Thursday, October 15, 2009

The Time Scale of Space II - Travel


A couple of posts back I looked at the historical time scale of space. Now let's look at the human time scale, the pace of travel.

We know how long this takes with current technology: about 9 months to Mars, and in the example of Cassini, three years to its Jupiter flyby and seven years to Saturn. Happily we do not have the choice of chemfuel or waiting for magic; the Dawn mission to Ceres and Vesta is already using that classic SF standby, ion drive. This is not suitable for large, human-carrying spacecraft, but other electric drives are.

Drive details matter less than the drive's power output, because for deep space travel with Realistic [TM] high specific impulse drives we must be concerned not only with speed (technically, delta v) but also acceleration. High specific impulse drives require enormous power in relation to thrust, and a top speed of 100 km/s will not get you to Mars quickly if it takes you a year to build up to it.

My convenient figure of merit for drive power density is one kilowatt per kilogram - on the same order as gasoline engines (and about 10x better than present day shipboard nuclear power plants.) At this power density, a drive with an exhaust velocity of 50 km/s has a thrust/mass ratio of 0.004, meaning it can just push itself along at 4 milligees. Attached to a ship, it might might waft it forward at 1 milligee or so.

By the bone crushing standards of SF acceleration - or actual Earth liftoff - this is feeble stuff, less than freight train acceleration. But keep it up for a month and you're booking along at 25 km/s - well above solar escape velocity for a tangential burn departing Earth's orbit.

Here are outline characteristics for a small ship, with a 100 megawatt power plant and full load mass of 750 tons, half of it propellant:

Drive engine, 100 tons
Tankage and structure, 75 tons
Payload section, 200 tons

Propellant, 375 tons

Given an exhaust velocity of 50 km/s this ship has a mission delta v of 34.7 km/s. It burns off propellant at 80 grams/second for a total burn time of 4.375 million seconds, 51 days, giving it an average acceleration of 0.81 milligees. It can reach Mars in about three months - its delta v is sufficient for a two month orbit, but the prolonged burns will add another month; in fact, the ship is under power for more than half the trip.

Replace the payload section with a much larger one, 750 tons, and mission delta v falls to 17.0 km/s, just enough for the Hohmann transfer to Mars, plus the (inefficient) spirals a low-thrust ship must use to enter and leave a planetary gravity well. This is good enough for slow freight, which in a thriving space economy will be the great majority of traffic.

All of these details are pretty arbitrary, except for the important ones, the basic relationships of drive power output, acceleration, and specific impulse that determine how fast you can get wherever you are trying to go.


Our concern is with passenger traffic in the broad sense, human travel, and for that we want fast orbits. Orbit calculations are far above my math pay grade. Happily the Atomic Rockets site has a wealth of information plus some handy links. For those who want to play along at home, this online calculator will give you the orbit parameters, delta v requirement, and travel time for orbits ranging from the economical Hohmann transfer to semi-fast orbits at just below solar escape speed. For faster orbits a flat space approximation starts to give decent results.

For travel in the inner Solar System, at least out to Mars, I am partial to solar electric drive. It has about as good a prospect as nuke electric does of hitting the 1 kW/kg benchmark, and it has the enormous virtue of having practically no moving parts. Whereas a nuclear electric plant is the ultimate steampunk maintenance nightmare, a steam engine in space.

The only problem with solar electric is that it gasps for light beyond the orbit of Mars. Sunlight at Ceres has only a seventh of its intensity at Earth, so a drive good for 1 km/s per day at 1 AU now takes a week to put on 1 km/s. A trip that might take 6 months by nuclear electric drive might take 9 months by solar electric due to sluggish performance in the asteroid belt.


For outer system exploration a VASIMR style variable specific impulse drive also becomes handy, and is probably not too difficult to achieve. If, for a given drive power output, you double the specific impulse and halve your thrust and thus acceleration, your total power requirement is (ideally) unchanged, but total delta v is doubled, while your propellant consumption falls by a factor of four.

The result? With a VASIMR type drive, travel time increases not in direct proportion to distance, but as the 2/3 root of distance. Suitably tuned, the drive outlined here reaches the main asteroid belt in about 6 months, Jupiter in a year, Saturn in a year and a half, Neptune in three years, and Eris, beyond the Kuiper Belt near 90 AU, in about 7 years. (These are careful guesses, not worked out orbits!)


