For Questions That Don't Merit Their Own Thread

[kerbiloid]

Afaik, the tested air-to-space antisat missiles were using IR guidance.
But obviously the were watching the target from beneath (i.e. on the cold night background), and the target was a satellite with regular stable well-known orbit, so it was the last mile guidance.

From above, the IR should probably have problems with hot and bright Earth at background.

The real  known antisat sats/orbital-rockets were equipped with a large radar antenna and (based on the pictures) explosively formed penetrator charges, so didn't need to hit the target themselves, just get close and shoot.

The previous antisat rockets launched from a single-seat orbital interceptor project were, according to the pictures, using semi-active radar guidance, with a large antenna on the interceptor and small receiving one on the missile.

Almaz could shoot from gun or launch missiles using a submarine optical periscope.

So, probably a combination of a launch station with active radar and missiles with weak bimodal radar guidance (passive + short-range active), with auxilliary IR sensor to select the target if it tries to jam.
With RCS to rotate and aim on a close fly-by and  explosively formed penetrator(s).

Edited November 16, 2020 by kerbiloid

[DDE]

10 hours ago, ARS said:

What's the best guidance systems used on missiles for space battles? Especially the one that takes place in-orbit of a planet? Could normal missile guidance be used normally? (Infrared, heatseeking, radar-guided, laser-guided etc.)

I hear jamming a helium-based neutron detector looking for the signature of an unshielded nuclear reactor is... challenging.

Similarly, we know of countermeasures against radar and infrared.

https://thespacereview.com/article/3536/1

[DDE]

I hereby recant my prior claims that Rods from God are an inefficient weapon.

 

[kerbiloid]

Now he has a convertible.

[StrandedonEarth]

1 hour ago, DDE said:

I hereby recant my prior claims that Rods from God are an inefficient weapon.

 

Okay, but in Niven’s Footfall the Rods were used to obliterate a column of tanks. How would a battle tank stand up to that slab?

[K^2]

2 hours ago, StrandedonEarth said:

Okay, but in Niven’s Footfall the Rods were used to obliterate a column of tanks. How would a battle tank stand up to that slab?

If it was traveling at mach 10? Not very well.

[magnemoe]

1 minute ago, K^2 said:

If it was traveling at mach 10? Not very well.

true, the main issue using rod from gods against tanks is that you are inside plasma all the way down who make it hard for the sensors and you need sensors to hit an small moving target.  
Now something as an 100 ton tungsten or DU long rod dropped by a starship will have some serious penetration able to kill everything not designed to withstand an direct multi megaton hit, but here you can miss by 10 meters. 
On the other hand experience in WW 2 showed that tanks was pretty immune against artillery, only benefit of the 16" battleship shells was that the tank might roll down the crater it created. 
On the gripping hand during gulf war 2 Iraq did an tank assault during an sandstorm. Genial move, the storm would make air support extremely hard and dangerous, it would negate the US advantages in sensors and recon, finally in the knife fight who would result the better armored US tanks would still be very vulnerable. 
The plan failed, even if planes could not directly engage they gave targeting data to the artillery who used cluster shells with sharped charges who penetrated the top armor on the tanks. 
Now you have various indirect fire smart weapons, bombs, rockets and artillery who would be more effective in normal settings. 
In short I don't see rods of god to be very useful outside heavy armored strategic targets. 

[K^2]

Just now, magnemoe said:

true, the main issue using rod from gods against tanks is that you are inside plasma all the way down who make it hard for the sensors and you need sensors to hit an small moving target.

No argument there. Even against static targets, say a bunker, it's hard to score a direct hit with something like this.

China has tested sub-orbital KKVs that they claim can hit an aircraft carrier with a double digit percentage chance. But that's a much, much larger target, and I'm not sure there is nearly as much plasma interference on ballistic trajectories they are using. Even then, they need a volley of 3-5 to score a hit reliably enough to use in combat, so hitting a tank from orbit seems... yeah. But it's hard for me to say if there are any real limits on precision that aren't just more engineering problems. It wouldn't shock me if that gets solved eventually.

[magnemoe]

3 minutes ago, K^2 said:

No argument there. Even against static targets, say a bunker, it's hard to score a direct hit with something like this.

