Recently, there have been rumor that China will test its anti-satellite (ASAT) weapon in the coming months. This post tries to analyze what kind of ASAT weapon China try to test, and which target China is aiming at.
There are two types of ASAT deployed in the world. One is Kinetic energy ASAT, a weapon head to head hit to kill a satellite, the other is Co-Orbit ASAT, a weapon fly close to a satellite and explode itself to destroy the satellite.
Of course, there are other ASAT weapons, for example, Laser weapon. However, even if China tests a Laser ASAT, it is unlikely for other countries to figure that out. . Therefore it is unlikely for China to announce that. So, I am not going to discuss it in this blog.
I divide the ASAT weapon into four types, based on the target orbits and killing mechanisms, and then estimate probabilities that each weapon is to be tested by China. See below table:
| Orbit | KE-ASAT | Co-Orbit ASAT |
| Low Earth Orit (LEO) | "Zero" |
Low |
| Medium Earth orbit (MEO) / Geostationary Earth Orbit (GEO) | High | Low |
LEO KE-ASAT
China could test LEO KE-ASAT again. But, the probability of another 2007 ASAT test is almost "Zero". The reason is, even if China does want to test the weapon again, it will not aim at an on-orbit satellite, but a missile. China will call it "missile defense test" instead of ASAT test, just like what it did in 2009. Debris created in such test will decay right after the test.
LEO Co-Orbit ASAT
The probability of testing a co-Orbit ASAT in LEO also seem to be very low. The reason is comparing to KE-ASAT, Co-orbit ASAT has many disadvantages:
It takes much longer time for the weapon to approach target, so that the target might have the chance to escape. That also gives adversary opportunity to destroy the weapon.
It is also much more expensive to deploy a co-orbit ASAT. The weapon has to accelerate to the orbital velocity, i.e. 7.7km/s, while the KE-ASAT does not have to. Moreover, the mass of co-orbit ASAT warhead is also higher than KE-ASAT. For example the Kinetic Energy Kill Vehicle of US missile defense system only weighs tens kilogram, while mass of Russia co-orbital ASAT warhead is 1,400 kilogram.
1986 DIA illustration of the Russia Co-orbit ASAT system attacking a target.
The advantage of co-orbital ASAT is it is relatively easy, because Slowly approaching a satellite is much easier than hitting the satellite with relative speed of 10 km/s. Chinese already had the KE-ASAT technology, it seems not necessary for them to develop outdated co-orbit ASAT.
But, if China really wants to test a Co-Orbit ASAT weapon, it is very likely to be a ground based system. Since testing a space based co-orbit system can be described as testing rendezvous technology. Which is a dual use technology, widely used in manned space flight. Test such technology probably will not raise any international concern.
Co-Orbital ASAT would also create a lot of space debris. Russian did many ground based co-orbit ASAT tests during 1960s to 1980s. There are still thousand pieces of space debris left in orbit from these tests.
MEO/GEO KE-ASAT
If China really want to do something "new" this time, I think, it is more likely to be a KE-ASAT against satellite at MEO or GEO.
The ASAT weapon is likely to be ground based. The Outer Space Treaty bans to put weapons of mass destruction (WMD) into outer space. ASAT may not be considered as WMD, but there is no country really put a destructive weapon in space, even during the cold war. If China tests a space based ASAT weapon, it will open Pandora’s box. Arms race in space will be inevitable, which might not be in China’s interests. If Chinese really want to do that, I personally think, it should also be U.S. interests to persuade Chinese not to do that.
If China want to blow up a satellite this time , these two satellites can be used as a target:
|
NORAD ID |
COSPAR ID |
Name |
Source |
Period |
Inclination (Deg) |
Apogee (Km) |
Perigee (Km) |
|
29516 |
2006-048A |
SINOSAT 2 |
PRC |
1,550.7 |
3.10 |
38,182 |
37,820 |
|
21833 |
1991-088A |
STTW-5 |
PRC |
632.6 |
31.5 |
33,928 |
2,135 |
SINOSAT is a dead TV satellite, it failed right after the launch. The orbit of SINOSAT 2 is 2,500 km above the GEO orbit, therefore debris created in the kinetic energy collision will not pose hazard to other GEO satellites.
In MEO, China has several Beidou satellites, but all these satellites are active. Moreover, if one of Beidou satellite is destroyed, debris created in the collision will threatens other Beidou satellites. STTW-5/DFH-2 is the only dead Chinese MEO satellite. If China want to test the ability to attack a MEO satellite, it could be used as target. Debris created in this attack would not pose significant hazard to existence satellites.
China already tested kinetic kill technology from previous tests, it may not need to blow up satellite this time. Instead, what China could test is how to deliver the kinetic energy weapon into appropriate orbit. Since it takes couple hours for the weapon to reach the target, target could maneuver away from original orbit, China may also test how to adjust the orbit of the weapon.
MEO/GEO Co-orbit ASAT
The probability for China to test MEO/GEO co-orbit ASAT is very small.
As I said, it is unlikely for China to test a space based weapon, unless it wants to be the first country to put a destructive weapon in space.
If China want to test a ground based co-orbit ASAT, it must have a missile that can deliver the warhead into MEO/GEO. To kill the target, the mass of the warhead should be hundreds kilogram. However, current Chinese ICBMs, i.e.
DF-4/31/41 are unable to deliver a 100 kg payload into GEO orbit.
Of course, China could use its Long March Rocket to launch the weapon, but such weapon system is very vulnerable and expensive. Since China already have the KE-ASAT technology, it would be stupid for China to develop ground based co-orbital ASAT.
All in all, The probability of testing co-orbital ASAT should be very small. China is more likely to have another missile defense test or test a kinetic energy ASAT against MEO/GEO satellites.
