The battlegroup is at the core of the modern navy. Since the beginning of the 20th century, the image of sea power has been a capital ship or group of such ships, surrounded by smaller vessels to protect against attack, first by torpedo boats and destroyers, and later by submarines, aircraft and missiles. But the battlegroup and the escort are surprisingly recent innovations, products of a major shift in the nature of naval warfare about 150 years ago.
Before the invention of the torpedo, naval warfare was fundamentally symmetrical. The gun was the only weapon of any importance from at least 1700 onward, and larger ships mounted more and heavier guns. As a result, combat power correlated directly with size,1 and it was rare for much smaller ships to overwhelm larger ones.2 Smaller ships were useful for missions that prioritized numbers over firepower, such as scouting, patrols, escorting convoys, or commerce raiding. The Line of Battle didn't need frigates to screen it against attack, because anything the frigates could handle, the Ships of the Line could handle more effectively. Frigates accompanying the battlefleet were there to scout and pass signals, not to fight. None of the 13 light ships (6 British and 7 French) present at Trafalgar suffered a single casualty.
The torpedo changed all of this. Although the first torpedoes were short-ranged and slow, they offered, for the first time, a weapon that could enable even the smallest craft to threaten a battleship. Worse, this was not a threat the battleship was well-suited to counter. A small boat, approaching at night, might well get a torpedo off before it could be detected and forced to stop by the battleship's light guns. Some other counter would be needed, and one was found in the form of the destroyer, which could screen the battleship, hopefully running down and destroying attacking torpedo craft before they could get within range of the battleships they were protecting. 3 A decade or two later, the submarine also took advantage of the torpedo, but in a platform that gave the target even less chance of fighting back. Destroyers were again pressed into service to protect the capital ship in much the same way, although they were initially limited by the primitive state of anti-submarine weapons. In both cases, the threat was relatively weak in a stand-up fight, and the ideal vessel was fast, maneuverable, and cheap enough to be deployed in large numbers. As a result, fleets began to operate with destroyer screens in addition to their scouts, and the concept of the escort, and thus the battlegroup, was born.
But the real tipping point was the invention of the aircraft carrier. Suddenly, you had a ship that was fundamentally incapable of protecting itself not just from surface or submerged torpedo attack, but also from surface gunfire. At the same time, it brought new capabilities for reconnaissance, long-range attack, and even some protection from the threat of other aircraft.4 A carrier by itself was hilariously vulnerable, but one integrated with the rest of the fleet was a tremendous force multiplier.
Escorts were also helpful in protecting against aircraft. Through WWII, AA weapons had a fairly low impact on the ship, and so to a first approximation AA firepower scaled with ship size. Escorting destroyers and cruisers were primarily useful for simply providing more guns, and for pushing out the perimeter of the battle group, increasing the time the attacking aircraft were under fire.
The end of WWII saw a major change in the nature of escorts, which created the battlegroup as we know it today. Improved performance from both aircraft and submarines demanded a new generation of systems to counter them, systems that were more expensive and more specialized than those that preceded them. Faster submarines meant bigger and more sophisticated sonars and heavier and more complex weapons. Postwar aircraft needed to be dealt with at greater range, particularly with the advent of guided missiles, which meant bigger and heavier guns. Surface-to-air missiles, arriving a few years later, made the problem much worse. Now, to keep ship size reasonable, most vessels had to specialize in one or the other, and the idea of the general-purpose destroyer with high-end capabilities in multiple domains, common in 1945, almost died off. The situation persists to this day, with the notable exception of the American Arleigh Burke class, which has probably survived because of the economies of scale offered by the USN's sheer size.
I bring all of this up because I want to apply it to different domains, particularly space warfare and science fiction. In essence, space is more likely to be like the age of sail, where all warships are on a similar scale, and less like the modern situation where a set of very different threats forces vessels to specialize. Aircraft and submarines are disposed of easily. Both work because they operate in a fundamentally different medium from surface ships, an opportunity which will not be available in space. This immediately debunks the idea of space fighters, and any attempt to salvage "space submarines" quickly runs into the simple fact that there's no stealth in space. Likewise, there's no particular reason the spacegoing equivalent of torpedoes need to be deployed by small craft which can be countered by "space destroyers". I won't say that there's no possibility of escorts and a battlegroup in space, but that's going to be heavily dependent on the exact technical details of the setting. Even when the setting isn't just "the modern/WWII navy in space", there's a strong tendency to import modern patterns with regards to escorts and such. Of course, there's an equally strong tendency to disregard the battlegroup because it makes things more complicated. But this isn't the place to hash out everything that is wrong with military science fiction. For that, go to Atomic Rockets.
1 I should probably add some notes here to avoid being nitpicked to death. Yes, boarding was a common tactic during the age of sail, but it was complementary to gunnery, something you did at close range after a gunnery action battered the enemy. Also, bigger ships had bigger crews, and so had the same advantage when boarding they had during a gunnery action. And while ramming was considered in some circles to be more important than guns during the second half of the 19th century, only a few specialized rams were built, and they didn't work all that well. Neither changed the basic equation that bigger ships were more powerful. ⇑
2 There were rare exceptions. Yes, the second one was the model for the capture of the Cacafuego in Master and Commander. ⇑
3 This is an oversimplification of the efforts to deal with torpedo attack, but the details of early anti-torpedo strategy are irrelevant to the point of this post. ⇑
4 Aircraft didn't become really capable as air-defense assets until the invention of radar just before WWII. ⇑
Comments
In the background of the boardgame Attack Vector Tactical some smaller missile armed combatants exist. Of course they have near magically powerful rocket engines that don't scale down to missile size, so that they can contribute a significant part of the closing velocity of their weapons. I could see myself getting dangerously invested in a 'Rule the Waves' like game in that setting. Lovely as the Al-Rafik is, I'd have built a very different fleet to the Medinans.
Lots of navies now have 'escorts' but no carriers or the like to form a battlegroup around. Sometimes they might join with allies, or escort merchant shipping, but there must still be other missions you can give an escort too.