In rocketpunk days they did not blink at multi-year journeys, and you could say that the true first orbital mission was Magellan's, three years to go once around. We can explore Jupiter and Saturn; human missions to the outer planets and beyond are problematic, at this techlevel, on human factors grounds.

I've suggested that a benchmark for 'routine' travel is about three months, experience with submarines showing that being cooped in a can becomes progressively difficult beyond this time. Even aboard luxury liners, shipboard romances start getting complicated, and threats to the piano player get serious. Oh yes, also the little detail of radiation - the longer your travel time, the more shielding you need, meaning penalty mass.

This doesn't mean that we can't go to the asteroid belt, especially if it turns out to be full of Valuable Asteroid Stuff; it just means that cabin fever becomes a challenge. (As does radiation shielding.)

For the bloodthirsty among my readers, which is most of you, note that warlike expeditions will tend to follow slower orbits than civil passenger transports, because they had better carry delta v for a round trip, or least an abort to a friendly base. Drop tanks won't really speed you up, because their mass reduces acceleration, making transfer burns more sluggish. For a faster military trip you'll have to revert to staging, and ditch power plants as well as tanks.


Faster travel would be helpful - for peaceful as well as warlike purposes - but speeding things up will be surprisingly difficult. For faster orbits we must increase not only peak speed but acceleration; in fact, for brachistochrone and semi-brachistochrone orbits the required acceleration goes up as the square of peak speed. (To make the trip in half the time you must go twice as fast in half the time, calling for four times the acceleration.)

Halving travel time - three months to Ceres, six months to Jupiter - thus requires an eightfold increase in drive power density, into the same range as jet engines, several kilowatts per kilogram. For this we will probably need a drive that generates its power directly, rather than requiring a separate power plant. Fusion drive is the classic if speculative example, though there are alternatives.

So what does all of this mean? For some period in the midfuture, perhaps a lengthy one, the pace of travel will be more or less as outlined here - about three months to Mars, six to Ceres and other points in the main asteroid belt, a year to Jupiter. Coming next, a look at the social and political implications of these travel times.


Related post: Last year I wrote a bit on getting around the Solar System, under much the same tech assumptions I've described here.

32 comments:

Anonymous said...

The time scale using a VASIMR-esque solar-electric drive does sound rather accurate, at least until some form of Torch Drive is created but that's for another time. Which would also mean that with a VASIMR-esque drive, outside Earth and Lunar Orbit the most populous off-world colony world would be Mars though that number may only reach a few thousand or even just ten thousand at best with the given technology at hand.

For those longer trips, I wonder if some form of suspended animation or even hyper sleep system would be preferred to keep the stir crazy down to a minimum. That is, for three months a skeleton crew is awake to make sure that the main systems and such are working properly while the rest of the onboard crew (and/or passengers) simply sleep the voyage away until it is their turn to wake up and keep the ship running.

However, now that I think about it, even now most cargo isn't flown upon cargo planes but instead sail upon cargo ships. Perhaps this is what interplanetary commerce would be like: Fast and High Specific Impulse Drives to ferry passengers while slower and more economical drives transport the cargo in between the planets?

As for Solar-electric beyond Mars, well one could potentially conceive laser transmitted energy from a power station perhaps closer to the sun than Earth that beams this energy to a reciever upon the Solar-Electric interplanetary spacecraft beyond the orbit of Mars. Though I have a feeling that there are some potential downsides to this scheme such as the accuracy problem and lightspeed drag.

- Sabersonic
Sabersonic@hotmail.com
jrposadas@gmail.com

Rick said...

Cold sleep or its milder cousin, hibernation, are the classic SF methods of dealing with space travel tedium, but I've heard basically nothing of these technologies in real life. (Granted they have little practical use other than long duration spaceflight.)

My gut feeling is that even with gene modding it will be difficult / unsafe to screw around with our metabolic rhythm that way. (Which applies to a lot of popular-in-SF human modifications.) Complex organisms are a lot like ecosystems; tweak one dial and a whole bunch of other things end up altering, probably in non-helpful ways.

Mark said...

Hibernation seems doable to me, something like a cross between a coma and hypothermia, hospitals sometimes induce hypothermia for some types of trauma and surgery, and induced comas have been around for awhile.

