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Docking and Rolling Fears Delay Soyuz and Progress Launches

By Keith Cowing
NASA Watch
June 1, 2016
Filed under , ,
Docking and Rolling Fears Delay Soyuz and Progress Launches

Launch of new series manned spacecraft rescheduled due to risk of docking disruption, TASS
“The launch has been rescheduled for July 7,” he said. “The crew is expected to come to Baikonur (the Russian space center located is Kazakhstan TASS) on June 24.” “Experts have established the ship will be rolling as it docks the ISS and they are unable to stop this rolling motion so far,” the source said.

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4 responses to “Docking and Rolling Fears Delay Soyuz and Progress Launches”

  1. duheagle says:
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    This story is almost completely incomprehensible. The Soyuz was weeks away from being launched, even on the original schedule, but – somehow – ground control was able to foresee that it would have an uncorrectable and unacceptable roll rate at the time of docking. Can anyone else here make sense of this? Is the shade of Madame Blavatsky now running Roscosmos?

    • Michael Spencer says:
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      An early Soviet attempt at docking- perhaps the first- was a failure.

      Reason? The cosmonaut had his Soyuz rotated 180° about the centerline of the approach vector. As a result, the little lights he was supposed to use were on the bottom, not top, and he couldn’t get it right. Didn’t figure it out until the attempt was aborted and he was back home, never to fly again.

      The Soviets/ Russians have been all over autonomous docking from the beginning, seeing the procedure as preferable to piloting; the policy was in effect when the pilot made the error I describe above.

      Maybe the Russian Bear has a long memory?

    • Jeff2Space says:
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      The only thing I can guess is that there is some sort of problem with the guidance system. Perhaps a gyro is drifting far too quickly out of spec?

    • fcrary says:
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      I don’t know anything about the Soyuz systems, but I’ve seen something similar happen to other (unmanned) spacecraft. The pointing profile may (and for other spacecraft is) built around aligning a couple of spacecraft axes with particular directions. An example would be pointing the Z axis along the direction of motion (docking port forward) while rolling about the +Z axis so that the Sun is as close as possible to the spacecraft +X axis (maximum power to the solar arrays) and then doing a roll so an antenna is pointed towards ISS. Those are made-up details, but it’s the sort of thing that often defines a spacecraft’s pointing profile.

      Then, once you’ve got all that worked out, and you plug in the geometry for a particular execution, you can get nasty surprises. If the direction of motion and the Sun are too close together (if you’re flying towards the Sun) that pointing plan can imply a rapid roll. Depending on how ISS is pointed, a turn from one orientation to another might be big or small. If the schedule didn’t have those calculations done until a month or two before execution, it would look a whole lot like what was reported.