This story was updated at 3:23 p.m. EDT.
The off-target landing of a Russian Soyuz spacecraft during its return to Earth on Saturday posed a serious risk to the three astronauts aboard, Russian space officials and reports suggest.
An apparent malfunction in a mechanism designed to jettison the Soyuz TMA-11 spacecraft?s propulsion module from its crew-carrying descent capsule threatened the lives of the three astronauts aboard, Russia?s Interfax News Agency reported Tuesday.
The Soyuz landed on Saturday about 260 miles (420 km) short of its intended target in the arid central Asian steppes of Kazakhstan returning to Earth under a backup, ballistic reentry path.
NASA space operations chief Bill Gerstenmaier said that while an investigation is still under way, the most likely cause of the atypical landing is a faulty cable, which may have had an electrical short that commanded the ballistic descent. The Soyuz astronauts also reported experienced unusual shaking and buffeting during reentry, suggesting a module separation malfunction as well, Gerstenmaier said. ?
?The Russians immediately set up a commission,? Gerstenmaier said. ?They?re going to go off and investigate this, they?ll get the capsule back and they?ll understand the data.?
The steeper-than-usual landing subjected Soyuz cosmonaut commander Yuri Malenchenko, returning U.S. astronaut - and Expedition 16 commander - Peggy Whitson and South Korea?s first spaceflyer So-yeon Yi to higher than normal gravitational loads that peaked at about 8-Gs for about one minute, Gerstenmaier said.
Yi described the descent as frightening in a post-landing press conference in Russia.
"At first I was really scared because it looked really, really hot and I thought we could burn,'' she said, according to the Associated Press, adding that later she noticed that it wasn?t even warm inside the Soyuz. "I looked at the others and I pretended to be OK.''
Russia?s three-segment Soyuz spacecraft are made up of an engine-carrying propulsion module, central crew capsule with a bottom-mounted heat shield and an orbital module. The orbital and propulsion modules are designed to be discarded during reentry, leaving the bell-shaped crew capsule to land under parachutes and retrorockets on the Kazakh steppe.
Citing an unmanned space official close to Russia?s post-landing investigation, Interfax reported that the propulsion module did not jettison properly, preventing the Soyuz?s heat shield from bearing the brunt of the fiery temperatures during reentry.
Instead, the spacecraft?s hatch side was facing forward and suffered some heat damage before the propulsion module separated for good and allowed a successful landing, the news agency reported.
"It is a great success that the crew are safe and sound. The whole thing could have ended much worse. You can say that the situation was on the edge of a razor," Interfax quoted its source as saying.
Saturday?s landing marked the second consecutive Soyuz landing to return to Earth on a ballistic trajectory, falling like a cannonball until the parachutes open.
Expedition 15 cosmonauts and a Malaysian astronaut also experienced a ballistic reentry during their Oct. 21, 2007 landing, as did the crew of Expedition 6 - which included U.S. astronaut Don Pettit - in May 2003. The 2007 event also included a module separation malfunction early in the reentry process , Gerstenmaier said.
?You?re always concerned about the crew on any reentry vehicle,? NASA space station program manager Mike Suffredini said in a post-landing interview on NASA TV. ?We had a few minutes there where we weren?t sure whether they had a ballistic landing, or something else.?
Russia has had additional experience with Soyuz module separation problems in the past. In January 1969, a returning Soyuz 5 spacecraft with Soviet cosmonaut Boris Volynov failed to separate immediately from its crew capsule. It eventually pulled free to allow Volynov?s Soyuz to perform a ballistic reentry and make a rough landing, according to the European spaceflight site Encylopedia Astronautica.
Russia?s Interfax News Agency and the Associated Press contributed to this report.
- VIDEO: ISS Commander Peggy Whitson Takes Charge
- NEW IMAGES: NASA's STS-123 Shuttle Mission in Pictures
- VIDEO: Europe's First ISS Cargo Ship Arrives