Hot answers tagged

33

Can a ship with a rotating habitat be stable as it travels space that fast for years? The speed it travels at is irrelevant. The stability is important, but quite unrelated... the interesting gyroscopic effects of rotating bits of spacecraft applies just as much to starships as "stationary" habitats. It is in the nature of starships that you will need ...


33

Generously spread the sail surface with self repair nanobots. Any impact with dust or sub-dust size object (which is more likely to happen) will pierce a hole through the sail (and leave a cloud of plasma behind it). Just "patch" it using the nanobots and keep traveling. For larger objects between the size of dust and meter sized asteroids, I would ...


28

A tiny piece of space debris is dangerous to the ship, as it may hit people, mechanisms, or fuel. But the damage to the hull itself would be negligible. It could simply be patched. The hull is the least of the concerns there. Solar sails typically don't contain people, mechanisms, or fuel that could be damaged. A solar sail with a tiny hole in it ...


26

Reinforced concrete and structural steel are not so strongly directional as, for instance, carbon fibers. They would handle a change of load better than, for example, the suspension arm of a F1 car, which can withstand tons of load in the vertical direction but shatters with a minimal horizontal load. And if you think of it, it must be like that, unless you ...


21

The sky-scraper would not even care Because otherwise people could bring down skyscrapers with their own bodyweight Think about it this way: If I run as fast as I can and jump against a wall, I can create more force than my usual body-weight due to gravity. Now - if a skyscraper could be brought down by some hundred people running and jumping against the ...


17

This is actually easy to calculate. There is no "gravity", so you just sum your starting velocity with your launch velocity. This makes your launch vector a straight line. Here's what makes it confusing: While someone from space would see a straight line, an observer on an adequately large cylinder world would see an apparently normal ballistics curve. ...


16

Why only one sail? The word here is redundancy. Your sail will take damage, that much is pretty unavoidable, but the great thing about solar sails (unlike wind sails) is that the continuity of the sail isn’t important: only total surface area is. So break up the sail into a cluster of smaller sails. If one gets damaged then unclip it, replace it with a ...


9

A solar sail is certainly fragile, and can easily by punctured. However, a puncture won't reduce the total area of the sail by very much, so it won't reduce the effectiveness of the sail by very much either. The real danger is tearing of the sail, because that can greatly reduce not just the area of the sail but also your ability to control how the sail is ...


9

Make a flashbang out of gunpowder. I'm stealing Trevor's comment above since I think that's a excellent answer. Gunpowder is actually VERY simple to make and, since for your purpose you just need a flash and a bang, a lot of the complexity required to actually propel a projectile to lethal velocity is bypassed. Many of us learned about this by watching ...


8

If you have ships capable of reaching .6 c, rotating habitats are not only unnecessary, they're counterproductive. Your main concern isn't getting 1 g acceleration to keep the crew from getting sick from weightlessness, it's getting only 1 g to keep them from turning into the new paint job. Accelerating at about 1 g, it would take about 200 days to get to 60%...


8

What @L.Dutch said OR realise that you are going to take irreparable damage and design a margin of safety into the sail. This will mean a "waffle" design of reinforced cells so that punctures don't turn into tears and a sail that is a certain percentage over-sized for the trip in question. This may be up to several times the size it needs to be to supply the ...


8

they get pushed perpendicular to it, falling west instead of down If I get this to the letter, it implies that they get to move in a pseudo circular orbit following a given parallel, because as soon as they wouldn't do it, they would be moving "west and up". Since you mention that they would keep accelerating, I deduce that they will, rather soon, reach ...


8

As others have noted, outside of the torus the throw is just a straight line. A 1 km world rotating at 0.95 rotations/minute has a velocity of 1.9 pi km / minute, or 100 m/s, or 360 km/h. So you have to add a 360 km/h velocity vector to the vector you throw the Javelin at. In the rotating frame of reference, there are some interesting cases. If you throw ...


7

Point-defense and Origami Sails Keeping a laser on target over space distances is really hard, requires a lot of energy and communication lag can lead to horrible accidents. So you don't do it for the entire journey unless there are laser highway pushing stations along the way. There will be an acceleration and deceleration window of several hundred to a ...


7

The basic answer is "of course" but that answer comes with a caveat which is "if you're willing to take the time to do it" i.e. if you only accelerate at 1/1000th of a gee you can almost certainly leave your rotational sections running while you do so. It will take your ship a very long time to get up to a noticeable fraction of the speed of light but you ...


