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bebe7
2009-Sep-30, 11:24 PM
I think it depends on what we are to really consider HSF as in the Voyager Probe will not reach its first star for 256K years as it moves along at 3.27 AUs a year. A light year is in the range of 63K AUs.

Major, major progress or some type of Quantum Leap will be needed in this area of we are to truly explore space.

Bebe

“We in the back are all agreed that your theory is crazy. But what divides us is whether your theory is crazy enough!” Neils Bohr

KaiYeves
2009-Sep-30, 11:30 PM
Well, space doesn't necessarily mean "Interstellar Space", it means "More than 62 miles (at least) above the surface of the Earth".

bebe7
2009-Oct-02, 10:01 PM
I guess when I think of human space flight, I am thinking of interstellar human space flight on a grand scale. To me that's what it should be all about, not LEO, anything else would seemingly be fruitless and a waste of resources.

Bebe

"I don't think the human race will survive the next thousand years, unless we spread into space. There are too many accidents that can befall life on a single planet." Stephen Hawking

Warren Platts
2009-Oct-03, 02:34 AM
Let's worry about the Moon first. After that, we can go after Alpha Centauri and 55 Cancri. ;)

Sharlos
2009-Oct-03, 06:01 AM
Interstellar flight is centuries away, don't hold your breath.

Neverfly
2009-Oct-03, 06:14 AM
Interstellar flight is centuries away, don't hold your breath.

No, actually... He would have to because there's no air in space.

Ara Pacis
2009-Oct-03, 06:58 AM
No, actually... He would have to because there's no air in space.

From what I've read, you survive longer if you exhale.

Neverfly
2009-Oct-03, 07:06 AM
From what I've read, you survive longer if you exhale.
Hang on...


We were supposed to give helpful advice?

This changes everything...

Glom
2009-Oct-03, 07:54 AM
From what I've read, you survive longer if you exhale.

When diving they always say never ever to hold your breath. I'm not quite sure why.

Antice
2009-Oct-03, 08:15 AM
Are we talking free diving or pressurized air diving?
for both it's a pressure equalizing thing.
for freediving it's not just between the lungs and the outside but also between the blood and gas in your lungs. having a lower internal pressure in your lungs allows more Co2 to turn into gas in them, thereby postponing Co2 poisoning.
Co2 buildup is the main cause of asphyxiation. not a lack of oxygen. as a full blood supply of oxygen can easily sustain an average human for at least 4 to 5 minutes.
as for pressure differentials. always exhale before breaching the surface. not doing so can cause damage to your ears nose and lungs. especially if you have been below 5 meters or deeper during a freedive.
(the pain is one thing but nosebleeds tend to put a damper on the vacation mood)

Neverfly
2009-Oct-03, 08:16 AM
When diving they always say never ever to hold your breath. I'm not quite sure why.

Depends on the depth.

But at great depth, the nitrogen in your lungs will be forced into your bloodstream.

KaiYeves
2009-Oct-03, 03:25 PM
"Never hold your breath." Is the first rule of scuba training. (The first rule of actual scuba diving is "Take only pictures, leave only bubbles.")

bebe7
2009-Oct-04, 03:30 PM
Yes, this is relevant as NASA uses the NBL to train for space.

mugaliens
2009-Oct-04, 08:05 PM
When diving they always say never ever to hold your breath. I'm not quite sure why.

Because pulmonary barotrauma (http://en.wikipedia.org/wiki/Barotrauma)can be a killer. It's what happens when a SCUBA diver takes a breath while at any depth and holds it while ascending. The expanding air can exceed the lung's capacity to hold it, resulting in a burst lung, which is fairly easy, as lungs do not sense pain while overexpanding.

This doesn't occur with skin/free divers as the full breath of air they took at the surface merely returns to normal volume as they ascend from their dive.

Again, this affects SCUBA and other divers who breath a supply of air while submerged. It doesn't affect snorklers, surfers, swimmers, or those who engage in platform or board diving.

In fact, for most of us, you definately want to hold your breat while submerged, for if you don't, you could easily encouter a panic situation where your body takes a gulp of water, which results in coughing and rapid loss of consciousness.

With a lungfull of air, however, that reflex is suppressed, and the only one you have to fight is the one to exhale.

Glom
2009-Oct-05, 07:51 PM
The expanding air can exceed the lung's capacity to hold it, resulting in a burst lung, which is fairly easy, as lungs do not sense pain while overexpanding.

That's a relief. Does it feel pain once burst?

mugaliens
2009-Oct-05, 09:10 PM
That's a relief. Does it feel pain once burst?

Relief. Hah. I get it...

Yes, but in the same sort of sense some of your other internal organs do when they're seriously injured. It's a dull pain, a feeling that something is really, really wrong, and you begin to feel nauseous.

Of course other signs are quite apparent, such as coughing up blood...

I've never seen it myself, but a fellow diver has, several times. He was a master commercial diver, following his first career as a Navy diver. Most of the time O2, antibiotics, bedrest and supervision are sufficient, but if the bleeding doesn't stop, they may have to operate.

Eardrums are the opposite - the more the pressure, the more the pain, but once they rupture, there's little to no pain (I ruptured my left eardrum, once).

Until the infection sets in...

Glom
2009-Oct-05, 09:44 PM
Not the ears! NOT THE EARS!!!

Ara Pacis
2009-Oct-06, 06:49 AM
Relief. Hah. I get it...

Yes, but in the same sort of sense some of your other internal organs do when they're seriously injured. It's a dull pain, a feeling that something is really, really wrong, and you begin to feel nauseous.

That would be the Vagus nerve (http://en.wikipedia.org/wiki/Vagus_nerve). I had issues with mine over the summer.

Glom
2009-Oct-06, 06:04 PM
That would be the Vagus nerve (http://en.wikipedia.org/wiki/Vagus_nerve). I had issues with mine over the summer.