Ah, yes. AVT. I have a copy, but haven't played it in like 5 years, or even looked at the ship book closely in about that long. The best RTW2-equivalent in space is Aurora, a 4X space spreadsheet game. It's free, and the ship-design engine is the only thing I've found to match RTW/RTW2. But the learning curve is very steep, and it takes a long time to play.
To some extent, the presence of escorts in navies that don't have ships to escort is a result of us importing terminology from navies that do have battlegroups. In a lot of ways, a Burke is the equivalent of an old cruiser, capable of independent operations as well as protecting other ships.
I do have to give props to the Honor Harrington series of space opera books where the author carefully selected the speed, acceleration and physical configuration of the ships, as well as the range and effect of both weapons and sensors, so that everything ended up a scale model of Napoleonic naval warfare (but with everything scaled up about 1 million times).
Then he had the huge backlog of fictional, and real, Napoleonic naval battles to
steal frombe inspired by when writing his battle scenes.Especially in the earlier books this worked very well, with a lot of the details about being in the correct orbit and having the momentum exchanges determine the course of the battle being very like the wind and weather related tactics found in Patrick O'Brian.
Sadly, as the series went on he fell into the temptation of always ramping up the tech compared to the previous book and the relationships between speed and range etc. broke down. (A similar problem occurred with the character development.)
A range of different ship sizes was explained by the (fairly justified) issue of budgets. Huge ships might be able to outfight anything smaller, but you can only afford a couple.
I also love the Honorverse books, largely because Weber has done a really good job of working out the conditions that will produce the kind of stories he wants to tell. He also knows the military well enough to convincingly capture the feel of a real organization, which a lot of SF writers don't. The stealth stuff is annoying, though.
Stealth in space, and space fighters, are both more physically reasonable than FTL. If I can suspend disbelief enough for FTL, I can allow the others, too.
Re space warfare being like the days of sail, I can see that, but I think space is generally going to be less fault tolerant of battle damage than wooden ships taking cannon balls. I would guess that you have a minimum viable size to have adequate sensors/weapons, and after that size your marginal dollar is best spent on building more ships rather than bigger, in order to better mitigate battle damage.
@DampOctopus
I actually have to disagree. Stealth in space probably requires thermo violations, and while that may not sound like a big deal, it basically implies perpetual motion machines. There are some things that look like FTL which are compatible with General Relativity (wormholes, which aren't actually FTL) and a bunch of other things (hyperspace) which don't actually violate the correspondence principle. Thermo violations are not to be taken lightly.
@Redrover
Quite possible. I suppose it depends on how you define "minimum viable", and how the scaling laws work. I doubt that we'll see every single ship be the same size. Minimum viable for a patrol ship won't be the same as minimum viable for a laser-armed main combatant. But I could easily see a fairly low cap on effective size, with fleets made up by numbers. If anything, the current state of having only a tiny handful of capital ships is a historical aberration.
@bean If you can accept wormholes, you can justify both FTL and stealth: wormholes to take you to where you want to go without crossing light-years at sub-c, and wormholes to let you radiate your heat to a distant region of space without violating thermodynamics.
If you restrict yourself to known physics, you can't justify FTL, but you can still justify some measure of stealth. Making your enemy-facing side specular and faceted works against "active" (sunlight) optical detection for the same reason it works against active radar detection: it restricts your detectable reflections to a limited solid angle. Cooling your enemy-facing side (and radiating the other way) works against passive infrared detection.
The Atomic Rockets page objects to this last case because (a) you can't be stealthy in all directions, and (b) it's really hard to be perfectly stealthy even in one direction. (I'm paraphrasing a lot of text here, but these seem to be the fundamental objections.) But these requirements are too strong. You only need to be slightly more stealthy than your opponent, from one direction, to detect them before they detect you. And what commander wouldn't want that advantage?
But now I'm getting well off-subject. Perhaps I should leave this for the next open thread.
Re wormholes giving stealth, that assumes you can drag the wormhole around easily, which may not be true.
My issue is that "detect him before he detects you" isn't a particularly likely scenario. Trying to spot a previously-unknown ship that isn't trying to thrust and that knows where you are in deep space isn't a particularly realistic threat scenario. Unless you have non-wormhole based FTL, there are a very finite number of points where ships can start from, and any vessel that wants to make a meaningful course change has to use a very detectable engine. There's no horizon to hide behind, and it's fairly trivial to analyze all burns you can see and make sure they aren't up to something tricky.
Directional radiation also has the serious issue that it's far easier to defeat than to employ. You don't just need to defeat me from one direction. You also need to make sure I don't put a sensor drone through your 60-degree radiation cone. And sensor drones are likely to be very cheap compared to spaceships. And they're much smaller, which means that the stealth problem is now working in my favor.
I can imagine a case where you "go stealth" and have no thrust, no active radar, no transmissions, and use a big tank of liquid He as a heat sink to cool your skin to the same temp as the background.
And you need to maintain a ballistic trajectory, and can only maintain it for a fix period before you need to go "decloak" because your heat sink is used up.
This isn't how it's done in most SF, but I can imagine the constraints leading to good story telling. It would be like a WWI or WWII era submarine, not a modern nuclear sub that zips around under the surface the whole time.
(As Terry Pratchett observed when he realised he was wrong to not want to map the discworld. He was trying to not restrain himself, but restraints are the essence of good stories. It's all about the woods you should not enter, the door you must not open, the rain that will not make it across this mountain range...)
@redrover Re space warfare being like the days of sail,
This works very well I think, especially with technology more like our own rather than thousands of years into the future.
You have fairly fragile weight craft with big, flimsy "sails". Either actual solar sails running on solar radiation, and/or solar panels, and/or great big heat radiators so you can run a nuclear plant or something.
