Travelling To The Next Star - Page 4

Alpha_Geek · November 4 2009, 10:28 PM

Jadzia wrote:

I Am Legend is perfectly entitled to post here. This kind of remark is unwelcome in Sci-Tech. We want our visitors to feel comfortable asking questions.

Of course he is, but he said he wasn't going to post things like this any more. I merely question what changed for him to return despite his statement saying he wouldn't.

Nevermind. I'm done with all this. Good day.

sojourner · November 4 2009, 11:03 PM

I Am Legend wrote:

Kaziarl wrote:

but if you have matter/anti-matter engines to push said chunk of lifeless rock out of orbit, you can probably

Why do I read such sentences around here so regularly?

Always claiming "if we can do that then we can probably do this instead making the original idea moot".
There's no reason to believe that being able to build a matter/anti-matter engine to slowly push a Moon out of orbit over a long period of time would make a journey for a ship any quicker or a better option.

Actually, Einstein's equation proves exactly that. The larger the mass of the object, the more power required to reach the same velocity. To move a _moon_ would take extreme amounts of power that could be better used for attaining higher speeds.

The faster you arrive the less chance of something breaking down enroute.

I would much rather get there in 100 years on a fast ship than in 10,000 years on a slow moon. With even a small group of colonists on the fast ship, assuming a habitable planet is found, the colony will grow much larger on the new planet given the lead time of 9,900 years.

Even assuming a trip time of over a 1000 years, you do realize that technology will still be advancing back here on Earth? Most likely a faster ship will over take your moon before it reaches it's destination. Your moon colony may arrive to find the target planet already colonized!

Now, a concept that would work better is a ship pushing a small asteroid (say, no more than 10km diameter) ahead of it. This way you still get the resources you preciously need + shielding from any thing in the way. Once you get close to the destination, release the asteroid to reduce the mass of the vehicle, making slowing down to enter the new system easier. If no habitable planet is found, pickup a new asteroid insystem and proceed to the next star.

You just don't realize how HEAVY (mass) a moon is.

Trekker4747 · November 4 2009, 11:27 PM

Protection from radiation and comet/asteroid impacts.

Protection from radiation can be accomplished with lead shielding. Protection from comet impacts can be accomplished by a)not having an object big enough to attract such objects b)having an object that is maneuverable to avoid such impacts.

Enough water for an enormous continually growing population.

Water is replenishable. A finite supply of it is enough as it can be reclaimed from waste.

Enough space to expand the colony.

There's no need to expand the colony enroute.

Enough surface area to build telescopes and other deep space research equipment.

Doing anything on the surface would be impossible enroute. Research and telescope equipment can easily be built in a conventional space-ship.

Enough resources to expand the colony, build new things and fix old things.

Simple tools can be brought along to be used at the destiantion. No need to have a friggin moon to store tools that can fit inside a small shed.

Enough resources to allow the colony once it arrives at it's destination to transfer materials and equipment to more easily colonise a planet or other Moon.

Again, this stuff can easily fit inside a spaceshp.

The Moon is so large compared to a mere ship it could store enough equipment, food and whatever else you can think of for the lengthy journey as well as vast lengths of hydroponics bays.

You really have no fucking clue how big a moon is, do you? How many equipment bays and hydropnoics bays do you think you need for even a few hundred people?

Enough space to store fuel, fuel converters, nuclear material and whatever else needs storing.

Again, can all be done with a conventional sized ship

Enough space to build multiple factory and manufacturing complexes.

Again, the surface would be useless enroute. And to build all of stuff enroute you need to bring equipment and such.

It's too much for no to little pay off. A very large, hell, even mile-long ship would be more than enough.

You don't need a goddamn moon to support a colony of travelers for a trip. 98% of the moon's materials would be dead weight as it'd have no use, be of no use, or wouldn't be used compared to what is used.

By the way Tacky: Moon = Luna, the object in orbit around Earth, moon = an object in orbit around a planetary body.

Zion Ravescene · November 4 2009, 11:30 PM

I Am Legend wrote:

Zachary Smith wrote:

I Am Legend wrote:

As far as I can see we will never develop propulsion that will get us quickly to the next star system, we will require a generational ship that will be on a LONG journey and the best kind would be a Moon colony.
I'm not proposing we knock the Moon out of orbit quickly, I propose this as a long term investment. It will take a long time to get the Moon out of orbit and the whole while it's being moved further and further out of orbit we can also develop the colony infrastructure and facilities.

So we don't do one thing then the other, we kill two birds with one stone and develop the colony as we de-orbit it.

You DO realize that knocking the moon out of orbit holds pretty dire consequences for the continuation of life on Earth, right?

At no point in this thread do I propose knocking Earth's Moon out of orbit. When I say "the Moon" in that particular post you quoted I'm referring to whatever small moon out there in the solar system we will choose to use.
If you've read the thread then you known damn well I've been talking about small moons in the outer solar system, that much has been made blatantly clear.

