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NASA’s Perseverance rover is perfectly balanced for its trip to Mars

Testing Perseverance's Center of Gravity

NASA’s Perseverance rover is preparing for launch in the next few months by undergoing final checks, and it has just made it through one more item on the list: Ensuring that it is correctly balanced.

Part of the final preparations for readying the rover for its trip to Mars is checking that its center of gravity is in the correct place, which is done using a tool called a rover turnover fixture. The rover is placed onto a frame support and spun around lengthways, like a pig on a spit, to check its balance along its x-axis.

With that checked, the rover is then moved to a spin table, which rotates around like a record player. This allows the engineers to check its center of gravity relative to its z-axis and y-axis (top to bottom and left to right).

This image of the Perseverance Mars rover was taken at NASA's Kennedy Space Center on April 7, 2020, during a test of the vehicle's mass properties.
This image of the Perseverance Mars rover was taken at NASA’s Kennedy Space Center on April 7, 2020, during a test of the vehicle’s mass properties. NASA/JPL-Caltech

Any small imbalances in weight distribution could cause problems like parts wearing down faster than expected or issues with balancing when the rover moves over rough surfaces or extreme slopes. So these are accounted for by adding tiny weights to the opposite side of the rover wherever there is an imbalance. In total, after its calibration, the team added 13.8 pounds of weight to the rover, which NASA says brings its center of gravity to within 0.025 millimeters of where it should be.

The total rover now weighs 2,260 pounds, which will make it the heaviest payload ever delivered to the surface of Mars. More weight means it is more difficult to land the rover safely, as the very thin atmosphere of Mars makes it hard to slow the rover as it falls. NASA has therefore been working on a supersonic parachute system that can slow the craft as it enters the atmosphere at more than 12,000 mph. Perseverance’s massive parachute canopy, made of nylon, Technora, and Kevlar fiber, deploys to a width of 70.5 feet and will slow the craft from Mach 1.7 to 200 miles per hour.

Perseverance is set to launch in a two week period beginning on July 17 this year.

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