A remake of When Worlds Collide

[Ripper]

I was reading the thread on which movies we would like to see remade, and I came across several recomendations for When Worlds Collide. I think it would be a great idea because of some of the issues it would raise. I have a few off of the top of my head, and I would like to hear any other idead form the many brilliant people on the board.

First we will have to accept a certain ammount of BA. The chances of the star about to collide with earth having an earthlike planet are slim to say the least. There is also the issue of how long it would take another star to reach us. Remember this is about how people would deal with the end of the world, not astronomy.

The technology that is available today would make for a very interesting story. For example, since we are talking about saving the human race, what about taking frozen sperm? This would allow for greater genetic diversity without taking up that much more space on the ships. Would the females (and their husbands, IF we are allowing married couples) be OK with being required to have a set number of children by different sources of artificial insemination?

Now that we have better knowledge of the human genome, would we screen the lucky few? I am sure there are a number of people we would want to take that carry things like Diabetes and Tay-Sachs. So how far do we go with the eugenics? If I remember the original movie, there were two classes of survivors, those determined to be indespensible, and those who got lucky on a lotery. The value of that is that everyone else has about the same chance of going. But then you still have to balance that with eugenics.

Keeping order will become ruthless. At the same time, are they going to take any military? The up shot is that they are generally healthy and young.

How far down the list of priorities will human rights be? I think the survival of the species will trump just about anything, but I would hope the intent was to have a real, just, and compasionate human society on the new planet when it is all over.

We have a very technology intensive society. The new world will rough place to live for a while. While modern Western nations may be the best equipped to build the ships, more agrarian people from the third world MAY be better prepared for the rigors of surviving on a new world. On the other hand, traditional farming techniques may prove useless on the new planet. There is not going to be a lot of room for luxuries on the ships.

So what do you think?

[daver]

First we will have to accept a certain ammount of BA. The chances of the star about to collide with earth having an earthlike planet are slim to say the least. There is also the issue of how long it would take another star to reach us. Remember this is about how people would deal with the end of the world, not astronomy.

The original was very much along the lines of "an act of God". An extremely improbable event (a rogue jovian with an apparently earth-like world orbiting it) just happens to come bowling through the system on a course that not only causes the rogue jovian to capture earth but also to drop the rogue terrestrial into a more-or-less earthlike orbit). This improbable of an event pretty much requires an act of God.

As i recall, there was several years lead-time from the discovery of the rogues until the impact. Several development teams were set up (privately funded initially--the governments (free-world governments, anyway) didn't want to admit to the possibility. Government scientists calculated that the jovian would pass close enough to perturb Earth's orbit, but not to capture it).

The technology that is available today would make for a very interesting story.

Orion. It's my default answer to almost everything.

For example, since we are talking about saving the human race, what about taking frozen sperm?

I believe frozen eggs/sperm were taken in the books for many of the farm animals.

Now that we have better knowledge of the human genome, would we screen the lucky few? I am sure there are a number of people we would want to take that carry things like Diabetes and Tay-Sachs. So how far do we go with the eugenics? If I remember the original movie, there were two classes of survivors, those determined to be indespensible, and those who got lucky on a lotery. The value of that is that everyone else has about the same chance of going. But then you still have to balance that with eugenics.

Yes, with a quibble. The ship was assembled in a remote region; i believe all the workers were pre-selected (young, healthy, intelligent). Some aspects of the lottery were fixed. If I were running the selection I'd pick about 80-90% female crew (you can provide your own Strangelove quote), at the time the movie was made this probably wouldn't have been viable.

Keeping order will become ruthless. At the same time, are they going to take any military? The up shot is that they are generally healthy and young.

They're pretty much going to have to be all military, in some aspect. All the women will be breeders and highly protected; the men are dispensible.

How far down the list of priorities will human rights be?

Human rights? Nonexistant during the construction phase. During colonization, extremely asymmetrical (see above. Women are priceless, men are scum. Women are first and foremost breeders, they will not be allowed to hazard their wombs with dangerous jobs or activities; when of breeding age they will be breeders, afterwards they might be allowed to take up other occupations).

I think the survival of the species will trump just about anything, but I would hope the intent was to have a real, just, and compasionate human society on the new planet when it is all over.

Eventually. The female/male value ratio will drop with each successive generation, although the first few generations may still be steered towards a high female:male ratio to try to incorporate as much of the preserved genetic material as possible.

We have a very technology intensive society. The new world will rough place to live for a while. While modern Western nations may be the best equipped to build the ships, more agrarian people from the third world MAY be better prepared for the rigors of surviving on a new world. On the other hand, traditional farming techniques may prove useless on the new planet. There is not going to be a lot of room for luxuries on the ships.

So what do you think?
I don't think less technological civilizations would have any particular advantage. Preparing the ground for terrestrial life is going to require knowledge and technology; maintaining the ship will also be paramount (and could easily become the basis of a technological priesthood).

If more than one vessel arrive, there may be conflict. This could get nasty (particularly if one civilization decided that the easiest way to get a working colony would be to stock military equipment and to take over someone else's colony.

The book went into a lot more detail as to the planning of the new ecology. There is a LOT of infrastructure that would need to be established. The matte painting at the end of the movie suggested that the new planet had had a technological civilization before it had been planet-napped, this turns out to be central to the second book (and it turns out that re-establishing a planetary ecosystem wasn't going to be nearly as difficult as they had thought).

