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I think the author is wrong on visibility. Put simply: things in space are very far away and hence visually small. You have to be looking in exactly the right p

I think the author is wrong on visibility. Put simply: things in space are very far away and hence visually small. You have to be looking in exactly the right place. Finding things when you know where they are is easy. Poking around randomly for things you might have missed is hard. Compare: the effort to find earth-crossing asteroids - objects that like a hostile ship are dark, drifting, and small.

rrss1122 12y ago
I assume the task would be made easier by having computers scan the space around the spacecraft through a wide range of wavelengths, from thermal to xray including visible. We generally find near-Earth asteroids the day of their encounter with Earth. This would be all that's needed for a spacecraft to respond to a potential threat.
cambion 12y ago
I can't find it now, but I read an essay a number of years ago that fairly well convinced me that we could (using the technology of the time) theoretically build a telescope that was small enough to be mounted on a space ship or monitoring satellite (~1 meter aperture IIRC) with sufficient angular resolution to spot the space shuttle engines firing at the distance between Earth and Jupiter. We had at that time enough GPU processing power to do a full scan of the sky every 5 minutes. Now, keep in mind that any ship bearing humans is going to need to radiate infrared photons at about room temperature, around 300 kelvin. What this implies is that you want to be using an infrared telescope and look for whatever lights up against the cosmic background. Spaceships would be easy to spot, at least inside of our solar system.
- stcredzero 12y ago
  Put the ship inside a deep parabolic cone, the outside of which absorbs EM radiation. Aim the cone away from enemy sensors. You have a stealth ship, only detectable by occlusion. However, if all of the enemy's sensor positions are known, such signals could be generated. Conclusion: you can have stealth ships, and will only be able to counter them by blanketing the volume you patrol with sensors or by deploying your own stealth platforms.
  - JohnBooty 12y ago
    > You have a stealth ship, only detectable by occlusion With engines firing, the ship would still be spottable from every angle except essentially straight ahead. From every other angle, the gas/plasma/etc flying out of the cone would still contain the same amount of heat energy, just dispersed over a larger area. Anything more than a few degrees above absolute zero will stick out like a sore thumb, and you'd have to disperse the heat from a single thruster over thousands of square meters to get close to that. That's where cheap remote sensor networks probably win. For the cost of your single "thermally stealth" warship, your enemy can likely afford thousands of cheap dumb probes that can spot you from many angles. "Stealth" will probably staying cold as long as possible. An attack ship/missile could be launched on an initial trajectory from somewhere in space by kinetic (rail gun-like?) means. It then remains dark/cold for most of its journey, until it is extremely close to the target. At that point it could launch chaff/flares and close in for the kill. Alternately (or complimentarilty? is that a word?) another effective strategy might be to park a bunch of dormant ships/weapons around the area you wish to attack/defend. Dark and cold, they'd be nearly undetectable... until they're needed.
    - stcredzero 12y ago
      With engines firing, the ship would still be spottable from every angle except essentially straight ahead. You've jumped to conclusions about the kind of drive it would have. Once launched it would only use mass drivers for course correction. Remember: think ahead. Remember also, that these are only supposed to have limited maneuverability. That's where cheap remote sensor networks probably win. For the cost of your single "thermally stealth" warship, your enemy can likely afford thousands of cheap dumb probes that can spot you from many angles. If they are so cheap that they are easily detectable, then enemy HQ can calculate a geometry that would preclude your detecting the ship. Also, I'm not necessarily envisioning a full-on warship. Being unmanned, small, and low energy as possible is a win for craft such as these, so they would also tend towards being inexpensive. On the other hand, the "more, dispersed" counter-strategy is disadvantaged by a factor of N^3. An optimal strategy would consist of multiple stealthed units to achieve dispersal/coverage. This