Your total deltaV budget is very constrained, so your movement is through constrained orbital paths with little opportunity to reverse course or something. Just like the sailing ships where the prevailing wind was dominating their movement. In both cases the gravitational effects of moons and the sun was a huge factor (ie. getting the tide)
IIRC the entire plot of "Master and Commander" was that the English ship would encounter the Americans, and they wouldn't be in the correct position relative to the wind so they'd be at a disadvantage in a battle. So they'd break off or not approach and try to spend days to get around them so they could approach from the good direction. And the other ship would do the same thing so they ended up chasing each other halfway around the world.
And with the physical size of the spacecraft dominated by heat radiators, physical damage would largely result in your power levels going down. Having a hectare of radiator shredded wouldn't kill you, (with any sensible system design you'd just isolate those circuits) but now you can't accelerate as hard, or have to choose between long range weapons or point defense.
Glen Cook’s book A Passage at Arms is “stealth in space” done right. It’s really really good if you are looking for sci-fi submarine storytelling.
@Doctorpat
The problem is that doing that, even if it's feasible (and the math isn't pretty) doesn't gain you anything. If you're on a ballistic trajectory, the other guy already knows where you are, and where you will be for the rest of time, or at least for the period of military relevance. Sure, he can't see you right now, but he can find you whenever he really cares to.
I think wormholes you can take with you have so many applications other than stealth that you basically break all of physics and have to rethink combat entirely from scratch. (For example, free logistics - any size of ship can carry infinite ammunition and energy for any size of gun it can physically fit on board; a carrier can have a planet-sized hangar and carry an effectively unlimited wing; a missile ship, again, would have no ammunition constraints except the capacity of the factories back at home base). At that point it seems unlikely that you'd end up with anything remotely like any Earth-historical model.
Regarding ballistic trajectories, you could coast in from beyond detection range and give someone a nasty surprise; that still has fighting applications even if you can't usefully "submerge" in the middle of combat. Think of the U-boat lines that Scheer tried to draw Jellicoe over - if he'd been luckier he might have gotten a torpedo into a dreadnought, and actually meaningfully attrited the Home Fleet. Also, provided the ordinary, detectable accelerations aren't too high, you could maneuver a little with solar sails, or with a very low-powered ion drive whose exhaust isn't hot enough for detection at any great range. Giving you an obvious analogy to early subs that are very slow under water but deadly if they get into just the right position.
A Passage at Arms is a very good book. Cook's "Climbers" are pretty close analogues for WW2-era diesel-electric subs; the speculative tech is generally well thought out and internally consistent, but the real meat is the story of a crew dealing with the pressures of a long patrol. And it is superb.
@bean
Sure, if you place some arbitrary constraints, you can permit wormholes that allow FTL but not stealth. Similarly, if you place other constraints (e.g. limited size/duration, strong tidal forces) you can permit wormholes that allow stealth but not FTL. The general case is that, if you have wormholes, you can permit both FTL and stealth.
(@bean @Rolf: Wormholes that you can't take with you are actually impossible, even in speculative variations of relativistic physics, because they break one of relativity's fundamental principles: that there is no such thing as an absolute reference frame. Put another way: a wormhole endpoint can be stationary with respect to a spacecraft just as easily as it can be stationary with respect to anything else. Yes, this means that if you have wormholes, all your Earth-historical models go out the window. SF authors generally ignore this for the sake of a familiar-feeling setting.)
If we assume stealth to be possible except for a waste-heat emissions cone, the possibility of sensor drones doesn't make it useless. It just means that the first phase of a battle is a skirmish between stealthy sensor drones trying to spot one another so they can be destroyed by the gunline. Whoever wins this phase will have the advantage of leftover sensor drones to negate the enemy's stealth in the battle proper.
Finally, I disagree that course changes are necessarily easy to detect. If you can radiate your heat away from the enemy, you can thrust without being detected - maybe only at a sub-milligee level, but for interplanetary trajectories with durations of months, that's enough.
@Rolf
Good point on the other implications of tactical wormholes, although I'm not sure they'd be quite that impressive. My understanding of physically-plausible wormholes is that they still obey conservation of mass. Put something in, and the wormhole gets bigger. Take something out, and it gets smaller. So you're limited by the mass of the wormhole, although that still opens up a whole range of possibilities that you can't normally do.
I will disagree with you on boost-and-coast, because John Schilling hasn't shown up to do it himself. Basically, detection range scales as the square root of drive power, and drive power to cross a distance in a given time scales as the square of distance, so you're basically stuck with a fixed time, which works out to about six months. That's enough time to make it tactically pretty useless.
@DampOctopus
I'm not disagreeing with portable wormholes on physics grounds, I'm disagreeing with them on engineering grounds. Basically, these are very weird space-time anomalies, and I don't think that the capability to stabilize a (relative) handful for interstellar travel translates to the capability to fit one into a ship for tactical use. It's probably the best idea I've ever seen for stealth in space, but it's not going to be good at masking drive heat, and there are practical problems.
Destroying a drone is probably going to give away your position, even if the drones come within range, which they won't. The practical limit on a directional radiator is about a 60-degree cone. It would be fairly easy to station a couple dozen IR telescopes on the outer fringes of the solar system looking inward. Far enough out that any practical battle area is fully covered, and there's no safe direction to radiate. Because they're unmanned and stationary, they can be way more stealthy than any warship, so taking them out is difficult. If such a constellation isn't available, then smaller drones are also an option, and again, the math really doesn't favor them, because they're so much harder to see. Being able to be stealthy drives up the size of your radiators and means you have to get all of my drones. I'll just skip that stage entirely.
It's really not. Yes, you can shift your course somewhat, but everyone is playing with the same physics, and probably roughly the same technology. If I see you make a burn and disappear, I'm going to be suspicious, and start looking at where you might be able to end up without me detecting you. That's not going to be everywhere. It's going to be a fairly constrained set of options, and I'll start keeping a particularly close eye on those options. Not to mention that the act of disappearance is going to be suspicious in and of itself.
@bean
I see you are ready to pivot the blog now after the creation of the Space Force.
I think you are underestimating the benefits of "vacuum-gapping" your weapons systems, by which I mean having numerous smaller ships. I imagine space combat is going to be fought with weapons of tremendous power against ships that are extremely fragile. I don't think there's going to be any duking it out, just split second fights with ghastly attrition where anyone who gets hit is dead.