But even so, by trying to forcibly remove a different moon from the Solar System, you'd be upsetting the delicate equilibrium involving the forces acting upon the moon, other moons nearby, and its nearby planet, and perhaps the forces against other planets and the Sun. Even a slight disruption in the tidal and gravitational forces in this system could have consequences elsewhere in the Solar System, be it the slight decay of the orbit of one other moon, the reduced tidal forces inflicted upon the planet it orbits, the effect of suddenly losing a body with a significant electromagnetic field, and also the effect of said forces upon other objects in the solar system such as comets and asteroids, which might end up on a much different trajectory, including (but not restricted to) Earthwards.

As I lack the scientific nous to provide accurate data on the exact impact of, say, removing Hyperion on the rest of the Saturnian satellite system (let alone the whole Solar System), I'm still aware that removing a small moon from the gravitational hold of the Solar System is thus analogous to removing the Indonesian rainforest. It seems environmentally short-sighted.

Zachary Smith · November 5 2009, 12:03 AM

I Am Legend wrote:

Regardless of propulsion method, sending a Moon has benefits that far outweigh sending a ship and I've listed them extensively.

The defence rests.

My considered opinion is that the "defence" is in need of a NICE LONG "rest".

Michael_One · November 5 2009, 03:22 AM

If in the future humans develop propulsion systems capable of shifting moons around I suspect they won't be used as starships. One of the smaller moons of Saturn has more than enough organic material and volatiles to jump start terra forming Mars so I suspect that project would be higher on the to do list.

If you have enough energy to move moon size objects around in reasonable time periods you almost certainly have enough energy to make terra forming a whole lot easier than with today's level of technology.

Let's use Real Physics simplified for playing around with.

Assume we want to move Mimas, one of Saturn's moons, around. That's the one that looks like the Death Star.

F=ma Force=mass times acceleration

rearrange to a=F/m acceleration = force divided by mass, to find how much acceleration will result when a known force is applied to a known mass.

v= (1/2)at^2 velocity = one half times acceleration times time squared

rearrange to t= square root [v/(0.5a)] to find time in seconds needed to gain the required velocity

okay, with F= 1 newton, mass= 4 x 10^19 kg, and v, velocity change = 3200 meters/ second, does anyone want to find out how long it will take to accelerate Mimas to Saturnian escape velocity? I worked it out and it comes to years. Lots and lots of them. You can try it again with Rhea at 23 x 10^23 kg.....

The ability to create an illusion is insignificant when set against the power of a newton of force...

Zachary Smith · November 5 2009, 06:20 AM

^^

Dude, you SO made that shit up . . .

Australis · November 5 2009, 07:52 AM

Protection from radiation and comet/asteroid impacts.
Enough water for an enormous continually growing population.
Enough space to expand the colony.
Enough surface area to build telescopes and other deep space research equipment.
Enough resources to expand the colony, build new things and fix old things.
Enough resources to allow the colony once it arrives at it's destination to transfer materials and equipment to more easily colonise a planet or other Moon.
The Moon is so large compared to a mere ship it could store enough equipment, food and whatever else you can think of for the lengthy journey as well as vast lengths of hydroponics bays.
Enough space to store fuel, fuel converters, nuclear material and whatever else needs storing.
Enough space to build multiple factory and manufacturing complexes.

To reiterate an earlier post, all this can be done with an asteroid, and won't require anything like the engines needed for a moon.

Red Ranger · November 5 2009, 08:41 AM

It's a Rube Goldberg contraption. Brought to you by Wile E. Coyote. -- RR

I Am Legend · November 5 2009, 11:22 AM

Trekker4747 wrote:

You really have no fucking clue how big a moon is, do you?

They come in all sorts of different shapes and sizes so it really depends on which one you're talking about.

Squiggy · November 5 2009, 06:54 PM

The satellites you mentioned in your opening post and their radii.

Rhea: 764.5 km
Oberon: 761.4 km
Titania: 788.9 km
Umbriel: 584.7 km
Ariel: 578.9 km
Dione: 562.5 km

sojourner · November 5 2009, 07:03 PM

All of those are too small to have useful gravity and would also not have geological heating, while still being HUGE amounts of mass.

I sense the OP is about to redefine the term "moon" to include asteroid sized bodies. And then, as he usually does, insist that the term used is not important.

Zachary Smith · November 5 2009, 07:43 PM

Ya know . . . though . . . if you HOLLOWED out the interior of the moon, mined it until you were left with a "shell" a few yards thick, it would be a LOT less mass to move and there'd be a LOT more area INSIDE . . . I'm just sayin' . . . .

sojourner · November 5 2009, 07:55 PM

Zachary Smith wrote:

Ya know . . . though . . . if you HOLLOWED out the interior of the moon, mined it until you were left with a "shell" a few yards thick, it would be a LOT less mass to move and there'd be a LOT more area INSIDE . . . I'm just sayin' . . . .

With the likely outcome of the "shell" collapsing or breaking apart, having never been designed for atmospheric pressure inside. Better to just build a hollow shell to begin with at that point.

Zachary Smith · November 5 2009, 08:29 PM

sojourner wrote:

Zachary Smith wrote:

Ya know . . . though . . . if you HOLLOWED out the interior of the moon, mined it until you were left with a "shell" a few yards thick, it would be a LOT less mass to move and there'd be a LOT more area INSIDE . . . I'm just sayin' . . . .

