6 ms·

But if detected early enough it might not take much more than a DART sized nudge of even a Chicxulub sized asteroid to change it’s course enough to miss the Ear

But if detected early enough it might not take much more than a DART sized nudge of even a Chicxulub sized asteroid to change it’s course enough to miss the Earth. The whole reason DART targeted a two asteroid system was so we could measure how much we changed Dimorphos orbit around Didymos. If we have to blow these things into rubble shortly before impact we might be in big trouble.

cubefox 3y ago
With a ten kilometer Chicxulub class asteroid, blowing it into rubble is not on the table anyway, even with rather large hydrogen bombs. We can only hope to deflect them.
LorenPechtel 3y ago
DART nudged it's target about 2.7mm/sec. To ensure a miss you need a sideways deflection of up to 4000 km (depends on the geometry.) To generate a miss by Dimorphos assuming the worst case you're looking at 1,481,481,481 seconds of lead time. That's about 47 years. Against the dinosaur killer you're looking at a lead time far beyond our ability to predict orbits. Note, also, that if you're throwing kinetic stuff at your target you get little choice in how it hits, you very well might not be able to shove it to the side. Despite the refusal to consider the option there really is only one choice against a major threat: Orion. We know it works (it has been flight tested with conventional charges, it has been tested with single impulses with nuclear charges), while there are some serious question marks about whether you could actually build an Orion capable of launching form Earth (how do you keep the pusher plate from getting too hot??) that does not apply if you're using it against an asteroid. You don't care what shape the asteroid ends up in, just that it get out of the way. Your only limit is that you don't want to make any given shove big enough to risk breaking the asteroid. By a crude approximation you can easily get 10% of the bomb energy to show up as impulse, this can be increased by putting the bomb closer (remember, you don't care about damage short of destruction) and some still-classified data says that it's possible to build a shaped charge that directs the majority of it's energy at the asteroid. Obviously, exact numbers are not known to us mere mortals.
- db48x 3y ago
  Gravity tractors would also work, with just a couple of years of lead time.
- cubefox 3y ago
  I think Orion requires SLS rockets, which are very slow and expensive to produce.
  - Vecr 3y ago
    Wrong Orion. This is the one with the nuclear bombs and pusher plate.

cubefox 3y ago

With a ten kilometer Chicxulub class asteroid, blowing it into rubble is not on the table anyway, even with rather large hydrogen bombs. We can only hope to deflect them.

LorenPechtel 3y ago

DART nudged it's target about 2.7mm/sec. To ensure a miss you need a sideways deflection of up to 4000 km (depends on the geometry.) To generate a miss by Dimorphos assuming the worst case you're looking at 1,481,481,481 seconds of lead time. That's about 47 years. Against the dinosaur killer you're looking at a lead time far beyond our ability to predict orbits. Note, also, that if you're throwing kinetic stuff at your target you get little choice in how it hits, you very well might not be able to shove it to the side. Despite the refusal to consider the option there really is only one choice against a major threat: Orion. We know it works (it has been flight tested with conventional charges, it has been tested with single impulses with nuclear charges), while there are some serious question marks about whether you could actually build an Orion capable of launching form Earth (how do you keep the pusher plate from getting too hot??) that does not apply if you're using it against an asteroid. You don't care what shape the asteroid ends up in, just that it get out of the way. Your only limit is that you don't want to make any given shove big enough to risk breaking the asteroid. By a crude approximation you can easily get 10% of the bomb energy to show up as impulse, this can be increased by putting the bomb closer (remember, you don't care about damage short of destruction) and some still-classified data says that it's possible to build a shaped charge that directs the majority of it's energy at the asteroid. Obviously, exact numbers are not known to us mere mortals.

db48x 3y ago
Gravity tractors would also work, with just a couple of years of lead time.
cubefox 3y ago
I think Orion requires SLS rockets, which are very slow and expensive to produce.
- Vecr 3y ago
  Wrong Orion. This is the one with the nuclear bombs and pusher plate.