I'd imagine the first foods would be hydroponic, and that few farm animals larger than a chicken would be brought (probably cows. I'd like to see dogs, but I don't think it likely. The most likely scenario for dogs would be if they were planning for future conflict). I expect that for the first few decades farming will be done by machine, eventually livestock will take over (as the number of farms increases and if the technology to maintain the machinery declines).

Nowadays, we'd probably bring along resource satellites--weather, limited communications, radar mapping, mineral identification. They're cheap, and can easily make the difference between life and death to the colonists.

Anyway, as I said, Orion. That makes deciding what to pack a lot easier.

[Ripper]

Thanks Daver. I was afraid this one was going to die on the vine.

I agree that the best way to describe the original scenario is "Act of God". I have been trying to think of a more plausible scenario.

I remeber that there were years of lead time in the movie. the thing is, in reality we would have to have centuries. I had forgotten that it was a rogue planet rather than an entire star system. A planet could get a lot closer before being detected.

I hinted at the Dr. Strangelove earlier. But hey, why bring men at all? You can freeze the most important parts.

Getting the right blend of talent would be of great improtance. So, if you have several decades, why go through a selection process? Just breed the perfect subjects and train them from birth for their mission.

I think we are in agreement that a high tech approach to farming wuld be the way to go. Also, there would be two different kinds of ships, passenger and cargo. Why bother with life support and shielding for hardware?

In Songs of Distant Earth they did not even bither with people at all. They jsut sent frozen sperm and ovum.

[daver]

Thanks Daver. I was afraid this one was going to die on the vine.

I agree that the best way to describe the original scenario is "Act of God". I have been trying to think of a more plausible scenario.

I can't think of one. You can have some catastrophe about to wipe out life on Earth (any of a number of ways this can happen), but if you want to settle a new world you're going to pretty much have to go the When Worlds Collide route. Maybe you could throw in some funky wormhole, but this is even more an act of God. It does have the advantage of giving you a suitably short time span to build your ship.


I remeber that there were years of lead time in the movie. the thing is, in reality we would have to have centuries. I had forgotten that it was a rogue planet rather than an entire star system. A planet could get a lot closer before being detected.

Yep. I expect we'd have detected an Earth-sized planet out to maybe 10 pluto-orbits away by now, further if it were coming in on the ecliptic.

I hinted at the Dr. Strangelove earlier. But hey, why bring men at all? You can freeze the most important parts.

Virgin Planet?

I think you need something that is dextrous, active, and disposable. It helps if it is strong and intelligent as well. Post-menopausal women might do, but I think youth might be important. Plus, you want some sort of a backup in case Lucas built the refrigerators for the sperm bank.

Redundancy is going to be a byword.

Getting the right blend of talent would be of great improtance. So, if you have several decades, why go through a selection process? Just breed the perfect subjects and train them from birth for their mission.

Given a few decades lead time, we'd have some time to see if our idea of perfect genetics was viable--we'd have time to correct for oversights (they're all geniuses, but they're all insane, or all depressed, or all more interested in video games than procreation).

I think we are in agreement that a high tech approach to farming wuld be the way to go. Also, there would be two different kinds of ships, passenger and cargo. Why bother with life support and shielding for hardware?

Well, Orion drives aren't too easy on their immediate surroundings. This is all right when leaving a doomed planet, or arriving on a (so far) pristine planet. But if your cargo ship lands within useful range of your passenger ship, your passengers might get a bit toasty.

You don't want to have two ships, both of which are necessary for your colony to succeed. You might have one ship that is primarily agricultural, one ship that is primarily technological, but you'd want either one to be able to succeed if the other was lost.

In Songs of Distant Earth they did not even bither with people at all. They jsut sent frozen sperm and ovum.
We'd need better technology--essentially sentient machines. Presumably the drill would be to let the machines do the terraforming while the genetic material lies in some sort of digital storage. After the planet is ready, humans are assembled to inhabit it. Something similar could be done if the machines weren't completely sentient, but semi-autonomous. Enough humans would be living to direct the machines and solve whatever problems crop up. Enough humans would be awake that one lonely watcher couldn't go mad and destroy the data banks. The process may take tens of millenia.

Another option is to not bother with colonizing a planet at all--build O'Neill colonies. This gets the inhabitants out of the way of the maddened hordes.

[Ripper]

I think the adantage of having unmanned cargo ships is that they will be easier o produce. They are also expendable. You are going to need a ot of hardware to terriform the new planet. This brings up another plot device. Whatever is happening is going to have to completely destroy earth. Otherwise it would be easier to terriform earth after the disaster. I guess you would have to contrive a rather inplausible scenario. No more so than some of the other movies out there though.


I think it is a given that all of the survivors will need to be young and healthy. But you make a good point that mental and emotional stability are going to be of equal importance. I know a few women who would think that a society of nothing but women would be utopia. I think at least a few men would help keep things on an even keel.

One thing that Clarke hit on in SODE is that resources would not be an issue. "You need 500 metric tons of pure gold? No prob. Give me a couple of days."

I am not sure there is a real concensus that you can breed for inteligence. I would be more concerned with eliminating genetic defects like diabetes.

[captain swoop]

You need two ships, an 'A' Ark proceeded by the 'B' Ark.

[MAPNUT]

First, I'd like to see a movie made that was faithful to the spirit of the book, to say nothing of having better special effects. I had heard that the movie was an early sci-fi classic, and was disappointed when I finally saw it.

