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Comment Re: Impact ejection is the whole purpose (Score 1) 63

The momentum of [asteroid + projectile] is the same as that of [remaining asteroid + asteroid fragments + projectile fragments]. Momentum of ejected fragments is momentum that could have been transferred (in an inelastic collision) to the combined [asteroid + embedded projectile]. You might say that the delta-V of the combined center of mass is reduced by the energy of the fragments (I'm mixing quantities, but you can visualize an event with and without debris cloud). It's different from a case with reactive bodies, or thermal/radiation transfer where heated material spalls off the asteroid and gives it a little push in the opposite direction.

Comment Re: Impact ejection is the whole purpose (Score 1) 63

Energy and momentum are conserved, so adding up all the many (1/2Ã--mÃ--v^2) terms should get about the same answer (some is converted to thermal energy; not sure about fracture mechanics). In the end, the velocity change to the main rock is *reduced* by energy imparted to the smaller bits.

Comment Re:Duh (Score 1) 60

It's not just profit, it's resource-rich entities. It's easy to think of historical examples to replace "AI" in that headline: farming, pottery, weaving, radio, rocketry. Garage/academic tinkerers just can't play at the same level. Some subjects circle back around if and when costs fall and methods get easier.

Comment Re:How is that meant to work (Score 1) 49

The truly curious can search the FCC and USPTO web sites for most of the technical information.
FCC: search results include "Technical Narrative" and "Sched S Tech Report".
USPTO: search "Lynk Global" or patent "10523313 B2", "Method And Apparatus For Handling Communications Between Spacecraft Operating In An Orbital Environment And Terrestrial Telecommunications Devices That Use Terrestrial Base Station Communications".

There are similar documents for AST&Space's SpaceMobile system.

Comment Re:A third of the country submerged? (Score 1) 94

No mod points, so I'll reply to the best answer so far...

The two Mississippi River basin floods of the last decade flooded an area maybe the size of Texas (eyeballing the flood maps -- all I can find are regional totals) for weeks and only 12 people died. The losses to agriculture, property (structures), and river commerce were tremendous, though apparently recoverable for the US. After the first week it's mostly farmers watching their crops and livestock expire in a foot of water that extends miles in every direction.

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