What happens to all that debris?

ThinksMarkedly wrote:I don't agree. Even if this is the last shuttle in SAR, there may be other reasons to come back. Vacuuming the debris field unnecessarily does not sound like good practice.

What I do expect is that the first SAR shuttles created a tunnel of safe volume through which using the wedge is acceptable. Incoming and outgoing shuttles would stick to it when going to their search zones and thereby avoiding areas of increased hazard.

Either way, that doesn't solve the problem of debris coming from all directions. The wedges help with up and down, plus a great deal of sideways because they're very wide. But they can't stop all sideways motion. And they especially don't help with the direction of motion and that's exactly where most of the debris is going to be coming from.

If you are searching for a pod, you are looking for a signal. That can be done by traveling perpendicular to the debris motion just as well as parallel. I believe that could give the shuttle a wider search area.

I do not understand why you think that there is "debris coming from all directions", unless you mean as the result of collisions with space junk. Mainly those are momentum killers, so if you are near the debris front, those are the pieces that traveled without a major collision. But if you are considering collisions like that, then you cannot have a "safe tunnel".

There is nothing wrong with "vacuuming", provided it is not done to a pod.

tlb wrote:

ThinksMarkedly wrote:I don't agree. Even if this is the last shuttle in SAR, there may be other reasons to come back. Vacuuming the debris field unnecessarily does not sound like good practice.

What I do expect is that the first SAR shuttles created a tunnel of safe volume through which using the wedge is acceptable. Incoming and outgoing shuttles would stick to it when going to their search zones and thereby avoiding areas of increased hazard.

Either way, that doesn't solve the problem of debris coming from all directions. The wedges help with up and down, plus a great deal of sideways because they're very wide. But they can't stop all sideways motion. And they especially don't help with the direction of motion and that's exactly where most of the debris is going to be coming from.

If you are searching for a pod, you are looking for a signal. That can be done by traveling perpendicular to the debris motion just as well as parallel. I believe that could give the shuttle a wider search area.

I do not understand why you think that there is "debris coming from all directions", unless you mean as the result of collisions with space junk. Mainly those are momentum killers, so if you are near the debris front, those are the pieces that traveled without a major collision. But if you are considering collisions like that, then you cannot have a "safe tunnel".

There is nothing wrong with "vacuuming", provided it is not done to a pod.

There's not always a signal, like many of the pods in this scenario. When that happens, only your radar returns are available. When they found the Admiral, their pod was no longer broadcasting. They weren't even sure what they had on radar WAS a pod. Remember, they were excited, "It IS a pod!" In fact, S&R dropped buoys very early on within the debris field so the debris field ITSELF could be found later, let alone any pods.

Also, consider that even though this was explained as one debris field which had spread out one million kilometers, it could actually have been comprised of several separate intersecting debris fields created fairly close together. Ships exploding at varying locations create different angles of emanating debris fields, traveling at different velocities.

So, finding pods which were dead, like the Admiral's, with only the skinsuits keeping the occupants alive is difficult. I understand TM's notion, it is like cutting grass with the huge tractors used in the Midwest and killing someone asleep in the grass. The debris field itself can hide a dead pod.

Can your wedge get in the way of your sensors looking for such a small, dead, object?

cthia wrote:Can your wedge get in the way of your sensors looking for such a small, dead, object?

Absolutely. Even for the ship creating the wedge the distortions they cause seriously degrade sensor aimed through them.

A shuttle may not even bother mounting radar arrays that point towards the wedge since such a small radar, with the limited computing power of a shuttle, probably can't make out much through the wedge anyway. But even if they do the resolution will be much much worse than they'd get pointing a nose or broadside radar array at a potential object of interest.

So while a shuttle could build up some momentum and then hide behind it's wedge as it coasted out of the debris field it'll have a hard time telling quite what its wedge is smashing out of its path. It could be unlucky enough to run over and obliterate a damaged pod or someone in a skinsuit. Even while picking through the field it might not notice debris on a collision course with either wedge plane before it impacts and is obliterated.

Better to take it slow and keep your best sensor facing the debris so you can both work your way around any problem chunks, but also continue your SAR work. You may not see everything, but you'll see far more than if you interposed your wedge between the shuttle and all the debris.

tlb wrote:I do not understand why you think that there is "debris coming from all directions", unless you mean as the result of collisions with space junk. Mainly those are momentum killers, so if you are near the debris front, those are the pieces that traveled without a major collision. But if you are considering collisions like that, then you cannot have a "safe tunnel".

It's a question of relative velocity between the SAR ship and the debris field. The explosions imparted velocity in a random direction, added to the base velocity of the ship when it exploded and stopped accelerating. The fact that the debris field is a million kilometres wide at this point means it had this extra velocity. So if the SAR ship is at relative rest to the the debris field as a whole, then relatively all the debris simply has random, relative velocity vectors.

If it were a single source, the vast majority of the debris would be expanding from a central point, so you could orient your wedge to face the centre, but that's not the case here. There were also five ships, four Loreleis, and one or two Keyholes just to name the biggest pieces. That's 11 locations debris is emanating from and by this time they're all overlapping.

