Community > Forum > Official JP Aerospace Forum > http://www.jpaerospace.com/

http://www.jpaerospace.com/

Posted by: Rob Goldsmith - Fri Jan 21, 2005 7:27 pm
Post new topic Reply to topic
 [ 178 posts ] 
Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8 ... 12  Next
http://www.jpaerospace.com/ 
Author Message
Moderator
Moderator
avatar
Joined: Thu Jun 03, 2004 11:23 am
Posts: 3745
Location: Hamburg, Germany
Post    Posted on: Sun Mar 06, 2005 6:15 pm
Hello, jpowell,

would it be possible to connect two or more DSS or floating ports to each other by cable(s)? This could provide one DSS access of local advantages - weather, wind and so on - another DSS is provided to. The cable could be used too for moving cargo from one DSS to the other - if they are at different altituds for example.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


Back to top
Profile
Space Station Commander
Space Station Commander
avatar
Joined: Wed Mar 09, 2005 1:25 am
Posts: 887
Post    Posted on: Thu Mar 10, 2005 7:18 pm
It may be that a very large orbital craft must blow ultrathin 'bubble-tubes" in orbit if airships that can transit to and from space with electric drives ever come about-if possible at all.


Back to top
Profile
Space Walker
Space Walker
avatar
Joined: Tue Jan 18, 2005 11:12 pm
Posts: 137
Location: Sacramento, CA
Post    Posted on: Fri Mar 11, 2005 10:45 am
I've never thought about connecting two stations together by a cable, very interesting idea.

JP


Back to top
Profile WWW
Space Station Commander
Space Station Commander
User avatar
Joined: Mon Oct 06, 2003 9:22 pm
Posts: 843
Location: New York, NY
Post    Posted on: Sat Mar 12, 2005 5:14 pm
Ekkehard Augustin wrote:
Hello, jpowell,

would it be possible to connect two or more DSS or floating ports to each other by cable(s)? This could provide one DSS access of local advantages - weather, wind and so on - another DSS is provided to. The cable could be used too for moving cargo from one DSS to the other - if they are at different altituds for example.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


heh, cue history joke. hypothetically speaking then you could network DSSes over a large portion of the sky and have people live up there (ok they'd have to be really advanced, strong, and enclosed but still). since jp is from the US, this would take our old concept of "city on a hill" to a whole new level: "city in the sky", who would want to live with americans who're that stuck up? :lol:

_________________
Cornell 2010- Applied and Engineering Physics

Software Developer

Also, check out my fractals


Back to top
Profile
Moderator
Moderator
avatar
Joined: Thu Jun 03, 2004 11:23 am
Posts: 3745
Location: Hamburg, Germany
Post    Posted on: Wed Mar 16, 2005 2:22 pm
Hello, TerraMrs,

your post reminds me to a special volume of Star Trek The Original Series too - "City in the clouds" (don't know if that is the correct english title - in German it's "Die Stadt in den Wolken") ...

Hello, jpowell,

it may be that connecting two or more DSSs could provide an advantage to a DSS.

The floating ports and DSSs have engines to be able to move within a current of air. If there would be two connected DSSs at different altitudes then the current could be different at these altitudes sometimes - different in speed or different in direction. This way one of the connected DSSs could decelerated the other, accelerate the other or change the direction of the other. If the differences last long enough and could cause the one of the DSSs to move to the desired direction then it wouldn't be required to use the engines during that time.

For this purpose there could be a mix of manned and unmanned DSSs and the DSSs that are used as substitutes for the engines may be capable of changing their shape - they would have to be able to shape stremalined if the current they are placed in shouldn't have effects on the movements of the other DSS for example.

Another possibility might be to use another current to drive wind turbines to generate electricity.

All this is theory completely - what do you think about it?



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


Back to top
Profile
Spaceflight Participant
Spaceflight Participant
avatar
Joined: Thu Mar 31, 2005 1:19 am
Posts: 67
Post    Posted on: Thu Mar 31, 2005 2:57 am
Hello Ekkehard,

I'm a lurker here, I've been checking this place out ever since the begining of last summer. I don't know why I didn't sign up sooner, I realy should have. this is a neat place.