The Vegas nerve? I hear it leads to burst pockets.

(Boy, I really need to make some proper contributions here some time. :doh: )

KaiYeves
2009-Oct-06, 11:18 PM
The Vegas nerve? I hear it leads to burst pockets.

(Boy, I really need to make some proper contributions here some time. )
It's okay, most of what I've said is either a joke or just agreeing with someone.

astromark
2009-Oct-07, 12:51 AM
Under the heading of ' Space exploration - Human space flight.' This post started out as a alarmist view of our future. That might well be correct. After all Mr Hawking seems to know a thing or two and he thinks we are in trouble... I agree with him.
We have three threads going here that are really the same thing. Can you join the dots... $ ...
Getting into interstellar space travel is hideously expensive. Expensive in human resource and costs. The very thought of generation ships is a form of imprisonment we do not have the right to impose upon our offspring.. So its a higher ability to get nearer to light speed. Can it be done ? Maybe not.
Is the human race destined to never leave this local group. That is a truth I can accept. About 15 Ly could mean a travel time of 30 - 40 years... Thats all you can hope for. Am I being too realistic. The answer is robotics and, micro robotics. Thats where I would invest our efforts.

neilzero
2009-Oct-08, 12:36 PM
Even if Voyager is aimed toward the Centaur solar system, it will likely miss by about a light year.
At about 1/10 of the speed of light, impacts with pea size objects release as much energy as an H bomb and the ability to deflect the pea or steer around it, becomes nearly impossible even with extremely costly and complex measures that we can presently imagine.
For example: Assume speed is 1/10 th c: 6 probes fly 300 kilometers ahead of the space craft arranged in an equilateral hexagon, 100 kilometers on an edge. Each has multiple radar sets that scan out about 70 kilometers (somewhat farther in the ahead direction) A pulse is reflected off the pea at t = 0. At t = 0.2 milliseconds the probe radar receiving antenna picks up the echo = 60 kilometers the reflected pulse traveled. The other 5 probes are beyond radar range of the pea. At t = 0.21 milliseconds the radar computer decides this may be a threat to the space craft, and radios the data to the space craft. The space craft antenna begins to receive the data at t = 1.22 milliseconds. At t = 1.23 milliseconds the spacecraft computer completes the analysis and order remedial action, including sounding the impact alarm. A crew member 11 feet from the alarm speaker begins to hear the sound of the alarm at t = 11.22 millisecond, shortly after the pea destroys the space craft, unless the remedial action possible with about 9 milliseconds advance notice is successful. Assuming my arithmetic is correct, moving the probes closer or farther ahead of the space craft does not help much, but farther is much more expensive and requires more than 6 probes. One or more lasers flying a few kilometers ahead of the space craft, may be able to vaporize the pea, but that is not likely. Please suggest some alternate strategies to save the space craft from the pea.
Grain of sand size impacts can likely be avoided with thin shields that travel about one kilometer ahead of the spacecraft, but the hard gamma rays that replace the grain of sand will cause significant radiation exposure to the crew. The shields need to be about 100,000 square meters in area, to insure that fast grains of sand do not angle in behind the shields to hit the space craft. Magnetic and electrostatic shields have some utility for deflecting ionized sub atomic particles but do not deflect neutrons. At 1/10 c, any that hit the space craft are converted to hard gamma rays which are very penetrating. Neil

publiusr
2009-Oct-09, 05:31 PM
With Medusa, the craft is towed behind the 'sail' though that doesn't sound like enough. Some type of towed crewspace might be best. Then the engine block or a second spacecraft might be ahead of the crew, Unless the engines are in a wide ring, exhaust issues might crop up.

Glom
2009-Oct-10, 11:03 AM
In deepest space, why would the radar range be only 70km? That sounds amateurish for ATC ground radar?

What would the radar returns look like? At 0.1c, the return frequency would be 0.9 of the wavelength, which I suppose is still pretty radar-ish.

Murphy
2009-Oct-12, 12:38 AM
At about 1/10 of the speed of light, impacts with pea size objects release as much energy as an H bomb and the ability to deflect the pea or steer around it, becomes nearly impossible even with extremely costly and complex measures that we can presently imagine.

Simple solution would be to have a very large solid shield at the top of (or in front of) the spacecraft, capable of surviving an H-Bomb explosion. It might weight a million tons, but if we are advanced enough to build massive fusion rockets, then why would we not be able to shield them.

You could get a small asteroid and stick it at the front of your ship. Or if that's too fragile, then several meters thick steel or tungsten sheets. It's all very heavy sure, but there's no real limit on how big you can make a spaceship, you just need a lot more engines and fuel to push it. And you only have to build one of these Behemoths to colonise a whole solar system. Difficult, but not impossible.

Ilya
2009-Oct-12, 01:56 AM
In deepest space, why would the radar range be only 70km? That sounds amateurish for ATC ground radar?

What would the radar returns look like? At 0.1c, the return frequency would be 0.9 of the wavelength, which I suppose is still pretty radar-ish.
I agree, 70 km range is ridiculous. Modern early-warning radars see for several thousand km. Granted, they cannot pick up a "pea", but I expect radar technology to advance a bit by the time interstellar spaceflight becomes possible.

And even with 9 milliseconds warning there is no reason an automated laser system could not pick it off.

danscope
2009-Oct-12, 03:09 AM
I guess when I think of human space flight, I am thinking of interstellar human space flight on a grand scale. To me that's what it should be all about, not LEO, anything else would seemingly be fruitless and a waste of resources.

Bebe

"I don't think the human race will survive the next thousand years, unless we spread into space. There are too many accidents that can befall life on a single planet." Stephen Hawking

You can't eat the whole cow at one sitting. Maybe a nice , small hamburger is best once in a while.
The human race is a lot smarter than you think it is, and a lot more resilient. And may I add "Inventive" . And none of that involves going to
the stars. We have extraordinary gifts within this planet and the capacity to
employ them to the advantage of all. It only requires the will to do so.
Best regards,
Dan

mugaliens
2009-Oct-12, 03:22 AM
The Vegas nerve? I hear it leads to burst pockets.