As far as a real situation, or a completely rewritten script, I think the notion of more than one mission should be give more emphasis. There would certainly be a scientific, government-sponsored mission dedicated to preservation of the species. Probably the US and the Russians could each (or together) assemble one. But I'd also expect a private or corporate mission dedicated to self-interest, i.e. the survival of the millionaires who would sponsor it. In spite of the inferior planning of such a mission, I don't think their odds for survival would be that much worse assuming they land on an Earth-like planet.

Given what we read about pseudo-science on this forum, it's easy to see why the governments would keep the knowledge of impending destruction from the public as long as possible!

[Ripper]

An interesting point about the corporate/millionaire angle. I have to wonder though, would wealth as we measure it today matter if the world is coming to an end? I think private property would fall by the wayside in general. Where there may be some conflict is if a well prepared corporation decided to build up its own army to defend its interest. A job perk could be a place on the ship, since material wealth would loose all meaning as doomsday drew near. They would have to move early enough to prevent their resources from being confiscated by the various governments. A lot of this will depend on how much lead time there is. If there is a century or two of lead time, conventional wealth would still have value for a while.

I think there may even be conflicts between the nations, as the US would want to export Constitutional Democracy while the PRC would want to export Maoist Collectivism.

[MAPNUT]

Suppose General Electric wanted to mount their own mission, or some other corporation with a lot of resources. Money wouldn't be the issue. The board of directors would all be going, along with their (trophy) mates. Other exectives and top engineers considered essential would have places. The rest of the workers would be in a lottery. Corporate propaganda would also be used to convince the workers they would be doing it for pride and for humanity. The government wouldn't interfere because they would need GE's resources too.

[daver]

Governements supposedly have control over the fuel for an Orion drive (there might be a couple of exceptions, but they aren't going to be enough to deliver much more than a manhole cover). Right now there are only two governments with enough resources, although China is coming along as fast as it can.

Chemical rockets could be used to deliver roughly 1-ton payloads, and maybe a bunch of people would try for those (these would be the equivalent of leeches--they'd launch with a few luxury items with which they'd hope to barter they way into better-equipped colonies. Maybe one payload would be a bunch of guys with M-16's hoping to take over a richer colony).

Old proposals (DUMBO, NERVA, Timberwind) would be dusted off, some people might look into newer concepts like a nuclear salt water rocket. These couldn't deliver the battle-ship sized loads a big Orion could handle, but the governments presumably have a looser grip on nuclear fuel than on nuclear bombs.

[Ripper]

Suppose General Electric wanted to mount their own mission, or some other corporation with a lot of resources. Money wouldn't be the issue. The board of directors would all be going, along with their (trophy) mates. Other exectives and top engineers considered essential would have places. The rest of the workers would be in a lottery. Corporate propaganda would also be used to convince the workers they would be doing it for pride and for humanity. The government wouldn't interfere because they would need GE's resources too.

I do not think you would need propaganda to get people to work on this project. Survival is the ultimate motivation.

Granted, chemical rockets are old technology, and not really suitable for longer space journeys. In the original WWC plot the ships did not have far to go.

I suppose that if my options were used up I would strap myself into a second hand MX and fire myself at the new planet. What is there to loose?

James Burke once said that there comes a time when you will have to decide to either curl up and die, or make someone else curl up and die. He seemed to think that a civilized human being would have a hard time making that decision. I believe that when that time comes, there is no such thing as a civilized human being.

[daver]

James Burke once said that there comes a time when you will have to decide to either curl up and die, or make someone else curl up and die. He seemed to think that a civilized human being would have a hard time making that decision. I believe that when that time comes, there is no such thing as a civilized human being.
I'd say the ranking goes to higher and higher levels of identification--survival of the individual, survival of the family, survival of [country, religion, philosophy], survival of species.

[Ripper]

I put my family first. My own survival is lower on the list. I am not sure any curent ideology would survive. At best it would be an ideal that they could aspire to restoring someday. In the short term it will be a modified martial law. In time they may aspire to some kind of representative or democratic government. Todays would will be viewed through the colored lens of time like people in the middle ages may have viewed the glory that was Rome, or Camelot.

That has been done a few times. A Sci Fi story set in a post collapse era where there is this myth of a lost time of prosperity, freedom, and justice. Maybe there are a few of the faithful who are dedicated to bringing it back. I am sure there would be some conflict there. On the new planet there are those who are being pragmatic and think they have to keep a tight ship, and those who think that it is time or a more liberal government. Even when some new freedoms are granted there will be conflict because of the principal of "relative deprivation". Once you have given the people a little moere freedom, they are going to want still more. When you try to reign it in you will have roits. This is more or less what happened in Tienimen Square.

[mike alexander]

Have to remember that the book was written in the late 1930's and science/technology weren't quite where they are today.

Credit to Wylie and Balmer, they had the approach of the planets from the Southern hemisphere so most of the major observatories of the day wouldn't see them until they were closer (As I recall they were first discovered by Bronson from South Africa). There was a close pass which caused much destruction, then the interloping body actually collided with the earth on the other side of the orbit half a year later.

Ripper wrote:
James Burke once said that there comes a time when you will have to decide to either curl up and die, or make someone else curl up and die. He seemed to think that a civilized human being would have a hard time making that decision. I believe that when that time comes, there is no such thing as a civilized human being.

I respectfully disagree, at least in part. There are many examples of people who have taken the third route of deliberately sacrificing themselves to save the lives of others. (And, of course, many more who didn't.) I think that when the time comes, there is still a chance that some people will remain civilized.