I have not seen Star Trek before, but in the second Star Wars movie there is a floating station called City in the Clouds. I think the entire concept of a sub-orbital space station is really exciting. My favorite part about it is the relatively low risk and level of training that seems to be involved with visiting the Station, not to mention lower cost. And I don't think missing microgravity would be much of a problem either, from what I hear it can make some people sick.

I see where you are going with the tethered stations idea. Have one in a lower part of the atmosphere where the wind is going a different way, and use the difference to pull one ship, say, away from the airspace of Libya, or to generate electric power. The only problem I can think of is that the tension on the cable will try to drag the two ships to the same level in the atmosphere. Does that make sense? But yes, I like you idea of unmanned stations that could act as sails or anchors.

Another thing I thought of. I read a paper some time ago in a fairly respectable online journal about the so-called clear-weather sky voltage. The principle is that large thunderstorms around the equator release ions into the upper atmposphere. The ions gradually fall down all over the globe. There is a voltage difference of about 100volts/meter, but not very much current is available. However, a DSS structure, especially high in the atmosphere with ionizing radiation, would be an idea collector of the sky voltage. But in order to use it, the station needs a circuit link to another station at lower altitude or to the ground. So I don't know if this would be practical.


Back to top
Profile
Moderator
Moderator
avatar
Joined: Thu Jun 03, 2004 11:23 am
Posts: 3745
Location: Hamburg, Germany
Post    Posted on: Thu Mar 31, 2005 7:48 am
Hello, LukeSkywalker,

good post - go on posting and welcaome at the board. By the way "The City in the clouds" is my own translation of the german title of that Star Trek volume "Die Stadt in den Wolken". As far as I remember there are two species at the planet - one working down at the surface in the mines and the other ruling up there in the city in the clouds. There's a conflict between them and the daughter of the governor is in love with one of the people working in the mines.

I think your last point at least should be asked to jpowell as interseting question.

Concerning my idea of using different winds at different altitudes by tethered DSSs at those altitudes asolution may be to provide several tethers between the DSS's and a "mechanism" keeping the lower DSSs at their altitudes. I could imagine two alternatives - a mechanism pushing down the lower DSS when it reaches a certain higher altitude (the criterion may be the cahnge of direction of wind or of the velocity of wind) or a weight that may be changeable.

Your point about the voltage reminds me to the scientific observation that there are lightnings too thta go up from the clouds to higher altitudes instead of down to the gorund. This might provide danger to DSSs if they are not designed as Faradayan cabines or cages.

jpowell, what about holding down the lower ones of tethered DSSs by a pushing mechanism or a weight, about using voltage differences to get electricity as mentiones by LukeSkywalker, about dangers by upgoing lightnings and about a DSS being a Faradayan cabin?



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


Back to top
Profile
Space Walker
Space Walker
avatar
Joined: Tue Jan 18, 2005 11:12 pm
Posts: 137
Location: Sacramento, CA
Post    Posted on: Fri Apr 01, 2005 3:31 am
The city in Star Trek was 'Stratos'. The Star Wars version was Besbin, (my favorite parts).

Tethering from the ground at 100,000 feet is pretty difficult. However, lowering a tether down from the DSS say five miles is very possible. The tether could be used for 'sheer wind manuvering' or power generation.


Back to top
Profile WWW
Spaceflight Participant
Spaceflight Participant
avatar
Joined: Thu Mar 31, 2005 1:19 am
Posts: 67
Post Sprites (not the drink!)   Posted on: Sun Apr 03, 2005 8:07 pm
Hi Ekkehard,

What you said about upward lightning reminds me of something called sprites and jets, which were supposedly seen from outer space. They are glowing discharges of some sort that can rise up from thunderclouds. Very little is known about them, and the DSS would be a great way to investigate that sort of thing. Another good sales pitch: meteorological outpost.

