Heimdall5008

Also some notes from my side: I think many sub-dicussions here face a bit of a chicken or egg problem: e.g. Moon colony is easiest with current technology --> when we have Moon colony we have better technology --> therefore we do not need to build Moon colony --> then we have no reason to develop new technology The only possibility to prevent such a situation is a combined effort to establish the precursors as described by PB666 (great post, thanks). I think a space based industry is a requirement before we can think about colonies (as defined by the thread owner). And to get a space industry it has to be somewhere ecomonically sound. The best chance I see here is astroid mining for rare earths (especially when you consider that China has about 98% of the current production and the ROW (rest of world) would probably like to remove this dependancy). Sure this is a long term project but with the usage of the Interplanetary Transport Network you could realize a steady supply of materials with low cost to earth. Reentry to earth should also be handable. BUT... The first difficulty that we would have to solve is to get to Earth orbit to resonable costs (and ressources). We just do not have the ressources on Earth to handle a space industry with our current propulsion methods. We need either a very efficient SSTO or better a space elevator (with graphene at least theoretically possible :P) So, to sum it up. I think many of the counter arguments in this thread come for a short term focus. It like we have just invented the first boats that can cross the Mediterrian Sea and discussing how we could establish a self sufficient colony in Antartica (yes, I know that we cannot do this today ;)).

The most realistic space battles I have read are from the Jumpuniverse series from Mike Moscoe/Sheperd (he's got a pseudonym after his first three books). Especially the space fights in his first book "The First Casualty" (also first book of the Unity War series) and in his third book of the Kris Longknife series "Invasion" contain extremly detailed space battle. Also the later books of the Kris Longknife series contain good space battle but they get more and more unrealistic with some new technologies that are used... Fleet action in this books is mostly defined by orbits, available reaction mass, sustainable accelaration and very brief engagements when the ships meet with several km/s dV. Stealth (in classical sense) is impossible and so everybody knows (almost) everything in the whole system. Everybody has to deal with heat dissipation (especially of the laser weapons) and so on... Does anybody know this series?

I have also read all five books of the series. As I'm living in Germany I will probably have to wait a few years till I can watch the series (at least legally :P) . I've read of the "major TV series" on the back of the last book and since then I'm wondering how they will do many things. Especially the elongated bodies of the belters and the ever changing gravity. Okay they can fake high g's, but large potions of the story take place in microgravity and this is always very dificcult to display (I suspect the only reasn why every major space show featured artificial gravity :P). Regarding the stealth in space point. In the first book this is a great thing. In the following books it is more and more downgraded. Seems like someone lectured Corey about this topic

So, after the Venutians have built a military space station way off the planet (on whatever stable orbit they could achieve), you would not observe this one really close? Regarding the argument "Burn behind planet": I assumed (a few pages back) a colonized solar system with dozens of colonies/settlements on/around different bodies. So realisticly you can not get a shadow on all positions. This may be a strategy to moons or asteroids. But not for habitable planets. They are way too valuable to simple be destroyed.

In space you cannot really "stay away" or "turn and run". This is the problem with all designs that require a control ship or the missile barge from Scoundrel to stay outside of battle range. All your ships are on some kind of transfer orbit. The only way to stay back would be to be behind. But then the enemy just exactly knows when your ship will be in weapons range. Maybe he just opts to send one of his ships on a high elliptical orbit (long time before the battle), so that it will cath up with your control ship from behind... The same thing for running. If you are in orbit, you cannot run, you have to leave orbit, wich means exposing your main engine to enemy fire. If you are not in orbit, you will pass through the battle zone and then go whereever your trajectory sends you. And this (basic) trajectory is not only know to you but also to your enemy and this at least hours, more like days or weeks before the engagement. Long story short: When you are on trajectory for the enemy, your committed. The point of no return is way out and you would have to make this decision long before the battle. That's not really correct. You do not need a special resolution to detect a strong enough signal. An easy example from the real world. We (mankind) daily measures the distance of the moon via a laser with help of the 3 retroreflectors left on the Moon by the Apollo missions. They are only some dozen centimeters big. We have no chance to resolve the way bigger lunar rovers or the debris of the landers, bt still we see with little problem the reflected signal. And in response to your other point: Sure, in the inverse square law is no magic. But your putting up completely made up distances. We know the sensitivity of current telescopes. So you can estimate what they can see. I do not know the sources, but two often referenced examples are the match on the Moon detected from Earth and the RCS of the Space Shuttle detected from Mars. Both distances are way longer than the proposed weapons ranges. So you cares if your cold gas thrusters cannot be detected a few million klicks out, when your weapons range is only 10000 klicks? First I assume, that you will have enough sensors over all your ship and also in reserve behind armor and as service parts in stock that to completly blind you, your ship will be a wreck nonetheless. Those sensors may not be good enough to lock your weapons but they will be good enough to calculate your course. I mean, look what kind of sensors do our probes have today? And they find their targets most of the time fairly well... On the other hand you will not have to navigate real good to escape (if you can do this). Inertial systems should be way good enough to get you on an escape trajectory the the general direction you want to go. After this you have months of time to repair your sensors and fine tune your course

