IPB

Welcome Guest ( Log In | Register )

2 Pages V   1 2 >  
Reply to this topicStart new topic
Anti-satellite weapon test?, Is this true?
Thu
post Jan 19 2007, 02:39 PM
Post #1


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?
Go to the top of the page
 
+Quote Post
climber
post Jan 19 2007, 03:06 PM
Post #2


Senior Member
****

Group: Members
Posts: 2603
Joined: 14-February 06
From: Very close to the Pyrénées Mountains (France)
Member No.: 682



QUOTE (Thu @ Jan 19 2007, 03:39 PM) *
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?

OK, weather forcasts are sometimes very bad. I didn't thought China will get THAT angry about it biggrin.gif


--------------------
Go to the top of the page
 
+Quote Post
Lorne Ipsum
post Jan 19 2007, 06:51 PM
Post #3


Newbie
*

Group: Members
Posts: 18
Joined: 17-September 06
From: USA
Member No.: 1151



Nobody really knows the details, but most reports I've read say the satellite was hit with a kinetic warhead (i.e., no explosives, just a direct hit with the sensor head). This pretty much mandates a "smart" projectile.

Lorne


--------------------
Lorne Ipsum, Chief Geek
Geek Counterpoint blog & podcast
Go to the top of the page
 
+Quote Post
nprev
post Jan 20 2007, 01:59 AM
Post #4


Senior Member
****

Group: Moderator
Posts: 6948
Joined: 8-December 05
From: Los Angeles
Member No.: 602



Anybody know what the inclination of the target satellite's orbit was? I got a sinking feeling that it might well have been in a polar orbit...worried a bit about the NOAA polar orbiters & that debris cloud... unsure.gif

EDIT: Yep, it was in a polar orbit, but a bit below the NOAA POES... smile.gif


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
Go to the top of the page
 
+Quote Post
OWW
post Jan 20 2007, 12:12 PM
Post #5


Member
***

Group: Members
Posts: 690
Joined: 28-September 04
Member No.: 99



QUOTE (nprev @ Jan 20 2007, 02:59 AM) *
I got a sinking feeling that it might well have been in a polar orbit...worried a bit about the NOAA polar orbiters & that debris cloud... unsure.gif

EDIT: Yep, it was in a polar orbit, but a bit below the NOAA POES... smile.gif


According to Jonathan's Space Report ( http://www.planet4589.org/space/jsr/latest.html ):

The FY-1C was in an 843 x 862 km x 98.7 deg orbit; the debris cataloged so far ranges from
165 x 850 km to 850 x 3500 km, a wide range of heights indicating an
energetic fragmentation with delta-Vs of -190 to +550 m/s. Of course,
we are missing the tail of dV significantly less than -190 since those objects
would reenter immediately.


Correct me if I'm wrong, but doesn't this put ALL satellites from 165 to 3500 km at risk and not just the ones around 850 km? blink.gif
Go to the top of the page
 
+Quote Post
Thu
post Jan 22 2007, 04:42 PM
Post #6


Junior Member
**

Group: Members
Posts: 96
Joined: 20-September 06
From: Hanoi, Vietnam
Member No.: 1164



Thank you all for your information. Still no official speak from China yet so I do believe the test was real sad.gif
There is no international law against this kind of test? How about the Outer Space Treaty?
Go to the top of the page
 
+Quote Post
djellison
post Jan 22 2007, 04:53 PM
Post #7


Administrator
****

Group: Chairman
Posts: 13705
Joined: 8-February 04
Member No.: 1



Very very close to becoming a political thread here - but the USA recently refused to sign up to an agreement banning such tests.

Doug
Go to the top of the page
 
+Quote Post
Chmee
post Jan 22 2007, 05:55 PM
Post #8


Member
***

Group: Members
Posts: 153
Joined: 17-March 05
Member No.: 206



The US did develop an anti-satellite weapon back in the 1980's and actually shot one down in 1985. I beleive the weapon was actually carried on an F-15 and shot into space (Pagasus style). While the US has not conducted such tests since then (that we know of..) it is beleived they still have the capability.

As for the Chinese anti-sat weapon being 'smart' or 'dumb' it is hard to say. You would not have to do a 'bullet hits a bullet' type of kill vehicle to accomplish this. Rather, a 'dumb' weapon could be used to spray some material, over a large area, in the path of the intended satellite, like sand or ball bearings. The relative speed would between the objects would be all thats needed.
Go to the top of the page
 
+Quote Post
djellison
post Jan 22 2007, 06:29 PM
Post #9


Administrator
****

Group: Chairman
Posts: 13705
Joined: 8-February 04
Member No.: 1



QUOTE (Chmee @ Jan 22 2007, 05:55 PM) *
like sand or ball bearings. The relative speed would between the objects would be all thats needed.


