Landing 2008 April 19: In preparation for landing, the Soyuz TMA-11 undocked from the station on April 19, 2008, at 09:06:27 Moscow Time (05:06 GMT, 1:06 a.m. EDT). The braking engine firing was initiated at 11:40:46 Moscow Time and was expected to last 258.3 seconds.
Onboard Soyuz TMA-11 were Yuri Malenchenko and Peggy Whitson, members of the Expedition 16 to the International Space Station and the Korean scientist So-yeon Yi, flying under the commercial agreement between Russia and South Korea. Malenchenko and Whitson spent 192 days in space. So-yeon Yi launched to the station April 8, 2008, with the Expedition 17 crew.
As it transpired after the touchdown, at the initial phase of descent, the reentry capsule of the Soyuz TMA-11 spacecraft switched to a ballistic trajectory, which is steeper than a nominal landing, when the flight control system is capable of taking advantage of the capsule's aerodynamic properties. The ballistic reentry trajectory increases G-forces experienced by the crew, however the acceleration should remain well within acceptable limits even for an untrained person.
As a result of the ballistic descent, the Soyuz TMA-11 touched down short of its intended landing zone, Anatoly Perminov, the head of the Russian space agency, Roskosmos, said at the post-landing press-conference. Perminov was also quoted as saying that the crew had not reported about the switch to the ballistic descent mode, leading to delays on the ground. According to Perminov, officials learned about the off-target landing from the crew of the aircraft, which, was assigned to "cover" a ballistic trajectory, however this information came too late for the recovery crews to arrive to the right spot ahead of the landing. As it transpired later, the aircraft detected the radio beacon of the crew capsule, which activated nominally eight minutes after the touchdown, using one onboard and one heat-shield antennas deployed after the landing. Pilots followed the radio beacon and then saw signs of fire near the landing site.
According to NASA, the Soyuz TMA-11 touchdown away from the planned site delayed the arrival of the recovery crews by approximately 45 minutes.
According to the RIA-Novosti news agency, the Soyuz TMA-11 landed near the Russian city of Orsk, which is 420 kilometers away from the nominal landing site near the town of Arkalyk in Kazakhstan. NASA announced that landing took place "around" 4:30 a.m. EDT on Saturday, April 19, 2008. The scheduled landing time was 12:31 Moscow Time (4:31 a.m. EDT).
Journalists who arrived to the landing site with the rescuers photographed extensive grass fires near the capsule. They also reported that the capsule's parachute was burning as well.
Speaking at the post-landing press-conference in Star City, on Monday, April 21, Yuri Malenchenko said that the late arrival of the rescue team did not pose any danger to the crew, because they "were not dying and needed no rescue." Exhausted crew members, still in their entry suits, started climbing out of their spacecraft. By that time, stunned local residents reached their capsule (several cars were seen on the photos of the landing site). Malenchenko was apparently first to get out of the capsule, he and the locals then helped his crew mates to get out as well. Cosmonauts asked their unexpected helpers to reach inside their reentry capsule to remove a telephone and GPS gear. Malenchenko was then able to call the search coordination center and confirm a safe landing. At the time, rescue helicopters were already heading toward the landing site based on the coordinates provided by the search aircraft.
This was the third landing of the Soyuz spacecraft in the ballistic descent mode in the past five years. The Soyuz TMA-1 mission in 2003 and the Soyuz TMA-10 mission in 2007 also ended with a ballistic descent.
The Soyuz TMA-11 planned landing sequence on April 19, 2008, according to Roskosmos (Moscow Summer Time):
| Hatch closing between the spacecraft and the station | 06:03 |
| Undocking | 09:03:30+3 |
| Deorbit engine burn activation | 11:40:42 |
| Separation of the reentry capsule from the habitation and service modules | 12:04:37 |
| Parachute release | 12:16:07 |
| Touchdown | 12:30:45 |
Source: crew faced danger during landing
The landing of the Soyuz TMA-11 spacecraft on April 19, 2008, could end in a catastrophe, sources told Russia's semi-official Interfax news agency on April 22.
Quoting an industry official close to the investigation of the off-nominal landing, Interfax said that during its initial plunge into the Earth atmosphere, the crew module of the Soyuz spacecraft was flying with its entry hatch first, instead of exposing its thermal shield at the bottom of the vehicle to the heat of reentry. As a result, the hatch experienced a considerable heat damage, which could potentially lead to the loss of pressure inside the capsule. In addition, an external portion of the valve, which equalizes pressure between the interior and the exterior of the module was also damaged, along with the communications antenna, which left the crew without contact with the ground.
Although all Soyuz crew members wear safety pressure suits, which designed to protect them in case of depressurization, further melting in the front section of the reentry module could potentially damage nearby parachute containers, leading to the loss of the crew.
It was not immediately clear what caused wrong orientation of the capsule during landing, however the failure of the propulsion module to separate completely from the crew module was suspected. During the separation, multiple connectors between two sections of the spacecraft should be activated. In 1969, two modules of the Soyuz-5 spacecraft failed to completely separate from each other, preventing the ship's flight control system from placing the capsule into the correct attitude for reentry. Following thermal and aerodynamic loads of the reentry eventually tore two modules apart, thus allowing the crew capsule to obtain the correct attitude. Cosmonaut Boris Volynov, who piloted Soyuz-5, was injured but survived a very rough touchdown.