China has tested sub-orbital KKVs that they claim can hit an aircraft carrier with a double digit percentage chance. But that's a much, much larger target, and I'm not sure there is nearly as much plasma interference on ballistic trajectories they are using. Even then, they need a volley of 3-5 to score a hit reliably enough to use in combat, so hitting a tank from orbit seems... yeah. But it's hard for me to say if there are any real limits on precision that aren't just more engineering problems. It wouldn't shock me if that gets solved eventually.

Yes, now with an very massive projectile you can miss with 10 meters. you could get gps from the tail like the shuttle did and rely on internals for the last 20 km. 
Ships can be pretty agile then they need to be so I say questionable unless closer ranges. 

Now an tank is an far less valuable target then an carrier. 

[DDE]

8 hours ago, magnemoe said:

true, the main issue using rod from gods against tanks is that you are inside plasma all the way down who make it hard for the sensors and you need sensors to hit an small moving target.  

Yes, but the peeps in the hypersonic field are saying that even at Mach 10 plasma isn't a big problem. Not actively trying to slow down and thus not shedding nearly as much energy also plays a role, I imagine.

11 hours ago, kerbiloid said:

Now he has a convertible.

Note that it's an imported car with the steering wheel on the right... and it still got hit square in the driver's seat.

Clever girl.

[kerbiloid]

Using tungsten rods to kill tanks, it's easier to sell the rods and buy out those tanks.

1 hour ago, DDE said:

Note that it's an imported car with the steering wheel on the right... and it still got hit square in the driver's seat.

Remember "Omen"?

Edited November 20, 2020 by kerbiloid

[monophonic]

2 hours ago, kerbiloid said:

Using tungsten rods to kill tanks, it's easier to sell the rods and buy out those tanks.

Most tanks use tungsten rods to kill other tanks anyway. Some have used uranium rods, but that has been somewhat disapproved of. Of course dropping them from orbit is less polluting that using crude chemical reactions to accelerate the rods. Just don't ask about how the rods got into orbit in the first place. 

[K^2]

52 minutes ago, monophonic said:

Just don't ask about how the rods got into orbit in the first place. 

They took the elevator.

[kerbiloid]

4 hours ago, monophonic said:

Most tanks use tungsten rods to kill other tanks anyway.

10⁰ kg, not 10¹ t.

Edited November 20, 2020 by kerbiloid

[JoeSchmuckatelli]

Is it fair to assume Mercury is a planet?  It does not look to have enough 'oomph' to clear its own orbit... 

 

Edit: also, how wide would the 'habitable zone' be around the largest star - and at that range, could it actually have a planet in orbit?

Edited November 20, 2020 by JoeSchmuckatelli

[JoeSchmuckatelli]

6 hours ago, monophonic said:

Most tanks use tungsten rods to kill other tanks anyway. Some have used uranium rods, but that has been somewhat disapproved of. Of course dropping them from orbit is less polluting that using crude chemical reactions to accelerate the rods. Just don't ask about how the rods got into orbit in the first place. 

You don't really need tungsten from space. 

The reason tanks are largely unaffected by arty - is that arty misses.

After a miss, the 'killing blast/shrapnel' that is so effective against soft targets goes from the impact site into the armor of the tank.  It's designed to defeat 'horizontal' threats.  So the tankers are relatively safe, but also become annoyed and decide to leave the area.  But arty that hits, craters the tank  (a key component of the annoyance felt by the tankers, btw).  You can also break up individual large shells into lots of smaller explosive bomblets and increase your chance of hitting - which really, really annoys tankers (see below).

Because tanks are expensive, the manufacturers and purchasers of tanks agree to skimp a little bit on the protection - so they don't spend a lot of time, energy or weight on armoring the top of the tank... so if you drop something hard going very fast onto the top - you get a nice crater.  You can also get really really clever and design a missile to fly over the tank and poop its load into the top of the tank.  This makes craters as well.  As does DPICM with lots of bomblets that rain down all over the place.  Even a little firey hole punched into the top of your tank can ruin your whole day.

So save some money and skip the tungsten - just drop a bunch of pointy iron rods from your orbital tank killing platform and watch the fireworks.

[testcrasher#201]

yes the people at nasa made sure of it

 

[DDE]

3 hours ago, JoeSchmuckatelli said:

So save some money and skip the tungsten - just drop a bunch of pointy iron rods from your orbital tank killing platform and watch the fireworks.

[Spacescifi]

2 hours ago, DDE said:

 

This is war folks...ouch!

