Printable Version of Topic

Posted by: imipak Apr 19 2008, 12:22 PM

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

..?!!

Posted by: PhilCo126 Apr 19 2008, 12:33 PM

First time a Soyuz spacecraft had 2 women onboard...

Posted by: ilbasso Apr 19 2008, 01:03 PM

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.

Posted by: Tesheiner Apr 19 2008, 02:12 PM

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.

Posted by: ilbasso Apr 19 2008, 05:02 PM

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.

Posted by: nprev Apr 19 2008, 05:33 PM

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.

Posted by: edstrick Apr 20 2008, 09:23 AM

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".

Posted by: djellison Apr 21 2008, 11:12 AM

A post about a whole different subject has been culled. That's not what UMSF is about, for, or going to allow.

Doug

Posted by: imipak Apr 23 2008, 07:56 AM

http://www.universetoday.com/2008/04/22/soyuz-capsule-hatch-nearly-failed-and-crews-lives-were-on-a-razors-edge/.

Posted by: jamescanvin Apr 23 2008, 08:23 AM

http://www.spaceflightnow.com/station/exp16/080422descent.html are reporting that the service/propulsion module may have failed to separate properly.

Posted by: djellison Apr 23 2008, 08:29 AM

Shocking that that can even happen. Remarkable that it survives the process totally intact.

Doug

Posted by: djellison Apr 23 2008, 09:17 AM

Deleted - another post on the same issue that doesn't even warrent posting. Not going to happen.

Posted by: edstrick Apr 23 2008, 10:43 AM

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).

Posted by: nprev Apr 23 2008, 12:20 PM

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.

Posted by: Mariner9 Apr 23 2008, 06:07 PM

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'.

Posted by: imipak Apr 23 2008, 06:57 PM

Interesting... that's what happened to Soyuz 5. If the service module doesn't separate, the vehicle re-enters with the hatch facing forward and the heat shield backwards... I remembered reading this in Oberg's "Red Star in Orbit" and googling "soyuz hatch bulge smoke" found it pretty quickly. Probably best avoided if you've an over-active imagination; this image kept me awake more than a few nights, and has stayed with me for probably 20 years since reading it...

http://www.jamesoberg.com/062002flightjournalsoyuz5.html :



[Edit: the Spaceflight Now article James posted does actually mention S5 right at the end. ]

Posted by: nprev Apr 24 2008, 12:10 AM

Man, what a harrowing story!!! Thanks for posting that link.

I'm amazed that Volynov ever slept again...talk about PTSD...

Posted by: ilbasso Apr 24 2008, 12:24 AM

It looks like they had a pretty hefty bounce when they landed, too. Check out the impact crater and how far the capsule is lying away from it.


And look how charred - and cracked - the front end of the capsule is:


The full-res images are on the Expedition 16 page http://spaceflight.nasa.gov/gallery/images/station/crew-16/ndxpage51.html.

Posted by: Pavel Apr 24 2008, 01:43 AM

To make things more interesting, local farmers were burning grass in the area: http://www.spaceref.com/news/viewnews.html?id=1284
I just hope everybody kept their teeth this time.

Posted by: ilbasso Apr 24 2008, 01:51 AM

I think the Soyuz is at the lower right of this picture.

Posted by: Oersted May 7 2008, 08:37 PM

New, excellent Jim Oberg write-up on the descent and landing:

http://www.spectrum.ieee.org/may08/6229

Posted by: ilbasso May 7 2008, 08:53 PM

From the article cited,
"In addition, Yi So-yeon, the South Korean flight participant, reported in interviews in Seoul that the final ground impact was not vertical but sideways, causing many heavy baggage items to break free from restraints and hit her."

Looking at the dirt stuck to the rear portion of the descent module (where the heat shield is before being ejected) it does appear that the Soyuz impacted vertically and then bounced, landing on its side.

Glad I wasn't on that ride.

Posted by: nprev May 7 2008, 11:52 PM

Lots of good (pardon the expression) stuff in that article; nobody does it like Oberg.

That attitude thruster burnout is particularly interesting; I wonder if anyone's ever tested their endurance for continuous firing? May suggest that the instrument-service module stayed attached for quite aways down.

Posted by: ilbasso May 8 2008, 03:21 AM

Here's the close-up of the attitude thruster from the above photo. That's what you'd call "not your typical wear and tear."

Posted by: tasp May 8 2008, 03:09 PM

Ghastly to contemplate how close this mission came to being eligible for discussion here in the main fora . . .

Posted by: climber May 9 2008, 12:33 PM

...and Peggy Witson commented she was not even sure they've bounced!
192 days in space could fool your internal references, don't they ?

Posted by: ilbasso May 9 2008, 06:47 PM

Yi So-yeon's comment that "many heavy baggage items [broke] free from restraints and hit her" on impact - "Be careful when opening the overhead bins, as contents may have shifted during the flight." I know, doesn't sound so funny if you're the one being hit!

Posted by: nprev May 13 2008, 01:48 AM

Yeah...that, or one hell of a sudden smack that leaves you wondering where you're at & trying to remember your own name for a few seconds...

This was beyond hairy.

Posted by: GravityWaves Jun 5 2008, 04:00 PM

I think many of us would gladly take the trip into space regardless of the risks, from what I've understood about Soyuz over its years of service - although the design is old its a lot more robust than other craft. For example do you think Shuttle would have been able to survive such a trip without a very serious incident occurring. I hope they are also able to build the new CEV hardy enough to survive entries which are less than nominal