I imagine a situation where you have tenders/carriers who provide for fleets of stripped down fighting craft and otherwise try to stay away from the action.
But back to the ocean: Have destroyers moved too far from their original purpose/become valuable enough to warrant their own screening elements?
No, this was unrelated to the creation of the Space Force. Inspired by something on acoup.blog, actually. The practical fragility of ships depends heavily on the tech mix. Lasers in particular are likely to be gradual weapons because of the range available, and there are potentially some strong economies of scale there.
The problem is the cost/utility of those potential screening elements. Right now, the gap between minimum and maximum viable warship is pretty small, so there's not a lot of room for screening elements for destroyers. With the exception of carriers, this is weirdly like the age of sail now that I think about it.
But this might be changing. We're seeing more and more emphasis on autonomous and unmanned systems, which could be thought of as screening the manned warships they work with. So I guess the answer is yes, but in a very weird way.
AEW and ASW aircraft provide a degree of screening to surface vessels by detecting threats further away. Of course they operate in a different medium to ships, as do the threats they counter, and part of the advantage of aircraft is the ability to see beyond the horizon, so none of that translates to space combat either.
@bean
It seems premature to object to some application of wormholes on engineering grounds, when we have no idea yet what the engineering considerations would be (assuming wormholes are even possible). Perhaps it would be easier to use them for interstellar travel; perhaps it would be easier to use them for stealthing. You're assuming the former.
I agree that if one side has a network of dozens of sensor platforms on the outer fringes of the system in all directions, then the other side can't be stealthy within that system by beaming their waste heat. But for this to apply to both sides, then both sides need to have such networks, without having used them to find and destroy the enemy's sensor platforms. I can imagine how that might happen, politically, but it's a bit contrived. I'd compare it to a naval engagement that starts with both sides' vessels in the same harbor: you need just the right kind of pre-bellum peace, followed by a sudden outbreak of war.
In any case, if everyone's deploying networks of stealthy sensors to the outer system to prevent the enemy's stealth from being effective, it seems to me that stealth is playing a major strategic role.
On the last point - whether a spacecraft can remain stealthy while making interplanetary transfers - I think we've hit the limit of what we can reconcile with qualitative arguments. I can crunch the numbers on this, in more detail than Atomic Rockets goes into, but before I go to that amount of effort, can you make a commitment: what sort of scenario, and what level of detail, would it take to change your mind?
You have a point re wormholes, and it's even something that would make quite a clever premise for a story when someone does it for the first time. But I don't think it's anywhere near a general answer, particularly if we throw FTL out.
These are not the same problem. A sensor platform is basically a spy satellite or space telescope, and uses maybe a couple kilowatts of power. (Hubble is rated at 2800 W.) In practice, it should be trivial to dress it up as a 50' asteroid, get it into position over the course of a couple years, and send data back via laser through a relay to make sure that it's hard to find. It doesn't have to move, doesn't have to keep people comfortable, and can generally come closest to stealth in space. It shouldn't even need to radiate directionally. Compare to a much bigger spaceship which is going to need megawatts of power and has to move. That's going to be orders of magnitude easier to detect.
I think you overestimate how much time and money these constellations will take. You're looking at ~12 for full, assured coverage. And they give you a really good general space surveillance system, too. Look at how much money has been spent on things like spy satellites and SOSUS.
Hmmm... That's a tough question to answer, because I strongly suspect that the results will depend heavily on some basic assumptions about what constitutes stealth. If we treat "ship can't be detected during cruise" as a victory, then it's possible in principle. But I don't really count anything as proper stealth if it isn't at least somewhat useful in the face of a competent enemy who has the chance to devise counters.
So my preliminary conditions would be: detection tech at least as good as that in the Atomic Rockets article, or cites to the effect that they're seriously optimistic. Ship must either depart undetected or on a course that gives effectively no clue to the final destination. (This has to be a general case, not just "in this one alignment, I can cheaply go from a Martian course to a course for Earth", which is also penalized because most ships don't suddenly disappear. Also, the detectors have enough surveillance/intel capability that you can't just mask the burn with a planet or the sun.) And it must arrive in an amount of time that is tactically useful. Let's say the larger of twice normal transit time or three months.
I am genuinely interested to see what you come up with. But I've seen a lot of challenges to this, and most came down to "I can hide a ship in a specific case", usually coasting in deep space, and didn't actually work when you started looking at the operational level.
I will disagree with you on boost-and-coast, because John Schilling hasn’t shown up to do it himself. Basically, detection range scales as the square root of drive power, and drive power to cross a distance in a given time scales as the square of distance, so you’re basically stuck with a fixed time, which works out to about six months.
Bean beat me to it, but then he gets a head start because it's his blog. But yes, all the things that can make stealth possible against a peer competitor, mean operating at a much lower energy level than the non-stealthy enemy. Rather like the case with submarines before nuclear power, but to a much higher degree. The math does tend to cancel in terms of power vs. distance, and so significant maneuvers have to be set up months in advance if you're trying to keep them stealthy. And once you actually engage the enemy, you're not going to have months to set up your "now I sneak away and return home alive" maneuver.
That doesn't make them entirely useless, but it probably does limit them to very specialized applications. Space supremacy goes to whoever doesn't care if you see them.
Which brings us to, beams vs. kinetics. Anyone contemplating the future of space warfare needs to make a a bet on whether directed-energy weapons (e.g. lasers) will dominate over kinetic weapons (e.g. missiles) or vice versa. Even small masses moving at spacecraft-like velocities carry enormous kinetic energy, which easily translates to big kabooms. If even a small fraction of them can reliably reach their target, missiles/coilguns/whatever are likely to dominate. But if directed-energy weapons can trivially burn them out of the sky, then the winner will be whoever can best use their excess laser (or whatever) firepower to directly damage the enemy. We don't know enough to say one way or another, yet, but it is unlikely to come down to "they are evenly matched".
