| | Russian recovery teams tend to the Expedition 17 Soyuz spacecraft following landing. Photo Credit: NASA |
Houston, TX - Investigations continue into exactly what caused the last two Soyuz spacecraft to subject their crews to punishing ballistic reentries. The latest landing, that of Expedition 16, was more that 250 miles off target due to the ballistic reentery.
Although the investigation into the latest incident is not complete, a few facts are emerging. Space Station manager Mike Sufferdini confirmed, at a news conference this morning, that there was a "late separation of one of the spacecraft's modules" and that the spacecraft was entering the atmosphere "nose first for a period of time". He also noted that there were reports of "smoke in the cabin at one point". When asked to characterize the reentry he said "It was defiantly a bumpy ride" but that "all Soyuz landings are bumpy".. In an article published last week, CBS News quoted unidentified sources as saying that the spacecraft re-entered the Earth's atmosphere with the service module still attached. A Soyuz spacecraft consists of three parts - an orbital module, a descent module, and a service module. During a normal reentry, the three parts separate with the crew returning in the descent module and the orbital and service modules burning up in the atmosphere. Should a module fail to separate, as has happened several times in the past, the Russians have developed several techniques to remedy the situation. The standard procedure is to reenter sideways and allow the struts that hold the sections together to burn away. After this, gravity will turn the descent module heat shield down, as it is supposed to be, for the balance of the reentry. This could explain why the spacecraft was entering nose first for a while. . Sufferdini cautioned that the late separation was probably not the cause of the ballistic reentry. He pointed out that the investigation into the last ballistic reentry pointed to a problem with the pilots hand set. In a series of interviews broadcast on NASA television, Expedition 16 Commander Peggy Whitson described the reentry as "challenging". She described going into a 17 degree pre second spin to help stablize the spacecraft during the ballistic portion of the descent (this is normal for a ballistic reentry) and fealing her face pull back as the gravity in the capsule built up to a punishing 8.5 Gs (8.5 times the gravity we feal on the ground. A 150 pound man would feal like he weighs 1,275 pounds). She compared the actual touchdown to "a car crash". Although the reentry was rough, Whitson was quick to point out that they train for ballistic reentrys and it is considered a nominal form of reentry - although they do try to avoid it. It should be noted that in the early days of space exploration all reentrys were ballistic. As a result of this latest incident ISS management has decided not to relocate the Soyuz spacecraft that arrived at the station two weeks ago as had been planed. The move was intended to free the port up for use by a Progress space freighter that is due to launch on May 14. Instead management has decided to dock the spacecraft at the stations Piers docking compartment. Management had hoped to keep that port open for use during a spacewalk planned by the two cosmonauts who are currently onboard the station. During that spacewalk the cosmonauts had planned to inspect the docking compartment to ensure that it is fit for future expansion of the Russian segment of the station. The first of three new Russian modules is set to arrive at the complex in 2009. In an unrelated note the United States has announced that it will not be purchasing any new Progress spacecraft from Russia once their current commitment is fulfilled. NASA believes that huge payload capacity of ESA's ATV coupled with Japan's planned ATV and America's domestically produced COTS and Orion spacecraft (both of which have unmanned cargo capabilities) have rendered Progress obsolete.
| | Diagram of a Soyuz spacecraft showing it's three major components Photo Credit: Roscosmos |  | | Diagram showing how the three major components of the spacecraft seperate during reentry Photo Credit: Roscosmos |  | | Diagram showing a normal Soyuz reentry vs a ballistic reentry. Photo Credit: Roscosmos |
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