The space program we have is a joke

[rigney]

It would only be a joke if science hadn't benefitted mankind in so many ways, which they have. I'm sure you have seen pictures of what the ISS looks like. What's very interesting is the concept of what to do with it once it becomes passe to science. Some pretty good ideas in the article below, but I don't know how well they stand up to scruiny. Lots of money sitting out there going nowhere fast (17,000 mph). Maybe someone can give NASA a hand in what to do with the thing once they are through with it? What a shame it would be to gaze up some day and see billions of dollars flashing across the sky in a final orbit.

 

http://www.universetoday.com/15561/the-space-station-as-an-interplanetary-transport-vehicle/

Edited December 10, 2010 by rigney

[nec209]

Well, it depends on the details. But both the weight of the engine and its efficiency are important. You could compare this to ion drives, which are absurdly efficient yet can't lift something off the ground because they're so heavy for the thrust they generate.

 

 

I thought you where saying nuclear uses 8% to 10% of it's weight of payload not like 4% to 5% of it's weight of payload now.So nuclear is 2 times more more fuel efficient than what it is now.And can take up 2 times the payload .

[D H]

Don't just make up numbers! That is not how engineering or science works.

[Mr Skeptic]

I thought you where saying nuclear uses 8% to 10% of it's weight of payload not like 4% to 5% of it's weight of payload now.So nuclear is 2 times more more fuel efficient than what it is now.And can take up 2 times the payload .

 

I said "suppose it were", since you were wondering about the extra weight of the reactor and shielding. The actual numbers would depend on the actual efficiency, which would depend on what type of engine it was. All I'm saying is that if your engine is sufficiently better, it doesn't matter that it weighs more since most of the weight is going to be fuel of which you will need less of.

[nec209]

I said "suppose it were", since you were wondering about the extra weight of the reactor and shielding. The actual numbers would depend on the actual efficiency, which would depend on what type of engine it was. All I'm saying is that if your engine is sufficiently better, it doesn't matter that it weighs more since most of the weight is going to be fuel of which you will need less of.

 

Okay I thought you where saying nuclear can take up 2 times the payload than now.So 10% of it's weight of payload not like 5% of it's weight of payload now.

[D H]

Instead of making stuff up, do some research and do a tiny bit of engineering. Rocket science is a bit of a misnomer. It really should be called rocket engineering. The stuff that is still science is a long, long ways from becoming reality. A bit of basic science can help, too. Science alone, for example, shows how silly the idea of laser propulsion is given our current level of technological development. The numbers just don't add up and won't add up until we are well above Type I on the Kardashev scale. That's 200-250 years off assuming a continued exponential growth.

 

Regarding fission power plants: That fission power plants are currently have too much mass per kilowatt by one to two orders of magnitude is a big problem. Think of it this way. If Robert Zubrin thinks its science fiction, it almost certainly is science fiction.

[Mr Skeptic]

OK, let's keep the comparison to the Saturn V. The saturn V's specific impulse is 263 sec for the first stage, and 421 sec for the second and third, and a thrust of 7.6 million lb thrust for the first stage. For one of the nuclear lightbulb rockets NASA gives a specific impulse of 1870 sec, and an engine weight of 70,000 lb and thrust of 92,000 lb. From the looks of it it would have trouble getting off the ground, but would be several times more efficient. Use this equation to calculate: http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

[nec209]

Science alone, for example, shows how silly the idea of laser propulsion is given our current level of technological development. The numbers just don't add up and won't add up until we are well above Type I on the Kardashev scale. That's 200-250 years off assuming a continued exponential growth.

 

Explain the pros and cons of laser propulsion before stabing me.I thought 300 feet is highest it gone up or some thing like that .Do you think in 50 or 100 years from now we will be using laser propulsion.

 

What is the engineering problems with laser propulsion .Has anyone made it go up higher than 300 feet?

 

Regarding fission power plants: That fission power plants are currently have too much mass per kilowatt by one to two orders of magnitude is a big problem. Think of it this way. If Robert Zubrin thinks its science fiction, it almost certainly is science fiction.

