Russians Close In on Cause of Soyuz Landing Anomaly

According to Gerstenmaier, the pyrobolts on the new Soyuz, which arrived at the ISS in October, were more modern versions that were less susceptible to EMI in general. Furthermore, he said, a bonding strap has been put in place to fill the gap in the bolt position’s electrical insulation.

With the suspect bolt from the last Soyuz now safely back on Earth, engineers in Moscow are debating the best test to measure any EMI-induced physical damage. ”They’re analyzing now what they want to do with the bolt,” Gerstenmaier told Spectrum . ”At first their plans were just to test-fire it, but now they’re thinking of X-ray and CAT scanning.” He expects a consensus on how to proceed will be reached this month.

The time needed to reach consensus suggests ongoing differences of opinion among the Soyuz manufacturer, mission control, the federal space agency, and independent analysis groups. Competing theories include fabrication and workmanship flaws (or even sabotage), unexpected thermal conditions in space, or freak command-path dropouts during critical parts of the descent. And not all top officials in the Russian space industry have acted as if the EMI hypothesis was the best explanation, or even a safe bet. Only days before the most recent touchdown, Aleksey Krasnov, the Russian Space Agency director of human spaceflight, telephoned Gerstenmaier and asked if NASA could somehow record telemetry from the Soyuz during its final descent to the landing zone.

Although this data was presumably also being saved on the data recorder inside the Soyuz, Krasnov’s request suggested that there might be some unique data as well. He may also not have been fully confident that the recorder—and perhaps the spacecraft—would reach the ground intact. And the data might be critically important for an accident investigation. Russian space officials did not respond to direct inquiries about their motives.

Gerstenmaier quickly dispatched a small team of radio engineers to Athens, directly under the descending track of the Soyuz, and they managed to record about a minute of data on the Soyuz telemetry frequency, 166 megahertz. The tapes were turned over to Moscow officials for decoding in an anomaly investigation that is still looking for hard evidence, as the plan for this month’s space walk indicates.