6

If she can fly carrying a load, it means she can exert a force equal to her weight plus that of the load, against gravity. The scenario you describe until terminal velocity can be described as an accelerated motion, starting from velocity 0 and ending with terminal velocity v. While this happens they cover a distance h. Since she wants to stop the fall, ...


6

Foreword: don't try this at home. You don't need explosives. You just need water, a sealable container and a fire. Put some water in the container Seal the container Throw it in the fire Water will boil and the steam will build up pressure Once the pressure is high enough, the container will blow off


6

An explosion that occurs by accident might be the best kind. From the late Roman period, at least, until modern times, open flames were prohibited in flour mills (more recently also in grain elevators) because flammable dust in the air can form an explosive mixture. Many years ago, there were "science magic" articles published for kids. One of the ...


6

Heh heh. You make me remember my high school geometry classes and polar coordinates. The thing to keep in mind is there is no gravity in this case. The path a projectile takes will just be a straight line while the ring rotates under it. So in the coordinates of a person watching from outside the ring the path is the red arrow, and its equations are just ...


6

The question was slightly editted and clarified in the original post and some comments, so my original answer has been replaced and you can find it in the edit history if you were interested. I've ignore some parts of the original question, because it was too broad. what are the advantages and disadvantages of... [a] 100 MW maser, laser or graser? Masers ...


6

Hmm, this is a tricky question because there are so many factors that go into making life possible that it's hard to really be sure about what changes we could make to physics that would still allow life. Hell, it's pretty difficult to even come up with an airtight definition of what constitutes 'life' in the first place. But even more pertinently, there's ...


5

For rotation, you need a bearing. For a section that size and operating that long I see no realisitc alternative except for an active magnetic / electric bearing. The benefits of this type over closest alternatives are: 1- low to negligible friction - less wear / decreased maintenance and risk of failure 2- gaps in front and back between rotor and outer ...


5

In short, it's a tough engineering problem, but it's not a physically impossible one. 500 degrees Celsius might sounds like a lot, but it's really not that bad. Aluminum melts at 659 C, and steel at 1371. That means we can use heat pumps to concentrate the heat from the habitat and raise it to a temperature higher than the 500 degree exterior, which means ...


5

According to the law of thermodynamics, perpetuum mobile is impossible. More precisely, due to the second law, it is impossible to produce work (mechanical energy) just by cooling a hot object. So basically, you can not win work by simply extracting heat form the oceans. You need also a cold place, a heat sink, and part of the heat would not be converted to ...


4

The practical answer is, you can't. The point of a solar sail is to be as light as possible so that the force exerted upon it by photons is enough to accelerate it. Shields are heavy and make acceleration much more difficult. Equipment to blast oncoming debris out of the way is heavy and requires more power than you likely have being solar-powered. ...


4

Consider the solution the Moties used in "The Mote in God's Eye" by Jerry Pournelle. They used the sail itself as a "weapon" to clear debris out of the way. Radar watch to detect rocks, then use the sail itself as a reflector to aim and concentrate a beam of sunlight to either vaporize small stuff or to use ablation as a form of propulsion on larger rocks ...


4

Well, for one thing, stars don't form in the Orthogonal universe. Stars and planets both are all primordial chunks of solid matter broken off of the "cosmic egg". Stars are just the ones that happen to have been set on fire--and the fact that that can happen to any planet is kinda the central driving conflict of the series! However, if we want to imagine a. ...


4

OK, here's my own answer. There are basically three options to work with: Delete the electromagnetic field, and replace it with something completely different. Delete the electromagnetic field, and try to adjust the other forces to make up for it in a way that doesn't re-introduce another kind of light (e.g., massless pions). Alter the electromagnetic ...


3

To build on Algebraist's answer, I would use thorium rather than conventional nuclear reactors. Depending on where you build the bunkers, you could collect the thorium while you dig, and you wouldn't have to deal with all the radioactive waste once the nuclear fuel is spent. And even if the reactor would spend most/all the fuel, you would have to maintain ...


3

The power required for cooling will be relatively significant, but not enough to make things wholly impossible. Although thermodynamics tells us that we must expend more power on cooling than we use in the habitat and this could limit things. Coefficient of performance for air conditioning is COP= T_Cold/(T_Hot-T-Cold), so assuming the average temperature ...


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