That's what I was imagining this to have been. Launch - on a high sub-orb trajectory, and disperse a cloud of lead shot etc - through the satellite goes - 7.5k/sec impacts - the remaining shot just re-enters harmlessly but the sat is blown to pieces.

Doug
Go to the top of the page
 
+Quote Post
tty
post Jan 22 2007, 07:34 PM
Post #10


Member
***

Group: Members
Posts: 683
Joined: 20-April 05
From: Sweden
Member No.: 273



Actually a satellite in LEO is not a particularly challenging target. Its position and trajectory is known in advance and it is usually a non-maneuvring target. Also it usually has a nice big cross-section in both the radar, IR and visual band and operates in a very uncluttered environment.

All that is needed is a reasonably precise suborbital rocket and a suitable warhead. However I doubt that the "ball-bearing/sand" solution is cost effective. Unless You release quite close to the target they would probably disperse too thinly to ensure a kill. It would probably be better to use a homing warhead with a proximity fuse. Anybody having the technology for the carrier rocket should be able to handle the guidance system and the warhead too.

tty
Go to the top of the page
 
+Quote Post
Bob Shaw
post Jan 22 2007, 08:18 PM
Post #11


Senior Member
****

Group: Members
Posts: 2488
Joined: 17-April 05
From: Glasgow, Scotland, UK
Member No.: 239



QUOTE (tty @ Jan 22 2007, 07:34 PM) *
It would probably be better to use a homing warhead with a proximity fuse. Anybody having the technology for the carrier rocket should be able to handle the guidance system and the warhead too.

tty


It's a tad more difficult than it looks. Most aircraft missile systems don't use thrust to control attitude, but instead rely on aerodynamic forces. An exoatmospheric vehicle has to be precisely stabilised, and because it has to actively hunt down a target then spinning probably won't do. You're looking at 3-axis attitude control, plus an ability to change direction at very short notice. Some of the Star Wars kinetic kill vehicles not only were 3-axis stabilised, but also spun to deploy arms at the last moment and then also disintegrated to provide further frontal area. All this has to be arranged in a space of seconds, with space-hardened computers. All in all, it's a very tough call, and the US has done it only a very few times (and sometimes by moving the goalposts after the event). China's success is a major milestone, and speaks highly of their space technology.


Bob Shaw


--------------------
Remember: Time Flies like the wind - but Fruit Flies like bananas!
Go to the top of the page
 
+Quote Post
helvick
post Jan 22 2007, 08:46 PM
Post #12


Dublin Correspondent
****

Group: Admin
Posts: 1795
Joined: 28-March 05
From: Celbridge, Ireland
Member No.: 220



So with a bit of luck they might now consider that they have successfully shown all interested parties that they are well in contention in LEO and that they now need to demonstrate some serious long range remote capability - expect Chinese Moon, Mars and outer planets missions to follow shortly.

So it's time to go and learn Chinese folks so we can stay on top of CNSA's PR department.

(Just looking for the bright side since this is my 1000'th post. smile.gif )
Go to the top of the page
 
+Quote Post
djellison
post Jan 22 2007, 09:01 PM
Post #13


Administrator
****

Group: Chairman
Posts: 13705
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
Go to the top of the page
 
+Quote Post
helvick
post Jan 22 2007, 09:24 PM
Post #14


Dublin Correspondent
****

Group: Admin
Posts: 1795
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.
Go to the top of the page
 
+Quote Post
tty
post Jan 23 2007, 07:32 AM
Post #15


Member
***

Group: Members
Posts: 683
Joined: 20-April 05
From: Sweden
Member No.: 273



QUOTE (djellison @ Jan 22 2007, 10:01 PM) *
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.



Well, not early Sidewinder at least since they used pursuit-curve logic. This would be a collision-course interception, preferably from nearly dead ahead and would probably use constant-bearing logic. That is: if You keep the bearing to the target constant you are bound to hit it sooner or later.
The main problem in this case is the very high closure rate which means that tracking and manoeuvring have to be precise at fairly long range otherwise very large and fast corrections will be needed at a late stage in the interception. The proximity fuse will also need to be fast and precise. The latter is more difficult than it sounds. Sufficiently precise fusing is one of the main challenges in building implosion-type nuclear weapons.

tty
Go to the top of the page
 
+Quote Post

2 Pages V   1 2 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 29th July 2014 - 04:48 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.