Anti-satellite weapon test?, Is this true? |
Anti-satellite weapon test?, Is this true? |
Jan 19 2007, 02:39 PM
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Junior Member Group: Members Posts: 96 Joined: 20-September 06 From: Hanoi, Vietnam Member No.: 1164 |
According to this link, China fired a missile to destroy an orbiting weather satellite last week: http://www.spacewar.com/reports/China_Tras...e_Test_999.html
I am curios about what kind of projectile could be used? A "smart" one with on board guidance system or just a dumb one? How close did the "killer satellite" came to the target? Does anybody have an idea? |
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Jan 22 2007, 09:01 PM
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Founder Group: Chairman Posts: 14448 Joined: 8-February 04 Member No.: 1 |
Just thinking in terms of 'impact window' - i.e. the time taken for the target to cover it's own size in terms of distance - the variable that identifies how accurate something has to be to hit something rushing past - not totally analogous ( you could drive 'down' the velocity vector for instance ) - but it gives you a sense of the scale of the problem.
Car - 4.3 metres - 26 m/sec - window is 0.165 seconds. Jumbo Jet - 57 metres - 223 m/sec - window is 0.255 seconds ( this is why a jumbo 'looks' so slow in the sky - it covers it's own length slower than a small car rushing past). F22 - .030 seconds. Satellite - 3 metre sized bus - 7500 m/sec - window is 0.0004 seconds i.e. stood watching the thing fly past - you've got to be 412 times more accurate hitting a spacecraft than a car doing 60 mph. 637 times more accurate than hitting a flying jumbo - and 75 times more accurate than hitting an F22 raptor. It's a big ask - I don't know how hard it actually is - but this isn't "let's modify a sidewinder' type thing. Doug |
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Jan 22 2007, 09:24 PM
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
Your calculations are only valid for an orthogonal impact, that's probably not the ideal way to do this.
Taking x-axis to be cross track relative to the target, y-axis to be on track and z-axis to be vertical. If you are going to rely on kinetics alone to do the work for you the ideal approach would be to lob your "warhead" into a z-axis ballistic curve that tracks along the targe's y-axis (so x-axis velocity relative to the target is negligable) timed to reach zenith just ahead of the target's arrival (so the z-axis velocity relative to the target is very small). The high y-axis relatively velocity then becomes an advantage as the probe will impact the "warhead" if it intersects the probe at any stage during it's "hang time". For a 25cm "warhead" that impact window is almost a quarter of a second assuming you can target the orbital track and altitude with the same precision. That is obviously not a trivial task but I think it should be simpler than active targetting with a 0.4 microsecond window. |
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