Combining the two will probably cause some hassle, but i expect the big problems will come from the effects of long term hypothermia, and the long term inactivity exacerbating the negative effects of microgee environments.

Too bad we can't have Charles Sheffield's S-space.

Citizen Joe said...

RE: Solar electric. I don't think it is quite the same thing as solar sails but I read someplace that while the intensity of light drops off with distance, so does the gravity so everything evens out.

RE: Human trafficking :) The inventor of VASIMR brought this up. In space, everyone is constantly bombarded by cosmic rays. While a few centimeters of shielding helps, it is nothing compared to the 50km blanket of atmosphere that we enjoy on earth. The point is that trips in space will be limited by the number of sieverts a human can endure. Whether you are asleep or awake, you're still absorbing radiation. And your nuclear reactor isn't going to help matters.

I've worked on a scifi setting in which both hibernation and full cryo were available. Full cryogenic suspension required some embedded cybernetic implants, not the least of which was an external memory device. Full cryo was used primarily for soldiers being transported to drop zones. The cybernetics allowed for rapid defrost and monitoring of vitals while the external memory could be uploaded with mission specific details. Long term health problems due to radiation were not really a problem since it is very likely that the soldiers would die from a bullet long before cancer got them. Civilian ships used hibernation instead. This required various medicines of which some people had toxic responses. Those people generally did not go on long missions. Those in hibernation would be awakened on a 4 month awake, 8 months asleep cycle so that their body could heal the damage done by the radiation. While awake, people would be kept very busy performing all the activities needed for ship operations.

Jim Baerg said...

"In space, everyone is constantly bombarded by cosmic rays. While a few centimeters of shielding helps, it is nothing compared to the 50km blanket of atmosphere that we enjoy on earth."

However, since air is rather thin stuff, the entire atmosphere is equivalent to 10 m of water for radiation stopping power.

Putting 10 m of water or 3 m of moondust around the living quarters is a lot of extra mass, but that much is likely not needed. There are places on earth with elevated natural radiation, (see
http://en.wikipedia.org/wiki/Background_radiation#Natural_background_radiation )

Studies of people living in such places have not found any greater health problems than in people living with lower radiation levels, so it would seem that at 10x the average background is harmless & more may be quite tolerable.

Also it would be very worth while to study radioresistance ( http://en.wikipedia.org/wiki/Radioresistant ) including such organisms as Deinococcus Radiodurans ( http://en.wikipedia.org/wiki/Deinococcus_radiodurans ), to find ways of enhancing human ability to repair radiation damage.

Jim Baerg said...

Some of those links got cut short. Is there some way to make a link attach to just a short word in these comments?

Rick said...

Jim - The comments will accept HTML link tags.


Hibernation is likely doable; making it safe is another matter. (Heinlein sometimes mentioned a 1 in 3 death rate for cold sleep.)

Solar electric is quite unrelated to solar sailing (though the big solar wings might be called 'sails'). For solar electric drive the sun is just the electricity source, feeding an electric drive such as ion or plasma jet.

Solar gravitation does drop off with distance, but the problem isn't gravity, it is getting decent acceleration in order to build up speed.


On radiation, providing full (presummably average Earth equivalent) shielding protection apparently requires 5 tons per square meter, which would pretty much rule out travel. But so far as I can tell, a hab structure should provide decent shielding for a period of a few months.

The biggest problem is for ships' crews, who over a career would presumably spend years 'underway.'

There might be something like a lifetime limit of a couple of years, which means a very different crewing system from the traditional maritime model.

Anonymous said...

With travel times that long, there might be a great deal of one-way passengers...If you are going to spend a year or two going somewhere, it would be easier for people going there for it to be the start a new life, then for the trip being a major pause in your life...

Instead of sleeping away the trip, games might become popular (chess, checkers, go, majoh, poker, rummy, ect)or even a new form of game could evolve to hold the crew's off-duty attention. I doubt that a really physical game would be a good idea in the cramped volume of a spacecraft, but you never know. Digitally stored movies and e-books could also become popular on these long trips.

Another thing that comes to mind is: would a prize for the best and lightest radiation sheilding be offered by various space agencies? It could happen...

I suppose, technically, a VASIMR drive IS a torch drive...just a very low powered one.

Having both fast and slow spacecraft, one type for freight and one for passengers, seems likely. Slow and reliable vs. fast and conveniant, sounds like something people would prefer.

