Space!

[Spddin Ignis]

I really hope this happens... I'm feeling more optimistic about the space program and I think with the so-far-success of curiosity, if NASA chooses to go ahead with it, it is likely to get the necessary funding.

 

http://www.newscient...oons-orbit.html

[Randomizer]

NASA is first one up against the wall for budget cuts.

[keira]

As cool as asteroids are, I don't understand the justification for hauling one back home, especially to the moon's orbit. If you're going to haul it back, haul it all the way to LEO so we can get some actual work done.

 

Or better yet, just leave it where it is and send people to it. Humanity's future depends on sending people away from earth, not grabbing a small rock and putting it in orbit. We already can dock in microgravity, we already can land on the surface of a rock, because we've already done it. All landing on an asteroid is doing is combining the two. It's a moon landing with tent stakes attached to the lander.

 

What we need to be doing is sending people past the comfort of earth's gravity well. We were so close with the Apollo program, putting men on the moon. Now we need to keep going. Put someone on Mars. Put someone above Venus. Send people to the asteroid belt and beyond. Our species needs to stop sitting on its collective thumbs with regards to manned spaceflight.

Edited January 4, 2013 by صيلي
There was a very good article, which I believe was posted here some time ago, that discussed the risks of manned spaceflight and how it has become too "risky". As my machine is nonfunctional, I cannot find it.

[Niemand]

One legitimate reason to be interested in asteroids is for mining, I think—the vast majority of the metal on, or rather in, Earth is buried unreachably inside the core. A metal bearing asteroid can't hide its contents near as stubbornly, although we obviously have no experience yet with mining in vacuum and microgravity. For decades asteroid mining has been a staple of science fictional economies, and while that doesn't automatically make it advisable to pursue, it seems worth investigating, and it can be hard to tell whether something revolutionary will actually work until you make a serious attempt at it.

 

I heartily agree with he interest in manned spaceflight in general, as well. No (sensible) person says that it will be easy, but the very long-term potential can be huge.

[Cairo Jim]

It would be nice if they cane develop a decent propulsion system while they're at it. It seems and awful amount of fuel is used just to get out of atmosphere, and once in space it takes months, sometimes years just to get seemingly small distances.

[Alorael at Large]

All distances in space are enormous. Low Earth orbit is some 2000 km. The moon is about 200 times as far. Mars is, at its closest point, 27,000 times farther away. Space is huge. Yes, it would be faster if rockets constantly burned fuel instead of coasting much of the way, but propulsion isn't really the problem. Fuel is. If you want to burn a ton of fuel, you have to send up a spacecraft with a ton of fuel. All that fuel is heavy and you have to add more fuel and bigger rockets to get out of Earth's gravity well. Except now you've added even more weight, which means more fuel.

 

Jetting around space is easy if you're patient. It's getting to space with enough gas to do anything that's hard.

 

The easy solution is a space elevator, for some very questionable values of easy. Even then something has to expend the huge amount of energy (G*M*m/r) required to haul mass against gravity. It's just more convenient to spend that energy from the ground.

 

—Alorael, who doesn't think it's men in microgravity that's the current fear, exactly. It's time, stress, danger, and radiation. You'd have to offer good incentives to get someone happy to go out on that kind of limb. (Incentives like being the first human to do it? Maybe!)

[Callie]

What's striking about space is that we know so little of it: objects are still being discovered in our own solar system. Voyager 1 was launched thirty-five years ago and is now in the heliosheath. A golden record is a hitching a ride with a few samplings of our civilization...and it hasn't even left the door. Maybe in the near-future we'll be able to construct a craft capable of reaching a speed one tenth that of light. It would be a feat of engineering and yet it would take over four decades just to reach the nearest star system. Explorations of our own planet have long been romanticized but have lost some of their meaning. Space is a different story though. We still look up and wonder, a wonder that will stay with us for many, many eons. And in all those many eons I will have long been returned to dust. It's rather sobering, really.

[Goldengirl]

All distances in space are enormous. Low Earth orbit is some 2000 km. The moon is about 200 times as far. Mars is, at its closest point, 27,000 times farther away. Space is huge. Yes, it would be faster if rockets constantly burned fuel instead of coasting much of the way, but propulsion isn't really the problem. Fuel is. If you want to burn a ton of fuel, you have to send up a spacecraft with a ton of fuel. All that fuel is heavy and you have to add more fuel and bigger rockets to get out of Earth's gravity well. Except now you've added even more weight, which means more fuel.

 

Jetting around space is easy if you're patient. It's getting to space with enough gas to do anything that's hard.

 

The easy solution is a space elevator, for some very questionable values of easy. Even then something has to expend the huge amount of energy (G*M*m/r) required to haul mass against gravity. It's just more convenient to spend that energy from the ground.

 

The obvious problem with a space elevator (besides building the thing) is how to keep it from collapsing. Space debris is the great danger that no one really likes to talk about, because it pokes holes (in more than one way) in all sorts of great schemes. High speed flying trash from the astronauts of yesteryear may destroy the space elevator and create more trash. This compounds until you have the Kessler Syndrome and there's so much space debris it's unfeasible to enter space.

