6 ms·

It seems that you always want to use deflection, despite what they did in the movies, and it is doubtful whether a nuclear explosion would be better than attach

by not2b 5y ago

It seems that you always want to use deflection, despite what they did in the movies, and it is doubtful whether a nuclear explosion would be better than attaching something to the object and generating enough thrust to alter its path, possibly using some of the mass of the object itself (stupid way: land a trebuchet, toss enough rocks into space to move it).

perihelions 5y ago
Nuclear detonations would also use the mass of the object itself. The short radiation pulse ablates material off of the surface, and that's what provides most of the impulse. Vaporized rock is the reaction mass.
- AnimalMuppet 5y ago
  I wonder. Is ablation better than having the warhead in the center of some mass, detonating the warhead to drive some of the mass at very high velocity into the target?
  - lazide 5y ago
    Considering that any mass as part of the launch vehicle will have a major trade off in time to intercept? It’s way better to use the asteroid or comet itself. Every bit of mass (or second of delay to launch) you add to the intercept vehicle allows the bolide to get that much closer, requiring that much more escalating delta-v be added to it to clear the planet in time. If the object is caught and intercepted far away, it may take only the slightest nudge. Up close and personal, it might require almost vaporizing it.
    - AnimalMuppet 5y ago
      Fair. Or, you could use the same boost capacity to send more warhead, instead of more inert mass.
      - lazide 5y ago
        Yup, though time to intercept is a huge part of this. Optimizing anything about the strike itself (more powerful warhead, or whatever) is rarely as useful as getting there sooner, which is usually done by using what we might already be able to get there and doing it as quickly as possible. Adding in that practically, we have no idea how to detect and intercept/prevent an actual issue in practice right now. All actual hits have hit. We have never successfully stopped a hit yet. We had zero warning either, or awareness it was happening until they blew up in the sky somewhere. We already know of a number of near misses that are large, but that is generally because they are near misses and not hits, so we have time to plot orbits, think about it, they are generally recurring so we can do this a couple times, etc. All the comet missions have taken a very long time, literally years. We’ve never actually tried to intercept an object on a short time line like we would with a surprise object and do anything to it. So it’s all still theoretical. Some of this is pretty basic stats - if large objects came about frequently, we’d all be dead. But because large objects don’t come about frequently, we have no real experience handling this.
dboreham 5y ago
The nuclear weapon is a very high power trebuchet.
ravi-delia 5y ago
I think in terms of force:mass you can't beat nukes. We know how to make them, we know how to put them on rockets, and we can can line them up to detonate a little away from the asteroid, while a landing would need to match velocity. Probably the best would be nuclear shaped charges a la Project Casaba-Howitzer, which I believe were initially explored as a vehicle propellant.

by not2b 5y ago

perihelions 5y ago

Nuclear detonations would also use the mass of the object itself. The short radiation pulse ablates material off of the surface, and that's what provides most of the impulse. Vaporized rock is the reaction mass.

AnimalMuppet 5y ago
I wonder. Is ablation better than having the warhead in the center of some mass, detonating the warhead to drive some of the mass at very high velocity into the target?
- lazide 5y ago
  Considering that any mass as part of the launch vehicle will have a major trade off in time to intercept? It’s way better to use the asteroid or comet itself. Every bit of mass (or second of delay to launch) you add to the intercept vehicle allows the bolide to get that much closer, requiring that much more escalating delta-v be added to it to clear the planet in time. If the object is caught and intercepted far away, it may take only the slightest nudge. Up close and personal, it might require almost vaporizing it.
  - AnimalMuppet 5y ago
    Fair. Or, you could use the same boost capacity to send more warhead, instead of more inert mass.
    - lazide 5y ago
      Yup, though time to intercept is a huge part of this. Optimizing anything about the strike itself (more powerful warhead, or whatever) is rarely as useful as getting there sooner, which is usually done by using what we might already be able to get there and doing it as quickly as possible. Adding in that practically, we have no idea how to detect and intercept/prevent an actual issue in practice right now. All actual hits have hit. We have never successfully stopped a hit yet. We had zero warning either, or awareness it was happening until they blew up in the sky somewhere. We already know of a number of near misses that are large, but that is generally because they are near misses and not hits, so we have time to plot orbits, think about it, they are generally recurring so we can do this a couple times, etc. All the comet missions have taken a very long time, literally years. We’ve never actually tried to intercept an object on a short time line like we would with a surprise object and do anything to it. So it’s all still theoretical. Some of this is pretty basic stats - if large objects came about frequently, we’d all be dead. But because large objects don’t come about frequently, we have no real experience handling this.

dboreham 5y ago

The nuclear weapon is a very high power trebuchet.

ravi-delia 5y ago

I think in terms of force:mass you can't beat nukes. We know how to make them, we know how to put them on rockets, and we can can line them up to detonate a little away from the asteroid, while a landing would need to match velocity. Probably the best would be nuclear shaped charges a la Project Casaba-Howitzer, which I believe were initially explored as a vehicle propellant.