Yeah...

I though it was the Vargas nerve. Burst pockets? Sure...

danscope
2009-Oct-12, 03:29 AM
I agree, 70 km range is ridiculous. Modern early-warning radars see for several thousand km. Granted, they cannot pick up a "pea", but I expect radar technology to advance a bit by the time interstellar spaceflight becomes possible.

And even with 9 milliseconds warning there is no reason an automated laser system could not pick it off.

Modern radars ( I used to work with these) are designed to detect reflections from large objects at these distances. Something the size of a cashew emits an extraordinarily small radar signature, a very small reflection indeed. And with the short reaction time....( if you consider a rate of closure of 1/6th C ) the system would surely have to be automatic. Also, for such a long journey, who is going to man a radar system 24/7 for 90 years?
And where do you get the spare parts to operate such a radar for 90 years?
Also, you would have to come up with some kind of super particle beam weapon which would deflect or disolve such an incomming particle....yea particles.... or larger.
As an acedemic exercise, this is an extraordinary challenge.
As a reality, it may be along the lines of the insurmountable.
Best regards,
Dan

IsaacKuo
2009-Oct-12, 01:58 PM
We've had discussions about what sort of protection system you'd want to use for interstellar travel. Active defense seems like a technical challenge, to say the least. Passive defense, in contrast, seems very doable.

The lightest/cheapest passive defense seems to be a lightweight thin "shield" to ionize the incoming backed up by a magnetic field to deflect the ionized particles (the main starship itself may be shaped like a large loop, around a superconducting magloop).

This "shield" may be a barely visible cloud of smoke, or a set of thin film sheets. Either way, the impact of any large particle will likely blow away the entire shield, so the starship needs the ability to put up a replacement shield if necessary. Thin film sheets may be annoying to deploy, but they can stay in place forever once deployed. A cloud of smoke is easy to deploy, but it will eventually disperse all by itself. I favor the smoke cloud.

Note that the "shield" doesn't need to "destroy" the incoming, or even to slow it down. It just needs to strip off the electrons, so the magnetic field can do its job of deflecting the resulting shower of charged particles.

In both steps of the process, the incredibly high velocity of the incoming is used against it. The high velocity means that as far as the incoming is concerned, the nebulous "shield" is actually an intense shower of ionizing radiation. This converts the incoming into a shower of ions and electrons, which are relatively easily deflected by a strong/large magnetic field (the lateral deflection force is proportional to the charged particle's speed).

danscope
2009-Oct-13, 03:11 AM
Mass times velocity. And you believe that smoke will work against such incredible objects??? Hmmm......

IsaacKuo
2009-Oct-13, 03:29 AM
The math works out.

First off, it's true that mere smoke could work. Look at it from the point of view of the poor speck of interstellar dust. That smoke shield is screaming at it at relativistic velocities! It will literally blow it away! The only question is whether it will be blown away completely before the starship itself arrives. You could ensure this by placing a decent distance between the smoke shield and the starship.

However, I am actually advocating a more sophisticated form of shield which requires much less smoke (and much less overall mass). The smoke shield I'm advocating doesn't need to blow away the incoming; it doesn't even need to slow it down. It only needs to ionize it. This requires much less mass. Then, the magnetic field does most of the work deflecting the incoming (which has now been converted into charged particles).

Jens
2009-Oct-13, 04:14 AM
Interstellar flight is centuries away, don't hold your breath.

It may be that the challenges are so great, and the potential gain so small, that it will never happen. That is my suspicion, actually. And the added bonus of this line of thinking is that it explains why we've never been visited by aliens.

danscope
2009-Oct-13, 04:32 AM
Hi Jens, I think you have got it in a nutshell, elegantly stated.
Anyone who tries to cross that pond will be dust for many centuries if they get there and slide on by. So... the question is moot.
But rejoice. We have been given the tools with which to see and investigate the heavens from right here on Earth. And with Hubble and her siblings, we extend our science . We can be proud.
It is the way of things.
Best regards,
Dan

IsaacKuo
2009-Oct-13, 04:47 AM
Never is a terribly long time. Interstellar flight in and of itself wouldn't be such a challenge for aliens with sufficiently long lifetimes. The timescales of "slow" interstellar flight are long compared to what we're used to so far, but that doesn't meant that ALL alien species have sub-century lifetimes. (It's by no means certain that we humans will always be limited to sub-century lifetimes.)

But really, the technological challenges of "fast" interstellar flight do not seem to be so great. We mostly already have the technology, but we're a few orders of magnitude away from sufficient economy.

Elukka
2009-Oct-13, 10:40 AM
How many pea-sized objects do we expect to run into in interstellar space, anyway? It's a real question, because I don't know, but I expect the answer to be "not many". They don't seem to hit spacecraft that often even inside the solar system.

danscope
2009-Oct-13, 03:27 PM
Inside our solar system, we have Jupiter and other large planets sweeping the orbital plane, collecting debris, and they have been doing it for countless centuries. In free space, you enjoy no such luxury. The small products of the Ort Cloud alone may be sufficient to destroy anything which trravels through that area. We cannot prdict what lies in deep space. If you collide with something, well that's it. It's not like gently bumping a sand bar.

Dan

IsaacKuo
2009-Oct-13, 05:26 PM
Certainly we don't know for sure exactly what's out there, but to suggest that interstellar space is MORE crowded than interplanetary space? That's pretty crazy. It's hard to imagine that interstellar space is more densely populated with any sort of stuff compared to interplanetary space.

Consider that we can see thousands of light years even in the worst directions. That tells us the chances are good for a photon to travel through thousands of light years without bumping into anything.

