Artificial gravity in long term space travel

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neutrino78x

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MeteorWayne":1h1bk05t said:
That's not correct. We (the taxpayers) pay for (not enough) well justified missions. Beyond that, rich people with money to spare need to step up.
I agree, that's why I think private enterprise is the future of space travel. :)

--Brian
 
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pathfinder_01

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Yuri_Armstrong":2g0pcm27 said:
kk434":2g0pcm27 said:
On Skylab one astronaut did run in circles around the stations wall, running this way for a while would create a brief period of artificial gravity.
The ISS could use a big huge module for the astronauts to move around instead of the ant tunnels they've got now.
Actually the ISS was built to reduce space sickness, big open spaces are not so good for that. Skylab had a problem with astronauts getting stranded with no wall or anything to grab hold off or push off of. Sometimes bigger isn't better.
 
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uberhund

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Exactly, Yuri. I am told that even the current ISS is plagued with low and high frequency vibrations (various fans and motors, treadmills, etc.) that damage or prohibit some kinds of experiments (whatever they might be). As everyone knows, I have no love for ISS or any man in space project, so the fact that the ISS can't do serious research into say, crystals, because its passengers are bouncing off walls comes as no surprise to me.

Here's a question - every time a module docks or station keeping rockets are fired, do harmonic vibrations begin standing and caroming through the various ISS modules and trusses? How long for these to dampen out? Crystal growth experiments must love this.
 
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Yuri_Armstrong

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uberhund":ii19q77a said:
Exactly, Yuri. I am told that even the current ISS is plagued with low and high frequency vibrations (various fans and motors, treadmills, etc.) that damage or prohibit some kinds of experiments (whatever they might be). As everyone knows, I have no love for ISS or any man in space project, so the fact that the ISS can't do serious research into say, crystals, because its passengers are bouncing off walls comes as no surprise to me.

Here's a question - every time a module docks or station keeping rockets are fired, do harmonic vibrations begin standing and caroming through the various ISS modules and trusses? How long for these to dampen out? Crystal growth experiments must love this.
Hey now. The ISS is doing important research on long term living in space, this data will be very useful for future missions away from LEO. I'm afraid that I can't answer your question on crystal growth experiments though.
 
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Larry_1

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I love talking about artificial gravity.

The need expressed here, i.e., "How do we use artificial gravity for long duration space missions?" will no doubt result in a wide range of proposals. They all sound wonderful. They all make your react in awe and give you goose-bumps. They all sound too good to be true. They are fun to talk about and bounce around other people.

In reality, they all fall short of receiving actual space funding since they all speak of things we have yet to even conceive to try.

Let's say you are a very powerful person and rich beyond belief. You ask this question and you will get 12,000 different responses on how to do it much like baby birds desperately chirp to their mother for her to feed them and not their siblings. Since you are only going to pick one way, you have a huge job to do in filtering 12,000 different responses down to one. The first thing you do is spot the obviously far fetched ideas that are too costly or too complicated such as rocket engines that produce a constant 1 G of thrust or massive rotating space habitats or tethered vehicles. You have just narrowed down the list of 12,000 proposals to about 100 proposals.

Next, you start the fine filter processing of proposals down to the ones you know without a doubt that you can do today with available technology and reasonable cost and schedule. The proposals that make this short list will likely include an on-board human centrifuge that intermittently exposes the crew, one or two at a time, to some prescribed level of centrifugal acceleration that does not make them sick. BTW, it has been shown in ground experiments that a short-radius centrifuge can spin a person for 2 hours without making them sick. They are simply told to not suddenly turn or tilt their heads to the left or right due to the Coriolis Effect that causes vestibular disorientation and nausea.

The amount is determined by extensive testing on human subject living in a zero-G space platform such as the ISS. It is not determined by educated guesses. Let's say it takes 2 hours a day of 0.2 G's to stop or limit muscle and bone loss. I don't profess to know how much and I am absolutely positively sure that everybody else is simply guessing and uses their level of professional credentials to coerce people into believing their guess. The amount of gravity the body needs is unknown and is not a function of the level of professional credentials someone has who professes they know the answer.

