and anti-abrasion properties to withstand the initial entry(speed about 3550km/hr) into atmosphere. After the heat shield braked it to a lower speed, parachute would come into play. Becos of the lo air density, it needs retro rocket for final touch down.

>>Mars gravity is a lot less than that of the Earth. So, the force that is pulling the probe down (the weight of the probe) is smaller<<

Look, during the initial entry, the gravity is still mostly balanced by the centri'petal/fugal' force.

>>terminal velocity<<

Just what U're talking about? I once did a 1st order differential eqt exercise on terminal velocity when I was in Form 6th in HK. Terminal velocity refers to that of an object dropping from rest at  great height: Its about 190 km/hr for earth(a figure I remember) (and 1000km for mars I just checked). Here we talking about braking an object from great entry speed to rest.