With the likely outcome of the "shell" collapsing or breaking apart, having never been designed for atmospheric pressure inside. Better to just build a hollow shell to begin with at that point.

SHHhhhh! You'll SPOIL it!

Besides, if you do that then it's no MOON! It's a SPACE-STATION! And I have a VERY bad feeling about that.

Middle Earther · November 6 2009, 10:53 PM

Zachary Smith wrote:

Ya know . . . though . . . if you HOLLOWED out the interior of the moon, mined it until you were left with a "shell" a few yards thick, it would be a LOT less mass to move and there'd be a LOT more area INSIDE . . . I'm just sayin' . . . .

Then you detonate the Genesis device and you have a whole new world!!

PurpleBuddha · November 7 2009, 01:39 AM

I Am Legend wrote:

That's what you believe because you are incapable of thinking outside the box.

I notice you use that a lot as an almost proxy argument. I favor thinking outside of the box, but just because you are outside the box does not mean your argument is sound.

There have been many good points raised against this idea and you have ignored most of them.

But I want to narrow on just one. The whole asteroid/meteor thing is not an advantage to your moon ship, but rather a huge draw back. Such a massive object as a moon would be more likely to be hit, with little to no hope of dodging, and may even attract objects. A head on collision with your accelerating moon ship would be devastating. Structures built on the inside, or carved out would collapse. People would simply be buried alive. If you want to say that the interior would be built in such a way as to withstand this, than you have negated the need for a moon. The construction necessary to build such an interior would be better served to simply build a ship with a lot less dead weight. If you want to use a moon, simply harvest it for the resources to build the ship, or better yet use an asteroid or two.

A smaller ship would be much less likely to hit or attract such an object, and actually stand a chance at dodging in the event it needs to.

This much has been pointed out already, but I bring it up because even if we can set aside all we know of physics and accept that this moon project has a chance, you still have to tell us what you plan to do to avoid this problem.

Trekker4747 · November 7 2009, 02:56 AM

PurpleBuddha wrote:

I Am Legend wrote:

That's what you believe because you are incapable of thinking outside the box.

I notice you use that a lot as an almost proxy argument. I favor thinking outside of the box, but just because you are outside the box does not mean your argument is sound.

If you think outside the box you're just in another, broader, box. Tachy is outside all of the boxes.

I Am Legend · November 7 2009, 11:15 AM

PurpleBuddha wrote:

I Am Legend wrote:

That's what you believe because you are incapable of thinking outside the box.

I notice you use that a lot as an almost proxy argument. I favor thinking outside of the box, but just because you are outside the box does not mean your argument is sound.

There have been many good points raised against this idea and you have ignored most of them.

But I want to narrow on just one. The whole asteroid/meteor thing is not an advantage to your moon ship, but rather a huge draw back. Such a massive object as a moon would be more likely to be hit, with little to no hope of dodging, and may even attract objects. A head on collision with your accelerating moon ship would be devastating. Structures built on the inside, or carved out would collapse. People would simply be buried alive. If you want to say that the interior would be built in such a way as to withstand this, than you have negated the need for a moon. The construction necessary to build such an interior would be better served to simply build a ship with a lot less dead weight. If you want to use a moon, simply harvest it for the resources to build the ship, or better yet use an asteroid or two.

A smaller ship would be much less likely to hit or attract such an object, and actually stand a chance at dodging in the event it needs to.

This much has been pointed out already, but I bring it up because even if we can set aside all we know of physics and accept that this moon project has a chance, you still have to tell us what you plan to do to avoid this problem.

I do not agree that an asteroid or comet striking the Moon would pose any threat to those located deep inside it even with the increase in speed of the Moon. More damage will be done to the surface but other than a bit of seismic activity further down I fail to see any significant threat.
This is the reason why using a Moon and having a colony deep inside where it is protected is necessary.

Since the Moon could be using matter/anti-matter engines for propulsion the moon could utilise the matter/anti-matter in rockets for hitting incoming threats of a certain size to either deflect it slightly, slow it down or break it up so the surface impacts aren't as large. Failing that they just use nukes.

Instead of having the underground colony tight and compact it could be spread out in a grid like fashion ensuring if an asteroid did hit with enough force and cause damage underground in the colony that very little of the colony actually got damaged and those section would simply be off limits until repairs could be made.

It certainly beats being in a compact ship that could be annihilated with one small strike.

O'Dib · November 7 2009, 12:03 PM

I've thought about how this would work as a sci-fi story, if you took intentionality out of the equation. Like, an outer dwarf planet with an existing, self-sufficient underground research complex gets thrown out of orbit of the sun by a system-wide cataclysm, making it impossible to go back.. so they resolve, as the only survivors of humanity, to travel to the next star. Even so, they wouldn't use the resources of the moon to beef up its propulsion and defenses. Rather, they would build a ship and get the hell off. In order to 1: get there faster. 2: boost their chances of survival. So yeah, I don't see a plausible way as to how something like this would ever happen.