The rovers reach the “top” of Mars’ atmosphere with a velocity of about 12,000 mph. A variety of techniques are used to slow the craft to a soft “touchdown” on the surface. During the first second, friction from the atmosphere slows the spacecraft from 12,000 mph to 1,200 mph. A polyester and nylon parachute is deployed about 6 miles above the surface. RAD motors (Rocket Assisted Descent) fire to help the parachute slow the spacecraft to a complete stop about 30-50 feet above the surface. The rovers hover for an instant as 4 giant, 6-lobed airbags inflate. Protected by the airbags, the rovers detach from the parachute, fall the final 3 stories, and bounce like a basketball to a rest on the Martian surface. Over the next 3 or 4 days, the petals of the protective landing shell open and the rover charges its solar-powered batteries to prepare for at least 3 months of exploration.