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Comment by burnerthrow008 | Hacker News Reader

> The brilliant pebbles were supposed to be stationed in orbit. What I'm talking about is simply an upgrade of the current ground based missile defense

How would that work?

Starship uses cryogenic fuel, and thus isn't something you can keep on active standby for years at a time, ready to be launched with a few minutes notice. It takes hours for a Starship to be loaded with liquid oxygen and prepared for launch. By the time you finished getting it ready for launch, it would have been nuked by the other side's second wave.

The only way Starship could be practically useful for missile defense is by launching some kind of defense system stationed in orbit.

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> How would that work?

Kinetic bombardment is possible by launching a satellite with (for example, since its a popular description) heavy tungsten rods, that are parked in orbit. The launch can be years ahead, and disguised as a communications hub.

The satellite can “shoot” at targets from orbit. A rod carries no explosives, and is hard to stop.

The speed due to falling/gravity makes the kinetic impacts huge, its basically small asteroids.

They can even be guided, like the landing boosters.

And to go full circle: the concept of aero-flaps on Falcon-9 (and later Starship Booster) was inspired by designs for falling guided bombs, where fins did not perform at the speeds achieved.

The stated goal for the Starship is to be able to go to orbit and come back and then refuel and do another round trip within the same day. Sometimes twice a day. And to keep doing that for a long period of time.

Compared to that, just keeping a Starship fueled for a long period of time, then emptying it, performing various checks, and refueling it for another period of duty seems quite mild.

Space-based interceptor missiles would have their own propulsion. You could lift to orbit, I don't know, 500 of them at a time with Starship—but each of them would need their own, individual, storable propulsion systems to do their function, which is intercepting.

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