So, all of this talk about artificial gravity methods and machines and making people dizzy and sick and solving this problem so we can go to Mars need to first solve the problem of "How are we going to determine how much artificial gravity exposure and in what dosages does the human body need to stop or limit muscle and bone loss?". Once that question is answered, everyone will have a better idea about how to proceed. The picture becomes much clearer.

I propose we first take the most minuscule step to get through the huge barriers to any space research involving artificial gravity by intermittently exposing mice (boned mammals) to partial gravity in one of three operating centrifuges on the ISS. Then bring them back to Earth along with a control group that was not exposed to artificial gravity and compare bone and muscle loss. If there is any difference between the control group muscle and bone and the test group, you have the momentum to take the next logical step and graduate the experiments to humans eventually.

If NASA refuses to even consider doing the most minuscule step to this approach, we are really just wasting our time talking about it because NASA is exposing their desire to never go to Mars. The alternative is to approach non-NASA space explorers such as Bigelow Aerospace to see if they are interested in such an experiment. Mr. Bigelow would likely try it assuming he gets most of the credit and notoriety for such an astounding scientific discovery.
 
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Yuri_Armstrong

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It's pretty simple actually. The more gravity, the less bone loss. If the crew is acclimated to .36 Gs which is the gravity on Mars then they will not have to recover from a long space flight trip spent in zero gravity.

Larry, your idea of putting people in a centrifuge for a couple of hours a day is a new and good idea. That combined with exercise and a good diet makes the Mars mission sound a lot more feasible.
 
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SteveCNC

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should make a chamber that can spin up to 2g for an hour a day , that'll get the kinks out . Why stop at 1g , I have been on one of those barrel rides at Carowinds though I don't think that ride is there anymore , that was 37 years ago , anyway , you would stand against the walls of a vertical cylinder then it would spin up and the floor would drop down and then you could crawl around on the walls and it must have been at least 1.5g or more for that to work so it can be done and it wasn't that hard to crawl around . I'd say the diameter of the cylinder had to be about 12-16 foot not all that big and personally I didn't feel sick but then again I didn't try to stand up either .
 
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Larry_1

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Once the question "Does any amount of artificial gravity on small vertebrate animals validate the postulation that it reduces bone loss?" is answered as a resounding "Yes, it does.", then the next logical step is to design and construct an exercise device that up to three people living in the ISS can expose themselves to during their daily regiment of 2.5 hours of aerobic and leg and back muscle strengthening exercises in a human rated centrifuge that takes up the minimum space required in the ISS.

The inside diameter of the ISS is about 14 feet or 4.2 meters. The centrifuge can fit in the space occupied by four experiment racks which is a cylinder of space of a diameter of 13.5 feet and in a width or height of about 3 feet. The racks are slowly being replaced by collapsible cloth racks so they can be easily disassembled and stored in another area and reassembled later if the centrifuge/exercise device proves invalid. The node modules and the Permanent Multi-Purpose Logistics Module (PMPLM) are the prime candidates for such an installation of a centrifuge/exercise device. Remember, none of this can happen or even be considered until we first establish the correlation between artificial gravity and bone loss reduction for vertebrate animals.

The construction of the centrifuge is designed with a short-radius arm (2 meters) connected to an exercise platform in which the user performs their exercises in the standing position. The head is towards the center of rotation and the body and legs are stretched out to the outside circumference of the centrifuge. Standing against the centrifugal force with the head still and the arms and legs moving up and down against resistance shows the most promise for stopping or limiting bone loss. Lying down in the centrifuge is no different than lying down on the ground and shows much less effect, if any at all. The postulation is that the bone structure needs the centrifugal force applied longitudinally along the long bones while in the standing exercise position instead of perpendicularly as is the case when lying down. This forces fluids containing required nutrients into and out of long bones. Blood circulation into and out of long bones, by itself may not be enough to stop bone loss as is the case when human subjects conduct ground experiments while lying down for extremely long periods of time. In other words, muscles and bones decay when lying down for long periods of time.

