Rakaydos

Mainly because the Space Warfare thread is running into context issues, I'm putting this thread together to give some of that context. Premice: colonies on all major moons of the jupiter system and on the 5 largest asteroids of the belt. A new religion spawned in jupiter that wants to convert their neibors by the sword- or by the laser, as the case may be. Earth/luna is a metaphorical sleeping giant- they could totally kick everyon's asses, but they are more worried about local scandals unless someone attacks them, and mars is trying to broker peace and failing. I'm also going to impose a "if anyone goes outright genocidal, Earth wakes up and beats everyone" limit. Technically, lets limit this to Technological Readyness Level 4 or higher, so no Warp Drives or Canne Thrusters. Edit: The religious fundamentalists come from the main moons of jupiter. Lets call it some form of neo-Olympian worship of Jupiter, if it matters. In addition to the main colonies on Ceres, Vesta and the others, there' also lots of mining ships throught the belt that are practically independant colonies, giving the Belters a very disperced infrastructure. Jovians are good with short range space travel, such as within the jovian system, but the Belters live with the realities of microgravity every day. Edit again: Refining the scenerio- The Jovians decide to start by conquering their trojan asteroids. When they star building Laserstars (see other topic) people get nervous and buillding their own ships- when the laserstars are launched on a good Jupiter-SJL4 transfer, the L4 trojan miners request assistance from the belters. How long will it take the jovian laser stars to reach L4, given reasonable TRL4 tech? With the same tech, what's the least time it would take any point in the belt to respond to help the trojans? What ships do you build to counter laserstars, with TLR4 tech?

Plasma shields might be made to work against lasers, but they are two way barracades, blocking your own sensors.

The primary weapon in these scenerios (lasers) deposits the entirety of it's energy on the first thing it strikes- any secondary effects are caused by diffraction through the sand and the destruction of the superheated sand.

If you're already at a range where lasers can target you with pinpoint accuracy, you've already lost, either by running out of fuel for dodging or simply by letting drones get in WAY too close.

Unfortunately, if your shooting at a ship that can dodge lasers at the range you're at, dodging shrapnel is childs play.

Boarrding actions require not just an intercept a missile requires, but a course-matching. Boarding actions in space are entirely impractacle. Realistically, space combat will be defined by the range you can dodge lasers from, which is relateed to your size and your acceleration, but will be measued in light seconds, possibly as high as a light minute. Close in lasers exist, but they will be a lst ditch wepon. "missiles" are drones with enough DV to get into laser hit range, where the missie can fire a laser. "torpedos" are precooled, railgun fired projectiles that are supposed to stay undetectable until they get to laser or even particle beam range.

in an enviroment where effective ranges are decided by evasion instead of loss of killing power, a particle beam has a shorter effective range than a laser. However, if you can get a drone armed with one into effective weapon range, well, we can make some pretty powerful particle beams from small emitters.

That's another reason for a warship to deploy laser armed drones- generating more firing angles makes angled armor and evasive maneuvers less effective.

There is no stealth for ships- however there might be stealth for bullets. Figure a tiny drone armed with a laser turret. (or a bomb pumped Xray laser) Have your ship supercool it and accelerate it in the direction of a target with a supervelocity railgun. It cannot stay stealthed forever, but it might be able to stay stealthed long enough to get into laser range.

War between 2 planets in the same system, id expect to see Orion Drive manned warships that deploy unmanned submunition drones. Only an Orion has both the isp and the raw power to give a vessel sustained combat maneuver capability- being a light minute away from a laser battery doesnt matter if you cant change vector by more than your sillouette in a minute. If you can make that change in vector, and can keep making it, it doesnt matter how long ranged the lasers are, they will probably miss you. A missile or submunition drone, however, doesnt need SUSTAINED combat maneuverability- it just needs combat maneuverability long enough to get into effective (the enemy cant dodge) laser range.this lets you use cheaper chemical drives on the drones. This leads to dedicated anti-drone drones. They will be called space supiriority fighters. Unmanned of course, but with autanimus decision making capability to handle other antidrones.

Newton got a few other things "almost" right- Relativity is an edge case in newton's laws of motion, after all. And I recall reading a suggested tweak to F=MA to explain supposed "Dark Matter" in the universe. He still gets taught, though, because his laws are close enough for everyday understanding. What I'm wondering is if a similar tweak could explain the EM drive, while keeping the existing Guage Theory as a "good enough approximation." (though I'm in the camp that the device is probably a low vaccum ion propeller, it's always fun to push the limits of possibility.)