SF writers can pick either paradigm; too many of them do seem to want them to be evenly matched so they can add more flavor to the fights.
If directed-energy weapons dominate, then you probably get something that looks like age-of-sail naval combat. Larger platforms carry more powerful beams, with larger apertures to better focus them at long range, and thicker armor, and so they simply rule. Battles will likely be prolonged affairs at whatever range allows directed-energy weapons to inflict modest damage on large, armored ships.
If kinetic weapons dominate, then you likely get swarm tactics with platforms no larger than are necessary to carry all the necessary combat systems (e.g. sensors and fire control) with a modest armament on top of that. A single serious hit will take out any of them, so numbers rule. Tactics are likely to look like jousting, with both sides maneuvering to make a single high-speed pass at whatever they consider the ideal velocity and standoff. Then each deploys whatever package of submunitions they feel best for A: destroying the enemy, B: destroying the submunitions the enemy has set to destroy them, and C: maintaining a reserve for the next fight. Guess wrong and die. And it is possible for both sides to guess wrong.
If either beams or kinetics might be dominant depending on assumptions I would be tempted to tweak them so that both had a role if that made combat more interesting. That is assuming that I would prefer to be entertaining than accurate though. If writers think the same way that might explain why they turn out to be roughly balanced in a high number of works.
How about: High accelerations come from Chemical rockets, high deltaV comes from nuclear powered ion drives that can boost for weeks?
Now we have a reason for a large mothership (big enough to have a reactor on board with associated radiators) that would want to carry smaller, highly accelerating fighters.
AND... kinetics rule IF you have a high closing speed, but beams rule if you are at slow speeds relative to each other. So if a big nuclear powered cruiser has 3 months to accelerate to 300 km/s they can do a charge while spraying a cloud of kinetic projectiles that are largely unstoppable. But in other situations you sit there shooting at each other with lasers.
Err... I still can't come up with a feasible story where the "fighters" a large ship launches are piloted by sexy young action heros, rather than nuclear missiles with automated guidance.
You can still have the "you can't take it with you" problem: if, say, a wormhole with a suitably large opening needed to have the inertial mass of a small moon, you're not going to be dragging that along with your battlefleet without startrek levels of unobtainium (and even startrek had enough sense to make their unobtanium drive only barely be able to accomplish the feat).
I'm inclined to argue in favor of kinetics over lasers. The big advantage of lasers is that the killing strike travels as fast as the warning of the killing strike, giving the opponent no opportunity to maneuver.
But if we're sticking to realistic physics, everyone is limited by orbital mechanics anyway. The opportunity to maneuver is already very slim. So if you know approximately where your opponent is going to be, you can fire a bunch of high-velocity projectiles at that area ahead of time, and they only have a limited ability to dodge.
The one wrinkle I can imagine that would return lasers to pre-eminence is everyone realizing that the high-speed projectiles that miss don't just hit the ground or burn up. So maybe everyone signs up to a space-Geneva Convention or something that bans the usage of weapons that have the potential to render large numbers of viable orbits hazardous for centuries after the conflict has ended.
Since this is apparently the sci-fi thread (no wonder it had 25 comments already!), I'm curious what you guys thought of Children of a Dead Earth, which lets you game a lot of this out.
@quanticle
The amount of maneuver required to throw off unguided kinetics is very, very small. With even a couple minutes of warning, the target ship can be anywhere in a surprisingly large area (several hundred to a few thousand meters across) and saturating that with kinetic projectiles does astonishing things to your mass budget. I believe Atomic Rockets has some numbers on this. Guided kinetics are much better, but they're also easier to counter.
@echo
I played it, and thought it was OK, but it didn't grab me.
@bean
Okay, I'll write something up for your next open thread (since we've derailed this one enough already!). Assumptions will include radiator areal density, rocket exhaust velocity, reactor working-fluid temperature, etc. The magic number that comes out of it will be the size of the cone to which emissions can be restricted, which in turn defines the number of outer-system sensor platforms you need in order to spot the stealthy spacecraft.
And sorry for going into full wrong-on-the-internet mode. To be honest, I'm not that certain about how it'll turn out.
It's fine. I'm really curious to see what you come up with.
As am I. At some point, I should probably write all this up, but that would be a major project.
For your burn to be outside of detection range, it requires that you make the burn on the other side of a planet from every detection system the enemy has active. SF-relevant drive systems are bright.
Bringing the space warfare subthread back to the nominal topic of "escorts", there is at least one case where a classic naval escort may make sense - anywhere from destroyer down to "space fighter" scale, depending on the technology.
If kinetic weapons are only modestly dominant over beam weapons, the effectiveness of a beam weapon as a missile defense can be substantially enhanced by putting it and its fire-control system on a missile-like propulsion system. Predeploy this escort along the primary threat axis, several times beam weapon range from the high-value targets.
In the event of saturation missile attack, the escorts can maneuver to approximately match velocity with the inbound kinetics, allowing a prolonged engagement rather than just a brief terminal window. Even if the escorts are limited to half the velocity of a missile (due to the need for recovery) the effective engagement time is quadrupled. Whether this is worth doing depends on the economies of scale in propulsion, but it is possible.
I don't think I can get you dogfights between "space fighters", though. The countermeasure to a fighter-sized escort is either having armored beam-weapon platforms crowd it in close to its own heavies, denying it the running room needed for such an engagement, or a preliminary missile attack against the escorts to force them off station.
Anyone run the actual numbers on the whole heat sink side of things?
Like how much CaCO3 you would have to decompose to keep your giant space laser cool.
It'll be a question of entropy as much of energy: the hotter the equipment is allowed to get, the more endothermic the reactions uncle Gibbs will allow you to do.
I think Atomic Rockets has some numbers for heat sinks in cruise. Not sure about the CaCO3.