 

Fortunately, magnets, lasers, nets, and all other sorts of odd mechanisms are being developed by NASA, Japan, and other entities to deal with the problem. Nothing is fool-safe, though.

 

Another idea that has been floated around is setting up a space station on the Moon. A space elevator is probably a prerequisite to that, though, or to any serious staffed exploration of space. There are lots of issues with setting up a space station anywhere long term, though. Radiation, terraforming, energy, heat, long-term effects of zero gravity, and many hypothetical questions about health such as how sex and pregnancy would work (rather important for any attempts at colonization).

 

—Alorael, who doesn't think it's men in microgravity that's the current fear, exactly. It's time, stress, danger, and radiation. You'd have to offer good incentives to get someone happy to go out on that kind of limb. (Incentives like being the first human to do it? Maybe!)

 

Good luck getting someone up after them, though!

[Cairo Jim]

The obvious problem with a space elevator (besides building the thing) is how to keep it from collapsing.

 

 

How tall would be built? There isn't anything can really you attach it to.

 

 

Yes, it would be faster if rockets constantly burned fuel instead of coasting much of the way, but propulsion isn't really the problem. Fuel is. If you want to burn a ton of fuel, you have to send up a spacecraft with a ton of fuel. All that fuel is heavy and you have to add more fuel and bigger rockets to get out of Earth's gravity well. Except now you've added even more weight, which means more fuel.

 

Jetting around space is easy if you're patient. It's getting to space with enough gas to do anything that's hard.

 

 

Fuel is part of any form of propulsion or locomotion, or any sort of motion. Improving the propulsion would not only help go a wee bit faster, but also fuel efficiency would come into it somewhere. Less fuel needed plus faster engines, anyone?

 

Patience with jetting around space is fine if you think you can live for 2 or 300 years.

[Goldengirl]

How tall would be built? There isn't anything can really you attach it to.

 

That's not really an issue. After a certain point, it will hold itself up, unless it gets hit by space debris and loses structural stability. The concept is simple to grasp, though hard to implement. Imagine yourself spinning around very fast with a length of rope that has a counterweight at the end, though that technically isn't necessary. As you spin, if you're going fast enough, the rope will pull out straight and level; as soon as you slow down, the rope falls back down. That's the basic idea behind a space elevator.

 

The term 'elevator' is also misleading. It's not a giant Tower of Babel or anything like that. Rather, it would be a series of cables made of a very strong metal, probably nanocarbon. These cables would extend from the Equator far, far up into space to the point where they serve as their own counterweight to keep themselves taut. Thus, they don't need to be attached to anything.

[Mosquito---Slayer]

I really hope this happens... I'm feeling more optimistic about the space program and I think with the so-far-success of curiosity, if NASA chooses to go ahead with it, it is likely to get the necessary funding.

I will just sit back in the couch and wait for conspiracy/blah blah theorists to come out.

Can't you just see how this is totally an act against god and how it's totally going to destroy the earth and how we need to pray for it not to happen.

 

Also last I heard some Japanese company was already preparing for a space elevator, the date is quite far(2050) but I don't see even NASA doing anything earlier than that, here's the article.

[Student of Trinity]

The problem with space elevators as a way to start space travel is that the problem they're trying to solve isn't getting out of Earth's atmosphere. It's getting out of Earth's gravity well. So it's not enough for the elevator to go up a few hundred miles. It has to go up N times the radius of Earth, because you're just cutting your fuel cost problem by a factor of N.

 

So you're looking at a wire ten or twenty thousand miles long or so, at least. The sheer volume of material involved, if it's strong enough to hold itself together, is pretty daunting. And if it ever falls down, it wraps itself a few times around the Earth when it lands. That would do really a lot of damage.

[Trenton.]

The Apocalypse would be a few years late, but the Mayans aren't perfect.

 

 

Also, Giant space elevator instead of giant planet, but again, nobody's perfect.

[keira]

It would be nice if they cane develop a decent propulsion system while they're at it. It seems and awful amount of fuel is used just to get out of atmosphere, and once in space it takes months, sometimes years just to get seemingly small distances.

They seem so small because our solar system is vastly huge and vastly empty. The largest object in our solar system is a bigass ball of fusing hydrogen 109 times wider than earth, and it's so far away you can blot it out with a quarter. And yet half of any vehicle's fuel is used to get into a stable orbit.To use xkcd's basketball analogy, that's just a centimeter away from the surface. Mars, for example, is six km away. Also, remember that rockets have to lift their fuel.

 

Good luck getting someone up after them, though!

This is the problem. If we hedge everything on being able to get them back, we will never go anywhere new. Ever. Realize, when the Apollo program occurred, there was zero way to rescue those astronauts if they got stuck there. And yet we still did it. President Nixon had a speech prepared if the Apollo 11 astronauts got stuck on the moon. I'd imagine the five seconds before firing the LEM engines on Apollo 11 was one of the most nerve-wracking in human history. And yet we still threw people at the moon.