As for safety, as long as the passengers are inside (and they will need to be) they should be safe. Since they are not grounded, it shouldn't matter if lightning hits them, many airplanes have been hit and survived. However, discharges may destroy electronics, and it might be necessary to protect them.

Oh, one more crazy thought! A DSS could serve as the docking platform for the lower end of a space elevator. But I'm not sure, it may be that these elevators need to be anchored to the ground because of the physics involved.


Back to top
Profile
Moderator
Moderator
avatar
Joined: Thu Jun 03, 2004 11:23 am
Posts: 3745
Location: Hamburg, Germany
Post    Posted on: Mon Apr 04, 2005 7:05 am
Hello, LukeSkywalke,

anchoring of the Space Elevator already has been provided by Edwards who studied that concept for NASA at the NIAC. There are concrete ideas to use an offshore platform at the ocean as anchor. This would provide the possibility to move the tether slightly if a sattelite is approaching the tether.

I already had your idea of using a DSS at the lower part or end of the Space Elevator too and talked of it in a few threads - may be in this one earlier too. The DSS also could assist in doing slightly moves of the tether.

The passengers of airplanes are safe against lightnings because they are in a Faraday's cabin while the airplanes themselves are not.



Hello, jpowell,

in my last question to you I had in mind something like what you answered only.

But the tether(s) may be nanocarbontube-cables - those Edwards has in mind to make the tether of the Space Elevator of. LukeSkywalker's answer reminded me to it.

I am assisting his idea - but the idea may include some new problems: moving cargo from the elevator to an Ascender while these both may have different capacity with the elevator's capacity being larger perhaps, requirement of several elevator-tethers instead of only one perhaps, ...

It is an idea that could be kept in mind for the time when the DSS is ready for use - an idea that could provide revenues if NASA or someone else or privates realy are going to build the elevator. But the should be no such mixes during development of DSS, Ascender and ATO I think.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


Back to top
Profile
Spaceflight Participant
Spaceflight Participant
avatar
Joined: Thu Mar 31, 2005 1:19 am
Posts: 67
Post    Posted on: Mon Apr 04, 2005 9:49 pm
Hello Ekkehard,

I guess you are right about not needing the station for the tether. A potential problem would be that transfering a large mass from the station would make it lighter, so it would try to rise, this might cause problems for the docking. The main reason I proposed the idea was that I remember hearing it would be easier to build a space elevator if it didn't hang all the way to the ground. But it seems like this has already been thought of. I will look for those posts.

Good point about the airplane. I would assume that the structure of the DSS would act as a Faraday cage to the crew compartments, and even if it were not metal it would probably still deflect bolts. The balloons might be at risk, though: it would be impractical to cage them.


Back to top
Profile
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post    Posted on: Tue Apr 05, 2005 8:19 am
LukeSkywalker wrote:
Good point about the airplane. I would assume that the structure of the DSS would act as a Faraday cage to the crew compartments, and even if it were not metal it would probably still deflect bolts. The balloons might be at risk, though: it would be impractical to cage them.


If the DSS is made of non-conducting material it would be invisible as far as lightning is concerned, even thin coatings or foil can be breached with a direct lightning strike and unprotected electronic equipment will still be subjected to the radiated EM pulse. A lightning strike would couple onto any unscreened wiring or control circuitry that runs to the engines used to keep position or sensors mounted externally. Long lengths of wiring should be avoided as these act as attractors for lightning and there have been instances of a strike hitting a aircraft wing to try to couple on to the wiring beneath its skin. The DSS will probably offer much less protestion than a conventional aircraft.

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Spaceflight Participant
Spaceflight Participant
avatar
Joined: Thu Mar 31, 2005 1:19 am
Posts: 67
Post Lightning   Posted on: Tue Apr 05, 2005 8:59 pm
Hello Andy,

I think you are right about the foil coating being penetrated and the fact that long wires will experience power surges during a strike. But the station won't be invisible: I've studied about electrostatics some, and what happens is any object, insulator or not, draws electric field lines to itself because of its density. This is why moving a glass rod near a charged sparkgap can trigger the gap, the glass rod increases the feild density in the gap which breaks down the air. So the station will likely attract lightning.