way, your enemy is always guessing whether all of their detection platforms have been located or compromised in some way, opening an attack vector to their vital in system transfer orbits. (Lines of commerce.) "Stealth" will probably staying cold as long as possible. An attack ship/missile could be launched on an initial trajectory from somewhere in space by kinetic (rail gun-like?) means. It then remains dark/cold for most of its journey, until it is extremely close to the target. At that point it could launch chaff/flares and close in for the kill. Indeed. But without special provisions, such an attack mothership would be highly visible from vast distances, so again there is a possible application of stealth.
- mcguire 12y ago
  The author mentions http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth http://www.projectrho.com/public_html/rocket/spacewardetect...., which has a link to this from 1998: https://groups.google.com/forum/#!topic/rec.arts.sf.science/-E6r2F8rgnQ[151-175-false] https://groups.google.com/forum/#!topic/rec.arts.sf.science/.... Me, I'm not a physicist and have no idea what I'm talking about, but I do know that if you're looking for a campfire in the desert and the desert is the size of Utah and Nevada, you're going to have a hard time.
iron_ball 12y ago
The author does mention that you could just shut down your engines and wait to spot your prey; but once you put yourself on an intercept (by firing your engines), the opponent will know where you are.
patmcc 12y ago
>>>objects that like a hostile ship are dark, drifting, and small Dark on the visible light spectrum, sure. But if you have active engines or live crew (or both), you will be much warmer than space-at-large. Asteroids are tricky because they're dark AND cold.
- stcredzero 12y ago
  Asteroids aren't that cold, even. If you had a ship with a deep parabolic shield, the outside of which absorbs EM radiation and the inside of which is highly reflective, the ship could be rendered invisible outside of a narrow cone where it's directing its waste heat. It would still occlude starlight, but unless some of the enemy's sensors are stealth platforms, false signals could be generated to prevent the occlusion. Such stealth ships couldn't maneuver much, but they could only be countered by other stealth platforms in a cat and mouse game reminiscent of Cold War submarine contests.
- JohnBooty 12y ago
  > But if you have active engines Maybe the "stealth" weapons of space combat look a lot like blimps. They use big, cold, dark tanks of compressed gas for thrust. No combustion; just spraying compressed gas for propulsion/steering until they're close enough to the enemy target. Then and only then, they activate active engines (or fire missiles with active engines) for the attack. I'm not sure if those physics remotely work. I guess you could at least get up to a few thousand km/hour with a decently big enough tank of compressed gas in space, when you don't have friction or drag to worry about.
- falcolas 12y ago
  This is one aspect of Mass Effect's lore that I particularly enjoyed. They took heat into account when building the the Normandy - a stealth frigate. It's a "stealth" ship because of two major things. Its hull's ability to deflect or absorb radar waves, and its heating/cooling exchange which was built in such a way that it can absorb heat into internal heat sinks for a limited amount of time, while cooling the exterior and engine emissions in order to reduce IR emissions. With the stealth systems functional, you would have to find it by sight, which is hard to do. They even discussed how the simplest way to disable many civilian craft was to disable their external emissive heat exchangers, since without them you couldn't run your engines for fear of cooking everyone inside. Warships had "tiger stripes" to limit the effect of losing one emissive surface would have on the ship's effectiveness. They also had methods of dumping massive loads of heat by ejecting molten salt (with an magic^w magnetic field collecting the cooled salt near the tail of the craft).
hluska 12y ago
Excellent comment! The only thing I would add is that I'd presume that if space was popular enough to fight over, there would be several ships flying around on several different trajectories. Between the vastness of space and an abundance of hot targets, it would not be trivial to locate another ship, especially if warships were designed with this in mind.
JohnBooty 12y ago
> objects that like a hostile ship are dark, > drifting, and small. A ship that is actively maneuvering or accelerating to tens of thousands of miles an hour would put out a considerable bit of heat.