You're right though that this negates the benefit of a tunnel. Debris is going to move into that soon after it's cleared...

And I still think the ships inside the field probably have the wedge completely down, so that important pieces don't sneak up on them from a blind zone and get obliterated by the wedge.

PS: the text says the debris field is hemispherical. Why hemispherical, not spherical?

Jonathan_S wrote:

cthia wrote:Can your wedge get in the way of your sensors looking for such a small, dead, object?

Absolutely. Even for the ship creating the wedge the distortions they cause seriously degrade sensor aimed through them.

A shuttle may not even bother mounting radar arrays that point towards the wedge since such a small radar, with the limited computing power of a shuttle, probably can't make out much through the wedge anyway. But even if they do the resolution will be much much worse than they'd get pointing a nose or broadside radar array at a potential object of interest.

So while a shuttle could build up some momentum and then hide behind it's wedge as it coasted out of the debris field it'll have a hard time telling quite what its wedge is smashing out of its path. It could be unlucky enough to run over and obliterate a damaged pod or someone in a skinsuit. Even while picking through the field it might not notice debris on a collision course with either wedge plane before it impacts and is obliterated.

Better to take it slow and keep your best sensor facing the debris so you can both work your way around any problem chunks, but also continue your SAR work. You may not see everything, but you'll see far more than if you interposed your wedge between the shuttle and all the debris.

Thanks, I was wondering why it took so long to match the debris fields velocity while traveling with it under power, then a fair bit of time more to match velocities with a pod. I could only think of the possibility the shuttle didn't have access to the wedge; and the only reason I could think of to explain that is it interfered with the sensors.

Then again, even simple, short time slices can seem drawn out in text.

tlb wrote:

ThinksMarkedly wrote:I don't agree. Even if this is the last shuttle in SAR, there may be other reasons to come back. Vacuuming the debris field unnecessarily does not sound like good practice.

What I do expect is that the first SAR shuttles created a tunnel of safe volume through which using the wedge is acceptable. Incoming and outgoing shuttles would stick to it when going to their search zones and thereby avoiding areas of increased hazard.

Either way, that doesn't solve the problem of debris coming from all directions. The wedges help with up and down, plus a great deal of sideways because they're very wide. But they can't stop all sideways motion. And they especially don't help with the direction of motion and that's exactly where most of the debris is going to be coming from.

If you are searching for a pod, you are looking for a signal. That can be done by traveling perpendicular to the debris motion just as well as parallel. I believe that could give the shuttle a wider search area.

I do not understand why you think that there is "debris coming from all directions", unless you mean as the result of collisions with space junk. Mainly those are momentum killers, so if you are near the debris front, those are the pieces that traveled without a major collision. But if you are considering collisions like that, then you cannot have a "safe tunnel".

There is nothing wrong with "vacuuming", provided it is not done to a pod.

Did you really mean "travel perpendicular to the debris motion?" Analogies I can think of is trying to drive your small motorboat perpendicular across a raging river of debris right after a flood. Trust me, that ain't happening. And it's downright frightening. The bottom of your motorboat will have more urine in it than water.

Or consider the difficulty of moving your ship perpendicular to the debris field—of missiles emanating from the top of the screen—while you are at the bottom of the screen in the old arcade game space invaders. Sooner or later, Kaboom!

Another analogy which makes me cringe is merging into speeding traffic on the freeway. It is designed for you to build up speed in the merge lane then enter the melee. In college, I was a passenger just leaving the mall in a small Toyota Corolla. The crazy driver wasn't paying close enough attention and pretty much crossed the merge line and the front end of the car got caught under the rear wheels of an 18 wheeler. We were dragged for a quarter mile. When the truck let us go, we spun around like a top halfway up the embankment. A bowling ball in the trunk had been smashed to powder. The contents of the entire trunk was smashed up against the back of the front seat. My homework papers were raining from the sky. The officer said he doesn't know how we survived that crash, let alone escaped without a scratch.

The driver pretty much entered the debris field at a perpendicular angle.

ThinksMarkedly wrote:It's a question of relative velocity between the SAR ship and the debris field. The explosions imparted velocity in a random direction, added to the base velocity of the ship when it exploded and stopped accelerating. The fact that the debris field is a million kilometres wide at this point means it had this extra velocity. So if the SAR ship is at relative rest to the the debris field as a whole, then relatively all the debris simply has random, relative velocity vectors.

If it were a single source, the vast majority of the debris would be expanding from a central point, so you could orient your wedge to face the centre, but that's not the case here. There were also five ships, four Loreleis, and one or two Keyholes just to name the biggest pieces. That's 11 locations debris is emanating from and by this time they're all overlapping.

You're right though that this negates the benefit of a tunnel. Debris is going to move into that soon after it's cleared...

And I still think the ships inside the field probably have the wedge completely down, so that important pieces don't sneak up on them from a blind zone and get obliterated by the wedge.