Ferrell

Jean Remy said...

Rick: I believe your figure of 5 tons per square meter of radiation shielding is based on shadow shields specifically designed to sponge off gamma rays from nuclear reactors, which are not a concern when dealing with natural solar radiation. Gamma protection requires high density materials (lead, beryllium, and tungsten) while solar radiation requires less massive materials. It might even be possible to use magnetic fields to divert them since most solar radiation is electrically charged. Let's not forget that our primary radiation shield is not the atmosphere but the Van Allen Belt.

As an aside, if we could build a big enough laser, we could have laser-powered electric drives. Keep the laser at a suitable orbit (most likely an L point) and shoot it at the ship, and you get both an efficient electric drive and the advantage of a far reduced mass since the laser is not part of the ship.

On hibernation and cryo:

--Hibernation should be possible. There are plenty of mammals that enter reduced-activity periods (hibernation--duh) Eastern monks (Shaolin or some other school, I forget) have shown an ability to endure cold without shivering (which wastes energy) we've mentioned induced hypothermia and comas. So the human body should be adaptable for hibernation, possibly even as-is genetically thereby avoiding the messy genetic manipulation thing that will have religious watchdogs go nuts.

--Cryo, on the other hand, is far more problematic, implants or not. The issue is the formation of ice crystals inside our cells (we are "ugly bags of mostly-water" after all) The problem with ice crystals (high school physics) is that ice is less dense that liquid water, which means ice will *expand* in the cell... and break the cell membrane and do to the nucleus (and the DNA it carries), the mitochondria, and all sorts of little unimportant things like that. I think you can imagine the global damage on a body when trillions of cells are ripped apart. The idea of repairing them one by one is staggering. It will really take a miracle to un-popsicle-ize all the people simmering in nitrogen tanks. As of right now that's just a very expensive form of burial. In the future, without extensive modification, also. The only way I see it could be done would be to instantly drop your temperature to absolute zero, thereby stopping any change at the atomic level instantly (hence, ice cannot even form). Since reaching absolute zero (not to mention instantly) is, well, impossible, there goes that idea.

Jean Remy said...

Oh yes, one last note. Perhaps a good way to release tensions is to embark a good selection of multiplayer FPS's. Therapy includes stuffing the two people with a problem in Halo 35.4 and let them go at it.

Other roleplaying scenarios can also help. In Iowa, because of the severe weather (lots of snowstorms and several inches of snow and sub-zero temperatures) the dorms could get quite cooped up. One standard activity that was organized was Hitman. The students are given targets they need to tag. If you tag a target, you have to kill whoever is on their lists. If it was a good player, you might have a half-dozen targets now. Some clever ways "assassinations" were carried off: A clever set-up included a tape recorder that was triggered when a person opened the door saying Boom. The tape recorder was a "bomb." Another person convinced a girl to help him set up a friend. She agreed. Turns out she was the target.

Scratch that. Paranoia is probably not a good thing to introduce to your crew at this time.

Anonymous said...

"As an aside, if we could build a big enough laser, we could have laser-powered electric drives."

That is pretty much what I had in mind when I was talking about transmitting the solar generated energy via laser beams to a spacecraft fitted with a laser receiver to convert said laser energy into electrical energy to power such drives that would otherwise have a decreased performance and acceleration beyond a certain distance from the sun.

Granted, I have yet to hear of any successful tests of laser delivered electricity (or of any laser delivered electricity for that matter) so I have no idea if it is a successful alternative to pure solar-electric generation.

As for hibernation or hyper sleep, well that was just one idea to keep the stir crazy from affecting too many of the onboard crew. Now that I think of it, there would probably be a lengthy preparation and recovery period to and from long term hibernation since the human body isn't really designed for such long periods of inactivity. A

s for electronic and virtual entertainment, well it is a good idea but it shouldn't be the only source of distraction of the crew beyond a busy work schedule, especially one so dependent upon electricity. Perhaps maintaining the onboard oxygen and food hydroponics and aeroponics for something a little less stressful?

- Sabersonic
Gmail Address

Rick said...

The main issue with long-range power lasers is Jon's Law:

"Any interesting space drive is a weapon of mass destruction."

Who are you willing to let have control of a multi-gigawatt laser system that can easily hit spacecraft sized targets at 10AU? How much does that list shrink when you consider that you are within 1AU of that laser station?

