QUESTION:
This airbag thing sounds a little shaky. How many times do you expect the
lander to bounce before it comes to a rest? And what's to keep it from
flipping over while its bouncing?

ANSWER from Rob Manning:
I would use the word "bouncy" rather than "shaky". The lander is completely
surrounded by airbags like a giant (5 m or 17 ft diameter) beachball; it can
bounce, roll and come to rest in any orientation. So there is no preferred
orientation. Remember that the lander will automatically right itself once
the bags have been deflated and retracted.

We fully expect many bounces before the lander comes to rest suspended
inside its airbag cocoon. Although we have designed and extensively tested
the airbags to withstand multiple very hard bounces (the equivalent of
dropping it from a 10 story building on Mars), we expect that the lander
will see about 10 or less significant bounces with what we consider a
"nominal" (average) impact after being dropped from about 12 m (40 feet)
above the Martian ground. 12 m is the "target" bridle cut altitude. Because
it is probable that the terminal descent solid rocket (RAD) motors in the
backshell will not be perfectly upright when they fire, the lander will
likely get a sideways push from the rockets that will also cause the
lander-airbag combination to roll along the ground for tens of meters before
coming to rest. The bags were specifically designed to BOTH be impact
absorbers AND automobile tires!

--Rob Manning