EatThePath

As I understand it the region of stability for orbits is dependant on both the distance and the relative masses of the bodise involved. The larger you make the jovian, the further out you can put the super earth, but the further out you need to.

The two aren't logically required to be exclusive, and SSTO doesn't necessarily imply reusability, though admittedly all the SSTO concepts I'm aware of aim for it. As I mentioned, SpaceX is working on launchers that if all goes well would be both staged and fully reusable.

My understanding is that in the case of the earth and luna, the energy is coming from earth's rotation. The tidal bulge is being carried forward by earth's rotation, and then pulls the moon 'forward' even as the moon pulls it 'backward'. Thus the moon gains orbital velocity and the earth's rotation slows. Estimates have the orbit of the moon much lower and the rotation of the earth much faster back when it was formed. It also seems plausible that the moon itself once had an unlocked rotation, and tidal forces have long since sapped all available energy out of that.

Honestly, is SSTO really desirable? The advantages of staging, that I'm sure we've all experienced in KSP, are so dramatic that giving them up just for the ideal of simplicity seems... foolish. You might be interested in SpaceX's re-usability concepts. they're currently working on a system where the first stage will fly back to the launch site under its own power, and do a powered landing. As I understand it, after stage seperation the first stage is so light that the amount of propellant needed to do this is actually amazingly small, so it's far less payload penalty then you would at first expect.

The thread title is a bit pessimistic, though. Mars landing may be currently outside our grasp, but it's definitely within what is physically possible and even plausible. The main impediments are political and economic.

The amount of cloud you'd have to scoop to get a useful amount of water is pretty impractically massive, and while you're in the clouds you've still got most of the work of getting to mars(or even just earth orbit) ahead of you so it wouldn't gain you much anyway.

This is actually the problem that was in my mind when designing the core structure of Atomic Space Navy/Tools/Race. As a consequence of that effort I think a version of KSP with a proper n-body simulation and predictable physics out to a useful duration is possible, but it's something that you'd have to build the whole game around, not something that could reasonably be patched in at this stage. To the original question, it all depends on what you're using it for. Broadly I'd say it's pretty good, but it breaks down in certain areas, and while the mechanics are pretty good the properties of things are rather wildly unrealistic.

A little update on that: I've been working on improving Orbit Toy Console's reporting. The new version is pretty rough, but I used a 94608000 second run(aprox three years) of the KSP system to stretch it's legs. The report before the run Kerbol is system center Moho orbits Kerbol at 6.315765E+09 meters Eve orbits Kerbol at 9.931012E+09 meters Gilly orbits Eve at 1.692783E+07 meters Kerbin orbits Kerbol at 1.359984E+10 meters Minmus orbits Kerbin at 4.700274E+07 meters Mun orbits Kerbin at 1.199863E+07 meters Duna orbits Kerbol at 2.176247E+10 meters Ike orbits Duna at 3290000 meters Dres orbits Kerbol at 3.518412E+10 meters Jool orbits Kerbol at 6.535038E+10 meters Pol orbits Jool at 1.707127E+08 meters Bop orbits Jool at 1.071973E+08 meters Tylo orbits Jool at 6.849674E+07 meters Vall orbits Jool at 4.315246E+07 meters Laythe orbits Jool at 2.71864E+07 meters Eeloo orbits Kerbol at 8.889949E+10 meters And after: Kerbol is system center Moho orbits Kerbol at 4.682423E+09 meters Eve orbits Kerbol at 9.820839E+09 meters Gilly orbits Eve at 5.920415E+07 meters Kerbin orbits Kerbol at 1.36333E+10 meters Minmus orbits Kerbin at 2266073 meters Mun orbits Kerbin at 1.178361E+07 meters Duna orbits Kerbol at 1.945858E+10 meters Ike orbits Duna at 6014023 meters Dres orbits Kerbol at 3.516957E+10 meters Jool orbits Kerbol at 1.587453E+11 meters Pol orbits Jool at 2.863533E+07 meters Bop orbits Jool at 3.339007E+07 meters Vall orbits Jool at 8.485741E+07 meters Laythe orbits Kerbol at 1.110553E+12 meters Tylo orbits Kerbol at 1.739705E+12 meters Eeloo orbits Kerbol at 1.10614E+11 meters The biggest thing to be aware of is that the reported distances aren't presently properly calculated semi-major axis, but rather raw distance at time of report. Still useful for getting an idea of what is where, though. Of particular note in my eyes is the migration of minmus.