 

No idea what you talking about here.

[Mr Skeptic]

There's a difference between using a laser + solar panel as an energy source, vs using a lase as a propellant. There's no way a laser-propelled device got even an inch off the ground in earth gravity. What you probably heard about is the idea of using lasers to power a climbing device, typically intended for use on a space elevator.

[nec209]

There is not much more for improvement with chemical that why they are turning to laser and fission and in the future fussion.

 

Well laser propulsion needs gigawatt power.The ground shines a laser beam to the craft to get it to go up.Other type of laser propulsion the craft shines a laser beem and it heats up the air and causes ther craft to go up.

 

The last type is pulse laser the craft rides on pulse of the laser going on and off very fast..If the craft use pulse laser or laser propulsion where it shines a laser beam and it heats up the air you will need a floating power station.This not a problem for the ground that has its own power station.

 

 

Well space mining and space colony is scfi has we do not have the technology to lower space cost by 50%. It is not the technology it is the cost with technology why we are not doing it.We have the technology now for space mining and space colony it is the technology is too costly.

 

When space cost dropped by 50% than space mining and space colony will take off big time.

Edited December 14, 2010 by nec209

[D H]

There is not much more for improvement with chemical that why they are turning to laser and fission and in the future fussion.

Who, exactly, are "they"? Certainly not NASA or ESA. Russia is supposedly working on a fission engine, but we'll see. Projects like these are incredible money drains that have in the past gone nowhere. They're easy to cut because they stick out so, particularly when times are tough economically. Fission has immense technical and political hurdles to overcome. Anything nuclear in space that has even the remotest possibility of being weaponized, well, there are treaties against that. Russia will have to undertake significant efforts to prove that their new system (if it ever exists) cannot be weaponized. Failure to do so is essentially declaring war against the western world.

 

Well laser propulsion needs gigawatt power.The ground shines a laser beam to the craft to get it to go up.Other type of laser propulsion the craft shines a laser beem and it heats up the air and causes ther craft to go up.

Given that continuously operating megawatt lasers are more than a bit problematic, magically asking for a gigawatt laser is just a bit more than a hand wave. Given that, a gigawatt is orders of magnitude too small. Let's do the numbers: What is the maximum thrust that a continuously-operating 1.21 gigawatt laser mounted on a spacecraft could produce? The answer is easy: 1.21 gigawatts / c = 4.04 newtons. Good luck going anywhere with a 1.21 gigawatt power plant plus a 1.21 gigawatt laser that produces 4 newtons of thrust. So let's up the ante. Instead of a paltry 1.21 gigawatts, what if we could harness the equivalent of the entire world's electric energy production, and feed that power to a laser propulsion device, and do all of this without any losses whatsoever. In 2005, this was 6.25×10¹⁹ joules, or about 2 terawatts. The thrust from this engine: 6,600 newtons.

 

 

Taking the laser with you is just a silly idea. So don't do that then. Use a laser-powered sail. This has the huge advantage of not leaving the power plant and laser at home and doubles the thrust (at least until speeds become relativistic) to boot. How to address the problems that

• State of the art in lasers that operate in continuous or quasi-continuous fashion is 100 kilowatts or so. Ignoring other problems, that would yield less than a millinewton of thrust. A 1.21 gigawatt laser (four order of magnitude improvement) would yield about 8 newtons of thrust.
  
• One of those other problems is keeping the laser beam collated over astronomical distances. For example, the lasers currently used to measure the distance between the Earth and Moon spread so much that almost all of the incoming photons miss the retroreflectors. While that beam dispersion makes it a lot easier to find the retroreflectors, it also presents challenges regarding use of lasers for powering a sail-based vehicle.
  
• The opposite problem occurs at short range. That 100 kilowatt laser is being developed as a weapon. The beam has to be dispersed at short ranges lest the laser cut a hole through the sail, then through the vehicle behind the sail, and then through the
  contents of the vehicle. This ground based laser would need adaptive optics that only exist in the minds of scifi authors.

