Be it Solar Sail, Photon Sail, Magnetic Sail, Plasma Sail, Repeller engine, or whatnot, just some sort of passive system. (Well, passive in the sense that it doesn't carry it's own reaction mass, or perhaps not even it's own fuel, too. What's the name for that?)
Yeah. I think that if a magnetic parachute can be made viable, it is really worth looking into. Then you can essentially skid to a stop (or a near stop, anyway) by using the matter around you- and you won't have to carry propellant.
For that matter, I'm a fan of Cryo. It's a pipe dream ATM, but if it's far enough in the future that we're sending an interstellar vessel, I seriously doubt cryo will still be impossible then, especially considering it's a medical technology.
I don't like the idea of being killed and brought back from the dead. It'd be pretty advantageous if you could do it right though. Still, I fear that keeping the person alive after rethawing (even if care was taken to minimise damage as much as possible) could be pretty difficult, there could be a whole host of things that could be biologically traumatic, etc.
Also, if it's far enough in the future to send a manned interstellar mission, then surely A.I.'s are good enough to run things. Heck, they'll probably be more than good enough in 50 years, just look at where they were 50 years ago compared to today, and in 50 years we'll be even further ahead than that comparison according to Moore's law.
Moore's law is not about software, it is about hardware. You can't predict what a computer can do 50 years on, but you might be able to predict what sort of processing ability it has. Again, processing power does not mean overall capability. My computer has far better mathamatical ability than I do, but fails to do things that are utterly fundamental to me.
And there are other things you need people around for... for example, you want human intelligence and intuition... and also human dynamic attributes. Those are very difficult to get with a fully automated system.
You can have a smaller crew, that rotates in shifts, for example. Or you could even have the main crew rotate in shifts. Natural radiation in the body will, over long periods of time, damage tissues to the point of death. When someone is alive that damage is constantly being repaired. When that person is frozen, all biological activity has ceased.
Anyways, why is it all these futuristic designs don't have staging? Staging is a great way to get your Delta-V up, decrease cosmic radiation exposure en route by increasing transit velocity, decrease need for life support.
Because it can increase complexity, cost, and even mass.
Daedalus uses staging though. If anything, I'd go for a two-stage system: an acceleration stage, and deceleration stage.
The ISV is not a staged design, because it has to be reusable...
If it's practical, then the ISV will carry re-usable shuttles that can be refueled from the infrastructure the robots built.
I already
seriously question the ability for a human crew to build such infrastructure in the wilderness, let alone the ability for a bunch of automatons to do it... :uhh:
Also, the vast majority of the colonists will be unborn. Embryos and the like are much easier to keep frozen, and also much lighter, than fully grown humans, and can provide genetic diversity just as well. There might even be children: #1. So there isn't an age gap, and #2 because they're lighter than adults.
Children onboard the ship (and even at the destination before the colony is properly established) are a bad idea. They tax resources while not being of much use to the operation of the ship or associated equipment.
The problem I have with embryos here, is that turnining people into baby-making machines can't be good socially.
Single adults will be a minority, since with the vast majority of the colonists are unborn you'd want most of the adult colonists to be married so each family isn't too large (which is a very subjective size).
Also, since parents won't be genetically related to many of their children, family trees may not sprout for the first generation...
Of course family trees would exist. To my knowledge you don't have to have genetic relation to someone to be on their family tree.
For back and forth travel, you'd either used a giant, many-staged beast, or if it's a civilized system you'd only carry half the Delta-V for the round trip, and re-fill at destination star system.
Antimatter, of course is the fuel of choice for making the flight as short as possible. With cryo, fusion would be workable, IMO I'd use cryo no matter what to save on the need for life support, and to keep the passengers from going insane being trapped, bored, in the same ship for years on end. Imagine cabin fever, for years instead of weeks, with hundreds, or even thousands of people. Not good.
Fusion is slower than antimatter. That is not only the problem to the crew (even in cryo), but a problem to the ship as well... for the longer the ship is operating the more likely things are to break, etc. For a colony mission if you get there in half a century, it doesn't matter much... but for actual... two-way travel between stars, you want to go
as fast as possible.
Multi-staged beasts would be utterly impractical for two-way travel. Reusing an interstellar spacecraft could prove extremely problematic... but hey, it is less problematic than reusing a multistaged interstellar spacecraft. Also, you don't want to leave that much... fast... stuff flying around in space.
Antimatter is a necessary evil here. But it is extremely, extremely evil.
Also using a closed ecosystem, and building facilities to keep passengers from going insane over the many years, and then designing the acceleration/thrust profiles to work well with the human need to walk around, you know, once every few weeks, would pose huge challenges, much more difficult than just doping the passengers out for all those years. Heck, if cryo isn't around, you could even use an induced coma, and that gets rid of the need for luxurious facilities and challenging acceleration profiles.
Some sort of coma-like suspended animation might be preferable where possible.
Of course you can make a ship that can accomodate people for years on end without them going insane... but... it would be big. And heavy.
(Quick word on acceleration profiles: Spinning arms that can rotate back along the spine of the ship, so "down" is always towards the ground, whatever the thrust level is. I believe the ISV Venture Star also used this design...)
That's only if you have high acceleration. You don't need such high acceleration (but the ISV had it anyway, for reasons that fail me), you can accelerate at a much lower rate, that a normal centrifuge could be built to cope with.
And all the staging designs in a vacuum would probably only stage the propellant tanks, no need to get rid of any engines.
That is better than staging away the expensive engine, even though the engine is quite heavy. But it still has problems.
IN My scenario a large 1.2 mile long ship departs a planet and heads to another planet 9 ly away at 0.2c... The first craft is one way just like the first 5 ships... It arrives after 40years so scientist can build another smaller .3 mile long ship with the most advanced propulsion possible and it takes 14 years to arrive assuming its traveling at .6c... This craft contains 500 embryos selected from a government program and 20 individuals along with a whole bunch of farm animals... Out of the 20 crew 5 are awake at one time as the rest are in ____.... Once at the planet they dock with the core of the first ship and settle down in the new base down on the surface meanwhile automata dismantles the second ship and uses it for whatever... A whole bunch other ships arrive so they can develop a colony the size of newyork and a space port so they can build their own vessels...After 50 years the first trading vessels arrive that can bring people to and fro the colony...
- What star is at 9 ly?
- Why 0.2c?
- What about scientists building smaller ships with "most advanced propulsion possible"? Why would such a ship be roughly 480 meters long, to be exact? Why would it travel at 0.6c?
- Selected from what govenrment program?
- Assuming your crew is 50% female, they'll each have to have 50 babies in their life. I'm not a woman, so I probably can't fully explain the absurdity of those numbers...
- How are the ships placed on the surface? Are they dismantled in space?
- What is the climate of this planet like? Is it naturally habitable?
- Why a city 'the size of New York'? Wouldn't that be a bit... large? I doubt 500 people could put that together.
- What are you trading that is so expensive to warrant interstellar travel? People? I don't even thing people are expensive enough...