In addition, there needs to be a counter-rotating mass to offset the torque produced by the rotating mass of exercisers, otherwise, the torque is transferred directly to the station structure which will cause the flight control system to activate to take out the torque.

The other problem we are facing is that the vibrations produced do not go well with zero-G space experiments. My opinion on this problem is that since the ISS operations schedule already includes periods of time when zero-G space experiments are halted while the vibrations from exercising begins, we can safely maintain the same type of procedures during centrifuge/exercise periods.

After all, our goal is finding a way to safely extend the human presence in space beyond the current 6 month limit so we can safely send humans to distant destinations such as asteroids and Mars someday and solve the bone loss problem once and for all using the cheapest and most efficient way compared to expensive and complicated ways. When funding comes into play, the cheapest and simplest way always gets the funding before the expensive and complicated ways.
 
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EarthlingX

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Wiki : Centrifuge Accommodations Module
The Centrifuge Accommodations Module (CAM) is a cancelled element of the International Space Station that would have provided controlled acceleration rates (artificial gravity) for experiments and the capability to:

* Expose a variety of biological specimens to artificial gravity levels between 0.01g and 2g.
* Simultaneously provide two different artificial gravity levels.
* Provide partial g and hyper g environment for specimens to investigate altered gravity effects and g-thresholds.
* Provide short duration and partial g and hyper g environment for specimens to investigate temporal effects of gravity exposure.
* Provide Earth simulation environment on ISS to isolate microgravity effects on specimens.
* Provide Earth simulation environment on ISS to allow specimens to recover from microgravity effects.
* Provide in situ 1g controls for specimens in micro-gravity.

ISS Centrifuge Accommodations Module (NASA)
 
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neilsox

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I suppose a gravity accommodation module would be useful in long term habitats most everywhere off Earth, but I suppose it was cancelled due to excessive cost, doubtful reliability and/or other possible problems. Months of acceleration at 0.01 g seems unlikely, in this century, so rotational gravity would only be modified slightly by about 1/2 of Earth's surface gravity or a bit more. Also collision with nanogram size particles possibly cannot be mitigated faster than about 0.01 c
 
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Larry_1

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My opinion on why the CAM was cancelled was that it competed with the true goals of the ISS program. It postulated that artificial gravity could stop muscle and bone loss and truly extend human presence in space. It turned out to be one of those "This town is not big enough for the both of us" conundrums.

We are seeing the results of the true goals accomplished on the ISS. They are:
1) Frequent dockings and undocking of visiting space vehicles. Each docking means $100s of millions of dollars in someone's pocket on the ground. This reason by itself is good enough to cancel the CAM. The reason they have such a high frequency of dockings and undockings is that the crew's muscle and bones are deteriorating at a rate of 1-2% per month and they need to replace the crew with a new crew with fresh bones. Its like the chicken or the egg. A perpetual cash machine that won't turn off. Very ingenious!
2) No science discoveries worth mentioning, except zero-G is very harmful on humans! Just pretty pictures and neat high school experiment stuff that helps justify having a space lab so something someday could be discovered. Parents of children who interact with the station crew in some manner whether it is sending and receiving a text message or planting a tomato seed from space in their backyard, cannot possibly use their vote against NASA. Yet another ingenious strategy to avoid the muscle and bone loss problem!
3) A space destination for the massive astronaut corps to go to. After all, you are not really an astronaut until you have gone to space. Without a destination to go to in space, you need no astronauts. Because there are practically an infinite number of astronauts willing to devote their entire lives to going to space for free, and they are willing to risk death on a second-by-second basis, who really cares if their muscles and bones are dissolved by zero-G? You are right. No one! Now, are you getting the picture?
4) The fact that if you are not an astronaut/cosmonaut, you do not really belong in space. You have no use to societies whatsoever because you are simply living out your childhood dreams. How selfish of you! Even if you try to make yourself useful, you will fail because everyone knows only astronauts/cosmonauts are the only ones allowed to go to space because they have paid their dues. Yet, you go there because you have huge sums of money that speaks for itself.

