April 3, 2020
Final assembly and testing of NASA’s Perseverance rover continues at Kennedy Space Center in Florida as the July launch window approaches. In some of the last steps required prior to stacking the spacecraft components in the configuration they’ll be in atop the Atlas V rocket, the rover’s wheels and parachute have been installed.
Perseverance received its six flight wheels on March 30, 2020. While the rover took a test drive last December, it was on “flight spares” that wouldn’t be making the trip to Mars. Designed for the kind of off-roading Perseverance will perform on the Red Planet, the wheels are re-engineered versions of the ones NASA’s Curiosity has been using on its traverses of Mount Sharp.
Machined out of a block of flight-grade aluminum and equipped with titanium spokes, each wheel is slightly larger in diameter and narrower than Curiosity’s, with skins that are almost a millimeter thicker. They also feature new treads, or grousers: In place of Curiosity’s 24 chevron-pattern treads are 48 gently curved ones. Extensive testing in the Mars Yard at NASA’s Jet Propulsion Laboratory, which built the rover and manages operations, has shown these treads better withstand the pressure from sharp rocks and grip just as well or better than Curiosity’s when driving on sand.
The Parachute
The job of adding Perseverance’s parachute to the back shell, where the rover will be stowed on the journey to the Red Planet, took several days and was finished on March 26. Tasked with slowing the heaviest payload in the history of Mars exploration from Mach 1.7 to about 200 mph (320 kph) during the rover’s landing on Feb., 18, 2021, the 194 pounds (88 kilograms) of nylon, Technora and Kevlar fibers are packed so tightly into a 20-inch-wide (50-centimeter-wide) aluminum cylinder that it is as dense as oak wood. When deployed at about 7 miles (11 kilometers) above the Martian surface, the chute will take about a half-second to fully inflate its 70.5-foot-wide (21.5-meter-wide) canopy.
The Perseverance rover is a robotic scientist weighing 2,260 pounds (1,025 kilograms). It will search for signs of past microbial life, characterize the planet’s climate and geology, collect samples for future return to Earth, and pave the way for human exploration of the Red Planet. No matter what day Perseverance launches during its July 17-Aug. 5 launch period, it will land on Mars’ Jezero Crater on Feb. 18, 2021.
Perseverance is part of a larger program that includes missions to the Moon as a way to prepare for human exploration of the Red Planet. Charged with returning astronauts to the Moon by 2024, NASA will establish a sustained human presence on and around the Moon by 2028 through NASA’s Artemis lunar exploration plans.
For more information about the mission, go to:
https://mars.nasa.gov/mars2020/
For more about NASA’s Moon to Mars plans, visit:
https://www.nasa.gov/topics/moon-to-mars
In some sectors, 20-inch car wheels are called “Dubs”.
So how much does one of those wheels cost?
“Endeavor to persevere!”
What am I looking at with the spokes?
Based on the shape this is also the suspension?
I am going to assume the rim is basically non compressible, but if you look at each spoke not only are the bowed out relative to the main axis, but they then turn 90 degs and run in an arc roughly concentric to the hub. This places the mounting point on the rim roughly 60degs or so out relative to the starting position on the hub.
At a quick guess this is also going to affect the transfer of torque between the hub and rim.
Anyone else support these observations?
Also we seem to have socket head cap screws holding it all together. Would they be COTS? I mean if you are spending billions putting this thing onto another planet I would guess your budget would allow you to get your own fasteners made as well if need be.
Curious 🙂
Also, new thought – is the hub springing to allow for the differences in thermal expansion with the different materials being used?
If the world is still in quarantine by the July-August launch and landing it will be watched by even more persons. Let’s hope it functions like the billions of dollars it costs and gives us a thrill while collecting data. Stay safe.
Yep, they better use a harder/more resistance material for the wheels. Maybe titanium instead of aluminum.
The aluminum used is an alloy that will have enhanced characteristics (strength/durability, etc), not pure aluminum.
As an engineer, I of course assumed that, yet any possible aluminum alloy still isn’t a particularly hard/wear-resistant metal like steel (too heavy for this job) or, lightweight & perfectly-suited titanium. I see the wheel spokes are indeed titanium, but the entire wheel should have been IMO.
What NASA should be doing. This is cool stuff!
Those tires don’t look to provide any resistance to sliding sideways. Didn’t Jeeps have similar problems with their original tires?
Yeah, they probably don’t.
Then again, I doubt they can get this baby up to a speed high enough where road holding becomes an issue.
On slopes I guess they intend to always up and down, not parallel to the contours