If the Oort cloud were really such a threat, then looking through it would be like looking through pea soup. It isn't, so it must be remarkably empty. There could still be significantly large bits of stuff out there--even as big as a gas giant--but if they exist they must be spread very thinly in order to not obscure our view of the universe. Just as an incoming photon has almost no chance of hitting anything significant, so an outgoing starship has almost no chance of hitting anything significant.

Ara Pacis
2009-Oct-15, 11:34 AM
But really, the technological challenges of "fast" interstellar flight do not seem to be so great. We mostly already have the technology, but we're a few orders of magnitude away from sufficient economy.

I think we, earthborn humanity in general, are capable of it now from a productivity standpoint. Politically, we don't have the will because we don't have the vision to unite for such an endeavor. Some people will argue that we have to feed the hungary first, but we could with proper management. The Theory of Realism camp in International Relations tends to limit the realization of the capabilities of the human race due to a preference to seek only relative increase of one over one's rival instead of attaining better efficiency and application overall. After all, the issues with the economy have a lot to do with over-production, not under-production. An interstellar probe program would provide work for lots of people who otherwise have nothing to do. Farming, mining and manufacturing are now highly automated (or can be automated) tasks and don't require a lot of people to perform. A large portion of the human race is superfluous for self-sustainability. Most of our social problems, in my opinion, come from humans having too little work to do, as opposed to working too much.

IsaacKuo
2009-Oct-15, 01:48 PM
I was initially going to protest that you don't have an appreciation of just how much energy and materiel is involved...

...but reading your post with an open mind I realize that you're talking about a radical realignment of humanity's social structure and basic philosophical goals. Given such a radical realignment, I suppose we could conceivably boost our global production rates by several orders of magnitude.

I was also going to protest that an interstellar probe project would not be "labor intensive", but would instead require the efforts of highly skilled engineers. And I was also going to argue with your definition of "nothing to do"...but I suppose with a radical realignment of humanity under a global totalitarian dictatorship it's possible to embark on a long term project to specifically educate a new generation of skilled engineers (probably also setting the older generation of largely uneducated persons out to pasture).

I have some ideological objections to such a radical realignment of humanity, but I'll admit that a lot of things I basically deem "impossible" are indeed "possible" under such a realignment.

Noclevername
2009-Oct-15, 07:07 PM
I guess when I think of human space flight, I am thinking of interstellar human space flight on a grand scale. To me that's what it should be all about, not LEO, anything else would seemingly be fruitless and a waste of resources.

Bebe

"I don't think the human race will survive the next thousand years, unless we spread into space. There are too many accidents that can befall life on a single planet." Stephen Hawking

Read your own quote. We have vast resources available right here in our own solar system, and even in one star system at least we wouldn't be confined to a single fragile planet. If we can learn to survive without planets, then we can park our habitat next to any star in the galaxy. And with access to the resources of space, the vast scale of interstellar travel becomes less daunting-- we could then afford to spend the energy and build up the supplies needed for the journey.

Besides, we can't jump from barely reaching our own backyard to cruising the galaxy-- we have to take the baby steps first and then build up from there, no way around it.

Ara Pacis
2009-Oct-15, 09:43 PM
I was initially going to protest that you don't have an appreciation of just how much energy and materiel is involved...

...but reading your post with an open mind I realize that you're talking about a radical realignment of humanity's social structure and basic philosophical goals. Given such a radical realignment, I suppose we could conceivably boost our global production rates by several orders of magnitude.I don't think it has to be a totalitarian dictatorship, not that such a system wouldn't work. BTW, I'm not talking about just up and doing it in the immediate future. It would take time, years or decades, to ramp up to it, but there's no real, physical reason we couldn't start the process tomorrow.


I was also going to protest that an interstellar probe project would not be "labor intensive", but would instead require the efforts of highly skilled engineers. And I was also going to argue with your definition of "nothing to do"...but I suppose with a radical realignment of humanity under a global totalitarian dictatorship it's possible to embark on a long term project to specifically educate a new generation of skilled engineers (probably also setting the older generation of largely uneducated persons out to pasture).How many engineers would you need for such a project? Do you mean for design of the systems or for implementation and fabrication or for operation and maintenance? It might not take a huge number of people, gobally speaking, to run such an operation. So, it might not actually be that large of a make-work project. It might, however, utilize the capacities of other industries we already have, expanding their workforces. Expanding into space in such a fashion might easily find collateral opportunities in space once a space access infrastructure is in place and the economy might expand in that direction with lunar based mining and manufacturing of all sorts of material and goods. I don't think we'd need to radically retrain people to be engineers as most of the increase in employment won't need to be engineers and the engineers will be able to use current knowledge since math and physics probably won't change much.


I have some ideological objections to such a radical realignment of humanity, but I'll admit that a lot of things I basically deem "impossible" are indeed "possible" under such a realignment.Me too, I prefer a less dictatorial approach and think it possible without one. Of course, that doesn't mean that some beneficial policies won't seem dictatorial by some people (cf. the healthcare debate). Some localities around the world might be problematic but instead of dictating to them, we might just let them fend for themselves. Who needs a dictator when anarchy (and Malthus) is cheaper and, ultimately, just as effective?

bebe7
2009-Oct-16, 12:39 AM
Read your own quote. We have vast resources available right here in our own solar system, and even in one star system at least we wouldn't be confined to a single fragile planet. If we can learn to survive without planets, then we can park our habitat next to any star in the galaxy. And with access to the resources of space, the vast scale of interstellar travel becomes less daunting-- we could then afford to spend the energy and build up the supplies needed for the journey.

Besides, we can't jump from barely reaching our own backyard to cruising the galaxy-- we have to take the baby steps first and then build up from there, no way around it.

