|  | Pedro Duque will be flying to the ISS in October 2003 | |
New Soyuz TMA spacecraft cleared for next mission with ESA astronaut
5 June 2003
ESA INFO 13-2003. The new Soyuz TMA spacecraft, which will carry ESA astronaut Pedro Duque
to the ISS and back in October 2003, has been fully approved for
operations.
This was announced by Nikolai Zelenshikov, First Deputy
President of RSC Energia, at an official briefing in Moscow on 26 May to
present the findings of the enquiry commission's investigation of last
month's ballistic re-entry by Soyuz TMA-1.
The maiden flight of the new series by the Soyuz TMA-1 spacecraft was
launched from the Baikonur Cosmodrome in Kazakhstan on 30 October 2002.
The crew consisted of ESA astronaut Frank De Winne from Belgium and
Russian cosmonauts Sergei Zaletin and Yuri Lonchakov. After completion of
his mission tasks on the ISS, Frank De Winne returned to Earth in a Soyuz
TM-34, one of the previous series of Soyuz spacecraft.
Soyuz TMA-1 remained at the ISS to act as the station’s ‘lifeboat’ for six
months, thereafter executing the first re-entry by a TMA on its return to
Earth on 4 May 2003 with the ISS Expedition 6 crew, Russian cosmonaut
Nikolai Budarin and American astronauts Kenneth Bowersox and Donald
Pettit, after completing their 162-day mission aboard the station.
Despite the unplanned re-entry in what is known as ‘ballistic’ mode, all
the new systems used within the Soyuz TMA-1 spacecraft performed according
to plan, including, in particular, the new soft-landing system, which
incorporates new engines and a new frame. This reduces the landing shock
from 12g in the old Soyuz TM series to 5g in the Soyuz TMA family. The
Soyuz TMA-1 parachutes also functioned correctly.
The problem, which caused Soyuz TMA-1 to perform the re-entry in ballistic
mode and land 150 km north of Baikonur 400 km short of the intended
landing site, was due to a failure in the BUSP-M guidance system, which is
necessary in order to carry out a controlled re-entry. This guidance
system reads gyroscopes and accelerometers and sends appropriate commands
to attitude control thrusters.
| | Soyuz TMA-1 docking with the ISS | |
The yaw control channel, a sub-unit of the BUSP-M produced ‘undefined’
readings, indicating a malfunction. This caused higher control functions
to take the BUSP-M system out of the control loop and convert to the
ballistic re-entry mode.
In this mode of re-entry the trajectory is steeper than in a controlled
re-entry and the capsule rotates around its axis of trajectory to increase
stability. The steeper trajectory reduces flight time and increases
deceleration. This had the effect of applying an 8g gravity load to the
crew of Soyuz TMA-1 as compared to a maximum of 6g in a controlled
re-entry mode.
The BUSP-M guidance system, where the problem occurred, first flew on
Soyuz T-5 in 1979 and has since executed 49 faultless controlled
re-entries. Tests as part of the official commission’s enquiry, which was
set up following the return of Soyuz TMA-1, could not find any problems
with the guidance unit. The problem could only be reproduced through
mathematical simulation. The chance of this problem occurring has been
determined to be about one in 7000.
This is only the third time in the history of the Soyuz programme that
such a mode of re-entry has occurred, though the ballistic mode is one of
four nominal re-entry modes that the Soyuz T, TM and TMA capsules could
employ under different conditions. The others are the automatic and manual
control modes, and a back-up ballistic mode.
The enquiry commission concluded that there is no need to modify Soyuz
TMA-2. This is the ‘lifeboat’, which is currently stationed at the ISS and
is due to bring ESA's Spanish astronaut Pedro Duque back to Earth after
completion of his mission later this year. Duque will be flying to the ISS
in Soyuz TMA-3 in October. Certain modifications will be made to this
capsule as recommended by the official enquiry commission.
The first of these recommendations was to improve communications
capability by including a mobile satellite telephone in the return
capsule. This will be implemented immediately on Soyuz TMA-2 and the
telephone is to be transported to the ISS by an unmanned Progress vehicle.
The incorporation of a satellite communications capability such as
Cospas-Sarsat is also recommended in the longer term.
| | The Expedition 6 crew returned using the Soyuz TMA-1 spacecraft | |
Secondly, modifications will be made to reduce the chances of incorrect
commands by crew members to an absolute minimum. The Expedition 6 crew
switched on the KURS rendezvous/docking system by mistake during the
re-entry procedure, though it is confirmed that this did not result in the
switch to ballistic mode.
Nikolai Zelenshikov also addressed some questions concerning the length of
time it took to locate the Soyuz TMA-1 capsule and crew after re-entry,
which was longer than expected but within the regulation recovery period
of three hours.
The Russian mission control centre in Moscow and the search plane, which
was flying over the expected landing area in Kazakhstan, were not aware
that a ballistic re-entry had taken place even though there was radio
contact with the Expedition 6 crew before the landing; the crew had not
mentioned the mode of re-entry in their discussions with the ground teams.
This led the search plane and helicopters to search the expected landing
area first rather than the ballistic re-entry landing area.
When they found nothing the recovery crew concluded that a ballistic mode
re-entry had taken place and proceeded to the corresponding landing area
400 km away. After landing, it seems that mistakes were made in certain
procedures, with the result that the onboard antennas were not deployed
and the radio signalling was not switched to an external transmitter once
the crew had erected an antenna outside the capsule. This added to the
delay in locating the crew. When the recovery team arrived, the Soyuz crew
had left the capsule by their own means.
To avoid any recurrence of these procedural problems, there are further
recommendations on revision of onboard documentation of procedures and
additional training for future Soyuz TMA crews.
“Though recommendations have been made for improvements for future
flights, they have no bearing on the systems of the new Soyuz TMA series
of spacecraft,” said ESA Director of Human Spaceflight, Jörg
Feustel-Büechl, commenting on the Russian enquiry commission’s findings.
“I am happy that the way is now clear for the next Soyuz mission in
October, the crew for which includes ESA astronaut Pedro Duque. This will
be a mission to relieve the ISS crew and to perform scientific,
technological and educational experiments. The exact time and date of this
launch will depend upon ISS orbital parameters and operating status.”
For further information, please contact:
ESA Media Relations Service
Tel: +33(0)1.53.69.7155
Fax: +33(0)1.53.69.7690
| 