[Ripper]

I am not saying that people are not capable of being unselfish. I do not think one can decide to just let themselves die with cold logical detachment. We are not talking about ideals or causes or family here. Just you and a stranger, and there is only room for one of you on the ship.

[Tuckerfan]

I'd imagine the first foods would be hydroponic, and that few farm animals larger than a chicken would be brought (probably cows. I'd like to see dogs, but I don't think it likely. The most likely scenario for dogs would be if they were planning for future conflict).Not necessarily. Dogs would be handy for finding a lost child (they have good tracking skills). Not to mention, they, like cats, earn their keep. Dogs can be used to herd livestock, and deal with many of the pests, which no doubt will find a way to stowaway on the ship. Also, humans have a need for companionship, and animals, like dogs, make great companions, so we'll take them along with us, I'm sure. And, in an emergency, you can eat your dog.

[Ripper]

In Titan AE they had frozen embryos of just about every species on earth. I guess we have to ask the space ark question. Are we going to just save ourselves and the species we can't do without, or are we going to try to save everything? And how many people will be left behind to make room for the red cocaded woodpecker? I think it would have to be frozen sperm and ovum. The two of every species Noah thing would not give you viable populations.

[captain swoop]

I'd imagine the first foods would be hydroponic, and that few farm animals larger than a chicken would be brought (probably cows. I'd like to see dogs, but I don't think it likely. The most likely scenario for dogs would be if they were planning for future conflict).Not necessarily. Dogs would be handy for finding a lost child (they have good tracking skills). Not to mention, they, like cats, earn their keep. Dogs can be used to herd livestock, and deal with many of the pests, which no doubt will find a way to stowaway on the ship. Also, humans have a need for companionship, and animals, like dogs, make great companions, so we'll take them along with us, I'm sure. And, in an emergency, you can eat your dog.

I can see it now. 'Don't take me, take my cat'

[Ripper]

I love cats, but real cat people are scary.

[Jpax2003]

Why not just go to Mars?

I mean, we could do quick and dirty round trips in months or weeks if we spared no expense. An OTUSC (One Time Use Space Craft) could probably be made today for less than a billion and make the voyage in a few weeks. Leave it in orbit and retrieve loads as time allows. Remember this is Doomsday. It's not something that needs to be paid for, it's something that needs to be done. We would need several ASSC (Aero-Space Shuttle Craft) for orbit-to-ground at Mars.

Basically, we would be able to clear the deck at earth well before the interloper was close enough to make transit feasible. Waiting a century for a select few to make the voyage when it becomes short enough would be crazy. You could take at least as many trips to mars every few weeks for a hundred years!

Forget waiting to send out a hardware ship to the interloper. Send manned and unmanned freighters into orbit around mars, jupiter, venus and even the sun to wait out the collision. Then take them out of their distant parking orbits for relocation to the new earth-interloper (planet Bob if you will :-) )

We have the technology to do this today if you use the brute force method. No more fuel saving super-slo-mo trajectories. We'll have constant boost ships to go to mars in months, weeks, or even days. Hell, even if the disaster were really close, just constant boost to anywhere except earth vicinity. Save half your fuel to get somewhere else. Anywhere is better than here.

Lets just hope that the interloper, doesn't have a moon that plows into mars. I mean, it might be good in the long run if it increases martian mass and gives it an earthlike moon binary, but it would not be good for our immediate relocation plans.

[daver]

Why not just go to Mars?

Good point.

There are some reasons Mars may not be particularly attractive--low gravity, high radiation. It might have been established that Bob (in the books was it called Bea?) has a decent gravity, atmosphere, and magnetosphere. Mars has raw materials, but it's not immediately clear if it would be better to settle Mars or just take up orbit (in O'Neills) around it.

If you were going to send O'Neills to Mars, you might as well build them in LEO and stock them there. If you had a beanstalk, you could build the O'Neill at the top of the beanstalk; when it was finished you could send up the people and fling it at Mars.

I mean, we could do quick and dirty round trips in months or weeks if we spared no expense.

Wikipedia gives Orion an Isp of 2,000 - 100,000, a thrust of 1e9 - 1e12. No estimates for the mass of the shielding. Presumably the higher Isp's are for some sort of microfusion; any Orion we build in the short term would likely be at the low end. Travel time of one month requires a delta V of perhaps 60 km/sec (30 km/sec at each end). A low-end orion would have a mass ratio of perhaps 21 for that delta V, a slightly better one with an Isp of 1e4 would have an Isp closer to 2. With an Isp of 1e5, your fuel ratio drops to 7% ship mass.

Orion is probably the best bet for a high thrust high Isp booster with only small advances on current technology. The nuclear salt-water rocket is a remote possibility. NERVA and DUMBO type rockets aren't going to be able to make the trip in a month, although they might manage in several. VASIMR is probably doable within about the same time frame as NERVA or DUMBO; any of those might be able to knock a few months off of the Hohmann time, but there's still going to be a couple years between launch windows.

An OTUSC (One Time Use Space Craft) could probably be made today for less than a billion and make the voyage in a few weeks. Leave it in orbit and retrieve loads as time allows. Remember this is Doomsday. It's not something that needs to be paid for, it's something that needs to be done. We would need several ASSC (Aero-Space Shuttle Craft) for orbit-to-ground at Mars.

I don't see how, and I don't see the need. It's not that much harder to get to Mars than to geosynchronous orbit--we could build rocket assembly lines now and every couple of years fire off a bunch of small (10 ton) payloads to Mars. It might take nine months to get there, but cargo doesn't mind. Once enough cargos have arrived for a Mars base, work could start on a cycler to carry people.

