2007 5:03:22 PM , Rating: 2
You are watching to much Star Trek.... While it would be possible in the future to use the plasma from a fusion reactor to provide a similar thrust such as from a jet engine. This is no where in the near future.

we are spending only 300 million a year on fusion research. If we really want free energy in the quantities needed for future growth without fossil fuels, we need fusion power.

We should be spending close to 300 billion on research.

Later...


RE: Or..
By masher2 (blog) on 3/30/2007 5:41:42 PM , Rating: 2
> "we really want free energy in the quantities needed for future growth without fossil fuels, we need fusion power..."

We don't need fusion energy. Fission-based designs like the energy amplifier (aka the "Rubbiatron") are possible with current technnology, cheaper than coal or current nuclear plants, less radioactive than fusion, and inherently safe and wholly unable to explode. Best yet-- it burns its own wastes, and can even use as fuel the waste from conventional nuclear plants.

Unfortunately, no one seems interested in pursing such designs. They'd rather waste hundreds of billions in politically-popular boondoggles such as windmills.


RE: Or..
By Grast on 3/30/2007 6:04:35 PM , Rating: 1
Masher,

while agree that fission based technology is a good step for the near future, it still requires a fuel which is limited in supply. A fusion enconomy does not suffer from such fuel issues.

I agree that too much research is being spent on wind, water, and solar tech. these are all pipe dreams for the uninformed. As a side note, wind and hydro power generation can be worse for the environment than fossil fuels.

Later..


RE: Or..
By masher2 (blog) on 3/30/2007 7:40:51 PM , Rating: 3
> "it still requires a fuel which is limited in supply. A fusion economy does not suffer from such fuel issues."

An energy amplifier can not only burn uranium, but thorium as well, which is many times as prevalent, as well as several other nuclides. That's enough energy to last tens of thousands of years, even without assuming new deposits found (which they surely would be) or the possibility of mining asteroids or other bodies within the solar system.

While this is less fuel than the millions of years we'd last from Deuterium-based fusion, both sources are still technically limited resources...but for all practical purposes-- unlimited for the foreseable future.


RE: Or..
By boogle on 3/30/2007 8:02:29 PM , Rating: 2
I would just like to see some (viable) alternatives to fossil fuels. It actually scares me how much we as a planet rely on extremely finite long-dead creatures for power.

Sure we have a rather large reserve of fossil fuels right now (especially if you don't mind mining antarctica), but that doesn't take into account rapidly increasing usage. Worse still the toxic effects are rather worrysome. I'm not talking about 'green-house' gases, especially since more of those gases come from intensive farming of animals - but the gases/chemicals that really screw over your lungs, and various chemicals that harm the environment.

Either way, near-infinite power for a fraction of the cost has got to be attractive? Oh wait, that would only benefit the consumer. Got to keep those oil companies in business, that's how you get to be a powerful government official don't ya know? Too busy mining a mega-volcano (Yellowstone Park) eh Bush?


RE: Or..
By masher2 (blog) on 3/30/2007 8:06:35 PM , Rating: 4
With today's technology, the only viable alternative to fossil fuels is nuclear power. Bush has actually been quite positive on it; the blame for our failing to utilize its potential rests solely within the environmentalist camp.


RE: Or..
By Scrogneugneu on 3/30/07, Rating: 0
RE: Or..
By Cincybeck on 4/1/2007 6:18:07 PM , Rating: 1
http://en.wikipedia.org/wiki/Rubbiatron

It's also stated that there's a possibility for it to used plutonium as a fuel which would be great.

I'm not very familiar with the process or the elements used but if you had a traditional nuclear plant next door to one of these plants is it possible that the Rubbiatron could use the plutonium which in turn produces Uranium-233 which then could be transferred back to the traditional plant to be used there. With the materials just going back and forth between plants? Maybe some kind of processing plant in the middle?


RE: Or..
By HilbertSpace on 3/30/2007 10:40:27 PM , Rating: 2
I don't think too much money is being spent on solar power. There are currently several promising organic electronic based solar cells which will soon become practical (say 5-10 years - or even 3-5 years optimistically). Efficiencies for these technologies are about an order of magnitude greater than current designs.

The enormous amount of current research in new forms of electronics will reap benefits quite soon - in my opinion.


RE: Or..
By masher2 (blog) on 3/31/2007 12:08:27 PM , Rating: 2
> "Efficiencies for these technologies are about an order of magnitude greater than current designs..."

I think you're misremembering. Organic solar cells are usually lucky to get 4% efficiency. The best multijunction cells can do ten times that...but they're extremely expensive, and require large concentrator assemblies to work well.


RE: Or..
By HilbertSpace on 3/31/2007 1:14:00 PM , Rating: 2
i was definitely wrong about the efficiencies...

i guess i was meaning that when you take into account the cheap processing techniques that could be used with "plastics" you reach a much greater viability for commercial applications. If you looked at the overall efficiency of producing the solar cells to how long it takes to recover the energy put in to its manufacture - well then i think organic cells can easily trump amorphous Si based devices.

Also once more research is done on improving conductivity in organic materials - through doping, or other means, then efficiencies greater than 5% will be realized.


RE: Or..
By masher2 (blog) on 3/31/2007 1:37:07 PM , Rating: 1
You realize that, even with efficiencies far above what organic cells are currently getting, that to power a city like NYC would require covering an area larger than the city itself with solar cells?


RE: Or..
By lompocus on 3/31/2007 5:32:53 AM , Rating: 1
afaik, this is a privately run r and d project by one of many corporations (amazingly, this is one i havn't heard about). This could provide a viable, cheap way to get resources into orbit (think: Build a big-ass spaceship where the parts don't way several thousand tonns.


RE: Or..
By masher2 (blog) on 3/31/2007 12:03:41 PM , Rating: 1
With this approach, you still need to get the parts into orbit...but you only need the very lowest of orbits, and thus much less energy. The tether then intercepts and boosts the payload to a higher orbit.


Exciting
By masher2 (blog) on 3/30/2007 3:21:47 PM , Rating: 4
This is one of the more exciting space-based research projects in recent years. It has the potential to one day provide a majority of satellite launch momentum directly from solar power, rather than from the launch rockets themselves.




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