Space Winch

[grooble]

Latest idea, a space winch.<br /><br />You have a platform in LEO, maybe 10x10 meters, nothing enourmous. It has the best solar tech available and gets constant power from the sun. It has some kind of electric propulsion to keep itself in orbit and also has a really long, powerful cable that could descend down to around 80,000ft, where it will connect with a spacecraft that was lifted by say a Giant balloon.<br /><br />It then tows the spacecraft upto LEO.<br /><br />Is that possible, or did i mess up on the orbital stuff? <br /><br />The platform will already be moving at 1000s of mph in its orbit, maybe instead of LEO it would have to be GSO?<br /><br />It isn't a space elevator because it isn't connected to the earth, nor does the winch descend that far down.<br /><br />Perhaps the winch would descend from LEO down to Sub-orbit of around 60 miles altitude and grapple a ship from there.<br /><br />

 

[vogon13]

Cable will burn up if lowered from LEO. If it didn't, docking with it at 80,000 feet and 17,000 miles per hour will overtax your balloon technology. Also, if it doesn't burnup, your solar thruster gadget will not makeup the power loss from atmospheric drag, and the platform will fall and burn up.<br /><br />Other than that, works fine, lasts a long time.<br /><br /><img src="/images/icons/wink.gif" /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[grooble]

Ah well, almost!

 

[najab]

General rule - there ain't no such thing as a free launch.

 

[mrmorris]

Perhaps you could work on the potential specifications and uses of a space wench. That would be considerably mre feasible and potentially entertaining. Er... probably more of a Free Space sort of thing though... or maybe Human Biology.

 

[grooble]

Well whats your idea morris? Other than mass producing cheap rockets and capsules, what else is there to make spaceflight cheaper?

 

[ldyaidan]

There is actually quite a lot of information available about this technology, and several companies and universities that are working on that very thing. Do a goggle search for "space tether" and you will be amazed. Here is an article that is only about a week old:<br /><br />A team of university graduate students and faculty from Tennessee, with the help of NASA engineers, have "launched" a subscale spacecraft model and caught it in mid-air with a unique rendezvous or "catch" mechanism. <br />Their successful demonstration of this mechanism that could grab a payload or craft traveling in space marks a critical milestone in development of a tether-based propulsion system. <br /><br />The professors and graduate students at Tennessee Technological University in Cookeville designed, built and recently tested the subscale tether catch mechanism in a university laboratory. <br /><br />Tether technology, as potentially implemented in space, transfers energy and momentum -- called momentum exchange -- from the tip of a fast-moving, spinning tether to a slower-moving object, dramatically increasing the object's speed. As the tether -- a long cable, approximately 60 to 90 miles in length -- spins end-over-end in space, it catches a payload in low Earth orbit via a catch mechanism, carries it for a half-rotation, and throws the payload toward its final destination. <br /><br />To restore the energy and momentum transferred to the payload, the tether then uses sunlight collected by onboard solar panels to drive electrical current through electrically conductive portions of the tether. <br /><br />The magnetic field generated by this current pushes against the Earth's magnetic field and slowly returns the tether to its original orbit. This technique, called electrodynamic reboost, restores the tether's momentum and energy, and prepares it for the next payload. Together, momentum exchange and electrodynamic reboost are keys to the Momentum Exchange/Electrodynamic Reboost or MXER tethe

 

[mrmorris]

<font color="yellow">"Well whats your idea morris?"</font><br /><br />You've seen my idea -- it's about five threads down from this right this second.<br /><br /><font color="yellow">"what else is there to make spaceflight cheaper?"</font><br /><br />Right this moment, I don't see anything other than the items you discounted which is also feasible given current technology. My idea then would be to make the most efficient use of the methods which <b>are</b> possible with current tech. Boosters may not be cheap, but they work. Technology advances will make them lighter, and the payloads being carried lighter. This will make for an evolutionary improvement in their capability over time.<br /><br />For revolutionary improvements, we need revolutionary technology advances. Advances in nanotechnology, superconductivity, and materials sciences have the potential to make ideas feasible which are simply 'woo woo' concepts today.

 

[nexium]

As you guessed the tether needs to be about 50,000 miles long, so that it travels slow enough that it can grab the pay load from the balloon, non-distructively, and with only modest heating due to air friction. If you can build one that long that is reliable you are almost to a space elevator which can be attached to a stationary sea anchor. See www.liftport.com Click on forum near the bottom of the screen. An alternate approach is to spin a tether about 20,000 miles long. The tips need to move at least 12,000 miles per hour to cancel most of the orbital speed to make a catch at 80,000 feet. I'm guessing at the numbers, but optimistic projections for CNT =carbon nano tubes are needed to build one for less than a trillion dollars. Neil