Hate to be those guys!

 

[Spacescifi]

 

When a fighter jet is locked on to by another is that the end all be all of combat?

It seems so. I watched a reenactment of the latest USA vs Iraq war and an American jet was locked on to by an Iraqi MIG.

The American was scared and dived toward the ground and pulled up before crashing.

The MIG never fired the missiles it had even though it had missile lock...the pilot lost control on the dive and crashed.

Makes me think maybe...missile lock is not everything.

Since in videogames if I fire a missile the target is usually going tp get hit if it lacks serious boost.

In real life? It probably pays to keep your plane's nose facing the target because your missile will run out of propellant faster than they do in videogames.

What do you know on this?

If you are locked on to by another jet with a missile and they fire, can you actually evade it?

Maybe it depends on missile type?

Maybe the Iraqi jet had cheaper missiles that would need more pilot input to actually land a hit.

I dunno...

Edited November 20, 2020 by Spacescifi

[JoeSchmuckatelli]

54 minutes ago, Spacescifi said:

 

When a fighter jet is locked on to by another is that the end all be all of combat?

It seems so. I watched a reenactment of the latest USA vs Iraq war and an American jet was locked on to by an Iraqi MIG.

The American was scared and dived toward the ground and pulled up before crashing.

The MIG never fired the missiles it had even though it had missile lock...the pilot lost control on the dive and crashed.

Makes me think maybe...missile lock is not everything.

Since in videogames if I fire a missile the target is usually going tp get hit if it lacks serious boost.

In real life? It probably pays to keep your plane's nose facing the target because your missile will run out of propellant faster than they do in videogames.

What do you know on this?

If you are locked on to by another jet with a missile and they fire, can you actually evade it?

Maybe it depends on missile type?

Maybe the Iraqi jet had cheaper missiles that would need more pilot input to actually land a hit.

I dunno...

its a lot more complicated.  Much easier for the side with the tech advantage btw; if you can get a lock outside his detection range and fire... he won't know he's dead and can't take evasive action.

 

But - Missile lock isn't everything - it simply says that the targeting computer of the missile has a solution and you're free to fire the weapon, and thus rely upon its programming and abilities to take out the target.  Yet for the target aircraft, there are countermeasures and evasive maneuvers and just dumb luck that come into play.  Note - the pilot actually has to make the decision to fire.  In the case you cited, the pilot may have been too busy flying the plane to realize he could fire.  This is where training comes in.

 

So if you have both a technological and a training advantage - odds are in your favor.

7 hours ago, JoeSchmuckatelli said:

Is it fair to assume Mercury is a planet?  It does not look to have enough 'oomph' to clear its own orbit... 

 

Edit: also, how wide would the 'habitable zone' be around the largest star - and at that range, could it actually have a planet in orbit?

 

[DunaManiac]

How fast does something need to go before time slows down noticeably? I know that all objects experience time slowing down when moving, but how fast until it reaches a substantial amount, like a couple hours or minutes?

Edited November 21, 2020 by DunaManiac

[Spacescifi]

2 minutes ago, DunaManiac said:

How fast does something need to go before time slows down noticeably? I know that all objects experience time slowing down when moving, but how fast until it reaches a substantial amount, like a couple hours or minutes?

 

Not. Fast. At all if gravity is high enough.

That is the only answer I can give right now...but suffice to say...uf you have scifi gravity generation...you can also slow time locally wayyy down.

That said...the gravity alone might crush anything in it...so that's an inconvinience if you were using this instead of a refridgerator for your food.

[DunaManiac]

1 minute ago, Spacescifi said:

 

Not. Fast. At all if gravity is high enough.

That is the only answer I can give right now...but suffice to say...uf you have scifi gravity generation...you can also slow time locally wayyy down.

That said...the gravity alone might crush anything in it...so that's an inconvinience if you were using this instead of a refridgerator for your food.

I know that gravity also slows down time, in fact you could sit in orbit around a black hole and time would slow down, but the specific question is that if time slows down when things move, how fast would it need to go before it would become noticeable.

[Spacescifi]

3 minutes ago, DunaManiac said:

I know that gravity also slows down time, in fact you could sit in orbit around a black hole and time would slow down, but the specific question is that if time slows down when things move, how fast would it need to go before it would become noticeable.

 

I would tell you if I could. KSP will likely...I think...