| |
 |
|
|
Science Forum Index » Space - History Forum » First NASA Soyuz TMA-11 documents...
Page 1 of 1
|
| Author |
Message |
| Pat Flannery... |
 Posted: Wed May 07, 2008 3:19 pm |
|
|
|
Guest
|
More info from James Oberg
http://www.spectrum.ieee.org/may08/6229
This is interesting:
"However, a suggestive detail in the postlanding photography, a thruster
mounting with jagged gaps alongside it, indicates that an attitude
thruster burned through. Such damage would have reduced or even entirely
eliminated the crew's ability to point the crew module during descent.
The thruster could have been lost as a consequence of a vain attempt to
steer the much-heavier-than-expected combined vehicle through the
initial buffeting."
Soyuz TMA RV thrusters use simple hydrogen peroxide decomposition to
generate thrust, so you'd think the comparatively low temperatures
involved wouldn't burn through a thruster... was the thruster damaged
during reentry?
Another interesting section:
"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."
After parachute deployment the capsule is supposed to fire a system that
releases a bridle from the side-mounted parachute housing that then
swings up over the top hatch, so that the capsule is descending
vertically under the chute. If it did hit sideways, that suggests
something went wrong with the bridle release and in that case the
landing rockets wouldn't cushion the landing much on impact.
Pat |
|
|
| Back to top |
|
| John... |
| Posted: Thu May 08, 2008 6:48 am |
|
|
|
Guest
|
On May 7, 4:19 pm, Pat Flannery <flan... at (no spam) daktel.com> wrote:
Quote: More info from James Oberghttp://www.spectrum.ieee.org/may08/6229
This is interesting:
"However, a suggestive detail in the postlanding photography, a thruster
mounting with jagged gaps alongside it, indicates that an attitude
thruster burned through. Such damage would have reduced or even entirely
eliminated the crew's ability to point the crew module during descent.
The thruster could have been lost as a consequence of a vain attempt to
steer the much-heavier-than-expected combined vehicle through the
initial buffeting."
Soyuz TMA RV thrusters use simple hydrogen peroxide decomposition to
generate thrust, so you'd think the comparatively low temperatures
involved wouldn't burn through a thruster... was the thruster damaged
during reentry?
Another interesting section:
"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."
After parachute deployment the capsule is supposed to fire a system that
releases a bridle from the side-mounted parachute housing that then
swings up over the top hatch, so that the capsule is descending
vertically under the chute. If it did hit sideways, that suggests
something went wrong with the bridle release and in that case the
landing rockets wouldn't cushion the landing much on impact.
Pat
Pat,
You seem to have an understanding of Soyuz systems. Although not
related (as best we know) to the current TMA-11 issue, I wonder if you
may have some historical information.
On the Soyuz spacecraft used today, a radar altimeter is used to cue
the firing of the braking rockets immediately before landing.
However, earlier versions of Soyuz used a radiometric system similar
to a gamma backscatter gauge that measured radiation scattered back
from the ground as the vehicle approached touchdown. If I remember
correctly the system used a Cobalt 60 source. The location of the
source on the bottom of the vehicle was marked by the international
yellow and magenta radiation symbol. But that is all I know (and I am
iffy on some of that information).
Do you have any specific information on this system, especially:
1. The isotope and the activity of the source, in either Becquerels
(SI units) or curies (traditional units).
2. The resultant radiation exposure or dose rates in the interior of
the reentry vehicle (again in either SI or traditional units)?
I have goggled for this information several times and even posted the
question here on the newsgroup a couple of years ago, without
success. Thank you in advance for any information or internet
references you might be able to share.
Blue skies to all,
John |
|
|
| Back to top |
|
| Pat Flannery... |
| Posted: Sat May 10, 2008 3:33 am |
|
|
|
Guest
|
John wrote:
Quote: In the case of Soyuz 5, the two modules apparently separated when the
hypergolic propellants in the SM cooked off and blew it to pieces.
Pat
Goood Grief!!!!!!!!!!!
Yeah, Volynov heard quite a bang when the tanks blew; here's the
description of the reentry from the book "Challenge to Apollo":
"Six seconds after
the termination of retrofire, Volynov heard the pyrocartridges
triggering to separate the three
major modules of the spacecraft: the living compartment, the descent
apparatus, and the
instrument-aggregate compartment. As he looked through the viewport, he
noticed something
deadly wrong: he could clearly see the antennas attached to the solar
arrays on the cylindrical
instrument-aggregate compartment, meaning that the section, also known
as the service module,
had not separated from the descent apparatus. While similar failures had
occurred on early
Vostok and Voskhod flights, it posed a much greater threat on Soyuz
because of the relatively
huge size of the module. Volynov immediately reported in code to ground
controllers about his
predicament. Most simply believed that Volynov had little chance to live?
The descent apparatus tumbled in somersaults as it remained attached to
the three-ton
service module and began its long journey through the atmosphere.
Turning over and over, with
the thermal shield unexposed to the heat because it was still covered by
the service module,
the heat began to affect unprotected portions of the descent apparatus.
Smoke began to appear
within the capsule as the light heat insulation began to burn. Normally,
during a reentry, hydrogen
peroxide jets would fire during this period to guide the capsule to
provide lift and reduce
thermal and gravitational stresses. In this case, Volynov noticed that
his instrument panel indicated
that the valves for the thrusters were open, but there had been no
firings. All the propellant
had been used up at the initiation of retrofire, when the computer had
tried in vain to
correct the spaceship's incorrect attitude.
Volynov recalls that he was sure that only a few minutes separated him
from death. The normally
unflappable cosmonaut considered saying goodbye to his relatives, but
instead decided to
hurriedly save all the recorded materials on the docking procedure by
ripping the important pages
from the log book, rolling them up tightly, and sticking them into the
middle of the book. Then,
amid the cauldron around him, he calmly began to speak into a tape
recorder, describing all the
details of his experience to assist in identifying the reasons for the
failure. Through it all, there
were terrifying moments. Once, there was a sharp clap, indicating that
the propellant tanks of
the service module had blown apart with such force that the crew hatch
was forced inwards and
then upwards like the bottom of a tin can. Plummeting through a
ballistic trajectory, he realized
that the service module had finally disintegrated and he had survived.
His relief soon turned to
anxiety when the parachute system triggered at an altitude of ten
kilometers. The straps on the
main parachute began to twist, preventing them from unfurling properly.
For the second time in
minutes, he was convinced of his end, Remarkably, the braids of the
parachute began to untwist
slowly: by the time that the descent apparatus landed with its
soft-landing engines, it was sufficient
to ensure Volynov's safety, although the landing was so hard that the
roots of his teeth
in his upper jaw were broken off. It was only the specially built
shock-absorbing seat that saved
him from broken bones and more serious injuries."
Pat |
|
|
| Back to top |
|
| |
|
Page 1 of 1
All times are GMT - 5 Hours
The time now is Thu Jul 24, 2008 11:16 pm
|
|
