shynung

I see what you mean. It'd be a really difficult task of avoiding that projectile. Note, however, that trying to shoot a target able to pull 6G in almost any direction from several light-seconds away will still be a difficult matter. The speed of the projectile won't matter at all if the aim was off in the first place.

Ten to the power of 33 (1033) ? Derped. Ignore me.

Yes, it is rather off-topic. Should I open a new thread? Anyway, a spaceship has a considerably more delta-v capacity than a missile. The first few km/s of a missile's delta-v budget is already spent to accelerate it towards the target spaceship. If the target ship jinks enough (changes its orbit by thrusting in a random direction), the missile could have expended all its fuel before reaching the ship, making it easier to dodge.

Even if the thrust's axis were perpendicular to the direction of travel? How about retrograde? Please enlighten.

That is where the high-thrust engine shines. If a target is accelerating erratically, the shooter would have plenty of difficulty making the shot count. It's like trying to shoot a rabbit that moves constantly in random directions with a sniper rifle. Of course, a good enough shooter will still hit it. It's just that shooters of that skill level isn't very common.

It matters a lot if it's a military ship. A ship capable of only 1G acceleration is a lot easier to target and attack than one that can pull 6G. In that case, an effective padding/restraint system to keep the occupants able to work is an essential requirement. Note, the engine doing these kinds of thrust doesn't have to be the main propulsion. The ship could have fusion engines for long voyages, and auxiliary nuclear pulse engines for when someone is throwing relativistic projectiles at it.

It could be determinism, but with a specific twist: the amount of input variables of the decision-making algorithm could be very large, so that the chances of all the variables being exactly the same are very small. In the end, we have a machine that is very hard to predict, but also being non-random.

Please enlighten me on how am I supposed to listen to something that should be read. Ah, now I see your point. Though, to be fair, we're simply splitting the delta-v requirements here, launching the vehicle and fuel on different rockets (fleets of Aquarii, anyone?). Sure, we can do ISRU and get the fuel elsewhere, but there's the problem of developing the necessary hardware (of which I have not known any of them operational), and getting it out to where we need it. The problem with nuclear thermal engines isn't technological, but political. To sum up, there's a deep negative stigma about launching anything nuclear these days (even earthbound nuclear power plants), that the space agencies capable of doing so (NASA, in particular) are simply unwilling to do it. Get this political view out of the window, and nuclear engines would have been as common as LV-Ns in KSP players' crafts. As for microwave thermal engines, I have not seen or heard any working, flight capable specimens. As soon as one comes out, we may then be able to assess its capabilities on orbit-to-orbit missions such as transfer stages. For now, we can only stick to chemical engines, and hope the people at NASA making space nuclear reactor (and Ad Astra, for good measure) will make something useful in the near future. Anyway... Cool! Get me my flight jacket, I want to fly it.

I'd imagine it would be similar to setting a Roomba free to roam a maze, and then programming it to always turn left when encountering an obstacle, no matter what the sensors detect.

That's what I think is free will. I realize that I may be wrong, but I have yet to understand enough to prove or disprove this belief. Though, if I later find evidence against it, I might fall back to the Rube Goldberg analogy. Which may or may not prove/disprove whether 'I' actually possess 'free will'. I'm not sure anymore.

In that case, it would look more like a complicated Rube Goldberg machine, in which every single thing has an influence on the next thing it touches, literally or otherwise. And this loop would have had a beginning: the big bang, similar to how Rube Goldberg machines has to be tripped by something. If that's true, then the only 'free will' that ever existed is the one happened at the big bang; in an infinitely small length of time, in which the original configuration of the entire universe, similar to the seed pattern on a Conway's game of life, is defined, and then left to the laws of nature (which may be defined at the same time as well) to shape and forge.