Yes, you can not actively dodge a laser. But also no jet fighter can dodge an auto cannon. The idea behind dodging is not to evade a bullet/laser that is already underway. The idea is to be in another place when the enemy fires. In a space battle you will not stay at the same course for any time longer the enemy needs to reload. You will jinx in completely random directions with completely random throttles of your thrusters. So the enemy computer can not calculate your position when the laser (or every other weapon...) would hit. So it goes down to randomly shoot a place in space where the enemy could be. To continue my space tactics from the last page: 1. One fleet holds the orbit around a planet/moon/whatever and another fleet is on an incoming trajectory. I assume the attacking fleet used external tankers for their injection burn and have more or less full fuel tanks. The attacking force cannot hide their approach (stealth is impossible in space), but they will try to hide their strength. Maybe the first ship will dispose a constant line of countermeasures (flares, chaff, water vapor, EM warfare, ...) to give the rest of the fleet a possibility to hide behind this screen. Or they have a kilometer wide metallic sail in front of them (or bubble around them, when you assume perfect survaillance in every direction) that will hide their numbers and exact positions behind it (really useful, when you have a ship with 10 m diameter and the enemy can only shoot to a kilometer wide target, at least for the first salvos...). Maybe the defending fleet hides behind/in a space station or so. 2. A rather long time before the encounter (but still short compared to the travel time), say some days travel time out, both fleets will start kinetic weapons at the enemy (also it is much easier for the attaching fleet, as they already dive into the gravity well, so they need much less energy). They can range from the dumb tungston rod, to fragmentation munition, to nuclear weapons. The chance to hit something will be small. But it will force the enemy to react (navigate or shoot) which will tell their numbers and force them to use propellant. Or they risk that one unengaged projectile is really a nuclear weapon... 3. The attacking force has to do their insertion burn. Of course they want to do this without showing their enginges in the direction of the enemy. So this will be a critical point in the tactics. Every side will want to enforce a resulting orbit that is good for their side. 4. In orbit at some time (2 times an orbit at anticycloc orbits) they will come into laser weapon range. This is when the real fight starts. No ship will stay on the same trajectory for more than a second and randomly change course and constantly drop countermeasures to not be hit. At the same time the weapons will try to lock on a target that is to slow to evade. As stated it is not easy to aim weapons over such distances at a stationary target, much less on a randomly moving target. So most shoots will miss. So this becomes a fight of attrition. The first side that has not enough reaction mass to dodge will loose (the will also use reaction mass for open cycle cooling as radiatiors are by definition big and hot targets that no side will want to show during combat...). 5. At this point the ship has about 3 possible ways to continue. Surrender, be destroyed or fight/flee with the remaning reaction mass and the real probability that they can never be reached by a tanker before the ship is lost in space. At really close range also railguns could be a possible weapon. Lasers have to burn trough an ablative armor. A bullet could just punch trough it... Yes and no. To hit the earth you have to lower the periapsis till it intersects with earth. The easiest way to do this is to fire retrograd. Therfore your tungsten rod will become an object on a highly elliptical orbit. You can use the Vis-viva equation to calculate its speed a periapsis. With e = 1/2*m*v^2 you can easily get an idea of the delivered energy (ignoring the atmosphere). - - - Updated - - - Why? In the atmosphere you need an aerodynamic form to fly. In space you have no aerodynamic reasons to build a "jet figther". The most efficient forms for space craft a a sphere (e.g. Borg sphere) as it has the best ration between surface and volume of any body and a cylinder (because you can use it easier than the complete round form of a sphere). And you want to have round shapes at least for the pressurised crew parts, because it is so much easier to have when you have no sharp edges. I think the basic space war ship (or any bigger spaceship) will look like a submarine for the crew space and completely "random" extensions for the non pressurrized parts.