Well we better get a move on anyhow. What I am referring to is that anything up to and including the Oort cloud could be considered LEO.

danscope
2009-Oct-16, 02:53 AM
You don't need much of anything fancy to have an interstellar probe. The question is... "Can it send a narrowly focused message back to earth at different times, and can it detect life forms and conditions near it's destination and then communicate back here...... someday."
We already sent Voyager. Are you talking a much larger and complicated
Voyager? Remember: it is the introduction of man that complicates the
Venture.
Then you have to convince people to pour great sums of money down a rat hole. Kinda like building a submarine with a remote control, sending it out to sea and waiting 200 years for it to send a message back.
Just think of the profits!!!

Dan

adapa
2009-Oct-16, 03:56 AM
Lately I have become a little more confident that humans will eventually achieve interstellar travel. However, it seems that it will happen quite differently from the ways that many people would expect.

When I see the exponentially accellerating advances in biotechnology since the sequencing of the human genome (i.e. tissue regeneration, etc.), it seems like we will eventually be able to extend the human life span by orders of magnitude if not indefinitely.

If this comes to pass, then there would be no need to travel at large percentages of c or deal with the induced cosmic rays or risk being pulverized by small unseen dust particles.

To be honest, boredom in the interstellar biosphere is likely to be a huge issue with this method. However, it seems much more plausible than wormholes or even having enough fuel to reach a large fraction of the universal speed limit.

Based on this, I believe that it will be the biotechnologists that are likely to make the breakthroughs that will eventually take us to the stars.

I could be dead wrong but it is just a thought.:think:

Ara Pacis
2009-Oct-16, 05:04 AM
Just think of the profits!!!Not everything has to make money. Lots of things are made for aesthetic reasons or because someone was bored.

NEOWatcher
2009-Oct-16, 02:57 PM
Well we better get a move on anyhow. What I am referring to is that anything up to and including the Oort cloud could be considered LEO.
I know what you're saying, but I would replace "be considered" with "equate to". You can't have the "E" if the "O" is determined by other more massive objects.

Although; I'm willing to reconsider changing the term to something like "Leisurly Expedition to Oort"

danscope
2009-Oct-16, 05:50 PM
Not everything has to make money. Lots of things are made for aesthetic reasons or because someone was bored.

Hi, That is a problem for the idle rich. But on terra firma, the people that pay the bills 'usually' want something quite tangible for their hard earned dollars.
What is the difference between dropping a cruise ship full of gold into the marianas trench and sending 50 billion dollars into interstellar space?
You are not going to see either one of them again..... (although you might be able to take a picture of the cruise ship). What you send is not comming back. This remains a practical paradox .
Best regards,
Dan

IsaacKuo
2009-Oct-16, 06:08 PM
We were never going to see any of the interplanetary probes we've ever sent ever again. We sent them anyway, despite that rather substantial expense involved for each and every one of them.

mugaliens
2009-Oct-16, 07:44 PM
How many pea-sized objects do we expect to run into in interstellar space, anyway? It's a real question, because I don't know, but I expect the answer to be "not many".

All it takes is one at interstellar velocities...


They don't seem to hit spacecraft that often even inside the solar system.

Our spacecraft have been hit and quite often, although pea-sized micrometeroids would hit spacecraft in LEO perhaps once a decade, if that. In fact, designing for it in terms of both spacecraft and spacesuite technology is a major engineering challenge.


Inside our solar system, we have Jupiter and other large planets sweeping the orbital plane, collecting debris, and they have been doing it for countless centuries. In free space, you enjoy no such luxury. The small products of the Ort Cloud alone may be sufficient to destroy anything which trravels through that area. We cannot prdict what lies in deep space. If you collide with something, well that's it. It's not like gently bumping a sand bar.

Dan

Micrometeroite bombardment accounts for 30,000 tons of material entering Eath's atmosphere every year. Most never reach Earth, but the number of particles transiting LOE is on the order of billions, if not trillions.

I imagine the Oort Cloud would prove more disasterous than the asteroid belt might, given the cloud is estimated to contain several trillion comet nuclei larger than 1.3 km. Who knows how many trillions (quadrillions? quntillions?) of smaller objects are out there.

mugaliens
2009-Oct-16, 07:46 PM
What is the difference between dropping a cruise ship full of gold into the marianas trench and sending 50 billion dollars into interstellar space?

The cruise ship would not only be cheaper, but wait 50 years and the technology to recovering the gold will be at hand!

IsaacKuo
2009-Oct-16, 08:05 PM
All it takes is one at interstellar velocities...This entirely depends on what sort of defensive measure you've taken. The simplest would be to cruise a safe distance behind a foil "shield". A single pea-sized impactor would merely punch a pea-sized hole in your shield; the impactor would be converted into a puff of plasma which disperses by the time your starship arrives.

So, one pea-sized impactor would not be a threat. A second one, though, at the exact same spot on your foil shield could slip through your defenses. What are the chances of that?

I imagine the Oort Cloud would prove more disasterous than the asteroid belt might, given the cloud is estimated to contain several trillion comet nuclei larger than 1.3 km. Who knows how many trillions (quadrillions? quntillions?) of smaller objects are out there.
But the Oort Cloud is many, many, orders of magnitude larger than the asteroid belt.

Elukka
2009-Oct-16, 09:29 PM
It may take one, or two or three, like Isaac Kuo said, but that doesn't answer how likely such a (relatively) large object is to hit your ship in interstellar space. One lightning strike would be enough to kill me, but it's not much of a practical concern.
Not saying debris necessarily isn't, but it's hard to speculate on that if we don't know what the odds are.

danscope
2009-Oct-17, 01:38 AM
The cruise ship would not only be cheaper, but wait 50 years and the technology to recovering the gold will be at hand!