rrss1122 12y ago

I assume the task would be made easier by having computers scan the space around the spacecraft through a wide range of wavelengths, from thermal to xray including visible. We generally find near-Earth asteroids the day of their encounter with Earth. This would be all that's needed for a spacecraft to respond to a potential threat.

cambion 12y ago

I can't find it now, but I read an essay a number of years ago that fairly well convinced me that we could (using the technology of the time) theoretically build a telescope that was small enough to be mounted on a space ship or monitoring satellite (~1 meter aperture IIRC) with sufficient angular resolution to spot the space shuttle engines firing at the distance between Earth and Jupiter. We had at that time enough GPU processing power to do a full scan of the sky every 5 minutes. Now, keep in mind that any ship bearing humans is going to need to radiate infrared photons at about room temperature, around 300 kelvin. What this implies is that you want to be using an infrared telescope and look for whatever lights up against the cosmic background. Spaceships would be easy to spot, at least inside of our solar system.

stcredzero 12y ago
Put the ship inside a deep parabolic cone, the outside of which absorbs EM radiation. Aim the cone away from enemy sensors. You have a stealth ship, only detectable by occlusion. However, if all of the enemy's sensor positions are known, such signals could be generated. Conclusion: you can have stealth ships, and will only be able to counter them by blanketing the volume you patrol with sensors or by deploying your own stealth platforms.
- JohnBooty 12y ago
  > You have a stealth ship, only detectable by occlusion With engines firing, the ship would still be spottable from every angle except essentially straight ahead. From every other angle, the gas/plasma/etc flying out of the cone would still contain the same amount of heat energy, just dispersed over a larger area. Anything more than a few degrees above absolute zero will stick out like a sore thumb, and you'd have to disperse the heat from a single thruster over thousands of square meters to get close to that. That's where cheap remote sensor networks probably win. For the cost of your single "thermally stealth" warship, your enemy can likely afford thousands of cheap dumb probes that can spot you from many angles. "Stealth" will probably staying cold as long as possible. An attack ship/missile could be launched on an initial trajectory from somewhere in space by kinetic (rail gun-like?) means. It then remains dark/cold for most of its journey, until it is extremely close to the target. At that point it could launch chaff/flares and close in for the kill. Alternately (or complimentarilty? is that a word?) another effective strategy might be to park a bunch of dormant ships/weapons around the area you wish to attack/defend. Dark and cold, they'd be nearly undetectable... until they're needed.
  - stcredzero 12y ago
    With engines firing, the ship would still be spottable from every angle except essentially straight ahead. You've jumped to conclusions about the kind of drive it would have. Once launched it would only use mass drivers for course correction. Remember: think ahead. Remember also, that these are only supposed to have limited maneuverability. That's where cheap remote sensor networks probably win. For the cost of your single "thermally stealth" warship, your enemy can likely afford thousands of cheap dumb probes that can spot you from many angles. If they are so cheap that they are easily detectable, then enemy HQ can calculate a geometry that would preclude your detecting the ship. Also, I'm not necessarily envisioning a full-on warship. Being unmanned, small, and low energy as possible is a win for craft such as these, so they would also tend towards being inexpensive. On the other hand, the "more, dispersed" counter-strategy is disadvantaged by a factor of N^3. An optimal strategy would consist of multiple stealthed units to achieve dispersal/coverage. This way, your enemy is always guessing whether all of their detection platforms have been located or compromised in some way, opening an attack vector to their vital in system transfer orbits. (Lines of commerce.) "Stealth" will probably staying cold as long as possible. An attack ship/missile could be launched on an initial trajectory from somewhere in space by kinetic (rail gun-like?) means. It then remains dark/cold for most of its journey, until it is extremely close to the target. At that point it could launch chaff/flares and close in for the kill. Indeed. But without special provisions, such an attack mothership would be highly visible from vast distances, so again there is a possible application of stealth.
mcguire 12y ago
The author mentions http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth http://www.projectrho.com/public_html/rocket/spacewardetect...., which has a link to this from 1998: https://groups.google.com/forum/#!topic/rec.arts.sf.science/-E6r2F8rgnQ[151-175-false] https://groups.google.com/forum/#!topic/rec.arts.sf.science/.... Me, I'm not a physicist and have no idea what I'm talking about, but I do know that if you're looking for a campfire in the desert and the desert is the size of Utah and Nevada, you're going to have a hard time.

iron_ball 12y ago

The author does mention that you could just shut down your engines and wait to spot your prey; but once you put yourself on an intercept (by firing your engines), the opponent will know where you are.

patmcc 12y ago

>>>objects that like a hostile ship are dark, drifting, and small Dark on the visible light spectrum, sure. But if you have active engines or live crew (or both), you will be much warmer than space-at-large. Asteroids are tricky because they're dark AND cold.

stcredzero 12y ago
Asteroids aren't that cold, even. If you had a ship with a deep parabolic shield, the outside of which absorbs EM radiation and the inside of which is highly reflective, the ship could be rendered invisible outside of a narrow cone where it's directing its waste heat. It would still occlude starlight, but unless some of the enemy's sensors are stealth platforms, false signals could be generated to prevent the occlusion. Such stealth ships couldn't maneuver much, but they could only be countered by other stealth platforms in a cat and mouse game reminiscent of Cold War submarine contests.
JohnBooty 12y ago
> But if you have active engines Maybe the "stealth" weapons of space combat look a lot like blimps. They use big, cold, dark tanks of compressed gas for thrust. No combustion; just spraying compressed gas for propulsion/steering until they're close enough to the enemy target. Then and only then, they activate active engines (or fire missiles with active engines) for the attack. I'm not sure if those physics remotely work. I guess you could at least get up to a few thousand km/hour with a decently big enough tank of compressed gas in space, when you don't have friction or drag to worry about.
falcolas 12y ago
This is one aspect of Mass Effect's lore that I particularly enjoyed. They took heat into account when building the the Normandy - a stealth frigate. It's a "stealth" ship because of two major things. Its hull's ability to deflect or absorb radar waves, and its heating/cooling exchange which was built in such a way that it can absorb heat into internal heat sinks for a limited amount of time, while cooling the exterior and engine emissions in order to reduce IR emissions. With the stealth systems functional, you would have to find it by sight, which is hard to do. They even discussed how the simplest way to disable many civilian craft was to disable their external emissive heat exchangers, since without them you couldn't run your engines for fear of cooking everyone inside. Warships had "tiger stripes" to limit the effect of losing one emissive surface would have on the ship's effectiveness. They also had methods of dumping massive loads of heat by ejecting molten salt (with an magic^w magnetic field collecting the cooled salt near the tail of the craft).

hluska 12y ago

Excellent comment! The only thing I would add is that I'd presume that if space was popular enough to fight over, there would be several ships flying around on several different trajectories. Between the vastness of space and an abundance of hot targets, it would not be trivial to locate another ship, especially if warships were designed with this in mind.

JohnBooty 12y ago

> objects that like a hostile ship are dark, > drifting, and small. A ship that is actively maneuvering or accelerating to tens of thousands of miles an hour would put out a considerable bit of heat.