Nobody told the NRO that stealth in space was impossible, because they are supposed to have done it ~ 20 years ago :P
But the ToughSF blog did a good write-up of a hypothetical stealth spacecraft – have any of y'all read it? I don't grok all the numbers, so it's possible he gets them wrong, but basically, from what I recall: 1) Cool your skin to be undetectable (by projected threat sensor) against the background temperature of the universe. Since sensors have limitations on their resolution and field of view, this can't be defeated simply by putting out the bare minimum amount of sensors needed to defeat directional radiation (although it could be defeated by enough sensor saturation – which is true of IRL stealth as well.) 2) Cold-gas thrusters or "real" engines cooled by expansive cooling can let you maneuver without detection.
It seems complicated and expensive enough that I think it would have a niche use, but the same is true for stealth aircraft. I think it's especially easy to overlook how useful this would be as a spy craft rather than a combat vessel – think a U-2 instead of U-96.
Regarding escorts in space: I am all for them. If kinetic or laser "battleships" are developed, they'll want to push their sensor envelope out further to prevent being swarmed by nuclear-tipped missiles with laser or shaped charge warheads.
The NRO is dealing with a very different set of threats than a hypothetical deep-space warcraft. They have a lot less need of propulsion, and can probably hide their IR emissions in parts of the spectrum that are blocked by the atmosphere.
I’ve looked it over, and am not impressed. Even if his solar engine is as efficient as it sounds, the delta-V numbers are way off because he seems to be using instant-transfer analysis for a very slow rocket. If I’m doing the math right (and it’s been about 5 years since I did anything like this), the spacecraft proposed in this article couldn’t make it from LEO to GEO at all with a continuous burn. It’ll run out of fuel first.
I'm equally suspicious of a lot of his other analysis, such as the expansively-cooled engine. I'm pretty sure that taking heat and turning all of the energy into kinetic energy in the exhaust is a thermo violation of some sort, even if the engineering is possible. Children of a Dead Earth is impressive, but it's probably applying equations outside of the domain of applicability.
I thought about this, although more in the context of a remote mirror than a full-fleged beam warship, but decided not to include it because it didn't look much like current warships, or fit particularly well into the point I was making. Yes, there is the potential for a forward missile defense, but it's a very different thing than the asymmetric rock-paper-scissors game we see at sea today.
Lurker lifting his ugly maw above the sea's placid surface here.
Of course--and I confess my scientific knowledge is more biological and quantum-mechanical--all this talk about delta-V and kinetic energy and beam weapons is so much begging the question. For a military in Earth-orbit? Sure. Just let the Outer Space Treaty lapse, then bring on the Space Force, a super X-37, some really big honking SAMs (SSMs? Better yet, a new ASM-135), and a burning need to destroy everyone else's satellites and--I don't know--keep the Russians from killing us all with fractional orbital bombardment or something, and you've got both combat in (not too far) outer space and plausible reasons for needing to duke it out. If you really want, maybe you could have a running fight to stop a high-profile resupply from going to a scientific outpost on the Moon (Mars will take too long to be sure of the propaganda fallout, and why pick on poor Watney? Growing spuds never hurt anybody in the Pentagon.)
But that's not this scenario (any of these scenarios).
We're not just granting (as DampOctopus noted) that wormholes do, in fact, exist and that we can manipulate them at will (!), but that an economic and social order has arisen in which sending anything beyond Earth orbit is more than a colossally expensive luxury for the richest, most powerful, and most populous nations in the history of the human race. No, not just more than a luxury: an ordinary way of life, like taking a walk down to a corner store. (The obvious analogy, the airplane, is still too expensive; no society uses airplanes for all ordinary transportation.) We humans have gone into a desolate, waterless, airless, lifeless wasteland, in which a moment's exposure means death, and brought or bred enough people and stuff that we actually need to fight over them. Even more unbelievably, sending people and stuff back and forth between outer space and Earth or the bases (cities? entire countries?) that cling to the endless deserts of Mars, Titan, and Kepler-443b is efficient and easy enough to rival simply staying on Earth. Forget fighter-jocks. This is metropolis of longbow-wielding elf-women deep in the Sahara levels of "say what, now?"
A bit of Google searching suggests that Falcon Heavy might run at ca. $1,000/lb to low earth orbit; Musk wants to get it down to $500/lb. Great. Compare that to the cost of delivering a pound across Earth's oceans, by ship (the scale of transport we need). For a 40-foot container, assuming (perhaps falsely) a maximum load, I get an estimate roughly in the $0.05-$0.1/lb range (I don't have insider-knowledge, again, so that might be off by a few multiples), costs seemingly varying by route or port more than by distance. We're talking about finding an energy source at least four orders of magnitude more productive than the best we have available, no more dangerous than a piston-engine, and not horrifically polluting, either. Conventional and nuclear rockets are flat out. We need something entirely new, even before we get to hyperspace and wormhole drives, and it needs to be something that won't just make life on Earth so much easier and better that everyone decides to stay here, after all.
Are those specifications possible within the physical order as we know it? I don't mean, do they violate the laws of thermodynamics (which they might), but does this kind of power-source exist in nature, and can we claim it is remotely plausible that we, who haven't even mastered hydrogen fusion yet, will ever get to it? The Atomic Rockets guy would have us believe there's a difference between Unobtainum and Handwavium, but I doubt it. A lot of things that the numbers might allow may not exist or, if they exist, be within human grasp; there may, in fact, be no conceivable scenario in which humans will ever go, by more than dozens, beyond Earth orbit. A story that relies on implausible premises, however "hard" the rules it applies thereafter, is no less a fantasy than a story in which the interstellar armada is swept along on sails of unicorn-hair, plucked from their silvery manes by virgins betrothed, spun while they grow big with their firstborn sons, and woven, after their untimely deaths, by their weeping daughters. Both are founded on a physical order that's different from the one that actually exists; the difference, and the artistry, lies in the aesthetic and its internal consistency.
In other words, if we've made Earth-to-space delta-V an amusing triviality, why worry about all the other things that used to be constraints on space travel? If it's to make a good story, sure; if it's to claim that a story that works differently isn't good, well, de gustibus and all that? We've let ion drives go the way of the dugout canoe; we can come up with a way of hiding ourselves in space just like we came up with a way of living, by the billions, in space; and we can most certainly overmaster the pitiful gravitational pull of planets, once we've broken free of the only one on which we've ever set foot.
