CHINA vs U.S.A. Anti-Ship Ballistic Missile Technology

[Reality Check]

Even while traveling 17,500 miles per hour in low Earth orbit, getting to the ISS ( International Space Station )takes a few days of maneuvering using phasing orbits to match the speed and position of the target.

True, but weapons, especially kinetic energy weapons, want to do the opposite of "matching speed and position". They just need to attempt to occupy the same point in space at the same time as the target. There are literally an infinite number of possible orbits that would do that. Matching speed and position of the target is the last thing you would want to do with a kinetic energy weapon. It is the matching speed and position that takes all the time.

Physics determine what happens when two objects traveling at very high relative rates of speed attempt to occupy the same space at the same time. The result is the same, even if one of the objects is very small.

[Reality Check]

If you are 160 km above seal level, you are traveling at 7.8 km/s and circle the Earth once every 88 minutes. Slowing down will shrink your orbit causing you to reenter, and speeding up will put you into a higher orbit that will have a longer period and slower velocity. 500 km up gives a velocity of 7.6 km/s with a period of 95 minutes. At 10,000 km, that gives 5 km/s and a revolution of 5.8 hours..

While an orbit can be circular, there are infinitely more orbits that are not circular. Elliptical orbits have many, many advantages over the type of circular orbit you describe above. They can pass very near the upper atmosphere at extremely high rates of speed. They can dip into the atmosphere to slow down rapidly, or skip off the atmosphere to change orbit suddenly.

The mathematics of such orbital mechanics is much more complex, but modern micro-computers can do such math nearly instantaneously.

[vincecate]

The mathematics of such orbital mechanics is much more complex, but modern micro-computers can do such math nearly instantaneously.

I even wrote a simulator that runs as a Java applet. It can simulate orbits, space tethers, reentry heating and drag, and lots of stuff. It is free and at:

http://spacetethers.com/spacetethers.html

[psCargile]

True, but weapons, especially kinetic energy weapons, want to do the opposite of "matching speed and position". They just need to attempt to occupy the same point in space at the same time as the target. There are literally an infinite number of possible orbits that would do that. Matching speed and position of the target is the last thing you would want to do with a kinetic energy weapon. It is the matching speed and position that takes all the time.

No argument there, but If I have the delta V budget to change my orbit upon detection of your kinetic energy weapon, I avoid a collision.

[psCargile]

I even wrote a simulator that runs as a Java applet. It can simulate orbits, space tethers, reentry heating and drag, and lots of stuff.

Have you ever played around in Orbiter? http://orbit.medphys.ucl.ac.uk/

Space tethers . . . would those be the momentum exchange tethers?

[vincecate]

I even wrote a simulator that runs as a Java applet. It can simulate orbits, space tethers, reentry heating and drag, and lots of stuff.

Have you ever played around in Orbiter? http://orbit.medphys.ucl.ac.uk/

Space tethers . . . would those be the momentum exchange tethers?

I have not tried Orbiter but it looks very nice. Might get my boys to play with it this summer.

Yes, rotating momentum exchange tethers. Also electrodynamic tethers that thurst against the Earth's magnetic field, and hanging tethers that rotate once per orbit so the same side is always down.