Steep slopes of unconsolidated material at planetary destinations of recent interest, such as craters and skylights, defy descent by rovers due to uncontrolled slip. This work proposes a novel method based on braking by plowing to arrest slip during descent maneuvers on planetary terrains. The method covers two fundamental maneuvers: direct descent and point-turning. For direct descent, an automatic control system estimates slip through visual odometry and actuates a plow accordingly. For point-turning, the plow is engaged as a point of rotation. Experimental results showed that the slip control system for direct descent kept slip within ±5% for slopes as steep as 31° and for different commanded driving speeds. In the point-turning tests, downhill displacement was less than 0.08 m on inclinations up to 30°. Thus, a plowing policy was developed that allows precise descent on extreme slopes by minimizing slip. As a result, this work expands current rover mobility and control capabilities.