It has been reported that Discovery banks in descent in order to help reduce speed.

Now to reduce speed I reckon you can do two things: increase ballistic coefficient or reduce vertical speed downwards to the point where the potential energy lost is less than the kinetic energy lost per time period due to friction (by increasing lift).

The only explanation I can give is that the banking is done to increase ballistic coefficient by presenting a smaller crossection to the direction of airflow in order to reduce the thermal stress on the heatshield - but not to reduce speed.

Or have I missed the point? Please would somebody enlighten?