But the reason you are not safe from lightning on earth is because you are connected to the ground. When you are in a car, you are not, and the car would also conduct a strike to the ground. The Faraday effect only protects equipment from fields, but I think you know that. If the walls of the station are thick plastic, the bolt will follow the path of least resistance through the air around the hull, rather than penetrating it. Air breaks down much more easily than plastic, especially at low pressure.

I think it is unlikely that there would be anything like lightning up that far. For starts, lightning usually involves clouds, and the station would be very far away from them. Another thing is that the atmosphere is thinner, and there are probably more ions caused by space radiation, so that big charge differentials will leak away before a bolt could occur. In fact, that reminds me of those sprites and jets. It seems like that's what you'd get at high altitude, a large-area glowing fuzzy instead of a crisp lightning discharge. This whole debate could be pointless! What do you think?

Edit: One more crazy thing. If the DSS was orbiting the Pole, as jpowell suggested, it would be right up amidst the Aurora, or directly below it. That would be quite spectacular!


Back to top
Profile
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post Re: Lightning   Posted on: Tue Apr 05, 2005 10:48 pm
LukeSkywalker wrote:
But the reason you are not safe from lightning on earth is because you are connected to the ground. When you are in a car, you are not, and the car would also conduct a strike to the ground. The Faraday effect only protects equipment from fields, but I think you know that. If the walls of the station are thick plastic, the bolt will follow the path of least resistance through the air around the hull, rather than penetrating it. Air breaks down much more easily than plastic, especially at low pressure.


Cars are not very good insulators as dirty or wet tyres can conduct much better than air. True plastic is a better insulator but if there is a metal surface on the other side of the plastic then the lightning strike will be attracted. Also any breaches caused by mounting bolts, wiring or framework will present a point of entry and may provide a path of lower impedance than the outer surface (a bolt will have less resistance than a thin layer of foil). This is protected against by EMC testing aircraft and is known as structure current where current flows around the outside casing of the thing being tested rather than through it.

LukeSkywalker wrote:
I think it is unlikely that there would be anything like lightning up that far. For starts, lightning usually involves clouds, and the station would be very far away from them. Another thing is that the atmosphere is thinner, and there are probably more ions caused by space radiation, so that big charge differentials will leak away before a bolt could occur. In fact, that reminds me of those sprites and jets. It seems like that's what you'd get at high altitude, a large-area glowing fuzzy instead of a crisp lightning discharge. This whole debate could be pointless! What do you think?


The DSS might have to fly through clouds to get to its normal altitude. Once above the clouds the problem might go away, I dont know much about electrical properties up near space. :) The air is dryer too (most water having frozen out) and this might cause ESD problems if charge were to build up during the vehicle's ascent.

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Space Walker
Space Walker
avatar
Joined: Tue Jan 18, 2005 11:12 pm
Posts: 137
Location: Sacramento, CA
Post    Posted on: Thu Apr 21, 2005 6:55 am
It's looking real strong for the Away 26 mission on Saturday. There's a storm on the way, however, it looks like it won't hit till Sunday.

On each delay we've added to the vehicle or refined a system. The team is very anxious to get this bird in the air. Any more weather delays and Away 26 will have a can opener and cup holders.

We've reconfigured the flight back to two balloon. It makes for a more complex launch and rigging but it will give us a higher peak altitude.

Space really begins in the snow and mud of the spring desert.

JP


Back to top
Profile WWW
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 178 posts ] 
Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8 ... 12  Next
Moderator: jpowell
 

Who is online 

Users browsing this forum: No registered users and 4 guests


cron
© 2014 The International Space Fellowship, developed by Gabitasoft Interactive. All Rights Reserved.  Privacy Policy | Terms of Use