The simplest way is to calculate the forces acting on an object(look up the proper equations for gravity and whatever else is involved) every frame, update it's velocity(velocity=velocity+acceleration*time), and then update it's position(position=position+velocity*time). There are more complex methods that achieve better accuracy and stability, but they aren't always necessary. To find relatively stable orbits to work with, look up the math for kepler orbits. From that you can get the starting velocities you need for orbits of given shapes. Though from the game you describe, I'm not sure if realistic orbital mechanics would necessarily serve your gameplay best.

So what happens to the momentum when those virtual particles wink back out of existence? If it just vanishes, then the drive is breaking conservation of momentum, isn't it?

Until it's been verified to hell and back, I will always distrust reaction-less thrusters and put them in the bad science category. I don't know enough quantum to debunk this myself, but it hits the right notes to get red flagged.

Well, it would be networked after a fashion, just using the existing wetware

Computers implanted in multiple brain regions and wired directly to the internet would almost certainly be a horrible mistake. The medical uses described would, if all implemented at once, allow a compromised system to show the user anything and direct their body to do anything. Even if thought control possible, a full hijacking of your body probably is. That said, there's first of all no reason at present to want that level of permeation. The chips described in the article are all corrective measures for forms of brain damage. They'd receive their inputs from the brain only, and so long as they were well shielded from outside electromagnetic influence there's no reason for them to be remotely hackable. If I had any of the issues described, I'd accept a chip in a heartbeat unless they had a poor track record. Anything else is purely speculative. I can conceive augmentations that I'd willingly take, and ones I wouldn't. I'd be extremely hesitant about anything networked, especially wireless.

Near term orbital shipyards would indeed probably be orbital assembly and fueling, and maybe patching up problems that arose during launch. From-scratch construction in orbit only starts to make sense when you've got some material sources other than earth.

Of course. But we don't have any orbital construction yards, and most sci-fi ships from games and movies aren't easily built out of modules we can currently launch.

Well, first off why should they have to? So long as they're sturdy enough to survive the recoil without getting torn apart, a momentum change is just a course change. No big deal really. But, math. Let us take a UNSC frigate as an example. I don't think they're given a mass anywhere, but they are given some dimensions on the halo fan wiki. The smallest is the Stalwart class, at 478m by 152m by 112m. If I had a model of one handy I could get the true volume, but I don't so I'm just going to eyeball it as a block coefficient of .3, so that is 2.4 million cubic meters of volume. Material is hard too. My instinct is to assume they're about as dense as a modern naval vessel, but I don't really know that number either. But I know a naval vessel can't be more dense than water, while a space ship doesn't have that restriction. So water might actually be a decent ballpark, and it's neat. 2.4 billion kilograms. The standard MAC is described as firing a 600 ton slug at 30,000 m/s. Force = mass*acceleration, so it's pretty easy to get our force out of this. 18 billion newtons, though it depends on what ton you use(I hate tons for this reason.). Dividing that by our previously arrived at mass.... gets us an acceleration of 7.5 meters per second. Which is fairly piddling as these things go. Of course the mass estimate of the frigate could be way off, but probably is good enough to get a rough idea of scale. To the first, yes that's definitely true. That's why I pointed out that to fusion powered space warships other options might be available, such as the free electron laser Rune mentioned. To the later, that is true, but the MACs were originally built before the covenant showed up with their highly accurate slipspace jumps, and are frequently used at long range in closing engagements. I've also spoken with engineers who work in related fields who've told me that the powers and switching times for c-fractional coil guns might actually be physically impossible. The ease of building personal scale hand made weapons says nearly nothing about their applicability to space combat.

Well, first off the navy railgun isn't that near ready for deployment yet as far as I'm aware. They may be getting the energies they want, but last I'd heard they were still firing a lot of rail along with each projectile, and that needs fixing. Second off chemical lasers presumably make for a much more portable solution, and I expect when you have fusion power plants in your space ships other options might be available to you. And in space you don't have horizons or atmospheres, which are two things that give the railgun a leg up over lasers. I do agree that at knife-fight ranges the railgun is probably pretty effective. I just don't think those knife fights are likely to happen often enough to matter in realistic treatments of space combat.

Which is why you pulse your lasers. A more pressing concern is probably keeping the spot on target. Well, we can put a lower bound on it. It's at least 1.2 million g. It's certainly a hurdle, but if you can build rails that survive running that much power through them, or coils that switch that fast, I'm not sure a guidance package that survives the launch is necessarily out of the bounds of sanity. And if you're launching a missile you don't necessarily need to go quite as high on muzzle velocity, because it's a missile.