Rick said...

Perhaps I should remember to add a tag when I post here:

Another Rick, not the one writing the blog.

Citizen Joe said...

Re: Cellular freeze damage. The inventor of frozen foods, Clarence Birdseye, discovered accidentally while ice fishing. It was so cold out that the caught fish were almost instantly frozen as he pulled them out. He noticed that they tasted good even after many days frozen. However, when he tried to slow freeze fish it had a degraded taste, due to the cell damage.

Also, if you've looked at ice from a tray vs. ice in a sculpture, you'll note that the sculptural ice doesn't have all those white bubbles in it. That is caused because air gets trapped under the frozen top layer. Sculptural ice is frozen from the bottom up.

I don't think that the problem is the final temperature so much as the insulating value of the human body. You need to freeze the whole thing evenly and rapidly. I suspect the process would involve a preliminary hibernation state. Then an infusion of radio triggered endothermic chemicals, probably replacing the blood just prior to freezing. Once the whole body is enfused, the whole thing is triggered with a radio pulse to snap from the liquid to solid form.

Anonymous said...

Rick: "I think you can imagine the global damage on a body when trillions of cells are ripped apart."

It's even trickier when you have to repair the dmaage caused by the cryo-facility employees playing baseball with the client's frozn head.

http://www.calgaryherald.com/health/Baseball+slugger+frozen+head+used+batting+practice+whistleblower+book+claims/2060438/story.html

Cold-water fish have adaptations to deal with freezing. Humans, not so much. I have to question whether cryo would really be worth the effort. Even if it wokred, which I honestly doubt. First you'd need the facilities and personnel to properly freeze the patient, then you'd need the equipment to keep them frozen, and then you'd need the facilities and personnel to defrost them. To say nothing of the hospital equipment you'd need on-hand just in case something went wrong. And you'd still need to haul food, water, oxygen, etc around for those times when the crew are out of cryo. All it does is add a layer of complexity to life support design.

My apologies if this post is incoherent. I've been over it twice to fix it, so it should be okay. I just woke up 15 minutes ago and my brain isn't really working yet.

Ian_M

Jean Remy said...

Ian: made perfect sense to me.

--though you did misattribute the quote ;)--

This article tells me more than anything what the spirit in those cry places is like: the popsicles are considered dead, nothing more, nothing less. They don't really believe what they advertise, but then again who does? As I said, cryo is a very very very expensive form of burial.

However, you are right. I simply started on the premise it was impossible, but even if it were possible it would require extensive (and massive) equipment. Maybe you could reduce some of it if the facilities were at endpoints, but that means sending the gear up ahead of time or fabricating it on location, so the first colonists won't enjoy a trip sponsored by Marie Callender.

Jean Remy said...

Oh, I forgot:

In response to Sabersonic: I wasn't trying to advocate gaming as the sole means of distraction, and actually even using it as a means of therapy. It was meant to supplement other activities that had been talked about, such as scientific work, hydroponics tending etc...

Rick said...

'Cool sleep' seems a lot less radical than cold sleep. If you could induce sleep for about 56 hours at a time, people will be up and about only every 3rd day. So 9 months in space only feels like 3 months, but you can also reduce by two thirds the cabin space needed for the galley, lounge, etc.

Cool sleep or not, you'll probably want spin gravity for deep space travel, even for a few weeks, if only for the convenience. One minor unfortunate consequence is no viewports. Contra Winch, I think viewports are generally desirable to avoid the cooped up sensation, even if there's nothing much to see for most of the trip. But looking out of a spinning hab would probably be disorienting.

'Assassin' role playing games are probably not a great idea in the confines of a long mission spacecraft! :-) But games of some sort, and other distractions, are highly desirable, especially for transports.

Whether or not you have luxury space liners, any setting with extensive human presence in deep space means passenger ships; in fact most human space travel will be passenger traffic.

Much as I like mixed cargo-passenger ships for story purposes (Serenity at the low end, 'Indiamen' at the high end), it is much more likely that cargo goes by robotic craft on slow orbits. Though passenger ships might carry a cargo pod or two, the equivalent of baggage/express cars on passenger trains.

Note, by the way, that in the examples I give the only difference between the two types is the payload section, a relatively low-mass passenger hab versus a cargo bay with much larger capacity.

