Soyuz Ballistic Re-entry 300 Miles Off Course

call-me-kenneth writes "Soyuz TMA-11, carrying a crew of three returning from the ISS, unexpectedly followed a high-G ballistic re-entry trajectory and ended up landing 300 miles off-course. The crew, including Commander Peggy Whitson and cosmonaut Yuri Malenchenko, are reportedly in good health. Soyuz capsules have previously saved the lives of the crew even after severe malfunctions that might have led to the loss of a less robust vehicle."

Re:Ballistic trajectory?

[figleaf]

The article also says
"He said the crew missed the target because they changed their landing plan at the last minute without telling mission control."

So most likely it was not a steering malfunction.

Re:Ballistic trajectory?

[trout007]

A capusle can "sort of fly" during reentry. You can use thrusters to change the attitude of the craft which changes the direction. This requires guidance. You usally use this because it's less stressful on the crew and you have pretty good accuracy. The ballistic trajectory is just like you said. Uncontrolled so you fall like a rock. So you spend less time slowing down in the upper atmosphere. You get to the thicker atmosphere sooner and when you do you are going faster which causes very high G deceleration. Not fun but the craft is designed to do it.

Re:How far exactly?

[whoda]

It says 420km, which gets rounded down to 400 in the headline paragraph.

420km in miles is 260, which gets rounded up to 300 for the Slashdot article.

Re:Full Manual Re-entry is Possible in Soyuz

[Phanatic1a]

But at 10G, the crew's probably not going to be conscious to operated that manual system. 10G is enough to cause G-induced loss of consciousness (GLOC) in anyone, even physically fit, properly trained, and prepared personnel. Even fighter aircraft, where the pilot is in a properly reclined position and is wearing a g-suit, limit maneuvering to 9g, because after that, that pilot's asleep.

Re:Full Manual Re-entry is Possible in Soyuz

[johnny cashed]

Addendum:

According to this link: http://www.astronautix.com/flights/mireo23.htm [astronautix.com] the landing rockets failed anyway, which resulted in a hard, but survivable landing.

And according to this: http://www.jamesoberg.com/soyuz.html [jamesoberg.com] the crew has no control over the parachute deployment. (This is written in entry 6 B under "Special Questions)

I'm not impressed.

[DerekLyons]

The fact that they survived the experience is amazing. Say what you want about Soviet technology, this was a very, very neat trick.

When it comes to Soviet technology only one thing needs to be pointed out: This brings the re-entry failure rate of the current mark of Soyuz to 20% and trending upwards. (This report [jamesoberg.com] on Soyuz landing safety with the older marks is sobering reading.)

Re:Ballistic trajectory?

[ThreeE]

The soyuz changes its CG position to change its attitude which rotates the lift vector which changes the trajectory.

There. I fixed it for you.

Re:I'm not impressed.

[Anonymous Coward]

One such failure happened last year. Apparently for this launch they changed all analog control stuff (that apparently failed last time) to digital, would be interesting to see if the problem will be traced again to this thing. Effectively ballistic re-entry is a fall-back scenario for this capsule, it is never a good scenario especially for people not trained for it. It is safe to say that safety of Soyuz re-entry is quickly becoming very questionable.

Re:Full Manual Re-entry is Possible in Soyuz

[J05H]

Ballistic reentry like this is still under computer control. Manual reentry is for an even-worse condition Soyuz. IIRC ballistic reentry is for off-nominal or main computer crashing. Article says they altered course before reentry without telling MCC so they were either having trouble or screwing around. This is another testament to Soyuz robustness - still the safest spacecraft around.

Uh, wait a sec here...

[Anonymous Coward]

Soyuze descent trajectories are planned so that a safe ballistic option is always available, no matter what happens to the control system. But excuse me, isn't this the THIRD ballistic re-entry of the TMA series?

TMA-1 : ballistic
TMA-10 : ballistic
TMA-11 : ballistic

If you ask me, I think there's going to be a few more people going ballistic over this... I don't think the previous Soyuz generations had this many ballistic returns.

Re:Nice Spin

[whitehatlurker]

Well, slightly higher in the wikipedia page referenced is a section on accidents [wikipedia.org]. Count the number there. I think the most infamous was Soyuz 11 [wikipedia.org], where the interior was vented to space.

It's rather a case of "we make them rugged, 'cause we got a lot of other problems we have to overcome."

Heavyside Layers

[Anonymous Coward]

Alan Shepard hit over 11g during re-entry, and he didn't pass out and could still hit switches. The early astronauts training- had them routinely hitting 10g or more and they didn't pass out.

There's a difference between the eyes-down load on a fighter pilot sitting in an ejection seat (even the semi-reclining versions, which aren't really very reclined) and the eyes-in loading on a astronaut laying on their back. The main difference is that the person on their back isn't having their blood trying to fill their boots when the Gs strike like the person sitting in a chair.

The two don't really compare. I'd advise you to do a little research before trying to make that case.

Re:Nice Spin

[mlyle]

Taken from a web forum, but I've seen similar stuff before:

http://www.airliners.net/aviation-forums/military/read.main/54404/ [airliners.net]

Soyuz (1967-Present)
Flights: 95
Failures: 4 (2 non-fatal)
Failure Rate: 4.21%

Cosmonauts Flown: 228
Fatalities: 4
Fatality Rate: 1.75%

Shuttle (1981-Present)
Flights: 116
Failures: 3 (1 non-fatal)
Failure Rate: 2.59%

Astronauts Flown: 692
Fatalities: 14
Fatality Rate: 2.02%

This is a statistical dead heat. There is simply not a big enough sample size to distinguish between a 1.75% and a 2.02% fatality rate. And the "who had an accident more recently" does not establish it either.

Both are good systems, each has respective advantages (simplicity and low-cost vs. a lot of on-orbit assembly and payload capability). It's good the world has both, and we may never know which would be safer with infinite flights.

Re:Something is missing from this story...

[kriptonus]

Yep; Switching to a Ballistic trajectory would tend to make you fall short of your target and land early; yet they overshot by almost 300 miles and landed 20 minutes late. There had to be a failure that caused them to spend too much time in the upper atmosphere, not losing momentum quickly enough. Once they realized they were overshooting they must have switched to plan B.... and without a time consuming chat with ground control.

Re:Ballistic trajectory?

[v1]

basically that's correct. "ballistic trajectory" means there is no course correction/adjustment/maintenance going on during the trip. Like firing a mortar, you initially set the angle and power, and fire it. If your math was good, it lands where you wanted it to. "ballistics" (or "dumb firing") more commonly refers to munitions firing.

He said the crew missed the target because they changed their landing plan at the last minute without telling mission control.

Certainly IS scary. You wouldn't expect the astronauts would have an overriding degree of control over their flight plan. Actually, I would have expected it to be nearly 100% determined from mission control. And even if they did elect to "fall different", it's simply amazing they would not notify mission control. I wonder what sort of reprimand the senior astronut is going to receive over this?

Re:Nice Spin

[call-me-kenneth]

[Citation needed.] You are astonishingly badly mistaken.