Long term space flight

there was a sciencish TV show that said they were toying with an induced hibernation technology - it might have been the recent speculative show about space travel.
I also just saw a blip implying they are a step closer to the artificial womb
of course, I am sure both of these technologies are way over the horizon - but if you ran your crew on 3 rotating shifts - with each crew being in hibernation for one shift and awake for two - that would allow for a continuity of command, while still reducing the apparent time of the trip by third. - if they could hibernate for twice as long as they were awake, you could run more shifts - I think you'd always want an overlap, though. that would give time for one grew to become accustomed to the current quirks of the vessel before they took command and began training the next crew.

All of that is very true, which is also why I think the only viable way of spreading ourselves out across the galaxy is to make a ship large enough to carry a small piece of our collective civilization that won't be coming back. They're out to colonize other planets and we can expect that to be an endeavor that will take them centuries (at least), even with technology 50-100 years from now. There's no getting around that the universe is a big place, so even if we could travel at light speed, it would still take us about 25.000 years to travel across a 4th of our own "little" galaxy.

The long term effects of medically induced comas are not well understood. The people that are placed in induced comas aren't exactly in the best of shape. They don't know if taking weeks to relearn to speak was caused by the coma or by the injury requiring the coma. People brought out of induced comas are looking at months and months of rehab.

Generational ships have many drawbacks.
You need gravity and we can only make gravity by either acceleration or rotation. Acceleration requires too much fuel (you have to be constantly accelerating) and rotation requires a massive habitat ring about 2Km in diameter. Astronauts on ISS lose around 14% bone strength in 6 months. A few have lost 30%. Even with their "vigorous" exercise routine, astronauts also lost around 13% muscle mass.

Every single person on the ship will need about 17.2Kgs of supplies per day, this doesn't count fuel. Air, water food and that figure includes recycling the air & water. You need a massive greenhouse to grow enough food to feed the people, which will consume lots of electricity and water, so your fuel & water usage will increase.

Side note on plants and oxygen: a human needs about 10,500 "average sized" leaves to make enough oxygen to use every hour. Or they say 353 plants with 30 leaves. So, you you want plants to produce oxygen for your ship, you need an even bigger greenhouse, or in reality, a hydroponics bay.

Then you have to forget about being human. You have to do away with notions of love and marriage and monogamous relationships until you land. Your main goal is the keep the gene pool going, healthy and diversified. That means somebody has to direct which offspring mates with which offspring or you end up with siblings having kids. And you have to ask what happens if the future generations start being male or female heavy. What happens if it is determined invitro a fetus has major birth defects, do you allow it to come to term and drain the limited resources?

Add maintenance. With zero support from the ground, how long do you think the ISS could remain in orbit?

Futurists are always optimists.

You want to travel to other planets? Build a better engine. It's really the only way.

well, yeah, building a better engine is a given.

however:
unless we develop some way to violate the law of inertia, the ship probably WOULD be accelerating for most of the journey - since it would take that long to develop any reasonable speed without subjecting the crew to unacceptable G-forces.
for a properly diverse gene pool, the ship would need to have a huge habitat ring, anyway - to accommodate the number of people needed.
so yes, taking a generation ship to another planet is not like driving down to the Kwickie Mart for a Slurpee. it will require a huge ship, a staggering amount of supplies, a huge shift in culture, and a lot of technology that doesn't currently exist.

then they will need the enviromental ring and rotation - which they will probably need the ring for the volume it will take.

A suggestion for the engine: Black Hole Drive

when I was reading about the "slingshot" maneuver I came to the opinion that "slingshot" is an overhyped concept. to slingshot around the sun, you would dive off earth towards the sun, accelerate gently towards the sun (using gravity to assist your acceleration) and then dump to full burn as you switched from towards to away. this would give you a little more oomph in attempting to escape the solar system. if you then attempted to "slingshot" off a planet, all you would do is alter your trajectory, relative to escaping the solar system.

for slowing at the other end, I would think they would want to come in orbiting the star system, and then gradually reduce speed and orbit until they could transition to orbiting the planet of their choice. - or sharing an orbit in the case of a truly massive ship.

as for atmospheric deceleration - it is possible - as long as you didn't skip it like a stone.

Getting a "slingshot" from the planets of this solar system might help boost the speed a little but it's not going to make a huge difference because the theoretical maximum increase in velocity is twice the velocity of the planet you're using. Voyager 1 used planetary gravity assistance to help increase its speed to the current 17 km/s. Which is fast by terrestrial standards but not exactly an interstellar velocity.

Another problem is alignment, for example, if your target planetary system is perpendicular to the plane of the planets, then any slingshot velocity isn't going to be any help.


Yes, it's the same technique just against the motion of the planet, which causes deceleration.


In theory you could use aerobraking to slow the craft. The risk is that with a very large craft, especially one that was spinning to provide gravity, you could get an undesirable asymmetric force acting the vessel causing it to tumble unpredictably (and, presumably, uncomfortably for the occupants).

actually, with a ship large enough to be a generation ship, any aerobraking would have the potential to cause a harmful instability.

that is why my inclination would be to adopt a shared orbit and then either transition to orbiting the planet or not, before deploying landing craft, either carried in kit form, or completely built at the destination (depending on the tech level of the pioneers)