 

Discovery is all about risk. We will go nowhere and die out, not even a blip on the universe's radar, if we don't reach into the darkness and take risks.

[Student of Trinity]

It's fine to take risks with one-way missions as first steps in a credible plan to develop something safer, but one-way missions alone probably won't open up space. So regardless where we stand on risk-taking, we've got to think beyond the risky phase.

[Alorael at Large]

I saw an article almost ten years ago in some pop science magazine suggesting (optimistically) that we had the technology to set up a research station on Mars. We could send people and enough starting supplies, and we could keep launching more supplies to them to keep the astronauts alive. What we couldn't do was ever bring them back. Getting them enough fuel and infrastructure for a Martian launch was simply too much.

 

Who'd volunteer?

 

—Alorael, who is aware that this is vague and has holes in it. If you can ship tons of food, why not tons of fuel? Why not enough tons of fuel to escape a third of Earth's gravity? But it still illustrates a problem: escape velocity is the big problem in space as it is on Earth. And it's the problem with a lunar base: the Moon's pretty barren. Everything for the base would have to be sent from Earth, and then it would have to be resent to space from the Moon. Launching from Earth is still more efficient.

[Khoth]

So you're looking at a wire ten or twenty thousand miles long or so, at least. The sheer volume of material involved, if it's strong enough to hold itself together, is pretty daunting. And if it ever falls down, it wraps itself a few times around the Earth when it lands. That would do really a lot of damage.

 

22,236 miles long, at least.

[Lilith]

there's actually very little you can achieve by colonising the moon or mars that you couldn't achieve more easily by building orbital space colonies and mining asteroids

[Randomizer]

Finding volunteers will be easy when you consider that some people have gone to live for months in deep caves, sailed around the world in small boats, and done other activities where they only have radio communication with the rest of the world. There's a lot to be said for getting away from it all.

 

I forgot Biosphere 2 in Arizona.

[Cairo Jim]

you couldn't achieve more easily by building orbital space colonies and mining asteroids

 

The moon and Mars' higher gravity would make construction and livability a lot easier, as well as Mars being a lot closer to more asteroids for mining.

[keira]

Finding volunteers will be easy when you consider that some people have gone to live for months in deep caves, sailed around the world in small boats, and done other activities where they only have radio communication with the rest of the world.

Hell, I'd do it if there was a somewhat decent IP uplink (sure the ping would suck but even dial-up bandwidth would be acceptable, which would be easy) and a nice computer.

The moon and Mars' higher gravity would make construction and livability a lot easier, as well as Mars being a lot closer to more asteroids for mining.

Not really. Gravity helps conventional construction methods, but really, once you get used to it, the lack of things falling has to be handy.

 

Also, if you want to be near asteroids, build your colony in the asteroid belt

[Mosquito---Slayer]

Not really. Gravity helps conventional construction methods, but really, once you get used to it, the lack of things falling has to be handy.

Dunno, being used to something is really a pretty important part of it, besides if I put a damn hammer behind me I want it to stay there for when I need it and not fly away.

 

Also, if you want to be near asteroids, build your colony in the asteroid belt

So, if I want to stay near the sea, I should make a home inside it and have fish as my friends and relatives.

[keira]

 

Dunno, being used to something is really a pretty important part of it, besides if I put a damn hammer behind me I want it to stay there for when I need it and not fly away.

microgravity != fly away. Unless you throw something or are on STS-126 (or are Ed White I guess), you should be fine. Besides, if you are working in space you'd damn well better get used to it.

So, if I want to stay near the sea, I should make a home inside it and have fish as my friends and relatives.

That is a poor analogy, because that would imply the beach is less dangerous than the ocean, which is not the case here. Mars has next to no atmosphere (just enough to worry about during reentry, not enough to be usable), plus has dust and gravity and a horde of other things. The same goes with the moon (except the atmosphere, of which it has none). An asteroid is just as hostile but you don't have to escape a huge gravity well to use it.

[Lilith]

The moon and Mars' higher gravity would make construction and livability a lot easier, as well as Mars being a lot closer to more asteroids for mining.

 

the moon probably doesn't have enough gravity to prevent bone loss in the long term, and it's a lot easier to maintain simulated gravity in a space station than on a planet

[Mosquito---Slayer]

An asteroid is just as hostile but you don't have to escape a huge gravity well to use it.

Maneuvering a space vehicle through a belt full of huge and little rocks moving at high speed should be risky, while Asteroid belt is sparsely populated it is still a risk worth considering, additionally the asteroid belt is farther away from earth compared to mars which is a factor as well, besides I'm pretty sure mars has caves/crevices which mean a better chance of surviving rather than a total open life on a piece of rock, Asteroids have also been known to colloid with each other/change their orbit due to gravitational effects which mean sure death.

 

microgravity != fly away. Unless you throw something or are on STS-126 (or are Ed White I guess), you should be fine. Besides, if you are working in space you'd damn well better get used to it.

