Manned missions into space -- a waste?

[hgc]

Re: Re: Manned missions into space -- a waste?

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I don't agree with this. I think that earth like planets might be relatively common in the Universe. Perhaps there is another "earth" within 20 light years which we could inhabit, providing there is no other intelligent life forms living there comparable or exceeding our own intelligence (a reasonable supposition). I think that some of us could get to such a planet within the next 1000 years

Yes, I also suspect there are other "Earth-like" planets. But how much like Earth would be necessary to support human life? The variables are so numerous as to drastically reduce our chances of finding such a place, even among 1,000,000 known lush green planets. Add to that the practical problem of the universal speed limit, and we'd have a hell of a time getting there even if we could find it.

I think that humans would sooner evolve into Martians than we'll find another Earth.

 

[Interesting Ian]

I guess I disagree with just about everybody.

Manned space exploration is valuable because I want to go. If I don't get to go, I want someone to go.

The reason I want to go is that I am a human.

Gorillas feed their community. Jackdaws gather toys. Cats mark their territories. Every creature lives, breathes, eats, eliminates, reproduces, dies.

I'm one of those creatures, but I'm also a human, and we explore. That's what we do. "We choose to do these things, not becuase they are easy, but because they are hard."

I think there's a great deal of danger these days in losing our humanity. When we decide that the only value of science is make some pill to give someone two more years of life watching Friends reruns, or we decide that the only value of space exploration is to fill up a disc with data as cheaply as possible, or we decide that the only value of learning is to get a better job and put more cholesterol on the table, we cut off bits of ourselves and throw them away. At the end of this process, we all may be healthy and long-lived and sane and sensible and comfortable. And we will be apes with cell phones, nothing more.

We will be like Nietzsche's Last Man. We will neither live where it is too hot nor too cold. Work will be regulated, lest it become a burden, and so will leisure, lest it become like work. We will be content. So says the Last Man, and blinks.

I don't know about you all, but I didn't evolve the biggest neocortex in the history of the planet so that I could do that.

A nice emotional outburst epepke I think probably most people would agree with you. On the other hand I think that we should settle for unmanned missions for the next 50 years or so until technology improves and we have more of an idea where the interesting stuff lies through the unmanned missions. A man on mars by 2020? No, but maybe by about 2069.

 

[Interesting Ian]

Re: Re: Re: Manned missions into space -- a waste?

Yes, I also suspect there are other "Earth-like" planets. But how much like Earth would be necessary to support human life? The variables are so numerous as to drastically reduce our chances of finding such a place, even among 1,000,000 known lush green planets. Add to that the practical problem of the universal speed limit, and we'd have a hell of a time getting there even if we could find it.

I think that humans would sooner evolve into Martians than we'll find another Earth.

I would have thought that earth like planets wouldn't be all that uncommon. What variables do you have in mind? As for the Universal speed limit we could maybe travel very close to the speed of light. Thus a journey of 20 light years might only take a few months ship time.

 

[Hexxenhammer]

Re: Re: Re: Manned missions into space -- a waste?

Yes, I also suspect there are other "Earth-like" planets. But how much like Earth would be necessary to support human life? The variables are so numerous as to drastically reduce our chances of finding such a place, even among 1,000,000 known lush green planets. Add to that the practical problem of the universal speed limit, and we'd have a hell of a time getting there even if we could find it.

I think that humans would sooner evolve into Martians than we'll find another Earth.

With the variety of environments that humans can live in on THIS planet without much technology, from sea level to the highest mountains, and above the arctic circle to the equator, I think we'd do ok on a sufficiently earth-like planet. The speed limit is a problem, but we could get a good fraction of light speed going and with advances in life support maybe the astronauts would be spry at very old ages if it took years to get somewhere.

 

[hgc]

Re: Re: Re: Re: Manned missions into space -- a waste?

I would have thought that earth like planets wouldn't be all that uncommon. What variables do you have in mind? As for the Universal speed limit we could maybe travel very close to the speed of light. Thus a journey of 20 light years might only take a few months ship time.