So, now read the complete thread. Some comments to posts on the last pages: You do not even have to change your wavelength. Because the product of time spectrum and frequency spectrum of a laser pulse is constant. So the shorter a laser pulse, the bigger the frequency range (or the "whiter") it will become. So single frequency/wavelength pulse lasers are imposible. And so also dielectric mirrors will not work for pulse lasers. All are very good points. I also assume that most shots will miss. But it will be more or less like modern warfare. One hit = one kill. At the moment every weapon system has at least another weapon system (or the same) that can one hit kill it. More or less any weapon -> infantry RPG / HEAT / other armour piercing weapons -> tanks AA missile -> aircraft anti ship missile / torpedo -> ship ... It is way easier to monitor emptiness 4 Pi around you with unlimited view range, no illumination change, no horizon and no weather, than to monitor a trafficed border with weather, vegetation, horizon, .... You will not detect everything in space, sure. But you will detect any ship. You may slip a small passive satelite or a "Rod from God" through the detectors, but not much more.

As so many stated before, it is critical to make some assumptions for the universe we're in. So I will assume a universe with the same laws of physics and no unexpected technological breakthroughs (so fusion power or space elevators are possible, but FTL or translation drives are out of discussion). To make any sense space warfare has to happen in a setting with more than one permanent (and fully independent) settlement. So let's assume a universe like Leviathan universe from James Corey (a colonized solar system with three power blocks) or the Jump universe from Mike Shepherd (many solar systems connected via "magical" jump points). So some predictions how warfare could happen under this constraints: Ships Ships will still have a (small) crew. You want to have human control over the fire button, therefore completely autonomous units will not be desirable. And drones only are practical when you have nearly instant communications. With speed of light limitations that is not possible. Even neighbor planets will have some minutes time delay. Therefore you need always at least a control ship nearby. As there is no cover in space the control ships have also to be battle capable. Ships will probably use some sort of nuclear reactor to heat reaction mass for propulsion (either fusion or fission) and be able to make sustained (low g) burns (at least hours or maybe days). So that they can accelerate the first half of the way and decelerate the second half to shorten travel time, which is still high even compared to naval warfare on earth. Additionally the ships will have thrusters that are capable of erratic, high g, lateral movements (dodging). Ships will be build more like skyscrapers than (naval) ships. As artificial gravity is out of discussion the sustained burns will be used to simulate at least a partial gravity to soften the effects of microgravity on the crews body. During combat the crew will most likely be placed in some kind of high g stations (semi-liquid shells or so, maybe even liquid breathing) so that they can survive far higher g forces. Weapons The most prominent weapons will most likely be kinetic weapons and laser/directed energy weapons (why always only lasers, microwaves to cook any living thing can also be fun). Kinetics weapons will be used against stationary targets (planets, space stations, ...) as they cannot move and their future positions are completely determined by the Newtonian laws. So attackers can strike from great distances and time away. And there is no real defense against an objects moving at high speed (say up to some per mille to the speed of light) into a gravity well. You can destroy the projectile but