Obviously you have never worked on construction/heavy work, when your fellow worker asks for something when you are busy painting/putting bricks on top of each other you don't move over there and hand it to him, you throw it, when you are working on making the second/third tier of buildings, you don't walk up and down the stairs, you just throw these things, again while It's good to get used to working in space, why not just go for something you are already used to.

[keira]

 

Maneuvering a space vehicle through a belt full of huge and little rocks moving at high speed should be risky, while Asteroid belt is sparsely populated it is still a risk worth considering, additionally the asteroid belt is farther away from earth compared to mars which is a factor as well, besides I'm pretty sure mars has caves/crevices which mean a better chance of surviving rather than a total open life on a piece of rock, Asteroids have also been known to colloid with each other/change their orbit due to gravitational effects which mean sure death.

Space is very large and very empty, and very old. If asteroids hit each other on that regular a basis we would not have an asteroid belt, we would have a dust belt.

Obviously you have never worked on construction/heavy work

Actually, I have

 

why not just go for something you are already used to.

because fuel is expensive and heavy and there's no ExxonMobil on Mars.

[Mosquito---Slayer]

Space is very large and very empty, and very old. If asteroids hit each other on that regular a basis we would not have an asteroid belt, we would have a dust belt.

I know,my point is that the risk is still not worth it.

Actually, I have

My apologies.

 

because fuel is expensive and heavy and there's no ExxonMobil on Mars.

This is equally valid for asteroids.

[Student of Trinity]

Prospect for rocket fuel on Mars. It's a planet. It must be full of stuff. Heck, maybe we can go there and make us some diamond armor.

[keira]

 

I know,my point is that the risk is still not worth it.

Not really, any sort of station would be able to move if need be, and the asteroid belt has much less junk (in relation to volume) in it than LEO or, for example, Saturn's rings.

This is equally valid for asteroids.

Of course, but you also don't have to waste fuel on leaving a gravity well. To get from the Martian surface to LMO require a delta-V of 4.4 km/s. The asteroid 1982DB requires 0.1 km/s. That's a lot less gas.

Heck, maybe we can go there and make us some diamond armor.

Someone has been playing Minecraft, I see

Edited January 5, 2013 by صيلي
clarify

[Mosquito---Slayer]

Not really, any sort of station would be able to move if need be, and the asteroid belt has much less junk (in relation to volume) in it than LEO or, for example, Saturn's rings.

 

Of course, but you also don't have to waste fuel on leaving a gravity well. To get from the Martian surface to LMO require a delta-V of 4.4 km/s. The asteroid 1982DB requires 0.1 km/s. That's a lot less gas.

Firstly, the comparison is to be done with Mars not with LEO and certainly not with Saturn's rings(nothing can be cooler than going there apart from maybe eating 10 cakes at a time )

Gas is a good point but in any case the amount for either asteroids or mars is still small compared to what you need to escape earth and the time factor(larger dist. of asteroid belt from earth should negate any economic advantage.)

Couple this with the cave/crevice stations(lot safer and less prone to radiation) and the fact that you can get water on mars, additionally martial soil contains sodium, magnesium, potassium apart from being alkaline which means that in the presence of artificial atmosphere over a small area you can grow plants.

 

The reason I'm discussing these factors is that this means you can stay on mars for a far longer time than you can stay an asteroid, thus instead of a lot of small mining trips(over a larger distance) you can make one big mining trip, which should lead to overall savings even in the fuel department.

 

(Besides I don't think you can get anything extra on an asteroid, mars has been bombarded by them for like millions of years,so whatever material you can get on an asteroid you can get on mars as well.)

[keira]

 

Firstly, the comparison is to be done with Mars not with LEO

That awkward moment when you realize I said LMO, not LEO.

 

larger dist. of asteroid belt from earth should negate any economic advantage.

you do realize the engines arent on all the time right

 

Couple this with the cave/crevice stations(lot safer and less prone to radiation)

Compared to digging a hole in a small asteroid, which has the same effect, not to mention you can simulate full earth gravity by spinning it.

 

instead of a lot of small mining trips(over a larger distance) you can make one big mining trip, which should lead to overall savings even in the fuel department.

First off you could still do one large trip, in fact it would be more feasible because you don't have to lift tons of metal out of orbit. it's called stockpiling until you have enough to warrant a return trip.

 

Secondly the asteroid belt is not that much farther than mars (and the extra distance it takes uses much less fuel than it would to get off of mars). Not to mention there are plenty of asteroids with orbits that pass near earth's, one could "hitch a ride on" one and save even more fuel. The only such method I know of for mars is waiting for a launch window where it is close.

 

(Besides I don't think you can get anything extra on an asteroid, mars has been bombarded by them for like millions of years,so whatever material you can get on an asteroid you can get on mars as well.)

so has the moon. so has everything else in our system. but, again, it's cheaper to get them where there is no gravity well to worry about.