What is beginning to breakdown is:
1) I hate to say the obvious but the astronaut corps, e.g. Lisa Nowak incident, as well as other misgivings from astronauts that we don’t really need to get into. Most astronauts are gold plated and will fair well and deserve huge credit and notoriety for some time. I am only trying to illustrate the beginning of a breakdown. Since the shuttle is retiring, there will be a massive re-assignment of astronauts. You see the beginnings of this in the re-assignments that use “astronauts” to play the role of public relations.
2) Astronauts are taking up a smaller piece of the pie in terms of who is going to space. Space tourists, for example, are bypassing astronauts with a credit card to get to space before an equivalent astronaut does. More and more Russians and Chinese and Japanese are going to space than before. When you take this to the limit, no astronauts will go to space. Without astronauts, NASA manned space cannot exist. Sad news if things keep going like they are going now.

As fewer and fewer astronauts go to space to visit the ISS, the need to launch diminishes, the need to discover something to justify going there increases, and the need to truly find a way to extend the stay of an astronaut beyond the current 6 month limit that capitalizes on results from artificial gravity experiments increases. That day is coming since the new goal of sending humans to a near earth asteroid has appeared. To go there and come back takes at least 180 days. The first time they go there, they are going to discover something on the asteroid like frozen water for instance that is going to justify longer and longer trips which helps the justification for a CAM-like module on the ISS.
 
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Yuri_Armstrong

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Yep, that's a good point about the docking/undocking scheme. They can't keep it up forever though if we plan to go anywhere outside of LEO. The CAM would've been a great module where we could do some really good work on artifical gravity.

The fact that if you are not an astronaut/cosmonaut, you do not really belong in space. You have no use to societies whatsoever because you are simply living out your childhood dreams. How selfish of you! Even if you try to make yourself useful, you will fail because everyone knows only astronauts/cosmonauts are the only ones allowed to go to space because they have paid their dues. Yet, you go there because you have huge sums of money that speaks for itself.
Are you referring to space tourism here? Actually the space tourists that have gone to the ISS did participate in some of the science experiments, they didn't just hang around. And any space tourist still has to pay millions of dollars to ride the Soyuz up there. It's going to be a pretty unwieldly endeavour until private agencies start offering their space tourism services.
 
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Larry_1

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In order to get permission to gain full access to the ISS in the past, the space tourists, i.e., paying passengers on Russian vehicles, were asked by NASA to agree to pose as scientists conducting experiments on the ISS to avoid the label "space tourist". It was a simple solution that worked.

You will never see another "space tourist" on the ISS, yet you may see space tourists posing as scientists conducting frivolous experiments designed to create the image of doing something useful for society on the ground when the space tourists begin bidding up the price for the trip to space to compete with NASA astronauts. NASA is one step ahead of the space tourists though in their recent contract agreements signed by the Russians to do business exclusively with them for several years to come.

I am sorry the space tourists can’t go to space right now no matter how much money they offer the Russians. This is where Bigelow Aerospace and space hotels become attractive for space tourists. However, NASA is still in the game of funding their astronauts to go live in space no matter where they stay. They no doubt want to remain the biggest piece of pie of those who go live in space. NASA has far more money and clout to get their people into space at the exclusion of any non-astronaut American. Oh well. I suggest the space tourists realize if they can’t beat them, they could join them. That’s what the Russians did.