Hi Mugs, I quite agree with both posts!!!!
Best regards,
Dan

adapa
2009-Oct-17, 04:20 AM
Hi, That is a problem for the idle rich. But on terra firma, the people that pay the bills 'usually' want something quite tangible for their hard earned dollars.
What is the difference between dropping a cruise ship full of gold into the marianas trench and sending 50 billion dollars into interstellar space?
You are not going to see either one of them again..... (although you might be able to take a picture of the cruise ship). What you send is not comming back. This remains a practical paradox .
Best regards,
Dan

Although I do not want to get into a debate about economics, there is another factor which you are not considering.

Whenever people push technological boundaries for any endeavor (space exploration, military, commercial, etc.), it inevitably creates industries (and jobs) in many technical fields. In addition, it often leads to future technologies and industries which are unforeseen by even the more far sighted visionaries.

For example, back in the 1960's, many people thought that a space program was a huge waste of money and said similar things to what you are saying now. Yet, whenever a weather satellite tracks a hurricane or typhoon and gives people enough advanced warning to prepare for it, many can argue that the space program has essentially paid for itself. This does not even mention GPS, satellite TV, satellite phone and the many advances in materials science.

danscope
2009-Oct-17, 05:00 AM
Sir: The benefits of space in LEO are quite a different game from pouring money into interstellar space. Sell it to congress.

Ara Pacis
2009-Oct-17, 08:53 AM
So, one pea-sized impactor would not be a threat. A second one, though, at the exact same spot on your foil shield could slip through your defenses. What are the chances of that?

Let's just hope the pilot isn't named Natty Bumppo.

Ara Pacis
2009-Oct-17, 08:57 AM
Hi, That is a problem for the idle rich. But on terra firma, the people that pay the bills 'usually' want something quite tangible for their hard earned dollars.

Really? Are you sure about that? Do you have any idea how much money people spend on intangibles? How much they give to charities? How much they throw away without hardly a thought for how it will affect their pocketbook? I think you overestimate the greediness of the average person, and underestimate their curiosity and philanthropy. The question isn't if the idea can be sold to them, it's how.

Elukka
2009-Oct-17, 03:32 PM
Nobody's going to try to do interstellar flight now, Dan. We're barely even in space yet.

I could make an argument that colonizing space, the solar system first of course, then perhaps other places, has a very high return. It means you've pretty much guaranteed humanity's survival.

adapa
2009-Oct-17, 04:35 PM
Sir: The benefits of space in LEO are quite a different game from pouring money into interstellar space. Sell it to congress.

There is probably nothing that will change your belief that interstellar travel is a bad idea. I respect our differences of opinion on this, but here are a few things to consider:

1. If you replace "space in LEO" with "jet aviation", and replace "interstellar space" with "space exploration", you will find that there were many people in the 1960's that said the same thing that you are saying now.

2. As pointed out by others, pursuing interstellar travel does not mean doing it now. Just as Low Earth Orbit can be a stepping stone to interplanetary travel, so can interplanetary travel be a stepping stone to interstellar travel. Even the task of constructing self sustaining ecosystems which are needed for such tasks would greatly increase our knowledge about environmental science. This knowledge can be very useful in protecting our own planet and would make such a program extremely valuable. Combine this with the benefit that was keenly pointed out by Elukka, and we have a program that is well worth pursuing.

3. I do not want to discuss current day politics and economics, but I cannot blame you for bringing them up as they are very real factors that must be considered. But while we are on the subject, you should also consider that our manned space exploration program (prior to budget cuts) costs only a tiny fraction of the money that is being dumped into AIG and other poorly managed companies. Also, unlike dumping many hundreds of billions of dollars into failed corporations, a manned space exploration program is guaranteed to create jobs.

danscope
2009-Oct-17, 05:09 PM
Really? Are you sure about that? Do you have any idea how much money people spend on intangibles? How much they give to charities? How much they throw away without hardly a thought for how it will affect their pocketbook? I think you overestimate the greediness of the average person, and underestimate their curiosity and philanthropy. The question isn't if the idea can be sold to them, it's how.

Sir: Have you any idea how many people live hand to mouth and in someone elses home because they lost theirs. Read the papers.

danscope
2009-Oct-17, 06:27 PM
There is probably nothing that will change your belief that interstellar travel is a bad idea. I respect our differences of opinion on this, but here are a few things to consider:

1. If you replace "space in LEO" with "jet aviation", and replace "interstellar space" with "space exploration", you will find that there were many people in the 1960's that said the same thing that you are saying now.

2. As pointed out by others, pursuing interstellar travel does not mean doing it now. Just as Low Earth Orbit can be a stepping stone to interplanetary travel, so can interplanetary travel be a stepping stone to interstellar travel. Even the task of constructing self sustaining ecosystems which are needed for such tasks would greatly increase our knowledge about environmental science. This knowledge can be very useful in protecting our own planet and would make such a program extremely valuable. Combine this with the benefit that was keenly pointed out by Elukka, and we have a program that is well worth pursuing.

3. I do not want to discuss current day politics and economics, but I cannot blame you for bringing them up as they are very real factors that must be considered. But while we are on the subject, you should also consider that our manned space exploration program (prior to budget cuts) costs only a tiny fraction of the money that is being dumped into AIG and other poorly managed companies. Also, unlike dumping many hundreds of billions of dollars into failed corporations, a manned space exploration program is guaranteed to create jobs.