[Lilith]

also it's not just a matter of whether resources are available but ease of extraction, which depends on the concentration of those resources. a single metal-rich asteroid can have more platinum than the entire world's known reserves. you'd have to dig up a whole heck of a lot of the martian surface to get a comparable amount.

[Mosquito---Slayer]

That awkward moment when you realize I said LMO, not LEO.

You did say LEO, your post is a proof, besides I wasn't even talking about small dusty particles.

 

you do realize the engines arent on all the time right

Yes, I meant the economic advantange due to larger distance of the asteroid belt.

Compared to digging a hole in a small asteroid, which has the same effect, not to mention you can simulate full earth gravity by spinning it.

Compared to a cave which already exists and gravity which again already exists.

 

First off you could still do one large trip, in fact it would be more feasible because you don't have to lift tons of metal out of orbit. it's called stockpiling until you have enough to warrant a return trip.

Very true, but to stay for a large enough period to stockpile you need resources which I mentioned and they are available on mars not on asteroids.

Secondly the asteroid belt is not that much farther than mars (and the extra distance it takes uses much less fuel than it would to get off of mars). Not to mention there are plenty of asteroids with orbits that pass near earth's, one could "hitch a ride on" one and save even more fuel. The only such method I know of for mars is waiting for a launch window where it is close.

The average distance of mars from sun is 1.5 AU.

The asteroid belt's is most dense and centred at 2.7 AU.

Asteroids that pass close to earth are few and the probability that they have the materials we need is approximately zero.

 

also it's not just a matter of whether resources are available but ease of extraction, which depends on the concentration of those resources. a single metal-rich asteroid can have more platinum than the entire world's known reserves. you'd have to dig up a whole heck of a lot of the martian surface to get a comparable amount.

Very true, but the key word here is "can have" it could also be a simple rock which you can get from the playground next to your home and from a distance of at least 2 AU's we have no means of finding out.

[Lilith]

Very true, but the key word here is "can have" it could also be a simple rock which you can get from the playground next to your home and from a distance of at least 2 AU's we have no means of finding out.

 

actually there are several ways to work out the composition of an asteroid without having to go there and take samples, including the reflection of light from its surface and calculating its density through its gravitational influence on other bodies. they're not perfect but you can tell a metal-rich asteroid from a metal-poor one

[keira]

You did say LEO, your post is a proof, besides I wasn't even talking about small dusty particles.

here let me highlight it. it was quite obvious from context the first LEO was referencing space debris. if you dont believe me on that look up iridium 33.

 

Yes, I meant the economic advantange due to larger distance of the asteroid belt.

See below.

Compared to a cave which already exists and gravity which again already exists.

If you want gravity you might as well get enough to stop the detrimental effects (such as bone loss), which you will still get on mars. also i'm not an expert on martian geology but based on what i believe is a relative lack of limestone and running water you're going to have issues finding caves anywhere, much less caves near anything useful like ore, which is notably hard to find when it's underground.

 

Very true, but to stay for a large enough period to stockpile you need resources which I mentioned and they are available on mars not on asteroids.

The amount of resources needed to grow even a small amount of food for a small crew would still require regular earthly supply freights whether you are on mars or not. you will need to ship in soil in any case because the martian soil doesn't have enough to grow crops for any length of time, plus there's plenty of other things plants need like mycorrhiza among other things.

 

The average distance of mars from sun is 1.5 AU.

The asteroid belt's is most dense and centred at 2.7 AU.

Asteroids that pass close to earth are few and the probability that they have the materials we need is approximately zero.

See below. In addition I did not say mine the near-earth objects, I said hitchhike off them as a possible transport method. not that it really matters.

 

Very true, but the key word here is "can have" it could also be a simple rock which you can get from the playground next to your home and from a distance of at least 2 AU's we have no means of finding out.

actually we have pretty good telescopes and have a pretty good idea what's out there. i'd encourage you to do some research.

 

 

re: it's further so it must be harder to bring stuff back from. I have no life so I ran some numbers for hohmann transfer orbits between earth and mars, and between earth and 216 Kleoptra (part of the main belt, made mostly of gravel apparently but still a good reference point). note that there are much more efficient ways to move about but hohmann is a pretty reliable way. don't forget to take into account the delta-v needed to reach the local parking orbit before the transfer/escape. the below figures are relative the sun.