Variables like the temperature gradients; chemical composition of the Earth, seas and atmosphere; weather patterns; incoming radiation from the local star; other life already resident; and so on.

I don't know how we would accelerate up to close to the speed of light, but I'll allow that it's theoretically possible for the sake of this discussion. But tell me more about this "ship time."

 

[hgc]

Re: Re: Re: Re: Manned missions into space -- a waste?

With the variety of environments that humans can live in on THIS planet without much technology, from sea level to the highest mountains, and above the arctic circle to the equator, I think we'd do ok on a sufficiently earth-like planet. The speed limit is a problem, but we could get a good fraction of light speed going and with advances in life support maybe the astronauts would be spry at very old ages if it took years to get somewhere.

Yes, humans appear to be tremendously adaptable, given that we can live just about anywhere on Earth. But the variety of environments here on just this planet is nothing like the variety of environments on all the possible life-supporting planets within some theoretical striking distance (allowing we could do some sort of trip to planets in this section of the Milky Way). All the land regions of this planet might just as well be considered to be quite similar if viewed from the perspective of an imaginary being whose been around the galaxy a bit. To say "we'd do ok on a sufficiently earth-like planet," is a tautology, given that sufficiently means humans could survive there, in this context.

 

[Interesting Ian]

So you dredged up one proponent. So what. No. I have never read any O'Niell. It seems his work is kind of old don't you think. Did he mention that the closest star is 3 light years away and the possibility that there is a habitable planet there is less than one in a billion.

Hi Morchello,

I'm a "woo woo" BTW.

Anyway, the nearest star is 4.2 light years away, not 3 light years away. It's true that it is very unlikely that there is a habitable planet there, but this is because I believe it is a binary star system I do not see that habitable planets should be all that rare. Perhaps you could provide some reasons why you think this?

Did he account for the fact that we cannot ever approach the speed of light?

Why can't we?

 

[patnray]

What it feels like to be standing on Mars.

That is not a fact about Mars, it is a fact about human feelings. Don't get me wrong, though, I, too, would love to experience that. Very romantic. But it will probably only be experienced by a hand full to a few dozen people at the most. Aside for such subjective experiences, what objective facts can we learn from manned missions that we can't learn from unmanned missions?

 

[Skeptical Greg]

Re: Re: Manned missions into space -- a waste?

.....providing there is no other intelligent life forms living there comparable or exceeding our own intelligence (a reasonable supposition).

So, in this case, we turn around and return to Earth?

 

[Hexxenhammer]

Re: Re: Re: Re: Re: Manned missions into space -- a waste?

I don't know how we would accelerate up to close to the speed of light, but I'll allow that it's theoretically possible for the sake of this discussion. But tell me more about this "ship time."

Ian's not off here (I'm amazed too ) As long as the ship's "gas pedal is down" it could probably get a good percentage of light speed going. I suppose limited by things like mass, fuel supply etc...things that take math and people smarter than me to figure out. When you get halfway to where you're going, turn around and start slowing down by firing the engines again.

Anyone know what % lightspeed a ship that uses conventional physics could get to? My wild-@$$ed guess is 20-35%. I reserve the right to be very, very wrong.

 

[hgc]

Why can't we? [ever approach the speed of light]

You have to put in energy to get acceleration. The amount of fuel that would be required to accelerate to that velocity would be a whole hell of a lot more than we have available. Don't forget that you have to decelerate too.

 

[Hexxenhammer]

Re: Re: Re: Manned missions into space -- a waste?

So, in this case, we turn around and return to Earth?

No that's when we fire the death rays while broadcasting "We come in peace."

 

[Interesting Ian]

Re: Re: Re: Re: Re: Manned missions into space -- a waste?

Variables like the temperature gradients; chemical composition of the Earth, seas and atmosphere; weather patterns; incoming radiation from the local star; other life already resident; and so on.