I've in general soured on mass drivers in sci-fi. .04c? That's impressive, but why not put all that power and tech into a laser? Even in Halo the covenant are described as dodging a noticeable percentage of MAC rounds, increasing your muzzle velocity 25 times seems like it might come in handy. If laser tech is woefully insufficient, then why not a rail launched missile? Get even a little guidance involved in things.

Quite simply, because most movies and TV series are just crap. Most forms of entertainment are a sea of bad to passable with the rare standout. The related question seems to be, roughly, 'why aren't any of these hard SF?'. Well, I think the answer to that is that hard SF by itself only appeals to a very small market. To make it appealing to a large market, and if you're making a movie to make money, that's what you want, you have to make it more accessible. You make it about human drama, or about explosions. And if you've got effective human drama or explosions, most of your audience isn't going to care if the SF is hard as cotton candy, so why bother with it? It might not actually get in the way, but if you don't need it to satisfy the majority of the audience, you might as well just ignore it from the outset.

Kerbin has much lower mass than earth. Surface gravity is related to mass and radius both. A planet with the radius of earth and the mass of kerbin would have a much lower surface gravity than either, and would most likely have a much thinner atmosphere too.

Ultimate... for what? What is it built for? Context is important.

Alright! Those updates have now happened. Anyone who downloaded the tools at their initial posting should check out the updated tools posted today. Lots of improvements have been made to many areas. The updated tools can be found at this link. ATOMIC SPACE TOOLS: Combined orbit toy and system builder into one project. Corrected improper camera positioning in both programs. Numerous changes to level files. Lots of under the hood cleanup and reorganizing. Added a visible scale reference to all current tools. Adjusted line width and look to something a bit nicer. Changed player settings to run in background. ORBIT TOY: Motion plots now scale to consistent screen sizes as the camera moves. Added an indication of what system is currently being simulated. Camera zoom is now adjusted to fit systems on load. Level listings now scroll if there are enough levels to require it. SYSTEM BUILDER: Corrected handling of phase angle(true anomaly). Twice. Paths and labels are now hidden when the visual size of the orbit is very small to avoid clutter. Duplicate body names will no longer be accepted. Added the ability to update all edited values of a body in one click. Added the ability to revert all unapplied changes to a body. The camera now auto-focuses on the furthest-orbiting planet at load. The tree view is automatic sorted by semi major axis whenever that is updated. Tool now starts properly even if Sol system is absent. I've also been doing some more simulation of the KSP system. Preliminary results suggests that Jool loses at least two moons and moves around noticeably, Minmus' orbit changes dramaticly, and Eve loses Gilly. Fun times!

Consciousness: I could write a book, but probably be pretty incoherent. I'm not really interested in having a protracted conversation hinging around if plants are conscious or not. I also think it's beside the point. Something like a plant that is 'made of pure energy' is just as nonsense as something like a human, or something like a rock. What in particular your personal view of consciousnesses is has no impact on that. Robots: We already have cyborgs today, quite a few of them, augmenting mobility, internal organs, and even senses. So far as I know, none of them have shown a marked reduction in humanity as a result of their increasingly machine-like nature.

Holo: Fine Structure is a great example of non-real science being applied well. I'd consider it fine sci-fi, even though most if not all of the things going on it aren't covered in any way by real science. Hyomoto: I don't have a rigorous definition of consciousness off the cuff, I don't think anyone has one that isn't in some way problematic. But if you open the definition too wide then it becomes a useless term, devoid of real meaning. Most of what you describe is to me covered under basic physical laws or automatic reaction. I wouldn't call them signs of consciousness any more than I would apply that label to human reflexes. Even so everything you describe has some defined substance. If you say the planet, or the galaxy, or the whole universe, is alive and thinking, then I'll probably disagree no matter how much fun I've had with that idea in the past. But at least they are objects you can say something about. 'Pure energy' is nonsense without some further definition. What kind of energy? Kinetic energy? Light? Heat? Arguably matter is energy, so anything could be described as pure energy! And the typical conception of a glowing blob of bright light is none of these thigns. Switching gears, I feel that the idea that a robotic form means lack of empathy is somewhat lacking in imagination. If your machines are such that they can contain the whole of a human mind, then surely they can emulate the human emotions. In fact I rather suspect that they need to. I recall reading about studies that found humans deprived of emotion tended to be unable to do much of anything. There may be other effective modes of thought, but I expect any uploaded humans or AIs based on human thought will need the full range of emotion to be at all functional.