Those may be part of the limiting factors of 'free will'. For example, I don't fully understand quantum mechanics, so my responses to threads that discuss them would be limited. Also, given a specific, defined goal, one's action becomes much more predictable, further limiting his possible responses to certain situations. A competent rocketeer trying to go to the moon will never attempt to burn retrograde, which would run against his goal. Note, however, that his eventual action does not necessarily agree with his intentions (his navigation system might be malfunctioning, for instance). What I'd consider 'free will' is the randomness, or unpredictability, of one's action when given an almost-equivalent set of choices. For example, if a man with no knowledge of the local road network encounters the first 4-way intersection in a town, he is just as likely to turn left, as he is to turn right or go straight. However, we cannot, for all practical purposes, predict his decision with 100% accuracy; that is left to his 'will' to decide.

I don't think it's a fallacy. 'Free' literally means 'unrestrained, unimpeded'. So, take away all the factors that limit the agent in question, 'free will' means the ability to be random, unpredictable, chaotic even. in before the (highly probable) lock

Huh. Didn't think of that one. Thanks.

I think a direct impact is more efficient than asteroid flybys. It'll shake the planet a bit, but hey, the original goal was simply 'move the planet'.

GSO satellites today weren't designed for in-orbit refueling, as far as I know. They were designed to stay in one place for a predetermined time (some 15-20 years), and had their delta-v budgets, and therefore their fuel tanks, scaled accordingly. Also, no NTRs or beamed-power thermal rockets are operational at this point, so it would not make sense to set up a propellant depot for these vehicles.

That was the original premise; slap the engine on the equator, and fire it skywards at dawn. However, there's an atmosphere in the way. Asteroids typically don't have an atmosphere, which would have eased the burden on the engine. Of course, I never limited what kind of engine it is. Not much people are going to whine if I theoretically mount a nuclear pulse drive on a Chicxulub-sized space rock and fly it here.

In that case, why use a nuke? Slap that engine left over to a big enough space rock, hurl it into a retrograde orbit around the sun, and set it into a head-on earth-impact trajectory. It'll be quite a smack, but at least the earth's perihelion should definitely be closer to the sun. Huh. Didn't think of that one before.

Well, it'd heat the atmosphere around it considerably, for one. A big gout of flame for another. It may also drive itself into the ground, if the mounts aren't sturdy enough.

I don't think 4500 m/s would be enough. The exhaust would be slowed down by the earth's own atmosphere, absorbing the kinetic energy of the the exhaust, like a sailboat with a fan blowing into the sail. I'm guessing something with much higher exhaust velocity would be needed.

This is a thought experiment that just crossed my mind. I'm considering submitting this to xkcd's What If? next. Suppose someone built a rocket engine, and set it at the equator, nozzle pointing up. He set the firing sequence to fire the rocket at 0600 (so that the rocket nozzle faces Earth orbit's prograde), in an attempt to get closer to the sun. How much of a rocket, in terms of both thrust and specific impulse, would this setup need in order to have any effect on the Earth's orbit at all?

Until the nuclear fuel run out, that is. Not that it matters much. Naval reactors only need to be refueled every few decades or so.

That makes me wonder. Suppose an infant, in the form of an embryo (still within a female), was launched to space. It survived, and was born in space in a station without a centrifuge onboard. How would the infant have developed compared to earth-born humans? Will it ever have any chance of returning back to earth?

Click on the process you want to kill, and click the button on the lower right (Zakoncz zadanie).

Every time the ISS passes through the night side of earth, it rotates its solar panels parallel to the ground. It does this to reduce atmospheric drag, saving propellant needed to keep it in orbit. Long-term satellites operating in LEO also have to deal with this drag, so most have propulsion systems to overcome it. Unlike those, however, Cubesats typically have no propulsion systems, especially ones designed to do short-term experiments. They are designed to be slowed down and deorbited gradually by the drag they'd encounter, which takes somewhere between days to weeks. Because of that, there is currently little to no risk of collisions with orbital debris in LEO; most would have deorbited themselves over time.