This doesn't necessarily mean modular ships, especially since the drive sections of passenger ships need to be 'human rated,' while those of robot freighter don't. But it probably leads to design families, e.g. two versions of the same basic drive section, one human rated, the other not.

Jean Remy said...

Rick (who is the on writing the blog) I agree with all of that with a minor caveat. In one episode Serenity transported cattle. I doubt we'd be transporting cattle in such a way, however could there be delicate cargo that require constant human attention and maintenance? That would justify the need for manned cargo ships.

Anonymous said...

Any cargo transported over long distances would have to be valuable. Raw ore can be processed on-site or sent by slow low energy orbits to a processor. Goods that would need to be transported by cargo ship might include high-end electronics, confidential high-value data, luxury foods, radioactives, high-energy or exotic materials, and medical supplies. Habitats away from any source of volatiles will also need regular shipments of carbon, hydrogen, oxygen, and nitrogen. None of these really need maintenance, although the data might need a shepherd for legal and security purposes. Cargo spacecraft will likely have minimal crews, like today's cargo water ships.

And they won't be in cold sleep or cryo, even if it works. If it's your job to repair the machinery, it doesn't make sense to install extra machinery to freeze/keep/thaw you while everything else is running.

'Cool sleep' or any form of extended sleep has the problem of dreams. Short of a medically-induced coma (A very dangerous procedure, with severe health effects) we don't know how to turn off the brain. How sane do you think you would be after 56 hours trapped in your own sub-consciousness?

Ian_M

Rick said...

I forgot to add a welcome to the Other Rick!

Ian - Really interesting point about cool sleep and dreams. Possibly dreams are themselves a corrective mechanism; I seem to recall that if you constantly disrupt REM sleep, when dreaming occurs, subjects start going wiggy even though permitted non-REM sleep.

That said, I'd worry about the sensory deprivation effects of very prolonged 'normal' sleep.

Short form, nothing I've heard of suggests that any form of extended sleep/coma/freeze/whatever is a 'Realistic [TM]' tech, i.e. one we can reasonably count on to be practical in the midfuture. (Like solar or nuke electric drives, for example.) And on the whole, in spite of gentech, monkeying around with the human organism looks trickier the more we learn.


On transport, 'cattle' - more broadly, complex living things - are one sort of cargo that might indeed require human tending, because they require a life support system.

One option for big freight carriers on slow orbits is to relieve the crew at intervals. In particular I've thought of entire stations being built in Earth space (where most of the building cages will be, for a long time) and flown out to their eventual positions on slow orbits.

For the crew it isn't a 'voyage,' it is a tour of duty. Life aboard Callisto Orbital is much the same while en route to Callisto as it will be once it gets there, except for not running shuttles to the surface.

The most high value or sensitive cargoes will take fast orbits in the baggage pods of passenger ships, which works fine for story purposes, because those are the kinds of cargoes most likely to figure in a story anyway.

Jean Remy said...

Cool Sleep: what if you can keep your subjects in Stage 1 sleep? Mo Alpha Waves but the appearance of Theta waves create a non-dream state from which it is easy to emerge. In fact, subjects who are awakened in Phase 1 sleep do not even remember having been unconscious at all. Basically it's very much like the space of an eye blink without any internal sense of elapsed time, or even awareness of a disconnect.

Rick said...

Is this in effect 'nodding off' sleep?

One final challenge for snoozing away the tedium of spaceflight is that it's sort of the extreme of a sedentary lifestyle. After months of it you might need weeks to get back into active condition.

Anonymous said...

"One final challenge for snoozing away the tedium of spaceflight is that it's sort of the extreme of a sedentary lifestyle. After months of it you might need weeks to get back into active condition."

That might justify a sort of mixed shift in the hibernation wort table with one group being active and two groups either preparing or recovering for their hibernation term while the rest of the crew and/or passengers are left in hypersleep. One might potentially extend the awake hours with said entertainment and work, however a vast majority of said entertainment had better be interactive and/or whose experience changes with each use.

One example would be seen in a scene from John Carptenter's The Thing where Childs and Palmer are watching a VHS or Beta cassette recording of what I presume to be a late 70s game show when Palmer states "I know how this ends" and changes tapes. On such long trips, you don't want that little interruption of distraction to occur often.