We have actual magic now.
Of course, our pilots still can't be hotshot, square-jawed heroes who make every girl's heart throb, but that's just because heroes who get all the girls are no fun.
In that case, I'll have to watch carefully for DampOctopus' calculations ;)
(But, FWIW, I'm not convinced that even very low delta-V is necessarily a fatal strike against a stealth spacecraft – again, thinking about stealth ships as spy vessels rather than combatants, even a simple orbital trajectory relying on insertion from a 'civilian' vessel and cold gas thrusters could be tremendously useful.)
Space elevators are the "sexiest" way to achieve these specifications. From what I've seen, a skyhook operating in tandem with a reusable spaceplane is probably more realistic (on Earth, we can make a space elevator on Luna with current materials, or so I've read.)
Of course I think that given enough scientific and economic progress, even modern rockets would do the trick. If (if!) economies continue to grow, then rocket costs will drop in comparison. But skyhooks and space elevators are cooler.
But now we need to nail down much more carefully what a stealth spacecraft is. I'm not claiming that there's no chance at all of any spacecraft going undetected. But a stealthed recon sat dropped off by a passing merchie is a far cry from Tough SF's rhapsodies:
This is the kind of stuff which simply won't happen, in this case because it's nowhere near as maneuverable as he thinks it is.
@goose
Yes, this is why I think actual space combat will be more like 3-d chess than starships and lasers. Surveillance is trivial, as bean et. al. have pointed out. Similarly, chess is traditionally played on an open board; there's no fog of war. And just as in chess, the difference between offense and defense is so vast, combat becomes pretty trivial. If you have a kill-shot (i.e. you've maneuvered in close enough to use your kinetics without them noticing, you have a nice line of sight shot with a high-powered laser), there's practically nothing the other side can do about it. So combat becomes a game of maneuver; a game where both sides engage in extensive maneuvers to ensure that when the exchanges occur, they're left with either a material or positional advantage. Finally, just as most high-level chess games end with one side or the other realizing their insurmountable deficit and resigning, I expect that most space combat won't be fought "to the finish", but instead will be fought until one realizes that it's outmatched and stands down.
But, that's no fun to talk about, so let's talk about wormholes, fusion drives, lasers and railguns instead.
The other dynamic that will serve as a potential limit on realistic space combat is the notion of a Kessler Cascade. If you kill your enemy's satellites too energetically you turn them into indiscriminate debris fields that potentially render entire orbits unusable. You therefore have to be careful in angles from which you attack, so that the debris from your attack either gets pushed down into an atmosphere-grazing orbit (where it will burn up) or up into a graveyard orbit.
My favorite concept is a swarm of small satellites that have manipulator arms and just enough maneuvering propellant to maneuver up to an adversary's satellites, grab them, and then drag them down into the atmosphere. You launch them interspersed with your own "legitimate" (i.e. communication, navigation, or reconnaissance) satellites, and at the start of a conflict they grab enemy satellites and either drag them down into the atmosphere or boost them off into orbits where they can't do their job.
Of course, then you have to worry about the adversary doing the same to your own satellites, so maybe you have your own "sheepdog" satellites to protect your assets from the "wolves".
@quanticle.
I suspect you're right about the dynamics of plausible space-combat. Close enough to Earth, some camouflage might still play an indirect role: you could have new forces, e.g. missiles or UCSVs (they're not air vehicles) on mobile launchers, unexpectedly enter the fight from the planet's surface. There are some options for drama, in other words, though it might reside mostly in cloak-and-dagger on the surface. (Spies in excursion suits sneaking into enemy Moon-bases would be good fun.) Fighting not to the death would also put out all kinds of interesting ramifications: is it "honorable" to surrender? do you fight precisely in order to gain captives? who deals with the political damage from a loss that they should inevitably have foreseen?
@Suvorov
Ah, space elevators. Yes, I suppose, if they can be made; but that's only the first hurdle. For the last two centuries, we've been able to reach a world previously unknown to man. It's far more hospitable than space, with abundant water after simple processing, breathable air, and in some regions decent provision of food, for which no exotic growing methods need be developed: all you need is a boat, a net, and, for better nutrition, some greenhouses. You can get there using long-established modes of transportation, not all terribly expensive; the giant blocks of matter that threaten to drift in front of your vessel are much slower-moving than asteroids; and, though solar radiation poses some danger, this new world is protected by an (admittedly partially depleted) natural shield. Somewhere, the place must hold useful mineral resources, and, since 1820, the Earth's population has grown more than seven-fold. Yet we still haven't established a permanent, self-sustaining village even on the balmiest parts of the Antarctic Peninsula!
But can space-elevators actually be made? I wonder whether we're like Medieval people discussing the most plausible way to get up to the Moon. God foiled the Tower of Babel, so a brick-and-bitumen space-stair is a no-go. Man-made flying machines are out: heavy things, after all, must fall towards the center of the universe, and the higher you go, the purer and more fiery the atmosphere is; the people who write stories about that kind of thing are just hopeless with physics. A very large bird is our best bet: we know birds can fly, you just have to scale them up, and--as an initial rebuttal to the "yes, but they're still heavy" retort--there are winged heavenly "beasts" (no doubt symbolic, yet somehow real) in the court of God. We don't know quite how to do it yet, but with a focused breeding program, it's at least possible.
We know, of course, that that is actually impossible. It's impossible because Ptolemaic cosmology is wrong, yes, but also because you can't have a bird big enough. (The high-end estimates for Quetzalcoatlus might, I suppose, make an extinct flying animal big enough to carry a human, but surely not terribly far; I'd want another order of magnitude for my trusty air-steed.) The first part (physical paradigms) is what talk about hard science fiction seems to focus on. How much of the details, however, is just postulating really, really large rocs with feathers of adamant? Needing a material or energy source that does not exist or cannot be manipulated still means that a particular mode of transportation (or anything else) is incompatible with the actual, physical order of the universe, whether or not Einstein will ever go the way of Ptolemy.
