What type of system will allow us reliable access to space? - Page 2

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[ARCHIVED THREAD] - What type of system will allow us reliable access to space? (Page 2 of 2)

Posted: 12/27/2005 9:03:39 PM EDT

[#1]

still not sure why we don't have antigravity devices? Seems like physicists would have already determined the way that gravity holds/pulls objects together and figured out how to reverse the charge.

<--------- slept through physics.

Posted: 12/28/2005 2:42:57 AM EDT

[#2]

We have such devices, but they're closely held military secrets.

No tinfoil hat needed. I believe this is probably the case given the mindset of our government.

CJ

Posted: 12/28/2005 3:13:19 AM EDT

[#3]

Everything negative I've heard about the space elevator was based on *current* ENGINEERING limitations.

I've heard once that the elevator will be built 10 years after everyone stops laughing. I think we stopped laughing last year.

Spinning one thread 3 km long was a laboratory exercise. When it is scaled up to industrial standards, 60,000 km is just made to order. One thread dropped down at the end of a 1 ton counterweight will be soon be two after the second is hauled back up, then 4, then 8, then thousands making a redundant system.

Angular momemtum changes can be minimized with rockets. Much easier countering momentum changes than powering vertical thrust.

Nine years to go....

Posted: 12/28/2005 4:00:07 AM EDT

[#4]

Quoted:
Everything negative I've heard about the space elevator was based on *current* ENGINEERING limitations.

I've heard once that the elevator will be built 10 years after everyone stops laughing. I think we stopped laughing last year.

Spinning one thread 3 km long was a laboratory exercise. When it is scaled up to industrial standards, 60,000 km is just made to order. One thread dropped down at the end of a 1 ton counterweight will be soon be two after the second is hauled back up, then 4, then 8, then thousands making a redundant system.

Angular momemtum changes can be minimized with rockets. Much easier countering momentum changes than powering vertical thrust.

Nine years to go....

You still have to get the machinery into orbit. Lack of fuel for minor orientation changes is a prime reason satellites go out of service. Fuel quantities for navigation at any speed practical for human use is nontrivial.

Gravity is the law.

Posted: 12/28/2005 4:20:17 AM EDT

[#5]

Quoted:
We've got to develop an economical aerospace vehicle to get us into space!

What's it going to be...

A Shuttle-derived disposable rocket and Apollo-type capsule?

A Hypersonic transatmospheric aircraft?

A Two-Stage-To-Orbit carrier aircraft/orbital vehicle?

Something else?

Forget it................If anybody needs to go to space it's me!

Anyways, Space travel for civilians isnt going to be anywhere in our future.......

It would be anywhere from I say...............5 - 10 generations from us...............

Posted: 12/28/2005 12:38:29 PM EDT

[#6]

Ya know- We would have been better off sticking with the big dumb boosters than going for the high tech Space shuttle.

Its time to revive project Orion.

Posted: 12/28/2005 12:43:59 PM EDT

[#7]

Giant beanstalk.

Posted: 12/28/2005 2:37:26 PM EDT

[#8]

Quoted:
Quoted:
The space elevator would take its angular momentum from the earth, not the counterweight. As you lifted mass to orbit the rotation of the earth would very slightly slow down.

If you're an engineer, draw a free body diagram of the earth, cable satellite, and anchor. You'll see that the satellite will pull on the cable like a bow and arrow. The earth's rotation will be ever so slightly slowed down. To a much greater degree, so will the anchor on the other end of the cable since the force acting on that anchor has a westward vector to it. As the payload climbs, more of the angular momentum will be supplied by the anchor. That's part of the reason why the plans are to have it over 60,000 miles out, well past geosynchronous orbit. To provide tension, mimize the westward vector, and maximize angular momentum. If it is heavy enough (like a massive asteroid), it won't be a major concern. When was the last time a large asteroid was seen approaching earth at a rate where it could be captured though?

If the cable were rigid, then the earth's rotation could provide all of the angular momentum as you said but you're not going to find any material that would be able to do it.

Then how was David able to slay Goliath using nothing more that a rock and a sling made of non-rigid cloth/leather?

I'll let Arthur C. Clarke explain it...

The explanation may be found by looking at one of mankind's simplest, oldest and most cost-effective weapons -- the sling. I wonder if Goliath's technical advisers told him not to worry about that kid with the ridiculous loop of cloth -- it couldn't possibly transfer any kinetic energy to a pebble. If so, they forgot that the system contained a rigid component -- David's strong right arm. So also with the space elevator. Its lower end is attached to the 6000 km radio of the Earth -- quite a lever.

and...

In other words, though one would have to do work to get the payload up to the geostationary position, once it had passed that point it would continue to travel on outwards, at an increasing acceleration -- falling upwards, in fact. Not only would it require no energy to move it away from earth -- it could generate energy, which could be used to lift other payloads! Of course, this energy comes from the rotation of the earth, which would be slowed down in the process. I have not attempted to calculate how much mass one could shoot off into space before the astronomers complained that their atomic clocks were running fast. It would certainly be a long time before anyone else could notice the difference....

from www.spaceelevator.com/docs/acclarke.092079.se.1.html I strongly encourage everyone to read this paper.

