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132

Nope, we don't even use them today. Reverse thrusters are completely unrequired. Just flip the ship and use the normal thrusters. All the ship needs is: A means to rotate the ship. Normal main engines. Once rotated so that the main engines are pointing in the way the ship is traveling, just ignite those engines. Take a look at a SpaceX booster, the ones ...


21

Two reasons Cost - it's not going to be cheaper to mine water in space. There's a massive energy cost to get something into space against Earth's gravity well, and if you're going to mine something like water, there are cheaper ways of getting it - like purifying salt water. Especially because asteroids only come in one size - bulk. If you've got need for ...


19

The only reason we would mine the rings is to bring water to solar system parts without water. That would NOT be Earth. We might go there for Mars or the Moon or fueling space colonies, but not for Earth. Earth has an abundance of fresh water. And we have continuously improving tech for filtration and desalination. It isn’t worth the space trip. Isaac ...


15

What do you mean by obsolete? They never were a thing to begin with. AFAIK, nobody even tried to add a propulsion system to the front of a space vehicle. Sci-fi (or rather space fantasy, as a commenter aptly noted) routinely takes energy for granted, but in reality putting stuff into orbit costs a packet. An X-wing starfighter apparently carries enough fuel ...


7

What you're basically describing here is not a million miles away from the Sail Beam concept by the late Jordin Kare. That idea seems basically sound, and is my personal favourite kind of fast, plausible, hard-science starship drive. There are a few variations on it floating around, but the underlying idea of using a stream of small laser-driven lightsails ...


4

In Star Trek and pretty much every other Sci Fi show you never see them turning the ship around and firing the engines in order to slow down. They have stupid things like inertial dampers and reverse impulse thrusters to slow the ship down. In reality, pretty much the only way to slow down in space is to turn around 180 degrees and apply thrust.


4

The first thing you need to keep in mind is that when two observers are moving relative to each other in a system, each one will perceive the other as experiencing dilated time. That means from your point of view, it will seem that whomever you are communicating with is experimenting slowed down time - but from their point of view, it is you who are ...


3

How and When? The answers to this question rely heavily on exactly how and how quickly you intend to remove all that water and ice. For the purposes of conversation and simplicity, I will consider the removal to be complete extraction without replacement of any kind, and two possible time scales, those being geological and sub-geological. Geological ...


3

Because it is DANGEROUS. Space travel is full of hazards, micrometeorites can wreck a ship. The asteroid belt is full of tiny stones milling about. Each one can make fatal impacts on the ship hull. By God's sake, a flack of PAINT shattered the windshield on a mission! Now the asteroid belt is full of amorphous bodies, with ice and frozen gasses that will ...


3

Would it be easier to mine rings, or to mine the icy bodies that feed them? How about icy asteroids, comets, or craters on the moon? Then there's the PR element. Which would be more likely to receive a huge public outcry against it: picking up ice from the dark side of the Moon and random asteroids nobody can see, or mining those rings that so many people ...


2

You do not need relativistic formula if you do not change the reference frame. From POV of a planet this comunication process is straightforward: first message from the ship travels 20y, when planet recieves it ship is at 20 - 0,5*20 +(1/160)*20^2 / 2 = 11,25ly distance. Reply would take +7,5y (27,5y from start) to reach the ship and so on. From POV of ...


2

Well... yes and no. Mostly no. If you are thinking spaceship as in Star Destroyer (and definitely if you are thinking rocket ship), then no. Reverse thrusters are a horrible idea. Although it would definitely be possible, having a second main engine would have these effects: Extra weight. Think about it: not only do you have one massive drive engine, you ...


1

Only one sci-fi universe I've seen has had main engines in multiple directions... the "Nightsdawn" series from Peter F Hamilton. The hyperspace rules made for spherical or nearly-spherical ships. Warships needed to dodge, that is, suddenly accelerate in various directions. Thus, each cubic face on the sphere had a full main engine, and a variety of direct ...


1

I suspect the limiting factor here is going to be societal, not technological. People are social; they like to cluster together, and remain within easy distance of friends and families. We wouldn't have a problem finding planets to colonize — there are always individuals who are drawn to the solitary life of an explorer, wandering off to look for discoveries ...


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