Author Topic: LIVE: Progress MS (№ 431) – Mission Events – From Dec. 21, 2015 (Read 64991 times)

Nicolas PILLET · « **Reply #180 on:** 07/01/2016 09:39 pm »

Quote from: Space Pete on 07/01/2016 08:45 pm

One speculation I could add is that, when the probe hit the cone, which always causes a change in attitude since the probe rarely hits the cone exactly head-on, perhaps the Progress tried to correct for this attitude change without being aware that contact had already been achieved? Or something along those lines?

When the probe hits the cone, the four DK1 sensors allow the ABU control system to know that the contact has occured. At this moment, if the speed/angle criteria are correct, the "CONTACT" signal is emitted.
The "CONTACT" signal has one consequence : it orders the firing of DPO thrusters to make the spaceship going deeper into the cone.

We could guess that, if at this moment there is a failure of some DPO, the movement will be non nominal.

BUT, the "non nominal movement" has not occured at this particular stage. It has occured AFTER the DK2 sensors have emitted the LATCHING command, which means that the probe is inside the deep of the cone. At this moment, the DPO thrusters has no reasons to start (if everything works fine, which obviously was not the case yesterday).

Danderman · « **Reply #181 on:** 07/01/2016 10:26 pm »

Firing the Y axis thrusters is bad. You don't want to bend the probe.

Firing the X axis thrusters is normal, it drives the probe into the cone.

Firing the Progress thrusters is normal, which is why ISS is in free drift at docking.

Chris Bergin · « **Reply #182 on:** 07/02/2016 09:13 pm »

Apologies if I've read over it, but what time is undocking? Supposed to be Sunday, I believe.

SMS · « **Reply #183 on:** 07/02/2016 09:40 pm »

Undocking is planned at 3:48 UTC on Sunday/11:48 pm EDT on Saturday night

Chris Bergin · « **Reply #184 on:** 07/02/2016 11:28 pm »

Quote from: SMS on 07/02/2016 09:40 pm

Undocking is planned at 3:48 UTC on Sunday/11:48 pm EDT on Saturday night

Thanks! I'll stay up for that one. Thanks also for some good posts in this thread that will help me with the article.

Chris Bergin · « **Reply #185 on:** 07/03/2016 03:58 am »

РОСКОСМОС ‏@roscosmos 1m1 minute ago View translation
Грузовой корабль #ПрогрессМС отстыковался от МКС, затопление несгораемых остатков запланировано в 10:50 мск.

Undocking article:
https://www.nasaspaceflight.com/2016/07/progress-ms-01-departs-following-off-nominal-test/