Why Did We Get Into Space

I am well aware of this xylene. My question was in response to a troll. I do appreciate your well stated and informative comment which I hope other readers of this forum can use. Many thanks.

 

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So the rich and powerful people can treat the planet as if it was disposable.

 

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There is only one benefit that I know of right off the top of my head from the space program..... oh yeah, the microwave oven.

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Oh come on diode man - what about the weather, GPS, rescue beacons, and watching disasters world wide as they happen.

 

I suppose the space program has done a lot more than meets the eye.

 

Nasa also does work on making cars, trucks, and RVs more aerodynamic to increase mileage.

Think about how well hurricanes are tracked from space. How many lives do you that has saved?

 

Also quality assurance techniques used throughout the world in manufacturing were originated for/ by the US space programme.

 

I don't think anyone who looks into it even half-seriously would argue that we haven't gotten anything out of the space program. The usual argument from NASA bashers is that we could have gotten far more out of the money if we had spent it on something else.

 

the rich and powerful??? Have you ever been to a slum?

 

AS TO THE ORIGINAL POST

AHEM.

The Cold War forced us to be the first to develop this technology. If there was no Cold War and the technology developed, then space travel would be little more than a novelty today, and trips to the moon would be brought to you by Pepsi and Nike.

I tried working out plans to colonize another Earth and see it as a near-impossibility for three main reasons:

-Distance. There are enough candidates for another Earth within 50 light years of Earth that we should expect to find one where we could land, breathe the air, walk on the terra firma and colonize within that area.

However, we would first need to send probes to the planet to confirm its habitability and it would take CENTURIES for the probe to arrive, and light years for it to send back information to Earth. So step two (confirmation) will take 300-400 years. This is of course assuming some entity is willing to spend a few billions to make the craft in the first place, no less wait for their great-great-grandparents to receive the news.


-Building the ship to colonize the new planet.

The ship must be built to house 300-500 humans for several CENTURIES during the trip. The ship would have to be the size of the Empire State Building and would cost several quadrillion dollars to construct. It would need to be a closed loop cycle and have enough raw materials to last half a millennium. It would need computers that can teach occupants every facet of the ship... it needs a HAL.

-Third, it needs 150-200 people willing to enter the space ship and depart Earth never to return; to cosign their children and grandchildren to living their entire life on this ship. Once you leave the solar system, it gets awfully dark and lonely out there.

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So let's say we find another Earth tomorrow. It'd take 5-20 years to build a probe to go there and let's say 300 years to get there (at 10% light speed, which is a reality with today's technology).

350 years later with proof, we build the spaceship which takes up to 100 years to build then send that to the new planet and wait another 300 years for it to arrive.

Roughly a thousand years later, we land on that new planet.

I just don't EVER see this happening with ANY civilization, never mind us puny Earthlings.

 

One obvious solution to this is to develop some sort of "suspended animation" technology that would allow the crew to travel frozen or something. That GREATLY simplifies things, since you don't have to deal with a bunch of people who are going to want to eat/walk around/raise kids/etc. during the trip. We don't know how to do this know, but by the time we're actually interested in sending out interstellar probes, who knows?

First of all, I don't think we can estimate how long it would take or how big of a project it would be for us to build a starship hundreds of years in the future. Who knows what technology we might use? It might end up being the sort of thing that "only" takes a few years and costs a few billion dollars. If you described a modern super-tanker to a sailor from 300 years ago, it would sound like an unimaginably huge, complicated, expensive ship - but today it's the sort of thing you can build in less than a year for "only" a few tens of millions of dollars.

Also, while we're currently limited to some small fraction of light speed, that might not be the case in a few hundred years. By the time a probe that we launched today reaches a star system and sends back useful data, we might be able to build antimatter powered ships or something that can travel at 90+% of lightspeed. This could also eliminate the need for having a such a huge, complicated ship and/or freezing the crew, since they might only be on it for a few years rather than decades.

 

I recall once where someone used E=mc2 and assumed 100% conversion of matter to energy and then computed how much mass was needed to accelerate a large spaceship to that velocity. It was huge, like a good chunk of the moon's mass.

 

To get up to 92% lightspeed and then back down to zero (remember, a colony ship would need to slow down when it reached the target system, so you actually have to go through all that acceleration twice) you would need a ship that had 22 kg of matter/antimatter fuel for every kg of spaceship. That assumes perfect efficiency in the engine, so in reality you would need somewhat more than this depending on how much inefficiency your engine had. That's a lot of fuel, but it certainly wouldn't need to be anything near the mass of the moon. At .92 C time will pass about 2.6 times faster for the crew, so if they are going to a star system 10 lightyears away, it will only take the crew about 4.2 years from their perspective.

If you are satisfied with only going 0.5 C, you would only need about 1.7 kg of matter/antimatter fuel for every kg of ship. But of course now you are going slower and lose most of the help from time dilation, so the 10 lightyear trip will take about 20 years (you had better either bring some boardgames or travel frozen).

Edit: As for how much the ship would actually weigh, you can probably just make up almost any number you want. I would guess that a colony ship + landers, supplies, etc. would have to be at least a few hundred tons, maybe a few thousand tons. So yeah, you will need hundreds or thousands of tons of antimatter, depending on how big your colony ship is. How difficult it would be to produce and store that much antimatter with technology hundreds of years in the future is probably impossible to say. Once you send self-replicating robots to the moon to start covering it with solar panels, maybe there will be such an excess of energy that we don't have anything better to do with it besides making antimatter for starship fuel.

 

Excellent post. I had no idea what the quantity was, but it is much smaller than I thought at 1.7kg per kg of ship.

 

Um, a light year is a measure of distance, not time.

Alternatively you go for the engineering view: build a few ships and send them in different directions, just behind the probes.
With enough fuel to go elsewhere if the target isn't worth anything, and a supply of their own probes to send ahead to more likely targets.
And then let them keep moving until they do find somewhere.
Much shorter in the long run.

 

Having a crewed starship with enough fuel to go to multiple systems seems unrealistic, unless you have unimaginably advanced technology. I agree that the most likely scenario would be sending a probe first, then the ship once you confirm that there's something there worth going it.

How likely it is that you'll find a planet that can support life anyhere in the neighborhood is a whole different question though. There's a chance that there just isn't anything we could move to in the immediate area. Of course, you might be able to do something like send automated machines ahead of you to a planet so that they can build you a nice big domed city before you send people.

 

At 1.7 kg of fuel per kg of ship?
We have far higher ratios than that now, with liquid fuels.
It's merely an engineering problem (once we get the m/a-m thing licked

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).
If we get to the stage of making ships for 300 -500 people I'd assume we'd have far better propulsion/ fuel ratios than we do now.

 

The 1.7kg fuel/kg ship was to get up to .5 c and back once. If you want to do it twice, you will need 6.5 kg of fuel per kg of ship. Three times, and it's 19 kg fuel/kg ship. The amount of fuel that you need to haul around snowballs very quickly if you want to make multiple trips.

Also that only gets you to .5C, which means you'll be looking at a looong trip. If you have to make multiple trips it will start to take an impractically long time. If you can really get a mass ratio of 20:1 for your ship, you would probably rather spend 4-5 years making one trip, rather than 60+ years making three trip.

And what happens if you run out of fuel before you find a place to live?

 

OOO..ooo...ooo! (raises hand enthusiastically to answer the question) I know the answer to that!

We're totally fucked...Right?

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