then you will just change it from one bullet to shot. A dumb tungsten rod of 1000 kg on a highly elliptical orbit (Pe 400 km, Ap 150,000 km) will need only some m/s on Ap to get on a collision course with earth and hit with about the same energy as the Hiroshima bomb and this is just from the "Rods from God" concept. When you go interplanetary the velocities will get much higher... The use of kinetic weapons against (populated) planets will probably be banned or proscribed, like nuclear weapons today. Laser weapons have a lot of advantages but also disadvantages. Advantages: No ammo, you just need energy They travel at speed of light. So your enemy cannot dodge. His best chance to be avoid to get hit is to confuse your sensors (flares, chaff, water vapor...) and randomly make massive lateral movements with powerful thrusters. [*]Disadvantages: If you speak of powerful lasers you will have to deal with lots and lots of heat. You have to somehow dispose of this heat. Also your lasers will get less efficient when they get hotter. So your firepower will go down with every shot. Lasers have a limited useful range. You can use any kinetic weapon over any distance (as long as you can still compute the problem...). Okay, but that can be dodged... Lasers will/have to vaporize their target. The plasma will quickly form a very efficient plasma shield in front of the target that should significantly lower the fire power of any further shots. Tactics As sterilization of a planet is probably not the goal (habitable room will be too precious), I assume wars will be over resources in space (asteroids, low gravity moons, ...) or about "control of sky/space" ( tributes, travel fees). You could thing about a scenario where a planet will be under siege. You cannot assume that the besieger will positions ships in low orbit. They would be too easy targets for ground based weapons. More likely the besieger would initiate a ablation cascade (Kepler syndrome). That would very effectively stop launches from this planet and (just my assumption) be way easier to avoid/stop when you have control of the space "above". As all battles will be dominated by orbital mechanics and (complete) stealth is impossible strategic surprises will be very rare or even impossible. So the focus will be on the tactical surprise. The enemy will try to conceal its size/ship type and numbers with different tricks (screen of water vapor, engines used below max power, ...). So you know something is coming but not exactly what. The first shots will almost always be kinetic weapons long before contact. Even if you have little chance to hit anything you can force the enemy to navigate or use their CIWS and give something of his secrets away. Maybe put one or two nukes in the kinetics for good measure or so... For the close in (thousands of kilometers ) fights I can think of basically three situations: Encounter in open space. There the encounter speed will be incredibly high and the battle will only last seconds and probably achieve nothing. So this will not be the standard battle. Encounter in cyclic orbit. The standard will more likely be one side to hold an orbit and the other side trying to conquer it. If they will go in the same direction it will result in a chance around the body. With an advantage to the defending side as they can use ground forces and intelligence against the attacker. Encounter in anticyclic orbit. So the most desirable situation for the attacker will be an anticyclic orbit to the defender fleet. Then they will have two shoot outs every orbit (more or less like ships of the line in the old navies). During the orbits both sides will try to navigate while they are below the horizon to surprise the enemy. At the same time they will try to use cubesats to spy on the movements of the enemy. Naturally every battle can be a superposition of all three situations