As for the manned passenger transport and automated cargo transport, well from what I have been reading in the comments, this seems to be more likely arrangement over manned passenger and cargo craft. Though now that I think about it, when it comes to livestock would it be better to transport full grown adults or some kind of fetal or even young offsprings of said livestock if a settlement is capable of handling these animals and even then would it be automated or manned.

Or are future off-world colonists suck with a vegan diet and in-vitro meat?

Another thought is that if journeys to the outer planets even in the use of Solar-Electric Drives such as the VASIMIR will take several months or even years to reach from earth. Would that limitation keep exploration of those planets strictly to robots and other probes until a higher impulse drive allows for manned exploration?

- Sabersonic
Gmail Address

Jean Remy said...

Saber: on Livestock

Well, we're pretty good at freezing eggs and sperm, I'm not sure about fetuses but I doubt it, they're already pretty complex, at least past a certain point. I think just-fertilized eggs can be frozen. Also one thing we can't yet do if grow them full term in vitro so you'll need to carry at least one female to serve as incubator. Medium term however I think vat-grown meat is more likely: livestock takes a lot of room. That depends on whether we can grow organs in vats thought. For now the results are promising but still it is a technology in its infancy. However, since a self-sustaining food supply would be a primary goal, battery-raised chickens might be easier to export to a colony than beef. Chicken battery farms are basically the animal equivalent of a hydroponics garden at this point. PeTA will no doubt have a fit, but the first Extra-Terrestrial franchise might be KFC.


Rick: on Phase 1 Sleep

Yes basically when you nod on and off, you enter Phase 1 and then wake up. Generally the only reason you realize you are nodding off is a/ you're tired and b/ there is only a disconnect because your head in in a different position. This is unlike the phases of dream that allow dream (Phase 3 and REM) in which case you awaken with the memory of those dreams, and the memory of time having elapsed. Also, note how much harder it is when the alarm clock wakes you as you naturally slip back up into the upper phases, opposite the times when you are forcibly awakened during a dream and feel confused and disoriented.

Of course maintaining this extended sleep poses a LOT of problems, even without the psychological ones: muscle atrophy, and bed sores, to name just two. The latter is caused by blood pooling in your back around your spine. This is actually lethal: people in hospitals have died from bedsores. Depending on how much you equate psychology with brain physiology, there will be problems with the reduced electrochemical activity and production of neurotransmitters. So beyond simply the idea you'd go crazy from being unconscious is the actual physical damage to the neurons... meaning you'd go crazy from being unconscious too long.

Hey I said phase 1 sleep was an idea, I never claimed it was a good one.

Oh one last point:

"Another thought is that if journeys to the outer planets even in the use of Solar-Electric Drives such as the VASIMIR will take several months or even years to reach from earth. Would that limitation keep exploration of those planets strictly to robots and other probes until a higher impulse drive allows for manned exploration?"

It would be very sad indeed if our drive to explore would be dampened by our desire for comfort. Cristobal Colon took months to cross the ocean, Magellan's fleet took years to circumnavigate the globe (and Magellan didn't make it.) Have we grown so damned lazy that such a duration--in conditions of comfort that would make the sailors of the Santa Maria pale with envy--is unpalatable? If they need some idiot to volunteer for the trip because nobody wants to leave the comfort of their suburban houses, sign me up. I'll go.

Rick said...

To take Jean's last point first, I don't think it is about comfort but efficiency. If most of the crew's effort is going into keeping themselves from going batty with cabin fever, it won't be a very productive mission.

But exploration will have a longer range than general travel because you can be more selective with crews.

It could also depend on the nature of the mission. Face it - if we found a black obelisk out there, we'd push limits that we wouldn't push for 'routine' exploration.


On food, much as I like beef it is poorly suited space conditions, taking up an awful lot of life support per prime rib. Even on Earth, I imagine that in a hundred years the only beef will be range fed, raised on grasslands best suited to cattle grazing.

Chickens, shrimp, that sort of thing, seems much better suited to space, where - an irony Clarke once pointed out - space is always at a premium.

Growing beef in vats somehow strikes me as the culinary equivalent of monorails.

Anonymous said...

In the future of space colonization, beef may be a luxury item...I fear that most people living off-world will have to make due with alge, yeast, and bacterial paste; at least until a colony is very well established and can afford such luxuries.
(Bob's Rocket Service slogen, "Steaks in Space!") KFC/Morton Thyikol...McDonalds/Rocketdyne?

