Faulty bolts could take Soyuz into another ballistic re-entry

William Atkins
Sunday, 25 May 2008 07:47

Science - Space

The Soyuz spacecraft—TMA-12—currently docked to the International Space Station contains the same type of bolts that supposedly made the last two Soyuz flights—TMA-10 and TMA-11— re-enter the Earth’s atmosphere in a ballistic trajectory.

An unidentified space industry expert talked with Reuters about concerns with the Soyuz spacecraft after Soyuz TMA-10 and TMA 11 both returned to Earth using ballistic trajectories.

Such “ballistic trajectories,” which are steeper flights back to Earth and cause crewmembers to be subjected to more gravitational forces (G-forces), are only used after the nominal trajectory has been rejected by the spacecraft’s computer for its intended route back through Earth’s atmosphere.

(Thomson Reuters is a leading source of information for the world concerning business and finance, law, tax and accounting, media, and science and healthcare. The Thomson Corporation and Reuters Group PLC combined in 2008 to form Thomson Reuters.)

The unnamed source stated to Reuters that the explosive bolts are used to keep two modules attached to Soyuz: one attached in front of the central descent module (which contains the crew, inside, and the heat shield, outside) and another one attached in back of it.

Before Soyuz is ejected from its orbit about the Earth and into the atmosphere of Earth, explosive charges are supposed to go off to separate the modules from the Soyuz capsule (the descent module). In the last two flights of Soyuz TMA, these explosions did not occur, thus, causing module separation problems.

Officials with the Russian Federation Space Agency (RSA) told Reuters that they would not comment on any technical problems with the Soyuz. They did indicate that the bolts would eventually burn off (if not nominally exploded off)—thus, releasing the modules—due to the high temperatures created as the capsule plunges into the Earth’s atmosphere.

RSA officials also told Reuters that the Soyuz is a safe and reliable space vehicle.

Please read the next page for additional information on TMA-11, TMA-12, and TMA-13.