Perseverance ejected two 70 kg "cruise balance masses" just before it became an airplane, to move its center of mass off axis and increase its angle of attack from 0° to about 16° to make it steerable.
Shortly before it stopped being an airplane, it ejected six more tungsten "balance masses," in something called the Straighten Up and Fly Right (SUFR) maneuver. This reduced its AoA to less than 5° before deploying its parachute.
- How many kg were those six masses?
- Why were that many needed?
If for sequential deployment to damp oscillations, why were so few needed? Why not spray a thousand, or even spray a heavy liquid?
Its 2012 predecessor Curiosity had 2x 75 kg and 6x 25 kg masses.