Orbital Lasers

[ericthered]

This conversation moved fast.

In the other thread, I mentioned the options were limited to hiding targets, moving targets, and building targets. Plus threatening to shooting down landing craft and troops.

The biggest challenge for the alien craft is that of all artillery: target acquisition. How does it distinguish between a cargo truck and a truck-mounted SAM system? How does it know where the missile silos are? It can kill civilians indiscriminately, but is it willing to, and what does that ultimately accomplish? Once the enemy leader is on the run, its difficult to distinguish him from all the other running humans.

The only thing the humans can do is resist, but that isn't to say that resistance can't be effective.

[kdtipa]

Originally Posted by AlexanderHowl

... Such a spacecraft could engage forty surface targets every space turn from GSO...

People keep talking about GSO... but... that would be a fairly limiting thing for a space station using lasers to attack the ground. Its options for targets are limited to the side of the planet it's on. Maybe it can manage a continent?

You might be better off with Lagrange Points. That way the station would have visibility to any place that also has visibility to the moon (assuming you don't choose point #2 in their diagram in that wiki article).

Originally Posted by AlexanderHowl

How would a TL8 world deal with such a spacecraft?

I mentioned a completely non-technology based solution earlier in the thread. No one has responded. But getting someone or a few people on board a supply shuttle to sabotage the place sounds like a pretty great adventure seed to me.

Alternatively, is there stealth technology? Can humans secretly spend a bunch of resources on developing stealth tech that works against alien sensors? Maybe steal something more minor of alien sensor technology so they have something to test with? And then create something that can reach the alien ship with that technology? Get it up into space with what looks like a normal satellite placement, and then launch a mission from there? Or just a stealth missile?

[Rupert]

Originally Posted by kdtipa

People keep talking about GSO... but... that would be a fairly limiting thing for a space station using lasers to attack the ground. Its options for targets are limited to the side of the planet it's on. Maybe it can manage a continent?

From GSO one can cover about a third of the globe, though the edges of that area will have annoyingly steep angles of fire and vision. However, if you're not in a tearing hurry you can just adjust your orbit a bit and let the planet slowly rotate until you're over whatever you want to blast, and then adjust your orbit back to an exact 24-hours.

You might be better off with Lagrange Points. That way the station would have visibility to any place that also has visibility to the moon (assuming you don't choose point #2 in their diagram in that wiki article).

That's a lot further away, outside the range of any of the beam weapons in Spaceships. Using Spaceships 3, that's inside the 1/2D range of a 100TJ+ Graser, X-Ray, or UV laser. However SS says that Grasers and X-ray lasers can't be used for orbit to ground attack through an atmosphere. Given that UT also sharply limits the range of UV lasers, they should probably also be so restricted. Thus the L-points are too far away to make useful positions from which to make beam weapon attacks on Eath's surface.

Sitting at the L-points also means that you are exchanging covering a limited area at all times for limited coverage times over the whole Earth. Neither is ideal, of course.

[kdtipa]

Originally Posted by Rupert

...However, if you're not in a tearing hurry you can just adjust your orbit a bit and let the planet slowly rotate until you're over whatever you want to blast, and then adjust your orbit back to an exact 24-hours.
...
Sitting at the L-points also means that you are exchanging covering a limited area at all times for limited coverage times over the whole Earth. Neither is ideal, of course.

The space station has thrusters for maneuvering? I missed that detail.

Maybe there should be three or four stations each covering their own area...

[ericthered]

Originally Posted by kdtipa

The space station has thrusters for maneuvering? I missed that detail.

Maybe there should be three or four stations each covering their own area...

The bombardment has been described as coming from a SM+15 hyper-drive capable ship with access to TL10^ technology, though we are discussing a subset of its abilities. I agree that if you want to cover the planet while orbiting, you want three or more locations. Though if you're only targeting one nation, a single ship is fine.

[kdtipa]

Originally Posted by ericthered

The bombardment has been described as coming from a SM+15 hyper-drive capable ship with access to TL10^ technology, though we are discussing a subset of its abilities. I agree that if you want to cover the planet while orbiting, you want three or more locations. Though if you're only targeting one nation, a single ship is fine.

Hyperdrive capable doesn't do it. But I suppose "ship" implies the ability to maneuver. I was working with my memory and impression... which is of an orbital station. I suppose if it's a ship... the kind of orbit you use can vary all you like.

Anyway... I still think humans finding a technological solution is less likely than a clever solution like boarding a supply shuttle and blowing it up from the inside.

[ravenfish]

Originally Posted by kdtipa

The space station has thrusters for maneuvering? I missed that detail.

A space station has some sort of minor thrusters almost by necessity. In low orbit, the outer traces of the atmosphere are thick enough that periodic burns are necessary to maintain velocity; they are needed to keep a precise position even when completely out of the atmosphere given the accumulation of small changes in orbital position from the complexities of earth's gravitational field, the force of solar radiation etc.

EDIT: In particular, a strict geostationary orbit (directly over the equator) is out of line with the orbit of the moon, so periodic burns are required to keep the moon's gravity from shifting the plane of orbit.

[AlexanderHowl]

A large enough spaceship can function as a mobile station. While a mobile station may seem less efficient than a static station, it has the advantage of being less vulnerable to ballistic attacks from a planetary surface and can always retreat. After all, the Death Star was a mobile station...though it was victim to commanders who did not seem to understand that mobile stations should retreat from attacks rather than heading towards them (dropping a squadron of TIE-fighters to engage the Rebel forces while the Death Star retreated would have been a much more logical reaction).

[Rupert]

Originally Posted by AlexanderHowl

A large enough spaceship can function as a mobile station. While a mobile station may seem less efficient than a static station, it has the advantage of being less vulnerable to ballistic attacks from a planetary surface and can always retreat. After all, the Death Star was a mobile station...though it was victim to commanders who did not seem to understand that mobile stations should retreat from attacks rather than heading towards them (dropping a squadron of TIE-fighters to engage the Rebel forces while the Death Star retreated would have been a much more logical reaction).

Star Wars is an environment that works like WWII aero-naval warfare (though the Death Star commanders and designers thought the Death Star was big enough that they could act like it was WWI). Carriers don't retreat from aircraft - they send up their own aircraft, or rely on AA fire.

[AlexanderHowl]

Honestly though, that only works when the secondary craft are much faster than the primary craft. When you can jump into hyperspace to avoid fighters, that makes it more ballistic submarine versus fighter jets. Ballistic submarines survive through stealth and by avoiding unnecessary combat, which is how the commanders of the Death Star should have treated it. It is not the combat abilities of ballistic submarines that are terrifying, it is the fact that they can pop up anywhere and use those combat abilities that is terrifying.

One of the problems with any large interstellar polity is that they have access to vast amounts of resources. The interstellar dust of a cubic light year alone masses more than forty Sol systems, and a polity that controlled a sphere 500 ly in radius (over one million star systems) has a volume of over 500 million cubic light-years, giving it ~20 billion Sol-masses of interstellar dust to work with. Even if they ignored the dust, they would like having enough debris in their star systems to allow them to support millions of spacecraft.