There are some effects in advanced, modern or quantum optics that require high order derivatives to explain. These effects are normally so small, that the will be neglected, but under some really special setups you can make these effecte measurable

I never said anything about superior technology or showing up. My assumption was that also our alien "freinds" have not (yet?) a way to travel interstellar distances. So I stay with aliens at a comparable technologly level as earth.

I have no idea to the religios side. I don't think it would have such a great impact in Germany. Although most people are formally Christians, most do not practice religion in a significant way. As way of contradiction, at least as far as I know the book religions there is no where stated, that the earth is the only part of the creation -By the way, I just realize just how unlikely scenario 4 is. I just considered that this ancient space probe accidently hits our solar system in our time. But this just the beginnig. We would have to detect it, it will probably not be larger than a few meters, it will have no power and should be without visuals indistinguishable from a meteor. So it would have to pass real close to earth and we would have to (accidently) get a high resolution image with a telescope. And when we realize what it is, it will travel with km/s away from earth, so we will have no chance to capture it... So let's just say, its impossible Or it would have to be an active probe, but this would be a completly different story. For the sake of the thread I think we should stay away from von Neumann probes.

Some days ago I had a discussion with some friends what would happen if someday in the future another species will find one of the Voyager Golden Records. During this we came to the conclusion that the real question (or at least the more interessting to us) is: How would we react, if we discover that we are not alone? We have distinguished four cases: Discovery of extraplanetary life: Some probe/rover discovers life on another planet/moon in our solar system. I do not think this will matter all that much to most people. The news will be full of it for some days, most people will tell everybody who wants to hear it, that this was always clear and no sane person ever doubted it. A not to tiny fraction will probably declare it as contamination from earth, a scam to get more money for space agencies or a mortal danger to all life on planet earth (like the film Evolution or so ). But in general I think most will have forgotten it after some days. In the middle to long term it will most likely help the space agencies to get more funding for exploration. Also most likely regulations for sterilization of space craft will get even tighter than now and return of samples at least from the "infected" planet/moon will be out of question for some time. Receiving a signal, but do not understand it: somehow like the WOW! signal, but longer and clearer to be artificial in nature I think there would be a great depate if this signal is artifical or natural or a scam. If it is artifical and only noticed by military/national controlled stations I suspect that they could try a cover-up. For thi scenario, although I deem it the most probable, I have no further idea what would happen. As information on public reaction and circulation is a bit scant and I was not alive then, I cannot really compare it. Receiving a signal and understanding it at least in parts: like the Aericibo message, also I really do not know how some other race should ever understand this message... This would probably be the most interessting solution. There we will get evidence of another intelligence. I do not know what they would send. If I had to compose my own message and just wanted to say "I'm no artifical signal, I'm from an intelligence!", I would just send a sequence of prime numbers (dit-dit pause dit-dit-dit pause dit-dit-dit-dit-dit pause ...). This does not really transfer any knowledge, but it should be understood by every being able to receive this message (as the count and prime numbers are the same in every numerative system). But let's just say we get a bit more complex message. We can decipher something like origin and there system layout or so. What would happen? Like in the first example I suspect that certain governments will try to cover-up if they can. Even if they have no good reason to do so, it will be a reflex. We do not know it, so it must be bad... If it goes to the public their will be a gigantic discussion how to interpret this message. Five "experts" will have six opinions how to decipher the message. But I think in the end the contents will not really matter. The fact that we are not alone will matter. Some people will clearly use the situation and try to immediately answer with a message of their own. So if the origion would not be too far away, we could (speaking in long term of one message per generation or so...) establish an interstellar "freindship" or at least post office. Other will try to hide. No message may compromise earth. They want to play dead. So this are most likely the extrem positions. I think the genral will either rush into an new Golden Age of space exploration (either united in face of the big unknown or as competition between the different agiencies) or we will go through something akin to the five stages of grief: denial (scam), anger (terroristic attacks against radio telescopes?), bargaining (What if they are evil?), depression and acceptance. I for myself would really welcome the first variant. I cannot hope to live for any extrasolar exploration but a radio message, although unlikely, might be the only chance to ever know if there is/was anything other out there. The thought that we are all alone out here is frightening and also the number tell us, that we should not be alone it is a completely other thing as knowing. Finding physical evidence of extraterrestrial intelligence: like the Pioneer plaque or the Golden Records The chances to ever find an alien artifact are way beyond slim. But if it happens, I cannot really think that it would change all that much in comparision to scenario 3. Maybe a global received transmission would be sooner admitted as real than any physical evidence. Here the same principles apply as above: cover-up, accusation of fraud, maybe panic of invasion. But in general I think it would have less impact as a message. The probe would be tens of thousands of years old (in minimum), so the probabillity that its builders are still alive is slim. But a message traveling at light speed is a completly other topic. What is your opinion? How would you react? How would mankind as a whole react?

I think it greatly depends on the mission and the available technology. Near the equator is great, if you want to use as little dV as possible when you start again. But if you are able to do interstellar travel, maybe you do not care how much dV you need. If you're landing vertical (e.g. with parachute and also start so like a "normal" rocket) you can basically land everywhere on land. Maybe even on water, when you land a swimming platform. If you're landing horizontal (e.g. SSTO approach for take off), you need a large even runway. On a non human altered planet you will probably only find it in the ocean, big rivers and deserts (salt, sand, ice, ...). Sure it will be a bit challenging to start from water, but you have the advantage that you can directly use the water as basis for propellant. With enough energy available you can use the water to build LH and LOX.

I've started a list here: http://wiki.kerbalspaceprogram.com/wiki/User:Heimdall

Difficult question... I cannot really decide.... How about.... ... Hassium: named after my home state and discovered at an institute attached to my Alma Mater ... Darmstadtium: named after the city of my Alma Mater ... Technetium: the lightest element without any stable isotopes ... Plutonium: the heaviest element that (still) occurs naturally ...