Basically, we would be able to clear the deck at earth well before the interloper was close enough to make transit feasible. Waiting a century for a select few to make the voyage when it becomes short enough would be crazy. You could take at least as many trips to mars every few weeks for a hundred years!

You couldn't get all the people off, but you could get a bunch. Doing so might make it easier to keep the people remaining under control (work hard enough and get a lottery ticket. You might not get to go, but maybe your offspring will).

We have the technology to do this today if you use the brute force method. No more fuel saving super-slo-mo trajectories. We'll have constant boost ships to go to mars in months, weeks, or even days.

We don't have constant boost ships (unless you're talking constant .001 g boost).

[Tuckerfan]

I love cats, but real cat people are scary.You mean like Nastassja Kinski (http://www.imdb.com/title/tt0083722/)?

[Jpax2003]

Daver, I am basing much of what I say on Heinlein, who wrote this in Expanded Universe. I know he's a fiction writer, but he's known for being on target and this was a non-fiction piece.

According to Heinlein for constant boost to mars (not closest approach)
.001 =145 days
.01 =45.9 days
.1 =14.5 days
1g =4.59 days

If we built in orbit and loaded lots of fuel on could we not just boost continuously. I'm not sure of the calculations required for balancing constant thrust to the mass of the added fuel, But could we not also have a long boost, coast, then reverse boost braking maneuver to parking orbit?

I know chemical rockets are massive, but in an earth-escape scenario, we would spare no expence and probably anything that could achieve escape velocity would have passengers.

I just think that if the planets collided I would not want to be in the neighborhood, not even in geosynchronous orbit.

Isn't there any mainstream research into constant boost propulsion?

[daver]

Daver, I am basing much of what I say on Heinlein, who wrote this in Expanded Universe. I know he's a fiction writer, but he's known for being on target and this was a non-fiction piece.

According to Heinlein for constant boost to mars (not closest approach)
.001 =145 days
.01 =45.9 days
.1 =14.5 days
1g =4.59 days

If we built in orbit and loaded lots of fuel on could we not just boost continuously. I'm not sure of the calculations required for balancing constant thrust to the mass of the added fuel, But could we not also have a long boost, coast, then reverse boost braking maneuver to parking orbit?


Hmm; looks like he calculated the time to traverse the max distance (2.5 au) ignoring complicating things like orbits. This is reasonable for high accelerations, less so for low accelerations. The Hohmann transfer ellipse, for comparison is about 260 days, but the alignment for hohmann ellipses only repeats every 26 months or so.

The mass ratio of your ship ((structure+payload+fuel)/structure+payload) is an exponential function of the time you accelerate for a constant boost ship. So, if your ship needs to be half fuel for one hour of boost, it would need to be 3/4 fuel for two hours, 7/8 for three, 15/16 for four. For 24 hours boost it would need to be 16777215/16777216 fuel. For 48 hours, 281474976710655/281474976710656 fuel. That's starting to strain credulity a bit.

The top speed of his 1 g constant boost craft is about 2000 km/sec--0.7% c. That might still be doable with fission, but it's starting to get into the fusion or antimatter range.

And yes, it makes more sense to boost, coast, and decelerate. Constant boost is extremely wasteful of fuel.

I know chemical rockets are massive, but in an earth-escape scenario, we would spare no expence and probably anything that could achieve escape velocity would have passengers.

I just think that if the planets collided I would not want to be in the neighborhood, not even in geosynchronous orbit.

Isn't there any mainstream research into constant boost propulsion?
Some. There have been a few probes launched with an ion drive; the Europeans just launched one that is supposed to take a few months to get to the moon. The problem is that for one reason or another the designers have had to limit themselves to low power high Isp, which means really really low thrust.

Go to this page: http://en.wikipedia.org/wiki/Spacecraft_propulsion

It has a better summary than i can give of the various propulsion options. Orion, particularly the super orion, with a ship mass of 8 million tons, looks just the thing for planetary evacuation. Not sure what to pack? Take EVERYTHING.

Medusa (an Orion variant) looks like a reasonable system for smaller scale drives.

Orion and its variants run afoul of the various UN treaties involving atomic weapons in space; obviously in the event of a planetary emergency these wouldn't carry much weight.

The nuclear salt water rocket is the other drive possibility that jumps out as worth exploring. Like all good 50's sci fi drives, it is high thrust, high Isp, and radioactive as heck. This might not even violate the treaty preventing nuclear weapons in space, although there are other treaties that might get bent a bit.

The problem with all the high Isp (umm, a slight digression here. The Wikipedea should have a good explanation of Isp, but it's basically a measure of how well the rocket uses its fuel--how much thrust it can get out of a pound of fuel) drives is that they need a boatload of energy. For inner system low thrust high Isp drives you can use solar energy; for higher thrust systems you pretty much need a nuclear reactor (or atomic bombs for Orion and the nuclear salt water rocket (that one is essentially a continuous atomic explosion)). And the problem with hauling nuclear reactors around, particularly space-rated ones, is that they are heavy. The reactor mass ends up being a significant portion of the weight of your vessel, and can eat up all the fuel savings that your high Isp thrust provided (which was one of the problems with NERVA.. There were plans for a nuclear third stage on the Saturn V; it wouldn't have done any good for a moon trip, but would have started being useful for Mars missions).

[Tuckerfan]

daver, you're correct that Heinlein picked the maximum distance between Earth and Mars. He did it to point out how quickly we could get to Mars if we really wanted to.