Imagine someday if the space tourists are lucky enough to outbid NASA astronauts and got the chance to go live in the Bigelow Aerospace’s hotel in space and wanted to stay longer than 6 months. After all, if they pay for an extended stay, Mr. Bigelow would gladly accommodate his hotel guests in any way they want. Mr. Bigelow could even put an exercise/gravity device up there to stop the muscle and bone loss for his hotel guests since staying at a luxury hotel is not supposed to be hazardous to your health, right?
 
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Yuri_Armstrong

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Astronauts and space tourists are two completely different things. Space on the ISS is limited so of course they are going to make them do more than just twiddle their thumbs while they're on board. Astronauts are actually doing real work for the future of human spaceflight, tourists are just there to have fun in space. Sorry but I just couldn't help but notice some hostility towards NASA astronauts in your post.
 
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Larry_1

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My sincere appologies. I will avoid being hostile towards astronauts in the future.
 
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orienteer

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Two ideas that I have never heard discussed.

1) instead of using centrifugal force to plaster objects to the out side of the hoop, why not use the spokes of the wheel? I believe that the wheel could spin much slower this way, but you would develop a lean towards the center.

2) would it be possible to wear a magnetic vest and walk on a steel floor? I know that many experiments would be sensitive to the magnetism, and steel is heavy. This may also require a pressure suit to make the blood work harder.
 
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dryson

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Obviously, a mission to mars will take a few months at least. Is it possible that the spacecraft going there will have one section spinning around enough to create aritifcial gravity on the same level that they will face on Mars? If so they could become acclimated to the martian gravity while on the trip, instead of recovering from a long period of zero g when they get to mars.

Centrifuges are commonly used in science fiction to protect space travellers from the health effects of long term zero g, but wouldn't the constant spinning make you dizzy and nauseous when you tried to get up and walk around?
I do not see why everyone is so centered around a section spinning to create artificial gravity. Every idea that center's around a centrifigual device necessary to create gravity always ends up being the magnitude of an Earth sized design which does not create an efficient vessel to ferry humans to a distant planet. One easy method to create "artificial gravity" would be create paramagnetic shoes. The paramagnetic shoes would be designed so that the sole of the shoe along with other parts of the shoe would be comprised of material that was only magnetic when in the presence of an externally applied magentic field. When the person walks through the magnetic field the shoes paramagnetic material would become slightly magnetized just enough so that the person walking could achieve an artificial bond to the surface they are walking on. The key to designing the shoe would have to be using material that is strongly paramagnetic along with a magnetic field that would provide enough force for the person to lift their foot and walk normally.

Here is an image of basic shoe. The areas in light brown would be the location of the paramagnetic material.
The bottom of the shoe has four disc like areas that would have the largest amount of paramagnetic material present.

 
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dryson

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2) would it be possible to wear a magnetic vest and walk on a steel floor? I know that many experiments would be sensitive to the magnetism, and steel is heavy. This may also require a pressure suit to make the blood work harder.
When the person walks across the magnetized plating the magnetic field might assist in the circulation process in the same manner that the magnetic fields of the Earth pull the blood through the body based on the magnetic interaction between the various metallic atoms that are present in the blood and body. A pressure suit like you mention would msot likely be needed to assist the circulation process as well.
 
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MeteorWayne

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dryson, It's hard to imagine anyone who posts on a science board could have such a complete lack of understanding of phyisics and feel a need to make up their own for everything!
 
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Yuri_Armstrong

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dryson, I think those boots are just to give astronauts orientation. They don't really "create" gravity because you're still in space and you're still weightless. This is why centrifugal force is the main competitor in all artificial gravity discussions because it's the easiest and most cost effective way.
 
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raptorborealis

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uberhund":gb9r0413 said:
Sadly, the title of this thread is a misnomer. There is no such thing as artificial gravity.
I agree. I cringe when I hear the term.

I understand the 'intent' of the discusssion but the term perpetuates a misunderstanding of the challenge and solutions.
 
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uberhund

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Thanks for the back up, raptorborealis.

