Three terminal descent engines provided attitude control and reduced the
lander’s velocity after parachute separation. The 2,600-newton (600-pound)
throttleable engines were located 120 degrees apart on the lander’s sidebeams.
They burned hydrazine monopropellant.
The engines used an advanced exhaust design that wouldn't alter the landing
site environment. An unusual grouping of 18 small nozzles on each engine would
spread engine exhaust over a wide angle that wouldn't alter the surface or
unduly disturb the chemical and biological experiments.
Two spherical titanium tanks, attached to opposite sides of the lander body
beneath the RTG wind covers, fed the descent engines from an 85-kilogram (188
pound) hydrazine propellant supply.