 

 

 

data used (semi-major axis of solar orbit, assuming circular because i dont have a degree in physics)

earth: 149598261 km

mars: 227939100 km

kleop: 417830000 km

 

[b]earth to 216 kleopatra[/b]
Starting alt:    149598261
Burn 1 -- From:  29.785
         To:    36.145
Time b/t burns:  52916.408
Burn 2 -- From:  22.703
         To:    17.822
Ending alt:      417830000

[b]216 kleo to earth[/b]
Starting alt:    417830000
Burn 1 -- From:  17.822
         To:    12.941
Time b/t burns:  52916.408
Burn 2 -- From:  23.424
         To:    29.785
Ending alt:      149598261

[b]earth to mars[/b]
Starting alt:    149598261
Burn 1 -- From:  29.785
         To:    32.729
Time b/t burns:  43163.32
Burn 2 -- From:  26.778
         To:    24.129
Ending alt:      227939100

[b]mars to earth[/b]
Starting alt:    227939100
Burn 1 -- From:  24.129
         To:    21.481
Time b/t burns:  43163.32
Burn 2 -- From:  26.84
         To:    29.785
Ending alt:      149598261

 

 

 

 

and the code i used (php, adapted from some java I adapted from some R on the ksp wiki some time back)

 

function hohmann($mu, $st, $dest) {
 $from = $st;
 $to = $dest;
 $grav = $mu;
 $r1 = $st;
 $r2 = $dest;
 $vc1 = sqrt($mu / $r1);
 $vc2 = sqrt($mu / $r2);
 $a = ($r1 + $r2) / 2;
 $t = 2 * M_PI * sqrt($a^3 / $mu);
 $dv1 = (sqrt($r2 / $a) - 1) * $vc1;
 $dv2 = (1 - sqrt($r1 / $a)) * $vc2;
 $time = $t / 2;
 echo "<pre>";
 echo "Starting alt:    ".round($from, 3).PHP_EOL;
 echo "Burn 1 -- From:  ".round($vc1, 3).PHP_EOL;
 echo "          To:    ".round(($vc1 + $dv1), 3).PHP_EOL;
 echo "Time b/t burns:  ".round($time, 3).PHP_EOL;
 echo "Burn 2 -- From:  ".round(($vc2 + $dv2), 3).PHP_EOL;
 echo "          To:    ".round($vc2, 3).PHP_EOL;
 echo "Ending alt:      ".round($to, 3).PHP_EOL;
 echo "</pre>";
}

 

Edited January 5, 2013 by صيلي
well that code tag was effective

[Aran]

As cool as asteroids are, I don't understand the justification for hauling one back home, especially to the moon's orbit. If you're going to haul it back, haul it all the way to LEO so we can get some actual work done.

 

I can't find a mass estimate for AO₁₀ (the current candidate), but I'd have a few reservations about pulling an asteroid into low orbit around our only inhabited world; particularly since this maneuver has never been attempted before.

[Mosquito---Slayer]

 

 

Composition

 

The physical composition of asteroids is varied and in most cases poorly understood. Ceres appears to be composed of a rocky core covered by an icy mantle, where Vesta is thought to have anickel-iron core, olivine mantle, and basaltic crust.^[47] 10 Hygiea, however, which appears to have a uniformly primitive composition of carbonaceous chondrite, is thought to be the largest undifferentiated asteroid. Most of the smaller asteroids are thought to be piles of rubble held together loosely by gravity, though the largest are probably solid. Some asteroids have moons or are co-orbiting binaries: Rubble piles, moons, binaries, and scattered asteroid families are believed to be the results of collisions that disrupted a parent asteroid.

Asteroids contain traces of amino acids and other organic compounds, and some speculate that asteroid impacts may have seeded the early Earth with the chemicals necessary to initiate life, or may have even brought life itself to Earth. (See also panspermia.)^[48] In August 2011, a report, based on NASA studies with meteorites found on Earth, was published suggesting DNA and RNAcomponents (adenine, guanine and related organic molecules) may have been formed on asteroids and comets in outer space.^[49][50][51]

Only one asteroid, 4 Vesta, which has a reflective surface, is normally visible to the naked eye, and this only in very dark skies when it is favorably positioned. Rarely, small asteroids passing close to Earth may be naked-eye visible for a short time.^[52]

Composition is calculated from three primary sources: albedo, surface spectrum, and density. The last can only be determined accurately by observing the orbits of moons the asteroid might have. So far, every asteroid with moons has turned out to be a rubble pile, a loose conglomeration of rock and metal that may be half empty space by volume. The investigated asteroids are as large as 280 km in diameter, and include 121 Hermione (268×186×183 km), and 87 Sylvia (384×262×232 km). Only half a dozen asteroids are larger than 87 Sylvia, though none of them have moons; however, some smaller asteroids are thought to be more massive, suggesting they may not have been disrupted, and indeed 511 Davida, the same size as Sylvia to within measurement error, is estimated to be two and a half times as massive, though this is highly uncertain. The fact that such large asteroids as Sylvia can be rubble piles, presumably due to disruptive impacts, has important consequences for the formation of the Solar system: Computer simulations of collisions involving solid bodies show them destroying each other as often as merging, but colliding rubble piles are more likely to merge. This means that the cores of the planets could have formed relatively quickly.^[53]

 

I will concede that I am not an expert on the matter but still I believe that we are nowhere near predicting that a given asteroid is a lump of platinum or gold, if we are so vague about the larger asteroids then well I don't even want to talk about about the smaller ones.

actually we have pretty good telescopes and have a pretty good idea what's out there. i'd encourage you to do some research.

See above.

 

If you want gravity you might as well get enough to stop the detrimental effects (such as bone loss), which you will still get on mars.

