hardervalue
hardervalue t1_iw59vy5 wrote
Reply to comment by johndburger in Will mankind ever travel outside our solar system? by savol_
1G of thrust is impossible to maintain for long without millions of times more energy than humans have ever generated during the entirety of human history. The most dense amount of energy possible is antimatter, which we've only created nano-grams of at a cost that would extrapolate to $67 trillion per gram.
And if the math on this page is correct,
https://www.desy.de/user/projects/Physics/Relativity/SR/rocket.html
for every ton of ship & payload you want to send to Proxima Centauri you need 10 tons of antimatter to get there and 37 tons to actually slow down to visit instead of flying right by. The reason for the difference is the tyranny of the rocket equation, which means every ton of fuel you add to try to go faster increases the amount of fuel you need to get to the same speed because you also have to accelerate that additional fuel And that assumes 100% perfect engine efficiency, which is unlikely.
In reality solar sails driven by huge lasers is going to be an important part of travel to nearby stars because it avoids the tyranny of the rocket equation.
hardervalue t1_isk9w74 wrote
>Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space.
>
> - Douglas Adams
The average distance between large asteroids in the asteroid belt is far greater than the distance from Earth to the Moon. In many cases it's larger than the distance between Earth and Mars.
hardervalue t1_iw5ajbr wrote
Reply to Will mankind ever travel outside our solar system? by savol_
It will happen, a big question is whether the first crews go willingly since it will certainly take many decades if not centuries.
The most likely vehicle is a solar sail like project starshot is based on. It would have to be enormous in size, very efficient, and we'd have to create ginormous lasers to accelerate it. And it would have to spend most of the voyage slowing in order to actually make orbit. For Alpha Centauri, which is a three star system it may need to fly very close to Centauri C (the closest star) and blow past it to do the same to the other two to slow down make orbit around one of them.