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Eyjölfur
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#1 kirjoitettu 25.05.2007 12:03

Kirjoitin alla olevan tekstin alunperinkin englanniksi eraalle foorumille. Joku suloinen sielu saa kaantaa paapointit suomeksi, jos haluaa. Keskustelu aiheesta olisi suotavaa. Hieman ohikin saa aiheesta menna kunhan avaruudessa pysytaan...

I was in a bus traveling towards China and my vietnamese visa was already expired by two days for various unfortunate reasons. I knew there was a chance that I might go to jail at least for a couple of days. Mile by mile my nervousness grew and I tried to put my thoughts to other things. I wrote the following "mind diary" in the bus:

"Random thoughts about interstellar and intergalactic traveling

I was reading a book concerning the super string theory and there was also some stuff about Einstein's special relativity and about the speed of light. After reading quite a while I started thinking about the distances between worlds and galaxies. I thought that if humans will never discover how to use wormholes in space travel we won't be going to the stars at least in my lifetime. And not in a thousand years either. Maybe some grand-, grand-, grand-, (etc.) grandchildren of our generation will live their whole lives in spaceships colonizing (horrible word) the universe. But further reading made me realize that we CAN travel to different galaxies in one person's lifetime. And we already have the technology and other means for that! In fact, we have had the basic technology for intergalactic traveling for tens of years already!

By now most of you think that I'm the kind of a person who gets too excited about certain kinds of books. Or that I've been reading some kind of a science fiction presentation of the issue taking all the contents as facts. Or that I could be high on medicine or something... But let me explain (just keep on reading). Later on you can check the facts from the internet or from a nearby library.

As many of you know from school, nothing can travel just as fast as light does. For example the light from the center of our galaxy, the Milky Way, has been traveling thirty thousand years to reach the Earth and our eyes. So if we build the fastest spaceship possible it still would take at least thirty thousand years to reach the center of our galaxy (if we ever wanted to go there). But here's the trick; the time it takes to travel to the nearest star or galaxy depends on the observer. From the Earth's perspective it really is at least 30 000 years one way to the center of the galaxy if the spaceship is traveling at the near speed of light. But on-board the time passes differently. It would take only 15-25 years (depending on how fast the ship would be accelerating) to cover the same distance at the same speed if you measure the time and the distance from inside the spaceship. Of course when the ship would return from the trip the passengers would be some tens of years older but the earth based observers would have died tens of thousands of years ago. Unless there would have been a scientific breakthrough on manipulating the genetic code concerning the aging of people... That's how it goes. I have never thought about it that way before.

So the spacecraft that I'm talking about wouldn't go at light speed but also not too far from it. It would have a long lasting nuclear engine. By the way, why don't the scientists build spacecraft with nuclear engines? Anyway, the ship would be so big that it would have to be built in the Earth's orbit (further out).

The past and present day astronauts have been struggling with the lack of gravity that plays games with their orientation after the missions and does harm to their bones and muscles. Well, the lack of gravity wouldn't be a problem because gravity could be simply simulated by accelerating at a steady 1g (the same force than thegravity on earth). So people could grow trees and other plants just like on earth because of the artificial gravity. Ok, a minor problem would be where to get enough light for all the trees and plants but I'm sure someone would come up with a solution (nuclear power once again?). So the people would do their business in the ship as they would on the Earth and the direction where they and the ship would be going would be "up" because of the acceleration. Halfway the journey they would turn off the nuclear engine and turn the ship around, start the engine again and start breaking at one g. From their perspective nothing would have changed except that now the direction where the ship would be heading to would be "down" because of the breaking (acceleration to the opposite direction).

And as all of you must know, there aren't many affecting forces or disturbances in space that would prevent the constant acceleration of the spacecraft to enormous speeds (except some very rare and small particles throughout the journey - the ship would have to have a some kind of a shield against them).

It would take maybe 30 years on-board to reach the next galaxy and that's not a very long time for that kind of a journey! One of the hard things for the travelers would be saying goodbye to everyone and everything they'd be leaving behind.

I'm sure that other people have also come up with the same conclusions/ideas as me but I haven't heard anything about any ongoing or future projects like that. I know about the ion propulsion satellite mission, which I think is already finished, but I haven't heard of any manned nuclear spacecraft plans so far. And I wonder why..."

After I got over the border (I had to pay a fine because of the expiration of the visa but no jail) to China. I did some research over the internet and found out that the next manned Mars mission was actually going to be executed with the help of nuclear power. I previously didn't reason that the nuclear material has to be transported in to the orbit and if the carriage rocket would explode in mid-air, it would cause a significant risk for many living things on the Earth. The wind could carry the radioactive particles (dust etc.) even thousands of miles to any direction. Nonetheless, nuclear power will be used on the next Mars mission if the alternative means won't work. However, some scientists are working on the issue concerning the use of antimatter as a fuel for spaceships. And so far things are looking really good. Antimatter can be produced in the laboratories by smashing atoms together. The procedure is expensive and it produces only very little of antimatter (as the time being). On the other hand, it requires less than very little of antimatter for a trip to Mars or further. There is the problem of storage because antimatter reacts with anything it gets in contact with but that can be solved by storing the antimatter in a closed space surrounded with electromagnetic field, for example. When antimatter reacts with matter, part of the resulting burst of energy is in form of gamma rays. Despite the undesirable fact about the side product of gamma rays, the use of antimatter would be safer than the use of nuclear power.

To reach the stars there has to be compromises to be done. For example at times the crew would have to strap themselves safely for certain periods of time and increase the acceleration from 1 g to, perhaps, 6 g:s (I wonder if the plants that would be on-board could take these kinds of forces). Or to two g:s for a longer period. The acceleration will take time so that's the reason why the trip to Mars would take atleast 50 earth days. The ship wouldn't have the time to accelerate to enormous speeds because of the "short" distance from the Earth to Mars. Also the human body can withstand the gravity forces only to a certain point so the acceleration should be quite gentle, although it would be possible to accelerate to the halfway of the journey at 20 g:s for example. So the further the distance, the more time the ship has for the constant acceleration and therefore it isn't an impossible thought of being able to travel the near speed of light. Though the breaking would double the traveling time. In theory it really should work.

You can check out some of the facts here:

http://www.nasa.gov/ce...

Some links for those who're interested about space relating issues:

http://www.nasa.gov/

http://www.esa.int/esa...

http://www.space.com/

Eyjölfur muokkasi viestiä 12:03 25.05.2007

Eyjölfur muokkasi viestiä 12:29 25.05.2007