Category Archives: Oxford American

What caused the failed separation of the Soyuz and Progress?

A good translation of this week’s press release from the investigation into the April 28 Progress failure indicates that the failure occurred because of an abnormal separation of the freighter from the upper stage.

After reviewing all the materials, members of the State Commission came to a preliminary conclusion that a version of the abnormal separation had been objectively confirmed, which includes two subsequent events related to the depressurization (disintegration after the cutoff of the third-stage engine) first of the oxidizer tank and then of the fuel tank, Roskosmos said.

In other words, the separation was so abnormal it put both the freighter and the upper stages in the wrong orbits, with the Progress tumbling and damaged, and with the upper stage almost immediately disintegrating.

They are now studying the data to try to figure out what caused the bad separation so they can inspect other Soyuz upper stages for the same problem and fix them before launch.