There is an easy way to solve all of these problems. Wave your hands and they go bye-bye.

[granpa]

the thrust produced by the rocket depends on how much mass it is pushing in the opposite direction.

we dont know how much air is being heated by the laser

[Mr Skeptic]

Using a laser to heat up air is just plain inefficient. And using it for thrust directly is impractically energy costly. The only reason to use a laser is to decouple the power generation and usage.

[nec209]

 

Who, exactly, are "they"? Certainly not NASA or ESA.

 

Gvernment ,private and NASA.Look it up on youtube there videos of this even on discovery channel.

 

 

Russia is supposedly working on a fission engine, but we'll see. Projects like these are incredible money drains that have in the past gone nowhere.

 

I don't even look at Russia any more there space program died after cold war.

 

They're easy to cut because they stick out so, particularly when times are tough economically. Fission has immense technical and political hurdles to overcome. Anything nuclear in space that has even the remotest possibility of being weaponized, well, there are treaties against that. Russia will have to undertake significant efforts to prove that their new system (if it ever exists) cannot be weaponized. Failure to do so is essentially declaring war against the western world.

 

The space program in US and Russia died after the cold war and my prediction in 50 years we will not be sending people up into space AT ALL , but space probes , robots that can do it much CHEAPER.

 

 

The lobbyist are hard at work on this now.That me say this again lobbyist are hard at work .In 50 years we will not be sending people up .The lobbyist will see to it.

 

It too costly to go in space.

 

space mining and space colony will NEVER HAPPEN to the space cost is lower by 50%.

Edited December 15, 2010 by nec209

[mytechuniverse]

I'm sorry, but what exactly do you mean by fusion or fission propulsion. These are methods for the production of energy. However, they won't produce thrust without another system. You could use them to produce power for an ion system, but you still need fuel. Fission reactors are not necessarily large though, NASA used small reactors for the Voyager probes I think. They weren't huge in spacecraft terms.

[nec209]

I'm sorry, but what exactly do you mean by fusion or fission propulsion. These are methods for the production of energy. However, they won't produce thrust without another system. You could use them to produce power for an ion system, but you still need fuel. Fission reactors are not necessarily large though, NASA used small reactors for the Voyager probes I think. They weren't huge in spacecraft terms.

 

 

What are you talking about there is no fusion or fission propulsion .They would have to build it .Has for fusion propulsion there is no point building it to they get working fusion .

 

Has for ion propulsion it does not have enough thrust to take any thing up in space same with plasma propulsion .That is why ion propulsion and plasma propulsion must be used for in space only.

[Mr Skeptic]

I'm sorry, but what exactly do you mean by fusion or fission propulsion. These are methods for the production of energy. However, they won't produce thrust without another system. You could use them to produce power for an ion system, but you still need fuel. Fission reactors are not necessarily large though, NASA used small reactors for the Voyager probes I think. They weren't huge in spacecraft terms.

 

Fusion could be used as a source of hot plasma, with the plasma being used directly for propulsion rather than via electricity. For example, Project Orion could use current tech to make a fission/fusion powered ship, using the products of the reaction directly as propulsion (it throws nukes out the back and has a huge shock absorber). On a smaller scale, the use of lasers to ignite fusion in pellets of frozen hydrogen, or in a magnetically contained fusion chamber, both of these could vent the plasma directly into space as propulsion instead of trying to get electricity from them first.

[nec209]

Mr Skeptic you still did not reply to my last post or say the pros and cons of laser propulsion and some of the problems they are having with laser propulsion.

[Mr Skeptic]

Your question is too ambiguous. Is the laser on the spaceship? Is the light used for propulsion or for energy via solar panels?

[nec209]

Your question is too ambiguous. Is the laser on the spaceship? Is the light used for propulsion or for energy via solar panels?

 

There are 3 ways a craft may get up into space using laser .

 

1.A craft shines laser beem out the craft to heat up the aire to get the craft to go up

2.Wel uses laser pulse and rides on the pulse to get it up into space

3.Well at the ground they shine a laser beem to the craft to get it to go up.

