Thank you for the link regarding Luna 9; I did not know that. You originally said, "Use of such is not incompatible with the use of retrorockets. As a matter o

Thank you for the link regarding Luna 9; I did not know that. You originally said, "Use of such is not incompatible with the use of retrorockets. As a matter of fact, the latter are used first." Just to provide clarity, I was referring to the EDL (Entry, Descent, Landing) profile of Spirit and Opportunity. Their EDL profiles first deploy the airbags, then fire the retrorockets. http://marsrover.nasa.gov/mission/tl_entry1.html http://marsrover.nasa.gov/mission/tl_entry1.html Step 12: Airbags inflate Step 13: Retrorockets fire