In reading your link to Wikipedea, I stumbled across this little gem The expense of launch for the largest size of Orion was 5 cents per pound to Earth orbit in 1958 dollars. :o Followed by this little gemWith special designs of the nuclear explosive, Ted Taylor estimated that it could be reduced ten-fold, or even to zero if a pure fusion explosive could be constructed. However, bomb designers are reluctant to design such an explosive, because it is thought to be destabilizing, and tempting to terrorists. :evil:

[daver]

daver, you're correct that Heinlein picked the maximum distance between Earth and Mars. He did it to point out how quickly we could get to Mars if we really wanted to.

I'd amend that a bit, something more along the lines of how close Mars really is given the right technology. The right technology doesn't require a magic space drive, but could be implemented with copious amounts of nuclear energy. The Orion entry shows that, given the will, we could have had a Mars base thirty years ago.

In reading your link to Wikipedea, I stumbled across this little gem The expense of launch for the largest size of Orion was 5 cents per pound to Earth orbit in 1958 dollars. :o

Yes. Imagine if it were cheaper to fly to the moon than it now is to fly to Australia (umm, if you live in Australia i suppose you'll have to imagine flying somewhere else).

Followed by this little gemWith special designs of the nuclear explosive, Ted Taylor estimated that it could be reduced ten-fold, or even to zero if a pure fusion explosive could be constructed. However, bomb designers are reluctant to design such an explosive, because it is thought to be destabilizing, and tempting to terrorists. :evil:
Umm, yes. Imagine if there were companies churning out kiloton fusion bomblets for spacecraft propulsion, at the rate of hundreds per week.

[Jpax2003]

But imagine if we had a real space travel/freight/exploration/vacation/exploitation/relocation industry. We might make life so bearable that people would decide to emmigrate instead of killing themselves in suicide attacks (or at least go chill in a low-grav spa).

But I digress. Heinlein did say he was using a garden variety opposition at about 60,000,000 miles. He was approximating because he was also relating it to Pluto. His conclusion was that at any rate of constant boost, pluto was only about 7 times farther than Mars.

Why would the nuclear reactor need to be so massive? I am sure massive is a relative thing. We would not need lots of extra shielding. All we need is a single radiation bulkhead. We would be protected mostly by distance and geometry. Of course that means no other ship could follow very closely.

How about laser-assisted-ignition fusion and magnetic bottleneck for reaction-mass propulsion? This could be powered by onboard breeder fusion reactors with massive flywheel backup. The fusion might be continuous or operate in a pulse or burst mode.

Think it has any merit?

[Tuckerfan]

Umm, yes. Imagine if there were companies churning out kiloton fusion bomblets for spacecraft propulsion, at the rate of hundreds per week.So, put the factories in isolated areas of the Moon. This makes it exceedingly difficult for terrorists to get to them. Limit the number of companies which can sell or use the bomblets, subject them to random searches and inspections, along with stiff penalties for any of the things coming up missing (say having the CEO jailed), and I don't think you'll have to worry too much about the stuff ending up in the wrong hands.

[darkhunter]

Umm, yes. Imagine if there were companies churning out kiloton fusion bomblets for spacecraft propulsion, at the rate of hundreds per week.

But how would they be ignited? IIRC the Orion design using the fusion bomblets used a battery of lasers on the ship itself to detonate them.

[daver]

But I digress. Heinlein did say he was using a garden variety opposition at about 60,000,000 miles. He was approximating because he was also relating it to Pluto. His conclusion was that at any rate of constant boost, pluto was only about 7 times farther than Mars.

Yep--grade-school physics. d = .5*a*t*t, or time is proportional to sqrt(distance).

Why would the nuclear reactor need to be so massive? I am sure massive is a relative thing. We would not need lots of extra shielding. All we need is a single radiation bulkhead. We would be protected mostly by distance and geometry. Of course that means no other ship could follow very closely.

When I googled for space-rated nuclear reactors, the best proposal i found was about 10 kg/kWe. There's the reactor itself, the turbines to extract energy from the reactor, and the cooling mechanism, as well as miscellaneous control mechanisms. I don't know the mass breakdown; it may be that most of the mass of the reactor was in the shielding. Much of this could be eliminated if you stuck the reactor out on a pole and were convinced that you wouldn't need to maintain any of it.

Anyway, you're going to need to get a few orders of magnitude improvement in the power/weight ratio before high thrust high Isp drive systems become reasonable--something on the order of kg/MWe.

How about laser-assisted-ignition fusion and magnetic bottleneck for reaction-mass propulsion? This could be powered by onboard breeder fusion reactors with massive flywheel backup. The fusion might be continuous or operate in a pulse or burst mode.

Think it has any merit?
I don't know. It depends on the timeline we're talking about. We've been trying for controlled nuclear fusion for about fifty years now with very limited success. If this was in a "the Earth will be destroyed in ten years" scenario, it'd be completely out of the question--a crash program to develop a super Orion would be the only option. If it is "the Earth will be destroyed in 200 years" you have some more flexibility.

[daver]

Umm, yes. Imagine if there were companies churning out kiloton fusion bomblets for spacecraft propulsion, at the rate of hundreds per week.

But how would they be ignited? IIRC the Orion design using the fusion bomblets used a battery of lasers on the ship itself to detonate them.