People always imagine that in the future mining companies or manufacturing consortiums will rule our off-world colonies...but it's just as likely that Budwiser, Coca-cola, or KFC will.

Anyway...spacecraft assymbled in orbit may be composed of standardized mix-and-match modules that the client orders from a menu to suit his needs. Grade of Nav package, type of mission module (passenger hab, research hab, cargo pallet, ect); size, type, and number of propellant/fuel tanks; kind of power and propulsion module, and the heat management system suitable for the final assembly.

Ferrell

Rick said...

The ability to provide a reasonably attractive diet at a reasonable price strikes me as one of the key prerequesites for true colonization.

I pretty much agree (no surprise) with your comment on spacecraft assembled in space - in fact, I'm working on a blog post on the subject.

zlionsfan said...

With respect to onboard entertainment, perhaps there's a way to address multiple issues at once: games that require physical activity on the part of the player. Even existing motion-sensing games (Kinect, Move, Wii) would give the crew a way to keep reasonably active in a confined space ... of course the consoles would have to work differently than the direction they're heading now. There's no reason to assume that communication with Earth/home planet would include an always-on connection to Xbox Live!

FPS games might be a good idea, particularly for military missions. Again, it could achieve multiple objectives: keep the passengers busy and give them some sort of training, depending on what the mission is. Foot soldiers might get some benefit out of a Call of Duty sequel, although that might be better off done with motion controllers; what seems more likely, ship-based combat, would also lend itself better to games/simulators (StarCraft?), and could double as practical training for the crew, although that does lead into the discussion about the degree to which flight would be manual (if any).

It would be significantly more important to consider the psychology behind the games and the opponents available than it is here, but perhaps the games could serve not only as activities, but also as monitoring tools. It might be time to take Watson aside if you notice that the only game she's played in the last month is Halo 11: Outer Planets, and she's constantly setting up deathmatches with Jones. A balance between competitive and cooperative games might also be good so that you have an entertainment system that appeals to a greater number of passengers and crew.

I suppose something else to consider is the technology that goes into the controllers, motion or traditional. I really don't know if wireless controllers would be a problem on a ship: would there be interference/would they generate interference with other systems on the ship? Might there be problems using traditional means of power (batteries/battery packs)? It seems to me that none of this should be an issue, but then I've never tried to use my consoles anywhere other than houses or apartments, and there may be a difference between having one or two consoles around and having one for each passenger and crew member.

Rick said...

Belated welcome to a new commenter!

I'm a bit embarrassed to say that none of these ideas even crossed my mind (granted that Kinect-style tech is a pretty recent development, at least for widespread use). Though I suppose you could say that the holodeck concept prefigures this general concept, if not the specific techs.

The wireless issues shouldn't be a problem, especially by the time interplanetary travel is common!

zlionsfan said...

Thanks, and don't be embarrassed! There are only so many ideas you can juggle at the same time ... and honestly I think you're better off going into detail with respect to orbital ships rather than onboard entertainment. I don't know that many people really want to read about people playing 2010s-era console games if you're also talking about orbiting Mars or mining Ceres or what have you, and Star Trek-style entertainment is known well enough that it can be a stand-in for "some sort of gaming we don't know about yet".

Besides, although motion gaming has been around in some form for at least 20 years (Power Glove, anyone?), it's still crude enough that it can't do much more than track an extended arm or leg. I believe that the precision necessary to make motion gaming similar to standard gaming practically requires some form of AI, especially with the hands-free approach Microsoft is taking: you need something that can identify different parts of your body, something that can track those parts, and something that can translate what movement of those parts means.

While it may be different in scale, it doesn't seem to me to be different in concept from the process your brain goes through when you move your arms. If we can develop technology that will allow you to stand in front of a screen and interact with a game as you would in real life - grasping, turning, throwing - then I don't think it's a stretch to suggest that we could also have the technology to project the game around you.

In fact, the latter may be closer than the former. I guess there are places that actually rent virtual reality games for corporate events and such. Some of those aren't so difficult to manage (the golf simulator, for example), but the goggles-on-your-head type is the path that I think leads to your holodeck.

Jim Baerg said...

Since there is talk about games for keeping people from going stir crazy on long space trips. I think it is worth mentioning the story 'The Saturn Game' by Poul Anderson (pub 1981), in which a role playing game backfires psychologically when the players reach the destination.