edit: Considering that the recent (23-Nov-2016) ESA update suggests that a saturation of the rotational sensors in the IMU may have set off a series of miscalculations leading to mission loss, the quote below continues to be relevant. I'm still looking for a posted answer to What are transonic oscillations (wrist mode) and would Schiaparelli have been transonic at 2 to 4 km altitude?
In the jan woerner's blog (director-general of ESA) post titled Spacecraft are Tricky ... and Engineering is an Art Form there is a comment that I don't understand. Could someone explain what is being discussed here more clearly to a non-rocket-scientist? And add a bit about how it applies to Schiaparelli's entry, descent, and landing?
What about transonic oscillation ? .
MSL descent scenario planned that wrist mode oscillations be mitigated by using little thrusters of its reaction control system to counteract these oscillations.
Contact was lost at 2 to 4 km altitude in the crtical area of transonic speed inducing resonant wave with possible parachute twist,.disturbing attitude control system and leading to a crtically reduced rocket burst.
I've used the NASA JPL site for the Mars Science Laboratory - Entry Descent and Landing and found that at 4km to 2km altitude the velocity of the MSL drops from about 95 to 80 meters per second. I know that the atmosphere is cold, but that still sounds safely sub-sonic.
Was Schiaparelli in a transonic state in that altitude range?
edit: some items incorporated from comments...
- Lessons Learned and Flight Experience from Planetary Parachute Development
- How Curiosity Will Land on Mars, Part 2: Descent by Emily Lakdawalla