Thursday, May 28, 2009

Mistakes About Space Stealth and Revamping Lasers

In 2005 I wrote a fairly extensive article on space combat called "Hunters In The Great Dark," which was published in Strange Horizons. One of my main assertions was that stealth in space was a given; the sheer scale immense of the battle field seemed to assure that. Also, one of main rationales for that was how real-life astronomers have had a lot of difficulty finding even the majority of near-Earth asteroids, objects that can dwarf many proposed space battle ships. If there's such a problem finding flying mountains, why would it be any easier to find much smaller ships?

However, in the years since, people have pointed out the problems with that, and with a great deal of reading on my part for how sensors and such would work in space, I now have to admit I was wrong about that. The hunt for asteroids has taken place only in a limited spectrum (visible light) so far, and doesn't take into account multiple-spectrum IR detectors and more. Life support, various ship systems, and engines create waste heat that can at best be masked for only a short time, more than likely not long enough to mount any kind of successful attack.

Given "realistic" projections for future space technology (on the OV scale, that would be up through Tech Level 15), stealth for manned ships is not very likely and for unmanned attack craft difficult at best. Like most things about future technology, I don't want to say its flat-out impossible, because too many dismissals of 'impossible' things have been proven wrong. I still think its probably doable in certain specialized circumstances, and some unforeseen innovation (like metamaterials, which looks like it may lead to a real life 'invisibility' cloak) may throw a monkey wrench into it all.

But otherwise, I was wrong. Oh well. Sorry about that. At least I got paid $100 for the original article way back when, so I think my pride will survive.

So anyway, I'm taking down "Hunters In The Great Dark" from the Essay section for a possible major rewrite at some future time. I'm also going to take down the "Laser Firearms" article in the "Firearms" section. The article is still accurate as far as it goes, but it was one of the first articles I did in for OV back in 2003. There have been a number of developments and rethinking about laser weapons since then, and I should rewrite the article to reflect all that.


NoXion said...

"I still think its probably doable in certain specialized circumstances, and some unforeseen innovation (like metamaterials, which looks like it may lead to a real life 'invisibility' cloak) may throw a monkey wrench into it all."

I doubt that metamaterials would be the answer, as there would still be the issue of waste heat - if you don't radiate it away at some point (thus giving away your position), something important is going to melt, and any biological crew would get cooked.

Were I to try and design a "stealth" spaceship, it would be an Autonomous Kill Vehicle that would be launched "cold" using springs, compressed gas or a (relatively) low-powered coilgun. The AKV would coast along on momentum alone (with perhaps minor course adjustments provided by gas tanks or low-profile ion drives), using passive sensors only. The AKV could be equipped with more powerful drives/thrusters and active scanners that are only fired up when it is "triggered" to attack.

I'm not a rocket scientist, so there are probably some flaws in my idea. My suspicion is that any kind of "stealth" in space would be entirely provisional based on how sophisticated the enemy sensors/scanners are and how much coverage of sufficient sensitivity they can use to detect you.

Paul Lucas said...

Your AKV concept is pretty much along the lines of what I was envisioning as far as "certain specialized circumstances." I mentioned metamaterials only to illustrate that real life will always throw "curveball" advances at us whose ultimate impact we can't easily predict.

Waste heat could be addressed in limited ways by using heat sinks and selective directional radiative methods. However, given the presumed travel times even within the inner solar system using 'realistic' projected technology (up through Tech Level 15 on the OV scale) these probably wouldn't work long enough to be effective.

The only modification I'd make to your AKV scheme would be to sculpt its outer shell with asteroidal material, so it will apear as a natural space rock even if it is spotted.

And don't worry, I'm not a rocket scientist either, but as far as I can tell your thinking is very sound

shneekeythelost said...

Actually, there is an even more simple reason why stealth is such a difficult notion for a futuristic and intergalactic civilization.

Look at it this way: Once, a major threat of seaborn ships back in the 14th century, were dangerous and almost invisible shoals which would destroy a boat's hull from mere inches underwater. It was to the point where they would map out these shoals in well-traveled waters, good Captains would memorize their locations on routes they took so as to avoid them.

In modern day, we have Sonar Mapping which can detect any potentially hazardous rock formation long before running into it.

You see, if you cannot find an asteroid many times the size of a starship, then you are going to end up destroyed by it. Thus, it makes sense that they would have sufficiently sophisticated sensor equipment to be able to detect possible threats, such as hostile ships.

In fact, it is vastly easier to detect a ship than an asteroid. After all, the ship will almost certainly be emitting something. A ship with Radar emits radio pulses at given frequencies which can be picked up by passive sensors and tracked back to point of origin. Propulsion emissions is another thing which is generally considered to be much easier to detect.

For you to have a true 'stealth' vessel, you would have to have the following:

1) special materials to deflect or re-direct 'modern' sensor equipment. Much like the B2 Stealth Bomber currently employed by the American Air Force, which diffuses it's RADAR signal to the point where its radar signature is nothing bigger than a bird.

2) Some form of insulation which keeps excess heat from life support and other systems produce from being visible. This actually isn't going to be too hard, and is going to be a logical extention of making ships more economical. Waste heat, that is to say, heat that escapes the living quarters, is a problem, because you have to constantly renew it. So, in order to relieve stress on the life support systems, better insulation which prevents heat from escaping will be practically inevitable. And because heat doesn't escape, it cannot be picked up.

3) Engine 'bafflers' which mask the engine emissions. This will be one of the hardest. The easiest way would be to come in 'ballistic', shutting down propulsion systems outside target's sensor range. However, this means you are unable to alter your trajectory. If your target changes its vector, you may end up missing them, and faced with the choice of either calling the run off or alerting your target to your presence by altering your vector to match.

Manned or Unmanned, it doesn't matter. Life Support will end up being a non-issue through application of economics. It will be finding ways to foil sensors and hiding your trail that will provide the real challenges in a 'stealthed' attack craft.

King of the Snow said...

For the consideration of stealthed space vehicles, one needs to take into consideration the high likelihood of a technology asymmetry. For instance, the U.S. vs. the Chinese. Chinese sensors are inferior to the Americans. In this situation the term, "stealthed enough" applies. Waste heat is unlikely to be a part of the electromagnetic spectrum a Chinese opponent would be looking for. A number of factors need to be considered when monitoring an IR source. The sensitivity of the sensors would be insufficient. Positive visual identification is problematic at best for any nation other than the U.S., given the degrees of arc that need to be scanned in a certain, finite amount of time required. One could park a space battleship in geostationary orbit over Indonesia, to deny the Chinese launch capability.

Given a similarity of tech levels, even large quantities of waste heat can be shed, so long as a ship were to focus the vector of excess thermal energy directly away from a single source sensor. In this scenario, the larger the ship, the easier it is to hide waste heat. Another alternative is to place a bright IR source at your "back", to mask your own signature. This tried and true method is feasible across a wide section of the EM spectrum.