New crew of space station
Mikhail Metzel  /  AP file
Yuri Shagarin, Salizhan Sharipov and Leroy Chiao will have to wait a few more days before launching off to the international space station.
By NBC News space analyst
Special to NBC News
updated 9/28/2004 3:44:31 PM ET 2004-09-28T19:44:31

The launch of the Russian spacecraft carrying a replacement crew for the international space station was delayed for the second time in two weeks Tuesday, raising questions about whether there are any deeper safety implications for Russia's cash-strapped space program.

Originally scheduled for Oct. 9, the launch first was postponed two days to replace a "pyro bolt" that accidentally exploded inside the Soyuz spacecraft as it sat in its test hall at the Baikonur spaceport in Kazazakhstan.

This new delay, which sources told involves a leaky chemical tank inside the crew’s command module, will reportedly push the launch off at least three more days, to Oct. 14, and perhaps later.

Once the new crew arrives at the station, there will be a 10-day overlap before the current crew, astronaut Mike Fincke and cosmonaut Gennadiy Padalka, returns to Earth after six months aboard the space station.

Landing in the dark?
The launch delays, combined with the space station’s orbital motion, force the returning crew’s  landing time to get earlier day by day. If the overlap of the new and old crews remains unchanged, the landing would now occur in pre-dawn twilight. Every further delay drives the landing time deeper into darkness.

The earlier and earlier landing time shift is caused by the slow twisting of the space station's orbital plane. The Earth's equatorial bulge twists the orbital plane westward about six degrees per day. On average, this makes each day's landing time about 24 minutes earlier.

The same effect can be seen in launch times, which must get earlier day by day to line up with the shifting orbital plane of the target station. The original launch on Oct. 9 would have occured at 1:04 AM ET. When the launch moved to Oct, 11, the liftoff time became 12:17 AM ET.

Space station timeline

While dark skies do not add any danger to the Soyuz landing itself, it would make any emergency search and rescue effort more difficult. In recent years, several Soyuz landings have encountered control anomalies that led to unusual landings. Consequently, a daylight landing has been deemed a ‘highly desirable’ safety feature.

Shortening the overlap time is a short-term solution that would raise the threat of rushed handover briefings and joint training activities. These efforts, during which the experienced crew passes on their practical experience to the new crew, are critical to safe and productive operations once the veterans leave the station.

The cause this time
The Russian space agency has not released any details of this latest problem, and spokesman Vyacheslav Davidenko merely called it "a malfunction in one of the spaceship's systems, revealed during tests at the Baykonur space site.” It is not related to the earlier problem, he added.

However, has learned that the problem involves a leaky pressure membrane inside a small tank holding hydrogen peroxide liquid. The tank is installed aboard the Soyuz module that carries the crew back to Earth, and the liquid fuels small thrusters that orient the capsule during the fiery atmospheric reentry.

As the fuel is drained from the tank, nitrogen gas is pumped behind a flexible metal baffle that expands to maintain enough "squeeze pressure" on the chemical. If gas leaked through this membrane and bubbles were then sucked into the fuel line, the firings would hiccup and perhaps even damage the thrusters.

The faulty tank is being replaced by the corresponding tank in the next-in-line Soyuz TMA-6, now being assembled in Moscow. After removal from that incomplete Soyuz, the part will be flown to Baikonur and installed inside the spacecraft now being readied for launch, where it then will undergo the same pressurization tests that the currently-installed tank failed.

The cause last time
Meanwhile, questions remain about the fault that caused the first launch delay. Initital accounts described it as something associated with the docking system by which the Soyuz hooked itself to the space station. Later information, first published by and confirmed days later by officials, described the failure as an inadvertent firing of an explosive bolt used to separate different modules of the Soyuz during its return to Earth.

Further details provided to since then explain that the explosive bolt is installed in an emergency separation ring in the nose of the Soyuz, which docks directly to the station. In the event of a mechanical or electrical failure to open the latches that hold the two vehicles together, the entire front end of the Soyuz could be severed by firing a ring of such bolts. This would allow a safe emergency return to Earth.

Russian officials have not provided any details of the cause of the actual bolt explosion. "That problem has been fixed as proven by the subsequent tests," a spokesman simply said. And NASA press officials in Houston have been unable to provide with details of the explosive system, such as how many bolts are installed, how big they are, and what is their explosive force.

Space safety officials have privately expressed concern about the cause of bolt firing, because it might indicate wider problems. If the bolt was triggered by a failed piece of ground test equipment, or a faulty manual procedure, that problem might be easy to isolate and correct. But if the bolt itself went off unexpectedly, that might indicate a flaw in the design or installation process that might also be shared by other bolts installed in this Soyuz and the one already in space.

Additional inadvertent triggering of one or more bolts could threaten the airtightness of the passageway leading from the Soyuz into the space station. Presumably the Russian space officials have considered this hazard and have briefed their NASA colleagues, but no confirmation of this has been offered publicly.

Last-minute delays rare in Russia
Despite NASA assurances that “delays are normal” and nothing to worry about, slips in announced Russian manned space launch dates have been extremely rare for decades. Those that have occurred have been small and usually due to navigation issues with the trajectories required to chase down the space station in its own orbit.

Space historians consulted by could not recall any similar incident in Russia involving last-minute technical glitches required hurried repairs, over the entire history of the space station and of its predecessor, Mir.

Although the current double delay might just involve two cases of "bad luck" that coincidentally hit the program now, it might also reflect continued loss of experienced personnel due to die-off or retirement. This is a long-term threat caused by the near-bankruptcy of Russia's space program, in which wage levels are far below other professions open to young technically-trained Russians.


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