You'd need a big pulse to ignite them--neutron pulse, laser or ion shockwave, something. But we're now assuming dozens of ships flying around the system using thousands of these bomblets. Pretty much every major university is going to have an ignition system, or most of one (my university was hardly a major one, but it had a reactor on campus and a hypervelocity cannon in the basement of the physics building). Anyway, the ignition source probably isn't going to be something you can pick up at your local Ace hardware store, but it's going to be very difficult to keep everything that could be converted into one under control.

[Jpax2003]

Ok, I made a typo. I meant a elecromagnetic and laser ignition of a fusion pulse that would be used to directly heat and propel a reaction mass through a reactor vessel to the exhaust. Pretty simplistic explanation I know, and probably lots of calculations to work out. But I wonder if it were possible. I said the Fusion lasers could be powered by breader fusion reactors. I meant Fission breeder reactors. I don't even know if you could make a fusion breeder reactor and what it would do. I'm sure it would require lots of mechanical stuff (liquid sodium cooling fluid and then a hot water loop then maybe another hot water-turbine loop).

Hmmm, maybe a better idea would be lunar based or spaceborne launching platforms using this idea. Ships could be laser launched. but instead of using a light-sail momentum transfer idea, the ship could also have reaction mass that is ablated by the distant laser. I think this has been thought of... but I don't know if it's been explored on the launchbase side.

Or how about a really long electromagnetic rail launcher? We would not need huge accelerations like a rail weapon would need. This could be powered by spacebased fission reactors. Since it is not traveling very far, the minimal thrust would only be needed for station-keeping. Would the massive size result in less proportional equal and opposite reaction to launching vessels?. Or it could launch two vessels in opposition to cancel out. Or it could catch and decelerate one as it is launching/accelerating another. We could even have relay stations in orbit. This would not be constant boost, but it may be faster than simple freefall orbits. Of course, we could take advantage of orbital mechanics whenever possible and follow gravity manifolds when we are able to map them in real time (if we can't already). Call it a space-tram or something like that.

thought?

[daver]

Ok, I made a typo. I meant a elecromagnetic and laser ignition of a fusion pulse that would be used to directly heat and propel a reaction mass through a reactor vessel to the exhaust. Pretty simplistic explanation I know, and probably lots of calculations to work out. But I wonder if it were possible. I said the Fusion lasers could be powered by breader fusion reactors. I meant Fission breeder reactors. I don't even know if you could make a fusion breeder reactor and what it would do. I'm sure it would require lots of mechanical stuff (liquid sodium cooling fluid and then a hot water loop then maybe another hot water-turbine loop).

The BIS Daedalus starship proposed ion- or laser-induced inertial confinement fusion to power an Orion-type vessel. Presumably (I haven't seen the descripton) the same idea is used in Medusa to drive a sail. In this case, there is no reactor vessel per se--the bomblet is exploded next to the thing it is supposed to push. This avoids a lot of the problems with conventional fusion, although it assumes that something like Shiva could be made to work.

Actually, a fusion breeder reactor makes some sense (initiate the fusion inside a lithium shell; let the neutron impacts on the lithium generate more fusion products), but it doesn't make all that much sense in the context of a spaceship.

Hmmm, maybe a better idea would be lunar based or spaceborne launching platforms using this idea. Ships could be laser launched. but instead of using a light-sail momentum transfer idea, the ship could also have reaction mass that is ablated by the distant laser. I think this has been thought of... but I don't know if it's been explored on the launchbase side.

One idea that has been proposed is a laser launcher. Your payload is stuck on top of a big ice cube (actual material may vary), a honking big laser (hmm. honkowatts. how many honkowatts in a jigowatt?) zaps the bottom of the ice cube. The bottom few molecules undergo something that i think was called laser-induced detonation--they flash instantly to plasma, and bounce off the rest of the ice cube, imparting significant momentum as they do so. Jerry Pournelle used this in some of his stories. There was some work being done on this during the laser SDI days. It'd obviously work better on an airless body then on the earth. There are also going to be severe range limits--it's probably only viable over a few thousand km.

Or how about a really long electromagnetic rail launcher? We would not need huge accelerations like a rail weapon would need. This could be powered by spacebased fission reactors. Since it is not traveling very far, the minimal thrust would only be needed for station-keeping. Would the massive size result in less proportional equal and opposite reaction to launching vessels?. Or it could launch two vessels in opposition to cancel out. Or it could catch and decelerate one as it is launching/accelerating another. We could even have relay stations in orbit. This would not be constant boost, but it may be faster than simple freefall orbits. Of course, we could take advantage of orbital mechanics whenever possible and follow gravity manifolds when we are able to map them in real time (if we can't already). Call it a space-tram or something like that.

thought?
1 g is .01 km/sec/sec--it takes 100 seconds at 1 g to gain 1 km/sec. 30 km/sec takes pretty close to an hour--about 45,000 km. That's a pretty long accelerator. There's a lower-tech proposal which does pretty much the same thing--a rotating tether. You dock somewhere near the middle, drift towards the end, and let go when you're pointing more or less in the right direction. The tether needs ion engines or the like to maintain its speed, but the ships themselves can get by without them (rather, with much smaller engines, mainly for maneuvering to the next rotating tether).

[Tuckerfan]

The biggest problem with an electromagnetic rail launcher I can see is that it really wouldn't be a good way to transport living cargo. Some of the experiment maglev trains can stop a pacemaker, given that the ERL is going to have to chuck something into space at a higher speed than a maglev train travels, you could wind up with some nasty "side effects" for any passengers who might be onboard. (You can shield the passengers, of course, but that adds weight to the craft.)