"The minimum g-force required to avoid bone loss is not known—nearly all current experience is with g-forces of 1 g (on the surface of the Earth) or 0 g in orbit. There has been insufficient time spent on the Moon to determine whether lunar gravity is sufficient"

Note that this is not an argument against your point, but I'd say it's not useful debating about things we don't even know.

also i'm not an expert on martian geology but based on what i believe is a relative lack of limestone and running water you're going to have issues finding caves anywhere, much less caves near anything useful like ore, which is notably hard to find when it's underground.

 

There has been enough indication that mars used to have running water at some point in history, I'm not sure about limestone but as you will notice I've included crevices as well as caves as places which are better to live in, mars has lots of volcanoes and lava flow can also lead to such structures.

The amount of resources needed to grow even a small amount of food for a small crew would still require regular earthly supply freights whether you are on mars or not. you will need to ship in soil in any case because the martian soil doesn't have enough to grow crops for any length of time, plus there's plenty of other things plants need like mycorrhiza among other things.

True, but my point is that it's still easier compared to living on an asteroid.

 

 

re: it's further so it must be harder to bring stuff back from. I have no life so I ran some numbers for hohmann transfer orbits between earth and mars, and between earth and 216 Kleoptra (part of the main belt, made mostly of gravel apparently but still a good reference point). note that there are much more efficient ways to move about but hohmann is a pretty reliable way. don't forget to take into account the delta-v needed to reach the local parking orbit before the transfer/escape. the below figures are relative the sun.

OK, I don't understand coding but maybe you could just give me as to what is the summary and conclusion, does it support your view or mine?

 

here let me highlight it. it was quite obvious from context the first LEO was referencing space debris. if you dont believe me on that look up iridium 33.

Maybe there was a little confusion there, I was certainly talking about the first sentence of your post.

 

(Also I'm sorry for not including your name in the quotes, I hope you will pardon me, I'm just feeling rather lazy. )

[edit]

[adc.]

How interesting... But we all should sit down and wait for a decade. It might cost a large sum of dollars, fortunately, we should all hope that the asteroid is worth it.

---------

-Red-eyed phantom

[Enraged Slith]

Let's say, hypothetically, that we find an asteroid with deposits of platinum and gold that far exceed what we have on Earth, and have the capability to drag it all back down to the surface. What would that do to the world's economy?

[Callie]

The high value of gold and platinum is only reflective of rarity, usefulness, and use in jewelry and investment. Platinum is an insanely useful catalyst and a sudden increase in supply would be a great boon to industry because it would become economically viable to use it in a wider range of applications (it would help immensely with the development of fuel cells, for example). Both gold and platinum are highly resistant to corrosion, with gold having a high conductivity, malleability, and ductility. Gold is used in spacecraft for that very reason (and its high malleability and ductility means you can make a very thin layer of it). Having more gold and platinum would be a boon for the economy. Some people would lose money they invested in gold, but it wasn't that great of an idea to invest in it anyway. Gold would still be used in jewelry because people have always admired its color and luster.

[Cairo Jim]

On the other hand, spending ridiculous amounts of money and time just to bring that one asteroid might not necessarily drop the price of gold and platinum straight away. One factor of the cost of producing anything is how long and how much it cost to produce and or acquire the resources.

[Sudanna]

Besides, people are definitely going to charge more for SPACE GOLD.

 

Like gold, but space.

Edited January 5, 2013 by Wander

[Student of Trinity]

I rather doubt that we're going to find any asteroid with big deposits of anything much other than nickel and iron. Asteroids were assembled by gravity, not Markus Persson.

 

The only scenario to produce gold asteroids that I can see would be if they were fragments from a much larger mass, in which molten metals had segregated by density. If they're all just planetesimals that accreted from nebular dust, they should have uniformly low content of anything further up the periodic table than iron.

[keira]

I will concede that I am not an expert on the matter but still I believe that we are nowhere near predicting that a given asteroid is a lump of platinum or gold, if we are so vague about the larger asteroids then well I don't even want to talk about about the smaller ones.

Even if these fears are unfounded, we'd most-likely send an unmanned probe that way first for more detailed scans. Because, you know, pictures.

 

Note that this is not an argument against your point, but I'd say it's not useful debating about things we don't even know.

If the effects of standard gravitational forces on a body are not detrimental, and the forces in free-fall are, then the midpoint between those is logically somewhat detrimental. Obviously there need to be more long-term studies, but the ability to manipulate "gravitational" forces on a station at will has a lot of potential utility.

 

True, but my point is that it's still easier compared to living on an asteroid.

Not...really? There would be a minor startup advantage, but that would be quickly offset by the fact that in a year you're going to have to send supplies anyway (and will have to for some time), and dealing with the gravity well (I don't think you are understanding just how much force it takes to get off a planet).

 

 

OK, I don't understand coding but maybe you could just give me as to what is the summary and conclusion, does it support your view or mine?