The investigation
On April 22, 2008, Bill Gerstenmaier, chief of space operations at NASA, told reporters that the cause of the problem during the landing of the Soyuz TMA-11 was still unknown. Yet, he provided several new details about the incident:
- Malenchenko and Whitson reported unusual buffeting, jarring and shaking before entering the ballistic descent, likely confirming previous reports that the propulsion module may not have detached properly.
- Malenchenko did report some signs of smoke inside the Soyuz spacecraft during reentry and powered down a display panel at times. The source of the smoke was unknown.
Later on the same day, NASA released a post-landing audio report by Peggy Whitson, giving eyewitness details about the descent. "Shortly after (separation of the crew capsule and the propulsion module) we switched automatically to the ballistic mode, which means we were going to be spinning up to 8 Gs and coming in on a steeper descent... I saw 8.2 Gs on the meter."
By April 23, 2008, the reentry capsule of the Soyuz TMA-11 had been delivered to RKK Energia's facilities in Podlipki. According to unofficial reports, preliminary examination of the capsule confirmed more extensive heat damage, however not to the point of a catastrophic failure.
Although Russian officials remained silent, on April 25, 2008, another report on the Novosti Kosmonavtiki web forum confirmed that the PAO service module failed to separate from the reentry capsule. Some 55 seconds after entering the upper atmosphere, the automated flight control system switched from aerodynamic to the ballistic mode of reentry upon the formation of the "Oshibka orientatsii" (attitude control error) command. (With the PAO module still attached to the crew capsule, the correct orientation was not possible.)
Some 100 seconds after the beginning of the reentry, the PAO module finally tore off from the crew capsule.
The reentry capsule and apparently loosely attached PAO were flying its entry hatch first, but with a slight tilt, which exposed the belly of the reentry capsule. As a result, a small gondola on the belly of the capsule, housing a pitch attitude control thrusters burned through, possibly becoming a source of smoke, which made its way inside the cabin and was reported by the crew. Fortunately, it happened late in the descent, when the loss of pressure was not as critical.
Although at the time of the report, the engine had not been yet removed from the vehicle, its preliminary examination revealed holes in thermal insulation of the capsule. In the meantime, the examination of the hatch showed that its integrity was not breached, even though it suffered more extensive heating than usual.
At the time, a failure of pyrotechnic devices in the PAO module separation system was suspected as the most probable culprit in the incident. However, the overload of the power supply system, which failed to deliver necessary electric current to the pyrotechnic devices was also suggested.
In the aftermath of the Soyuz TMA-11's botched landing, the assembly of the next Soyuz vehicle (Production No. 223) was stopped, until the root cause of the problem was found. At the same time, an unmanned landing of the Soyuz TMA-12 spacecraft, currently in orbit, was under consideration. The ship's move from the Pirs docking compartment to the nadir port of the FGB control module, originally scheduled for May 7, 2008, was also under review. In case of the failure to dock to the new location on the station, the crew of the Soyuz TMA-12 would have to land, something, which had to be avoided until the investigation of the Soyuz TMA-11 landing is completed.
On April 29, 2008, reports came from South Korea that So-yeon Yi was hospitalized at the Aerospace Medical Center in Cheongju, North Chungcheong with back pain previous morning. One source described So-yeon Yi symptoms as "severe pain in her waist." According to the Korean media, So-yeon's face was expressing pain on April 28, as her mother hugged her at Inchon International Airport. At the time, bodyguards were helping her walk.
It wasn't immediately clear if the pain was a result of a trauma during landing, however Gagarin Training Center in Star City, was quick to announce that a post-flight medical examination of So-yeon at the facility hadn't found any problems and she had no complaints about her health. As a result, she was allowed to leave Russia for South Korea on April 27, Star City said.
A meeting of So-yeon Yi with South-Korean President Lee Myung-bak scheduled for April 28 was cancelled, South-Korean media said.
On April 30, France Press news agency quoted a hospital director colonel Jung Kee-Young as saying that Yi was suffering from mild dislocation and bruising of the vertebrae. Jung said that injuries were "not severe and did not pose a serious health risk."
According to the transcript of the interview with So-yeon Yi which was also released on April 30, she experienced much higher G-forces during the descent than she had expected. She also mentioned that at least one alarm light was on in the cabin.
"I'm pretty good when it comes to dealing with pain. Usually I can get by with a little 'ouch.' But at the time of the landing I couldn't help but scream out," So-yeon Yi said, "I thought that this is how I might die..."
So-yeon Yi also said that a manual and a bag fell on her, apparently as the crew capsule hit the ground. She said she ended up at the very bottom of the cabin (after the touchdown), perhaps an indication that the capsule landed on the side, where So-yeon was.
SOURCE :http://www.russianspaceweb.com/iss_soyuztma11.html#investigation