PS: the text says the debris field is hemispherical. Why hemispherical, not spherical?

No, the SAR shuttle was moving slowly compared to the debris in its locality. The only way it could be at rest to the debris field "as a whole" would require it to be at the location where the ships would currently have been based on their last velocity (at that point all the debris is moving away). The velocity of the ships is why it is described as hemispherical, because that base velocity is greater than any velocity imparted by the explosion; so for an observer at the point of the explosion, all the pieces are moving away with a forward component (none with backward motion). Is is only from the moving point discussed about that it appears spherical. From that point all the debris is moving radially outward, not in random directions; except for those pieces that have collided with space junk. The collisions between pieces of debris can be ignored, because momentum is still conserved, so they are still headed outward.

If the debris front is a million kilometers across now, then the explosions of the five ships can be treated as a point source to a high degree of accuracy (since they were within a few hundred kilometers of each other).

If the wedge is down, then the shuttle can only maneuver by reaction thrusters and would not be able to search more than its immediate area.

cthia wrote:Did you really mean "travel perpendicular to the debris motion?" Analogies I can think of is trying to drive your small motorboat perpendicular across a raging river of debris right after a flood. Trust me, that ain't happening. And it's downright frightening. The bottom of your motorboat will have more urine in it than water.

Or consider the difficulty of moving your ship perpendicular to the debris field—of missiles emanating from the top of the screen—while you are at the bottom of the screen in the old arcade game space invaders. Sooner or later, Kaboom!

Yes, I did mean perpendicular to the motion of the debris field. Your radar can look for pods ahead and anything that is not a pod can impact the wedge. You can even rotate the wedge so the search can include everything moving toward you (just rotate back before the Kaboom).

This is nothing like crossing a raging river in a small boat, because space is a vacuum - there is nothing to rage. the only things moving are the shuttle and the debris. You can use the radar to ensure that never the twain shall meet.

cthia wrote:Then again, even simple, short time slices can seem drawn out in text.

That depends on whether the character in question suddenly decides to ponder some details that just happen to be relevant to the reader, then spends 8 pages on that before returning with no time having passed at all.

tlb wrote:

cthia wrote:can't she just roll ship while exiting? Keeping in mind that all of the debris, though traveling together, isn't traveling at the same speed. I suppose a shuttle has no sidewalls.

If all the explosions happened at about the same time and place, then the debris in any particular region are all traveling at roughly the same speed (distance from explosion divided by time from the explosion). There is no sidewall, but you can interpose the wedge. However there is a limiting velocity depending on the angle between the shuttle and debris directions and the debris velocity; if you go too fast the debris that clears the wedge can be overtaken by the shuttle.

When you're passing through the debris zone roll the wedge and go ballistic. You're completely safe.

tlb wrote:No, the SAR shuttle was moving slowly compared to the debris in its locality. The only way it could be at rest to the debris field "as a whole" would require it to be at the location where the ships would currently have been based on their last velocity (at that point all the debris is moving away).

Completely agreed. Once destroyed, the ships stopped accelerating and therefore the debris was inertial.

The velocity of the ships is why it is described as hemispherical, because that base velocity is greater than any velocity imparted by the explosion; so for an observer at the point of the explosion, all the pieces are moving away with a forward component (none with backward motion). Is is only from the moving point discussed about that it appears spherical. From that point all the debris is moving radially outward, not in random directions; except for those pieces that have collided with space junk. The collisions between pieces of debris can be ignored, because momentum is still conserved, so they are still headed outward.

That I don't agree with. I mean, your explanation that from the point of view of someone who is at rest relative to the primary at the point where the ships exploded, the debris field is moving away at the speed it had when it exploded. But that does not translate that the shape of the expansion is hemispherical, exactly because the velocities imparted by the explosions are so much smaller than the base velocity of thousands of km/s.

That is to say, while there is no piece of debris that has a velocity vector (relative to the primary or orbital velocities) pointing backwards, the shape of the blob remains spherical. The shape isn't determined by the base velocity[*], but instead by the relative velocities between components. The shape is the same for everyone, regardless of their frame of reference.

[*] Except, of course, if relativistic effects are relevant. If the relative base velocity is great enough that space contraction becomes pronounced, the shape won't be a rough spherical blob, but instead a rough ellipsoidal blob (not an ellipsoid of revolution; I don't know if this 3D geometric shape has a name).

If the debris front is a million kilometers across now, then the explosions of the five ships can be treated as a point source to a high degree of accuracy (since they were within a few hundred kilometers of each other).

That's almost touching wedges. The separation between ships in a formation was never explicitly mentioned, was it?

If the wedge is down, then the shuttle can only maneuver by reaction thrusters and would not be able to search more than its immediate area.

Aye. No one said SAR was easy. It's a long process. But if Honor can accelerate at 50 G in reaction thrusters, an SAR bird can pull one or two. Working outside in, the SAR birds can clear the periphery first, which would allow later birds to use their wedges until further in, before powering down.