Posted: 12/28/2005 2:45:51 PM EDT

[#9]

"What type of system will allow us reliable access to space?"

Who cares?

Don't mean to sound like a cynic, but until it becomes of some REAL use to human beings, then I really don't care what they use. When we can colonize Mars or something, then it will matter to me.

Posted: 12/28/2005 2:49:45 PM EDT

[#10]

Quoted:
Quoted:
Quoted:
The space elevator would take its angular momentum from the earth, not the counterweight. As you lifted mass to orbit the rotation of the earth would very slightly slow down.

If you're an engineer, draw a free body diagram of the earth, cable satellite, and anchor. You'll see that the satellite will pull on the cable like a bow and arrow. The earth's rotation will be ever so slightly slowed down. To a much greater degree, so will the anchor on the other end of the cable since the force acting on that anchor has a westward vector to it. As the payload climbs, more of the angular momentum will be supplied by the anchor. That's part of the reason why the plans are to have it over 60,000 miles out, well past geosynchronous orbit. To provide tension, mimize the westward vector, and maximize angular momentum. If it is heavy enough (like a massive asteroid), it won't be a major concern. When was the last time a large asteroid was seen approaching earth at a rate where it could be captured though?

If the cable were rigid, then the earth's rotation could provide all of the angular momentum as you said but you're not going to find any material that would be able to do it.

Then how was David able to slay Goliath using nothing more that a rock and a sling made of non-rigid cloth/leather?

I'll let Arthur C. Clarke explain it...

The explanation may be found by looking at one of mankind's simplest, oldest and most cost-effective weapons -- the sling. I wonder if Goliath's technical advisers told him not to worry about that kid with the ridiculous loop of cloth -- it couldn't possibly transfer any kinetic energy to a pebble. If so, they forgot that the system contained a rigid component -- David's strong right arm. So also with the space elevator. Its lower end is attached to the 6000 km radio of the Earth -- quite a lever.

and...

In other words, though one would have to do work to get the payload up to the geostationary position, once it had passed that point it would continue to travel on outwards, at an increasing acceleration -- falling upwards, in fact. Not only would it require no energy to move it away from earth -- it could generate energy, which could be used to lift other payloads! Of course, this energy comes from the rotation of the earth, which would be slowed down in the process. I have not attempted to calculate how much mass one could shoot off into space before the astronomers complained that their atomic clocks were running fast. It would certainly be a long time before anyone else could notice the difference....

from www.spaceelevator.com/docs/acclarke.092079.se.1.html I strongly encourage everyone to read this paper.

let's start snaking that 60,000 mile long cable right up into the sky.

doesn't really sound practical, in spite of the fact that the energy/momentum/etc stuff can be worked out on paper.

Posted: 12/28/2005 2:58:39 PM EDT

[#11]

Quoted:
"What type of system will allow us reliable access to space?"

Who cares?

Anyone with two brain cells to rub together and even a modicum of foresight.

Posted: 12/28/2005 6:43:32 PM EDT

[#12]

Quoted:
Quoted:
"What type of system will allow us reliable access to space?"

Who cares?

Anyone with two brain cells to rub together and even a modicum of foresight.

Right, spending money on manned spaceflight is useless.

Let's spend it creating a welfare state instead.

Posted: 12/28/2005 7:53:12 PM EDT

[#13]

Quoted:
Quoted:
Quoted:
"What type of system will allow us reliable access to space?"

Who cares?

Anyone with two brain cells to rub together and even a modicum of foresight.

Right, spending money on manned spaceflight is useless.

Let's spend it creating a welfare state instead.

Exactly. Some of the "geniuses" here think if we stopped spending the FRACTION of the budget we put into space exploration we would somehow pay off the debt with it. Horseshit. Our Congress would find some pork barrel rathole to throw it into. If our economic crusaders want to cut some fat, they should look at pork, because it DWARFS all the money EVER spent on space.

Posted: 12/28/2005 8:44:28 PM EDT

[#14]

Keep in mind that NASA isn't in the business of putting things into space as much as they are in DEVELOPING NEW TECHNOLOGIES. The Saturn series rockets, or a larger replacement, could have done more than the shuttle for less money, BUT they aren't the "new technology" that NASA was looking for in the late 60s.

The commercial/private sector already launches far more space vehicles than NASA, for far less, using existing, proven technology. But again, that isn't NASA's goal. It is far, far easier to put a 1-ton satellite into orbit than it is to carry 100 tons out of Earth's gravity well and out into space (to go to Mars, for example).

The problem in NASA is the conflict between supporting existing systems and developing new ones.

-Troy

Posted: 12/28/2005 9:18:02 PM EDT

[#15]

Right. But how many "systems" since the Shuttle has NASA poured money into...with no operational system to show for it? Off the top of my head:

National Aerospace Plane

Venturestar X-33

X-38 ACRV

Orbital Space Plane

[ARCHIVED THREAD] - What type of system will allow us reliable access to space? (Page 2 of 2)

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