@ bean
Very possibly. But even non-mobile stealth platforms (torpedo mines) would be enough to potentially check "bright, bold warships pumping out gigawatts without care" from cruising all over the system at reckless speed, I'd think.
@ quanticle
Surveillance is trivial before the conflict. Day one is when your enemies point two or three $150 lasers they bought at Wal-mart at your $150 billion ISR sat so you can't see what they're doing.
@Goose
It wouldn't be hard to do, but I'm pretty sure the entire continent is off-limits to economic development. Hard to be self-sustaining when you can't eat the penguins!
Possibly not on Earth. Definitely on the moon!
I believe it was Einstein who said "Compound interest is the most powerful force in the universe." In a long enough time-line, economics wins out over gravity given enough human incentive. That's the real question, IMHO.
@quanticle
Kessler Syndrome is a reasonably serious concern today. It's a lot less of a concern in a world where we have any sort of serious space combat capability. Orbital debris is a lot easier to deal with than incoming kinetics.
This is the really hard way to do coorbital ASAT. Even if debris is a serious concern, you could still attack more directly. Small shaped charge through an important part of the satellite, or even just a pair of wire cutters. These also don't require a bunch of delta-V to deorbit a much larger satellite.
@Suvorov
I don't think that follows. What sort of weapons are these mines using and how are they deployed? You can read mass reasonably accurately from a drive plume, and while I could see it being possible to slip a couple tons of spy satellite in and dump it without anyone noticing, you're going to need a lot more mass for a weapons platform, or a lot more of the platforms. As for weapons, well, you're looking at kinetics, but you'll probably have to boost them with chemical rockets, which sharply limits delta-V, and makes you very vulnerable to countermeasures. Not to mention that each one of these you plant is another chance for a prewar diplomatic incident.
That assumes they know where it is. (And that you can't just spin a filter for the right frequency in front of the sensor and push on.) ISR satellites are by far the easiest thing to hide, because they're almost entirely passive and need little power, and thus produce little heat.
You know, the contact mines with the nubs that stick out!
But seriously, whatever weapons you typically use, depending on the expected engagement range and target. The Project Excalibur-style nuclear-detonation-powered laser seems like a good option, or you could use Casaba howitzers/nuclear explosively formed projectile weapons. The point of the stealth is to get the enemy close enough that a laser weapon will have less problems with diffusion at range, or a kinetic weapon would be harder to dodge. Ergo, you'd probably go for more powerful versions of your standard hardware that are single-use – since your platform is slow or immobile and won't be much good after you take your first shot. I particularly like NEFP, since in theory it lets you put a projectile in a target 10,000 kilometers away in under 20 seconds with enough force to fracture the target.
Eh, single-shot weapons aren't very big – Atomic Rockets puts a small Cabasa at around 115 kgs including guidance package. Much smaller than the high-end surveillance telescope you'd deploy to try to find it from across the system (Hubble is 11,100 kg – an ISR sat could likely be smaller.)
We can't (today) reliably detect large space objects until they are "close" – and they're just dark-colored rocks. Hunting for small dark-colored rocks that are trying to evade your sensors is going to be hard enough that it would probably be worth developing the capability just to make your opponent spend the money to detect it. Especially if you're putting them around a planetary body they don't control.
Which they would, for all the same reasons you would know where a mine was, unless you took precautions.
@Suvorov
It is, yet treaties are hardly the sole obstacle (indeed, if they were, then they would not have been made--human greed can move mountains). Greenland receives a large part of its revenue from the Danish government $535,000,000 in 2017, according to the CIA World Factbook, or 25% of GDP). The question, as I should have made clearer, is not hunter-gatherer subsistence (easy for a small population--just fish and trap or shoot penguins, and bring in some tourists for hard cash), but the ability to sustain sufficient economic productivity to support itself as a modern community. That, I think, you are very unlikely to do in Antarctica in the foreseeable future, even if international law allowed it. Mutatis mutandis, likewise for space.
We could be more confident if Einstein had figured out gravity.
If one is sure of continued economic growth like we have seen over the past few centuries then, yes, eventually we must start using Greenland, Antarctica, and outer space (the former two made easier if the ice caps do recede much). But it might prove that the difficulty of going to outer space puts a hard cap on human growth. There must be a novel in that (and maybe there has been): a new Malthusian ceiling, and the desperate efforts of a debonair civil servant and a beautiful pilot-tinkerer to break it.
But I'll cut this off now, as the Open Thread is here and people will no doubt want to talk about other things!
@Suvorov
Hadn't thought of nukes. The issue there is cost and politics, although the latter depends on how much in the way of earth norms get imported into space. Also, I've heard somewhere (can't give cites offhand) that there's considerable skepticism around the various shaped nukes from people who should know.
@Goose
You're free to keep talking about this stuff. My necro policy is "if it's up here, it's free to talk about". I've closed exactly one post's comments, and it was because it was getting like 75% of all the spam that made it through the filter.
@Goose of Doom
The USAF is already playing around with "quick launch" capability, where they prep some satellites and launchers and have them ready to go up on short notice in case the ones in orbit get taken out.
Another concept the USAF is playing with is using "swarms" of smaller satellites to overwhelm adversaries' ASAT capabilities.
Also, with regards to Antarctica, I would make the counterclaim that we have managed to extensively drill the Prudhoe Bay oil field on the northern coast of Alaska, despite it being almost as remote and inhospitable as Antarctica. We don't need a self-sufficient colony in space, we just need one that can extract and export enough resources to Earth to make it worth the setup and maintenance costs. Something like asteroid mining or moon mining could be plausible, depending on whether it's more cost effective to have some humans "close to the action" or whether it's more cost effective to make everything as autonomous as possible.
@suvorov
I was talking more about observations of the satellites themselves. All you really need for that is a radar on the ground and you can compute the orbital ephemera of satellites as they pass overhead.