Wheels and Legs

The Mars 2020 Perseverance Rover Wheels and Legs

The Perseverance rover has six wheels, each with its own individual motor.
The two front and two rear wheels also have individual steering motors. This steering capability allows the vehicle to turn in place, a full 360 degrees. The four-wheel steering also allows the rover to swerve and curve, making arcing turns.

Tech Specs

Legs
  • Materials Made of titanium tubing formed with the same process used to make high-end mountain bike frames.
  • Other Enable the rover to drive over knee-high rocks as tall as 40-centimeters (15.75-inches).

Wheels

  • Materials Made of aluminum, with cleats for traction and curved titanium spokes for springy support.
  • Size 52.5 centimeters (20.7-inches) in diameter
  • Other One full turn of the wheels with no slippage drives the rover 1.65 meters (65-inches).

The Perseverance Rover Wheels

How the Wheels Move

Perseverance uses a similar "rocker-bogie" suspension system that was also used on the Mars Science Laboratory, Mars Exploration Rovers, and Pathfinder rover missions. The suspension system is how the wheels are connected to the rest of the rover and control how the rover interacts when the Martian terrain.

The suspension system has three main components:

Differential: Connects to the left and right rockers and to the rover body by a pivot in the center of the rover's top deck.

Rocker: One each on the left and right side of the rover. Connects the front wheel to the differential and the bogie in the rear.

Bogie: Connects the middle and rear wheels to the rocker.

When driving over the uneven Martian terrain, the suspension system maintains a relatively constant weight on each of the rover's wheels. The suspension also minimizes rover tilt as it drives, keeping it more stable.

The rover's rocker-bogie suspension enables the rover to drive over obstacles (such as rocks) or through depressions that are as large as the rover's wheel (52.5-centimeters, 20.7-inches). Each wheel has an aggressive tread composed of 48-grousers (or cleats), machined into its surface. The grousers give the rover excellent traction when driving in both soft sand and on hard rocks.

Perseverance is designed to withstand a tilt of 45 degrees in any direction without tipping over. For added protection and safe driving, the rover drivers avoid terrains that would cause a tilt of more than 30 degrees.

Rover Speed

By Earth vehicle standards, the Perseverance rover is slow. By Martian vehicle standards, however, Perseverance is a standout performer. The rover has a top speed on flat, hard ground of 4.2-centimeters per second, or 152 meters per hour. This is a little less than 0.1-miles per hour. For comparison, a 3 mile-per-hour walking pace is 134 centimeters per second, or 4,828 meters per hour.

In the case of exploring Mars, however, speed isn't the most relevant quality. It's about the journey and the destinations along the way. The slow pace is energy efficient consuming less than 200-watts. Compare that to a 200-horsepower car engine, consuming nearly 150,000-watts!