I would hope that a such a great domain name as Space.Com could be used by its editors to dispel myths and common misunderstandings of physics in general, and space sciences in particular. No doubt many of which I hold unwittingly on my own as well.

But this much is fact: Without radiation shielding and gravity, there is no long term space flight for intelligent lifeforms as we know them. These two requirements alone will always put space travel between planets out of reach for humans. Period. Sorry.

NASA: Please dismantle the ISS and put its funds into something productive (probes to Triton and Europa are my two current favorites).

Also - congratulations, Yuri. I see you've been promoted to a comet. Nice.
 
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Yuri_Armstrong

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uberhund":2fhwvvg2 said:
Thanks for the back up, raptorborealis.

I would hope that a such a great domain name as Space.Com could be used by its editors to dispel myths and common misunderstandings of physics in general, and space sciences in particular. No doubt many of which I hold unwittingly on my own as well.
They do the best they can. I'm not sure why you have dislike for the term artificial gravity, what would you prefer for it to be called instead?

But this much is fact: Without radiation shielding and gravity, there is no long term space flight for intelligent lifeforms as we know them. These two requirements alone will always put space travel between planets out of reach for humans. Period. Sorry.
Here you should see that you are on the wrong side of history. People always used to say that flying was impossible, 15 mph would tear humans apart, you can't escape Earth's gravity, you can't get through the Van Allen belts, etc.

But all of those things we have accomplished. And there are many good theories, papers, and books out there that show the methods for proper radiation shielding and artificial gravity in long term spaceflight. It's only impossible if our politicians do not grow the backbone needed to boldy go where no man has gone before.

NASA: Please dismantle the ISS and put its funds into something productive (probes to Triton and Europa are my two current favorites).
Yes, let's throw away a $170 billion multi-national science investment! Unfortunately the ISS has been scaled down because politicians seem to hate scientific progress but they are still being productive. A Europa probe is set to launch in 2020 with a drilling/melting apparatus, check this out:

http://en.wikipedia.org/wiki/Europa_Jup ... em_Mission

I do not understand people who think that manned spaceflight is pointless and it should all be done by telescopes and robots. Manned missions can do much more science experiments and data/sample retrieval than any probe could. And plus it's a bad idea to keep all of our eggs in one basket (Earth). I'm sure you're aware of Carl Sagan's "two-planet" reasoning, that we should colonize other worlds in case something bad happens to one of them humanity could survive elsewhere.

Also - congratulations, Yuri. I see you've been promoted to a comet. Nice.
I'm curious about these ranks we have under our names, do you "rank up" whenever you make an intelligent post or something? And thank you.
 
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neutrino78x

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uberhund":2cpr7bh7 said:
But this much is fact: Without radiation shielding and gravity, there is no long term space flight for intelligent lifeforms as we know them. These two requirements alone will always put space travel between planets out of reach for humans. Period. Sorry.
No, dude, we can easily simulate gravity with centripetal force. This is a well established idea in engineering.

Any time you are going to have a ship which plans on coasting for long periods of time, you would build a big one with a spinning section for the crew.

Why don't you call up Stanford and tell them that their world renowned university is not up to your standards. All the Nobel Prizes in Physics awarded to people working at Stanford seem to disprove that notion.

David Darling (click on this link for bio), who has a BS in physics from Sheffield University, and a Ph.D. in physics from Manchester University, wrote the following:

David Darling":2cpr7bh7 said:
artificial gravity

The simulation of the pull of gravity aboard a space station, space colony, or manned spacecraft by the steady rotation, at an appropriate angular speed, of all or part of the vessel. Such a technique may be essential for long-duration missions to avoid adverse physiological (and possibly psychological) reactions to weightlessness.

The idea of a rotating wheel-like space station goes back as far as 1928 in the writings of Herman Noordung and was developed further by Wernher von Braun.
That is found on this link.

But hey, I guess a Ph.D. in physics knows less than you do, uberhund. After all, you claim it is impossible to use centripetal force.

--Brian
 
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