[Jpax2003]

Heinlein, that bad bad man, made me think we could actually get into space in a real way. Barring some theoretical breakthrough, none of us will live to see space travel, will we?

[Tuckerfan]

Possibly, Jpax2003, there's a big push now for a space elevator, this would cut the cost of getting into space significantly, and the X-Prize is also pushing for a low-cost method of getting humans into space. If us geezers can hang on long enough, we just might get to go.

[Jpax2003]

Do we have the tech for a space elevator now? I heard of a new material called Spectra that is supposed to be about as strong as spider dragline silk. Of course we will still have the problems of magnetic flux, right? Also, If I remember correctly, the far end would need to be weighted past geostationary orbit, in order to balance centrifugal force. Otherwise it would fall and "wrap" around earth.

Do you think it is possible to create an electromagnetic rail as proposed by Heinlein in tMiaHM, such as at Nanda Devi (a tall mountain)? It would be several hundred km long, and if we upped it to several g's of acceleration, would it be feasible?

I'm just thinking that there should be a way using multiple technologies in serial:
1-use a nuclear powered steam catapult to get initial speed
2-maglev rail catapult to increase speed up a very long ramp (again powered by nuclear reactors)
3-if needed, a reusable-ejectable solid rocket booster to kick in after ejection from maglev catapult.

Could this get us into LEO, if not escape velocity? Then once we are in micrograv, we have other options, such as laser ablation, mini-orion, or others.

Has anyone considered using a reusable form of solid rocket? I know that when you fire it up, it keeps going until it's done. Can't we use some sort of pellet type system. The vessel could load a cartridge into the reaction chamber and then fire it up? It seems that this would be less dangerous than using refrigerated propellants. Wouldn't we be able to get more bang per mass and for the buck?

any ideas?

[Tuckerfan]

Do we have the tech for a space elevator now? I heard of a new material called Spectra that is supposed to be about as strong as spider dragline silk. Of course we will still have the problems of magnetic flux, right? Also, If I remember correctly, the far end would need to be weighted past geostationary orbit, in order to balance centrifugal force. Otherwise it would fall and "wrap" around earth.Current estimate is $6 billion and 15 years to get it up and running. If you do a search on this board, you can find a bunch of threads devoted to the space elevator.

[DreadCthulhu]

Currently the only material we know of that has the strength to be used in a space elevator is carbon nanotubes - the current problem is we can't make them anywhere near long enough. Still, research continues on making them longer.

[Tuckerfan]

Currently the only material we know of that has the strength to be used in a space elevator is carbon nanotubes - the current problem is we can't make them anywhere near long enough. Still, research continues on making them longer.Uh, that's not exactly true. What about the problem of length? Things might not be too bad as they stand. Nanotubes have a tendency to "rope up", or stick together side by side, and the cohesive forces between them seem strong.Cite. (http://www.spacedaily.com/news/future-01f.html) And while I'm at it, I might as well slap up every related link that I know of.
NASA requests money to research space elevators. (http://www.space.com/astronotes/astronotes_sept28_oct11_03.html)
NASA's recently hosted a large conference on nanotube technology. (http://www.nasatech.com/nano/)
Motorola's announcement that they've discovered a cheap way of fabricating nanotubes. (http://www.motorola.com/mediacenter/news/detail/0,1958,2981_2436_23,00.html)
Web site of a company that's leading the effort to get the space elevator up and running. (http://www.isr.us/SEHome.asp)
And the official website of the US Gov'ts research into nanotubes. (http://nano.gov/)

[DreadCthulhu]

[quote=DreadCthulhu]Currently the only material we know of that has the strength to be used in a space elevator is carbon nanotubes - the current problem is we can't make them anywhere near long enough. Still, research continues on making them longer.Uh, that's not exactly true. [/url]

Well, from your links, one could build a space elevator out of other materials, but you would need an insane amounts materials to build one. Carbon nanotubes are only material strong enough to do it at a more practical size. Still, we can't make them long enough - yet.

[Tuckerfan]

[quote=DreadCthulhu]Currently the only material we know of that has the strength to be used in a space elevator is carbon nanotubes - the current problem is we can't make them anywhere near long enough. Still, research continues on making them longer.Uh, that's not exactly true. [/url]

Well, from your links, one could build a space elevator out of other materials, but you would need an insane amounts materials to build one. Carbon nanotubes are only material strong enough to do it at a more practical size. Still, we can't make them long enough - yet.If you read the first quote, it's not that we can't, it's that we haven't.

[Jpax2003]

Well, if Geosynchronous orbit is the fulcrum, perhaps we need to start there and build out and down at the same time...

At any rate, we wouldn't have enough time to build it before we got smacked, right?

[eburacum45]

You might like to see my new page about elevators; it is a little pessimistic according to some, optimistic according to others;

who knows?
http://www.orionsarm.com/historical/space_elevators.html

[AstroSmurf]

You might like to see my new page about elevators; it is a little pessimistic according to some, optimistic according to others;

who knows?
http://www.orionsarm.com/historical/space_elevators.html
You missed one problem with them...

http://www.dangermouse.net/cgi-bin/comic.pl?comic=43

[Zombywoof (Jedi Knight)]

I think that would be a good idea. I liked the original. And there should also be a sequel. "After Worlds Collide". I read the book when I was in college and there had been an "After Worlds Collide" sequel. It was about the settlement onto the new world. Of course it had cold war stuff in it because there were other rockets from other countries that made it there too. And one of them was from the Soviet Union. But they could bring it up to date I'm sure.