I dont think an ASAT missile is going to do much if orion can get it's pusher plate between it and the attack. Edit: also beside the point- in a hypothetical interplanetary conflict, there WOULD be targets that cant simply be hit with an ASAT weapon.

What is a "local symmetry group?"

That's the Orion battleship. We could have built it in the 60s.

They question then becomes, If something we "know" has to be wrong for it to work, what woud be the smallest error we could have made in physics for this to work?

Hmm.. Ring shaped craft that ionzes interstellar hydrogen in the ring's path, pulls it into the emty center of the craft, and magnetically pushes off the ionozed "rail" it creates, while actually reducing interstellar drag.

Rocket fuel makes the best heat sink.

First generation stars had only hydrogen- there wasnt any heavy elements (anything beyond iron on the perriotic table) to build a technological civilization till the first generation stars exploded. This isnt Robinsun Cruso- you need more than bamboo to make a TV. The first geneation stars that exploded first would have been in galactic cores, where stars are very close together and there's a nova every few thousand years- a super high radiation enviroment that would kill ANY life attemptig to develop there in a second generation star. Out in the arms here, it is safer for organic life to develope, and now we have heavy elements for technological development. Other galaxies could have reached this point faster, but they are far enough away to not matter. In our galaxy, we might not be the first, but we're close enough that the others havnt conquered the galaxy yet.

Compared to the planetary profile most likely to produce life-as-we-know-it, NASA, ROCOSMOS, ESA, ect all have it easy. a mere 1g, 1 bar of atmosphere, with even a free 465 meters/second of rotational speed at the equator. Moreover, we have a nearby celestial object clearly visible our entire history to inspire us, an internatial rooster-measuring contest that drove most of our space tech R&D (well beyond the bounds of common sence), that actually DIDNT kill us all, and a potential colonization target the next orbit over. Let life be common in the galaxy. Let inteligent life be inevitable, 1 per world. How many lotteries did Earth win to have as good a shot as we have now of colonizing space? Even for us, as NASA said about the SpaceX explosion, Space is hard. How much harder would it be for aliens lacking the helpful coincidences we have? Would it even be worth attempting?

Without a military industrial complex to drive things, I doubt the liquid engine rocket would get invented, let alone a nuke. Rendering the question of meeting them in space moot. - - - Updated - - - The answer to the fermi paradox is that space is hard. We have it relatively easy and we're still arguing whether it's worth doing.

That we have managed not to kill ourselves with nukes does not mean other species in similar situations did not have their own "cuba missile crisis" during the period between the harnessing of the atom and the colonization of another world. For that matter, we're not entirely out of that zone ourselves, with North Korea having nukes and Iran wanting them. The majority of inteligent aliens probably never develop technoligy- like dolphins, they perfectly adapt to their enviroment. Many human tribal societies also fit this description, supporting the hypothisis that this is a default state for even inteligent life. Of the aliens that devlope technoligy, they will inevitably discover the power of the atom eventually. And given how hard space travel is, using the atom makes colonization easier. But it also makes killing themselves off easier. We humans were blessed with stabilized nuclear tensions (we survived the missile crisis), a reasobably borderline world we could potentially colonize (mars), and a planet we can escape with purely chemical propulsion. Other species may not be so lucky.

Keep in mind that the reason the Falcon 9 and Facon heavy are the diamiter they are, is because that's the largest size they can legally transport by interstate freeway. Any larger, and they either have to construct the rocket entirely at the launch site, not just assemble it there... or come up with an alternate means of shipping parts. (My vote for shipping the MCT first stage by Grasshopper.)

Also, the planets with conditions that give them wider habitable zones also have conditions tha SUCK for launching spacecraft. Larger worlds, denser atmospheres. In order to conquer the galaxy, first they must colonize their mars equivalent. See other threads on how hard that is, then make getting even to the ISS twice as expensive.

An interesting concept, and even with your conservitave numbers for maxumun DV (.05C) you're looking at 80 years to Alpha Centauri. One of the benifits of a medusa format also, is you can use it as a Solar Sail for stopping at your target system, too, though you should probably reserve some DV for slowing down to managable speeds first...

A rocket doesnt have to reach earth's escape velocity to escape earth's gravity either. Elon is using the same technique- letting shrt term gains pay for long term research. Merlin was a NASA study, but SpaceX is using the profit from Falcon 9 (and soon falcon 27- er, I mean falcon heavy) to develope the Raptor engine on his own, no direct taxpayer involvement at all. (Taxpayers are paying for orbit launches and getting them, not R&D that comes out of SpaceX's profit.)