ISS performs collision avoidance maneuver

[tblaxland]

From the ISS Daily Report:

Using ATV thrusters, the ISS performed a DAM (Debris Avoidance Maneuver) burn at 12:11pm EDT (in lieu of the IWIS Thruster Firing Test originally planned) to remove the risk of collision with an orbital object,- #33246 (part of the Kosmos-2421 satellite). [Miss distance of the object, tracked over several days, was predicted this morning to be 1.627 km, with a collision probability of 0.0139 (odds 1:72) which brought it over the ruled threshold into the RED box (FR B4-101, i.e.,” greater than 1 in 10,000”), requiring a DAM. The burn, calculated to last 5 min 2sec, was performed with two thrusters of the ATV main propulsion system. Predicted delta-V was ~1 m/s, in retrograde direction, so that future Soyuz launch, Soyuz landing and Shuttle ULF2 launch constraints can be met. An automated timer-controlled confirmation check by the RS CCS (Command & Control System) software of the transition to the proper system configuration for the thruster burn did not take place and had to be done manually by MCC-H Flight Control in time for the burn. Note: The last DAM was performed on 5/30/03.]

A relatively rare event (thankfully).

 

[Andy44]

A DAM maneuver, huh. DAM maneuvers are a nuisance, I tell ya. Just when you think your orbiting fine, along comes the need to do another DAM maneuver.

 

[SiberianTiger]

Funny thing is that Russian Ministry of Defence consistently denied that disintegration of the Cosmos-2421 ever happened. So it turns out, there was nothing to avoid.

 

[W35M4N]

Andy44 is awesome.

 

[simonpro]

Funny thing is that Russian Ministry of Defence consistently denied that disintegration of the Cosmos-2421 ever happened. So it turns out, there was nothing to avoid.

Judging from the radar data it didn't disintegrate. The main body of the satellite is still in one piece but from the RCS it seems to have lost a solar panel.


Some of it's (fully functioning) sister satellites exhibit debris coming off them too, but nothing as large as a solar panel.

 

[Notebook]

ESA's view on the manouver:-

http://www.esa.int/SPECIALS/Operations/SEM64X0SAKF_0.html

N.

 

[SiberianTiger]

Judging from the radar data it didn't disintegrate. The main body of the satellite is still in one piece but from the RCS it seems to have lost a solar panel.

Some of it's (fully functioning) sister satellites exhibit debris coming off them too, but nothing as large as a solar panel.

Whose radar data do you refer to? How small are the objects the radar can detect? From what I've got:

Some debris from the first fragmentation of Cosmos 2421 on 14 March 2008 were thrown into orbits with apogees up to 300 km higher than the pre-event orbit of 400 km by 420 km and perigees as low as 200 km. A little more than six weeks later on 28 April, a new cloud of debris from Cosmos 2421 was observed with some fragments now reaching
above 900 km at apogee.

The third and thus far final fragmentation event occurred on
9 June when the orbit of the main element of the Cosmos 2421 had
decayed slightly to 390 km by 415 km. Once again, more than 100
new debris were observed by the SSN, bringing to 500 or more the assessed
total number of debris created as a result of the three fragmentation events

Sounds like a result of a pressurized vessel's explosion to me.

 

[simonpro]

NORAD tracking data, can't check it again now as I'm at home but there were something like 400-500 fragments, all with absolutely minute radar cross sections.

(i.e: Their radar cross sections in LEO are smaller than the lens cover that fell of MSG-2 in GEO). They are at the absolute limit of radar capabilities.

 

[Notebook]

As a generic query, would the ISS yaw or pitch to change its attitude?

N.

 

[tblaxland]

An Update

Again from the ISS Daily Report:

A second possible conjunction with another piece (#33248) of Kosmos-2421 has been identified for tomorrow (8/29) at 9:09pm EDT, currently predicted to be in the RED box. This would require another DAM (Debris Avoidance Maneuver), but more tracking is required for a burn decision. Estimated prime TIG (Time of Ignition): tomorrow 7:00pm. Prop strategy is currently under study. If a second DAM is necessary tomorrow, using ATV prop, the Progress 29P undocking on 9/1 (Monday) can be supported by SM thrusters. Ballistic calculations must continue to account for future Soyuz launch, Soyuz landing and Shuttle ULF2 launch/rendezvous constraints.

-----Posted Added-----

As a generic query, would the ISS yaw or pitch to change its attitude?

N.

The only reference I could find was in this 2000 NASA document (page 3-64). It talks about the station yawing 180° to use the US propulsion module (which is no longer part of the plans for the station). It is interesting because I would have expected pitch to be used since there should be less inertia to overcome?

 

[Sherrif of Nottingham]

Andy44... Wow, I love it, I love it! Just became my favorite quote!

Um, any particular reason the ISS in Orbiter can't do this?