Hi, The point in debate is to illustrate all sides of an issue amoung the participants we have, and they are many and extraordinary. And by the way, you would find that I am a fan of Star Trek. I am also a realist.
When you close the hatch and pull the cork, you would be a realist as well.
And yes, I am a fan of space activity in LEO, both as a robotic presence and especially a manned presence when required...ie servicing Hubble ST,
Perhaps building a better space station once we solve the radiation problems
and a few others. These things I see as doable, have practical usefulness
and are insiring enough to find funding.
I don't think anyone is happy about AIG, but if we hadn't done what we did when we did it, we wouldn't be pulling out of a crash today or two years from now. Depression is a state that you wouldn't want to live with.
I know old folks who are still so scarred from that experience that they still hoard aluminum foil, they are subconcious misers scorched by the thought of those hard times. I see at least a few heads nodding.
So,... I see those funds beyond LEO as competing with several thousand kids going to college and becoming quality tax payers. I see funds competing with building a reliable renewable energy infrastructure ie windpower.
There are real and pressing issues for which we must borrow the money.
......... You do understand that you are spending borrowed money?
Economics is not an easy subject. We prefer to think of all the great things we are going to do in space. Paying for them is somebody else's problem.
And yes, supporting our industrial infrastructure is painful, but not as painful as depression. Don't go there. It is a tar baby difficult to get out of.
To conclude, there is much we can accomplish in LEO with manned space flight. Much of which may translate into sustained chemical processes
for medicine and industry. These are worthy goals and inspite of our
economics, will still find support.
When you want to send men to the stars, they will ask you why. If you tell them "Because it's fun", they will think you have been watching too much TV.
Men of luxury climb mountains. They even risk their lives to do it.
When people ask why? They say..."Because it's there".
Reason is a process. A rational process. When one advocates the spending of billions to take a one way trip to a star for which there can be no possibility of return, I think most will find a lack of rationale.
It's like paying for and launching the TITANIC,.... never to return.
Where is the incentive?
May I thank you for at least hearing my replies in this. Your respect and patience is most appreciated.
Best regards,
Dan

IsaacKuo
2009-Oct-18, 06:18 AM
When one advocates the spending of billions to take a one way trip to a star for which there can be no possibility of return, I think most will find a lack of rationale.
While I personally consider a one way manned mission to be worthwhile, I've designed missions around the assumption of a return journey. This is not only incredibly expensive (far beyond what I would consider economically possible in the near term), but it's technologically challenging also.

Nuclear rockets can't do it. Nuclear runway propulsion can just barely do it, but at terrible expense. Anti-matter rockets could just barely do it, but at stupendously heroic expense and great technological challenge.

The only really practical methods I've come up with so far are the use of sacrificial nuclear powered laser drones or using a relativistic impact powered rocket. The former is an older idea which is workable but has a terribly poor mass ratio. The latter is a newer idea which is better all around.

From the standpoint of scientific results, a manned mission offers compelling advantages over unmanned probes in that you avoid multi-year lightspeed delays. A 2-3 decade dwell time for the main mission could provide results that could take millenia for unmanned probes to provide. Along with about 2-3 decades of travel time, no advances in human lifetime extension are required for the scientists to be able to return.

Ara Pacis
2009-Oct-18, 09:17 AM
Sir: Have you any idea how many people live hand to mouth and in someone elses home because they lost theirs. Read the papers.

I don't have to, I'm one of them. It doesn't stop me from remembering my college courses in reality.

danscope
2009-Oct-18, 04:31 PM
Hi, Then your understanding is keen, ... and I shall be considerate.
And my best wishes for you immediate and brighter future.
Dan

Elukka
2009-Oct-18, 09:24 PM
Dan, how about almost guaranteeing the survival of humanity? I think that's a goal better than "it's fun".
If we go to space, colonize the solar system, there will eventually be a day when it is full, there is nothing more left to colonize. This is where I see manned interstellar flight happening. Not today, not in the near future. It is not something I think we should spend any considerable resources on as of now.

danscope
2009-Oct-19, 04:37 AM
Hi, I would not argue with that. In a refined future where we have solved so many problems, we will have the time and resources to dabble in the esoteric such as star travel. I should prefer robotic probing of whichever destinations
would offer 'some' chance at finding an habitable world.
But, for now, I should think we have some work to do.
Best regards,
Dan

GOURDHEAD
2009-Oct-19, 01:47 PM
Dan, how about almost guaranteeing the survival of humanity? I think that's a goal better than "it's fun".
If we go to space, colonize the solar system, there will eventually be a day when it is full, there is nothing more left to colonize. This is where I see manned interstellar flight happening. Not today, not in the near future. It is not something I think we should spend any considerable resources on as of now.Well said! A mandatory perspective!

If the Earth were a more perfect sphere, it would be covered to a depth of two miles by the curent volume of liquid water resulting in an environment that some of us could survive, but at great expense. There appears to be no star, capable of going supernova, near enough to Earth to destroy it, but one could approach over time. There are uncounted asteroids within the solar system that could crash into the Earth thus rendering the probability of survival near zero. We aren't sure just how big coronal mass ejections can get nor how destructive they can be. Some of you can name other events or conditions that could cause the demise of humans if the Earth is the only basket available.

We need to develop interstellar transportation, and when you do the arithmetic, systems engineering, and mission planning, you will likely find that neither nuclear propulsion, matter/anti-matter, sail, nor any of the more exotic proposals will suffice to expediently transfer humans from Earth to safety once the disaster is pending. It will take 500 years to implement a solar orbiting power beam powered system exclusively capable of supporting a mass exodus. It's time to start.

danscope
2009-Oct-19, 06:24 PM
Point of curiosity; has anyone here on Earth ever accelerated a large mass ie ship/probe ....( something substantial )with this laser energy ?
If you are exhausting steam, you shall run out of water soon. This pure energy to acceleration concept is wanting for proof that it exists and has possibilities. So far, it seema to be made up of whole cloth, with more holes than cloth. I am quite curious.
There are some brilliant minds here. Do any of you find this concept bordering on the fantastic ?
I find it interesting but..... unproven.

Best regards,
Dan

IsaacKuo
2009-Oct-19, 06:32 PM
In a refined future where we have solved so many problems, we will have the time and resources to dabble in the esoteric such as star travel. I should prefer robotic probing of whichever destinations would offer 'some' chance at finding an habitable world.
Whether you like it or not, we have spent millions on manned and unmanned missions with no chance at finding a habitable world. We will continue to do so, largely in the name of science.

