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Soyuz TMA-11 lands 400km off course, Ballistic trajectory
imipak
post Apr 19 2008, 12:22 PM
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BBC: "A Russian Soyuz spacecraft has returned to Earth, but came down more than 400km (250 miles) away from its planned touchdown point, say Russian officials. The crew are safe, but were subjected to severe G-forces during re-entry, said a spokesman for Mission Control according to AP news agency."

http://news.bbc.co.uk/1/hi/sci/tech/7355912.stm

..?!!



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Guest_PhilCo126_*
post Apr 19 2008, 12:33 PM
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First time a Soyuz spacecraft had 2 women onboard... unsure.gif
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ilbasso
post Apr 19 2008, 01:03 PM
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CNN had an extra digit in their reporting - they were stating the landing was 2420 km off target! Actually, if the landing was 20 minutes later than anticipated, as the BBC reported, that would seem more plausible than the BBC's stated 420 km miss.

Isn't this the 3rd or 4th time that a Soyuz TMA has had a ballistic reentry? I remember TMA-1 had a bad landing. Energia officials initially blamed it on the cosmonaut pushing the wrong button. Later, it was determined that a problem in the avionics box caused the flight computer to select a ballistic trajectory. Energia said, "engineers suspect that under very rare circumstances a complex combination of signals in the system could accumulate into a slight delay measured by fractions of seconds in the firing of the spacecraft engines and result in the switch to the ballistic reentry mode." I thought it had been corrected, but apparently not. Maybe these "rare circumstances" are not as rare as they thought.

Also, if ballistic entry mode is so bad, why would the computer have that as an option? I guess for emergency circumstances only.


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Tesheiner
post Apr 19 2008, 02:12 PM
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Also, if ballistic entry mode is so bad, why would the computer have that as an option?

Because that's the entry mode any capsule will go "without computers" i.e. without any control.
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ilbasso
post Apr 19 2008, 05:02 PM
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Footage on the BBC website says that Russian space officials say the crew made a last-minute change to flight plans without informing ground staff. Sounds like the same blame they tried to pin on the TMA-1 reentry crew.


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nprev
post Apr 19 2008, 05:33 PM
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I don't think anyone's gonna want to take the risk of experiencing 10 gees, to say nothing of landing far afield from the intended site, unless they were seriously worried about the possibility of an unsuccessful dynamically controlled reentry, which seems very unlikely in this case. Procedural (switch-flipping) problems in addition to possible avionics sensor input threshold/timing issues? Events like these usually arise from a chain of causality.

In any case, glad they're down and safe.


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edstrick
post Apr 20 2008, 09:23 AM
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An unhappy point is that for a minute <approximately> after structural failure of it's wing, Columbia had switched from a lifting entry to a ballistic entry. With no crew-survival capsule, as it cannonballed into the atmosphere,Columbia broke apart under the rapidly increasing dynamic loads and heating and the unpotected crew died.

Being in a cramped capsule with 100% heatshield coverage around you may not be elegant, but it's a good way to survive an "uhoh".
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djellison
post Apr 21 2008, 11:12 AM
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A post about a whole different subject has been culled. That's not what UMSF is about, for, or going to allow.

Doug
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imipak
post Apr 23 2008, 07:56 AM
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UniverseToday now says things were hairier than first reported.

ph34r.gif


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jamescanvin
post Apr 23 2008, 08:23 AM
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Spaceflight Now are reporting that the service/propulsion module may have failed to separate properly.


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djellison
post Apr 23 2008, 08:29 AM
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Shocking that that can even happen. Remarkable that it survives the process totally intact.

Doug
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djellison
post Apr 23 2008, 09:17 AM
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Deleted - another post on the same issue that doesn't even warrent posting. Not going to happen.
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edstrick
post Apr 23 2008, 10:43 AM
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That sounds like John Glenn's entry with the retro-pack still attached.
It was considerably more hazardous and "hairy" than reported at the time.
but not as bad as having the heat shield deployed before there was aerodynamic pressure against it (which might or might not have worked).

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nprev
post Apr 23 2008, 12:20 PM
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I find it more than passing strange that issues apparently are emerging for critical events such as module separation for a system this mature. Understand that the pace of production was drastically increased as well as aging workforce issues, but still: this sort of thing should have been down pat long ago, and seemingly was until quite recently.

Unless there was some sort of new (within the past 2 years?) design change related to this, I would suspect some sort of anomaly in contractor-supplied components.


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Mariner9
post Apr 23 2008, 06:07 PM
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As far as I recall there were two Soyuz produced every year for the last few years. Plus an additional batch of Progress (which use the same service module and I think the Orbital module is largely the same).

I'm not aware of Soyuz production being increased yet. Starting in 09 or 10 we go up to 4 flights a year to support the six man crew, but given the long lead times for these spacecraft, the last couple Soyuz (which had the failures) would seem to have been produced well in advance of the coming 'rush'.

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