If we consider a star similar to our own, and we discover a planet similar in size to our own at a comparable distance from its parent star, would it not be the case that there is a good chance it will turn out earthlike? If not then why not?

I don't know how we would accelerate up to close to the speed of light,

The application of force. This could be exactly the same as the gravitational force so that the astronauts would have normal weight. The spaceship could accelerate for half its journey to a given star, then decelerate for the other half of the journey.

but I'll allow that it's theoretically possible for the sake of this discussion. But tell me more about this "ship time." [/B]

Einsteins special theory of relativity. From the astronauts perspective, if they travel very close to the speed of light, instead of the star being 20 light years away, it might, say, only be 1 light year away

 

[patnray]

Re: Re: Re: Re: Re: Re: Manned missions into space -- a waste?

Anyone know what % lightspeed a ship that uses conventional physics could get to? My wild-@$$ed guess is 20-35%. I reserve the right to be very, very wrong.

Mass increases as the velocity increases and becomes infinite at the speed of light. It would take an infinite amount of energy to accelerate even one milligram to the speed of light.

My very rough calculations show mass increasing about 25% at half the speed of light and about 50% at 3/4 the speed of light.

Using conventional (inertial thrust) means, how fast could one go (and still be able to stop at the other end of the journey)? Inertial thrust requires mass to accelerate in the opposite direction and energy to accelerate it. If you carry the mass you will eventuall eject along with you you will have to accelerate that mass, too. I remember some science fiction stories invloving a kind of space jet that scoops up gas and dust particles and accelerates those to produce thrust without having to carry the mass along. Given a sufficient supply of energy and a very long time to accelerate, I think maybe 5% to 10% of c might be possible...

 

[patnray]

To put things in perspective, the Mars lander traveled about 0.0038% the speed of light as it left earth (about 7 miles/second)...

 

[Hexxenhammer]

Re: Re: Re: Re: Re: Re: Re: Manned missions into space -- a waste?

Given a sufficient supply of energy and a very long time to accelerate, I think maybe 5% to 10% of c might be possible...

I guess we'll just have to invent hyperdrive.

 

[Psiload]

What it feels like to be standing on Mars.

It would feel exactly like standing in the middle of a Wal Mart in a stuffy, uncomfortable spacesuit.

Oh, did you mean feel in the emotional sense? Like how it felt when you got a gold star, and a smiley face on a third grade spelling test?

Aren't there less expensive ways to stroke our egos?

 

[Interesting Ian]

Why can't we? [ever approach the speed of light]
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You have to put in energy to get acceleration. The amount of fuel that would be required to accelerate to that velocity would be a whole hell of a lot more than we have available. Don't forget that you have to decelerate too.

Recall that I didn't propose a trip now, but rather sometime within the next 1000 years. I don't know how one would acquire the energy, but I'm unconvinced that it will be an insurmountable problem if we experience the same rate of technological progress over the next 1000 years as we have done over the past 300 years. Maybe energy can be extracted from the empty vacuum of space, or maybe we could get sufficient amounts of energy by matter getting directly converted into energy, or maybe we could somehow utilise the use of anti-matter. Hell, I don't know.

How would the denizens of 1000 AD have proposed getting to Mars?

 

[Skeptical Greg]

How would the denizens of 1000 AD have proposed getting to Mars?

A sufficiently long ladder, perhaps?

 

[patnray]

It isn't just a question of finding a source of energy. Relativity places some severe constraints because mass increases as velocity increases...

The human cargo also places some constraints. Extreme acceleration is not an option. Acceleration must be limited to something around 1 g.

Here's a puzzle for those with time on their hands: Assume you have a space ship with an unlimited energy supply and a non-inertial propulsion system that can produce 1 g of acceleration when the mass of the ship equals the rest mass. Assume the mass of the ship does not change except for the relativistic increase due to velocity. How long would it take (measured by an observer on earth) to get to a star 10 light years away (remember you can only accelerate for half the journey, then you must deccelerate)?