 

Note solar sails cannot be used to get the craft up into space it must be used for in space propulsion only.

 

From what I understand payload is problem has laser propulsion the craft has to be very small and need so much power gigawatt power.I think this where they stuck trying fix this problem.

 

A power problem and payload too small has the craft does not allow for bigger payload .

Edited December 30, 2010 by nec209

[Mr Skeptic]

1 won't work once the craft gets into space.

 

2 and 3, is that laser being used as propulsion or as an energy source?

[nec209]

1 won't work once the craft gets into space.

 

2 and 3, is that laser being used as propulsion or as an energy source?

 

Why would it not work in space.You add energy to laser the laser heats up the air and cause the craft to go up.

[InigoMontoya]

Why would it not work in space.You add energy to laser the laser heats up the air and cause the craft to go up.

Are you serious?

 

Space = no air.

 

Where is this air that you're going to heat up coming from?

 

A system like you mention may work great a low altitudes, but once the air starts getting thin it's effectiveness is going to suffer drastically due to lack of sufficient reaction mass - i.e. air. And this is going to start happening loooong before you get to space. Space is generally accepted to be on the order of 100 miles. At 20,000 feet - less than 4 miles - your air density is already half of what it started as. At 40,000 feet - we'll be nice and call it 8 miles - you're dealing with 25% and you've still got 92 miles to go.

 

Further, once you're supersonic you're going to have even lower density than ambient air surrounding the base of your vehicle courtesy of expansion shocks.

 

Admittedly, air breathing aircraft prove that you can use air as a reaction mass up to 80,000 feet... But they convert their thrust to lift much more efficiently than your rocket is going to (wings are great for this) and they're still what - 84 MILES short of the goal.

 

In summary: It's awful tough to use a laser to heat up the air when there is no air.

Edited January 1, 2011 by InigoMontoya

[nec209]

Nice video how a laser -propelled spacecraft concept would work.

 

Note loss me about 5:05 in the video what they are talking about and what Microwave and solar has to do with it.

 

[InigoMontoya]

Nice video how a laser -propelled spacecraft concept would work.

 

Note loss me about 5:05 in the video what they are talking about and what Microwave and solar has to do with it.

Dunno how recent that video is, but everything in the first five minutes could have been said 10 years ago. At least, that's when I became aware of it. I don't know what if anything has changed, but at the time nobody took it too seriously. It was seen as a sort of "Let's hope this guy can do something with these cool lasers we spent all that money to develop for a program that just got canceled." IE, they were hoping to find a silver lining. That was 10 years ago. If that video is current, it doesn't look like he's made ANY progress (He was doing those sort of short flights in the late 90s!).

 

As for the microwave comments, I'll spell it out for you... Rather than focus a tight beam of light energy (ie, a laser) that if you aim poorly it will set forests on fire or whatever, we'll use a very wide, but much less intense beam of microwave energy. That way, if we aim poorly the consequences are less dire. In addition, microwaves are much less sensitive to atmospheric conditions so aiming the beam should be much easier.

 

Beyond that, however, the second half of the video strikes me as a complete ball of crap intended not for serious science, but rather entertainment value. Really, they want to use the energy to create an aerospike? Why? That's a $10,000,000 answer to a $10,000 problem. Aerospikes are already out there and in use particularly on Russian-designed manpads and the US Trident system. Except that the aerospikes in use are mechanical rather than formed via gas manipulation via energy beams.

 

And they didn't address the problem of "where is this air that you're going to superheat at high altitude?" They just show their little spaceship blazing through LEO (flying by their satellite) with no serious discussion of reaction mass. They hinted at Helium, but Helium is very expensive now and getting nothing but more expensive every year (a problem that would be compounded by a space launch system that required large quantities of it). Even if the new system were to use He at 6X the efficiency as conventional systems, it's likely to be more expensive even if you only need 1/6 as much. Not much point in that.

Edited January 10, 2011 by InigoMontoya