We haven't waited for all of the world's problems to be solved first, and we won't wait until all of the world's problems to be solved first. Don't like it? Deal with it.

adapa
2009-Oct-19, 06:33 PM
I don't think anyone is happy about AIG, but if we hadn't done what we did when we did it, we wouldn't be pulling out of a crash today or two years from now. Depression is a state that you wouldn't want to live with.
This sounds very much like Henry Paulson's words. You obviously have great faith in what he says (in spite of his connections in the financial sector).

*As a side note, United Airlines, Delta, US Airways, and Northwest all kept operating inspite of bankruptcy without demanding hundreds of billions to "prevent the collapse of our international air transport system".*

Although there are many other reasons why I am less trusting on this issue than you are, I will not mention them in interest of staying on topic.

Not only is our space program budget a tiny fraction of the bailout money, but it is also less than the amount which has funneled to overseas banks through AIG. If you think that this is a better use of our money, then I beg to disagree.


You do understand that you are spending borrowed money?
As stated above, sending an even larger amount of borrowed money to overseas banks is even worse.


It's like paying for and launching the TITANIC,.... never to return.
Using this line of reasoning, we would have never sent out Voyager or any other space probe.


Dan, how about almost guaranteeing the survival of humanity?
Well said. All civilizations ultimately will become either space faring or extinct.

IsaacKuo
2009-Oct-19, 06:37 PM
Point of curiosity; has anyone here on Earth ever accelerated a large mass ie ship/probe ....( something substantial )with this laser energy ?[...]I find it interesting but..... unproven.
We have performed experiments which confirm that the photon pressure produces exactly as much thrust as in theory. Laser propulsion has not yet been used on a space mission, but there's no reason to doubt its theoretical basis.

danscope
2009-Oct-19, 07:59 PM
Link Please.
Best regards,
Dan

publiusr
2009-Oct-19, 08:06 PM
You asked for a link about laser propulsion? Search under Leik Myrabo--or get the book:

http://www.cgpublishing.com/Books/lightcraft.html
http://www.cgpublishing.com/space.html
http://www.cgpublishing.com/

Other propulsion books. Be discriminating about some of these titles.
http://www.amazon.com/s/ref=nb_ss?url=search-alias%3Daps&field-keywords=propulsion+space&x=7&y=10

IsaacKuo
2009-Oct-19, 08:12 PM
Here's the laser photon thruster which is arguably closest to practical application:
Y.K.Bae Photonic Laser Thruster (http://www.baeinstitute.com/tech_precFormation.html)
It uses mirrors to repeatedly reflect the laser beam; this produces several orders of magnitude more thrust than a "single bounce" laser sail when used at non-relativistic speeds. (At relativistic speeds, severe red-shifting eliminates the potential usefulness of the "multi-bounce" approach.)

They have a working lab version, which has verified the photon thrust produced.

timb
2009-Oct-19, 08:27 PM
We need to develop interstellar transportation, and when you do the arithmetic, systems engineering, and mission planning, you will likely find that neither nuclear propulsion, matter/anti-matter, sail, nor any of the more exotic proposals will suffice to expediently transfer humans from Earth to safety once the disaster is pending. It will take 500 years to implement a solar orbiting power beam powered system exclusively capable of supporting a mass exodus. It's time to start.

Does putting your demands in bold make them more credible? Does it work for facts too? It's not happening.

adapa
2009-Oct-19, 09:51 PM
Link Please.
Best regards,
Dan

If you want links to support my point, then here they are:
http://www.lipinski.house.gov/index.php?option=com_content&task=view&id=874
Please note this part:

This week, AIG disclosed that it has awarded over $55 billion in American taxpayer funds to foreign banks, including $11.9 billion to Societe Generale, France's third largest bank, $11.8 billion to Deutsche Bank, Germany's largest financial institution, and $8.5 billion to Barclays PLC, headquartered in England.
Note that this was from back in March so the real numbers are likely to be higher.


Now compare (or contrast) it with the space exploration budget on SUM-10 of the NASA Budget:
http://www.nasa.gov/pdf/344612main_Agency_Summary_Final_updates_5_6_09_R2. pdf
The 3.9 billion dollars for FY2009 is enacted. However, the 3.96 billion in FY2010 up through the 6.2 billion in 2014 are requests by NASA. What they get is likely to be less.

If you think that the amount that goes to overseas banks is more well spent than putting it into our own space program, then I beg to disagree.

danscope
2009-Oct-20, 05:36 AM
Here's the laser photon thruster which is arguably closest to practical application:
Y.K.Bae Photonic Laser Thruster (http://www.baeinstitute.com/tech_precFormation.html)
They have a working lab version, which has verified the photon thrust produced.
********************************************
It will be interesting if they ever do an experiment of some size in space
ie LEO. A pingpong ball in a vaccuum chamber isn't really a lot.

GOURDHEAD
2009-Oct-20, 12:58 PM
Does putting your demands in bold make them more credible? Does it work for facts too? It's not happening.Puting them in bold does not make them more credible; it's just an attempt to display the firmness of my conviction--kinda like voice inflection being an indicator of the imminence of the occurrence of a hazard about which a warning is being issued.

publiusr
2009-Oct-23, 08:40 PM
Here's the laser photon thruster which is arguably closest to practical application:
Y.K.Bae Photonic Laser Thruster (http://www.baeinstitute.com/tech_precFormation.html)
It uses mirrors to repeatedly reflect the laser beam; this produces several orders of magnitude more thrust than a "single bounce" laser sail when used at non-relativistic speeds. (At relativistic speeds, severe red-shifting eliminates the potential usefulness of the "multi-bounce" approach.)

They have a working lab version, which has verified the photon thrust produced.


We have the photon rocket, now we just need the anti-matter for some real power.

mugaliens
2009-Oct-24, 12:17 AM
Puting them in bold does not make them more credible; it's just an attempt to display the firmness of my conviction...

The firmness of one's conviction does not imply credibility, either. :)