The first part wasn't code, but I'll oblige you. Hohmann transfer orbits are simple elliptical orbits used to transfer between two circular orbits around the same object (in this case the sun). They involve only two burns--one prograde at your start and another retrograde once you reach your destination. Obviously an actual flight would use more refined methods, but this gives you a ballpark estimate of what it would take to get to your location. The spoiler box gave the initial and final speeds for each burn, the difference is the delta-v. this is the amount you have to increase or decrease your speed to make a desired maneuver (remember that it takes more energy to make a heavy ship change it's velocity!). You would add these two values (one for each burn) to the amount it takes to escape the gravity well.

 

Let's say, hypothetically, that we find an asteroid with deposits of platinum and gold that far exceed what we have on Earth, and have the capability to drag it all back down to the surface. What would that do to the world's economy?

People with gold and platinum investments would be irritated, industry would squee and fangirl about. Bringing back massive amounts of iron would also be very useful, as 1) there is a bunch of it, and 2) it's also useful.

[Randomizer]

"Why use lead if gold will do?" = Motto of Lawrence Livermore Laboratories (at least according to less wealthy research institutions )

[Mosquito---Slayer]

Even if these fears are unfounded, we'd most-likely send an unmanned probe that way first for more detailed scans. Because, you know, pictures.

Ha, things found on Mars.

 

If the effects of standard gravitational forces on a body are not detrimental, and the forces in free-fall are, then the midpoint between those is logically somewhat detrimental.

That's just guess work, total zero is always a special condition in any situation and can have effects different from all other values, as you said experiments are needed.

Not...really? There would be a minor startup advantage, but that would be quickly offset by the fact that in a year you're going to have to send supplies anyway (and will have to for some time), and dealing with the gravity well (I don't think you are understanding just how much force it takes to get off a planet).

Well, I totally agree with you on the gravity well department, my whole argument depends on the other factors(time,ease,familiarity) offsetting this disadvantage and the fact that the martian gravity well is still small compared to the earth well which is going to be countered in both cases, the ship being heavier due to mined objects is countered by the loss of weight due to the mining equipment which can be stored/left on the permanent mars station(another thing not possible if you are hopping from asteroid to asteroid.)

 

Let's say, hypothetically, that we find an asteroid with deposits of platinum and gold that far exceed what we have on Earth, and have the capability to drag it all back down to the surface. What would that do to the world's economy?

Indian weddings will get even more ridiculous.

[keira]

Ha, things found on Mars.

Yes, and there are much larger rocks of that same composition in Mars

 

That's just guess work, total zero is always a special condition in any situation and can have effects different from all other values, as you said experiments are needed.

It's not guesswork, it's a logical extrapolation from the available data. More data, of course, would be helpful, but I don't need a data point to tell me that getting hit by half a freight trail would suck.

 

the ship being heavier due to mined objects is countered by the loss of weight due to the mining equipment which can be stored/left on the permanent mars station(another thing not possible if you are hopping from asteroid to asteroid.)

One, if you mine less than the weight of your equipment you are a horrible miner. Two, it'd be easier to move your equipment in a microgravity environment rather than dragging it across the martian surface. Three, you might not even have to move a notable sum of it, one central ore processing plant, with mining outposts bringing in ore. Four, there are currently 211 asteroids are larger than 100km in the JPL database and a Harvard study shows 1.2 million 1km+ asteroids, so I think it'd be a bit before you'd have to move to another hugeass asteroid.

[Mosquito---Slayer]

It's not guesswork, it's a logical extrapolation from the available data. More data, of course, would be helpful, but I don't need a data point to tell me that getting hit by half a freight trail would suck.

Extrapolation from only two points of data doesn't mean anything.

One, if you mine less than the weight of your equipment you are a horrible miner.

Not valid if you are mining for a short period of time and then coming back, I'm only talking about material gained from one shift.

Also not valid for precious metals.

Two, it'd be easier to move your equipment in a microgravity environment rather than dragging it across the martian surface.

Not true, it might actually be more difficult because of unfamiliarity with those conditions and honestly dragging is a big factor only for large distances.

Three, you might not even have to move a notable sum of it, one central ore processing plant, with mining outposts bringing in ore. Four, there are currently 211 asteroids are larger than 100km in the JPL database and a Harvard study shows 1.2 million 1km+ asteroids

True, but again, mars is easier to handle.

so I think it'd be a bit before you'd have to move to another hugeass asteroid.

I'm going to complain to an asteroid, preferably a female one conscious about it's weight , that will teach you to be disrespectful about them.

[A less presumptuous name.]

 

Extrapolation from only two points of data doesn't mean anything.

Have you heard of the Mean Value Theorem? It lets you do wonderful things between two points (which, for the record, is called interpolation, not extrapolation).

[Mosquito---Slayer]

Have you heard of the Mean Value Theorem? It lets you do wonderful things between two points (which, for the record, is called interpolation, not extrapolation).

I think MVT is applicable to a function which is differentiable + continuous, if it's a continuous function then Sylae is right in any case, I'm basically saying that it's possible that it might be a step function.