Both the Global Surveyor
and the Mars 0rbiter
spent months carefully air braking, trying not to generate too much heat. There are all kinds of indications (in the remarks of the principles), that they were 'puzzled and amazed" by the amount of heat they had to dissipate.
*After watch Spirit
fall, they forced the deployment of Opportunity's parachute higher in the atmosphere. It still landed at about the same velocity - 20m/s, 12m/s of which they assigned to a horizonal vector.
Originally Posted by Hamlet
On your list I can count at least four landers
where contact was lost for unknown reasons. They think the Air Bags exploded
hit, Mars 3
plowed into Mars at 61m/s
and managed to send two minutes worth of garbled data. There is some evidence the Polar Lander
also may have plowed into Mars, but a new crater spotted by intellegence imagers appeared to be ‘much to large’ to have been the Polar Lander at the expected velocity
, even though it is in about the right place, if the Polar Lander
failed due to a heat shield failure. (The most probably cause entertained by NASA was "generation of spurious signals when the lander legs were deployed during descent", causing the engine to shut down prematurely, but that does not explain why both of the independent probes also failed.