  
| ||||||||||||||||||||||
| CNC Machining Magazine | ||||||||||||||||||||||
|
The team from Next Intent is not the only one looking to Mars, though. The scientists and engineers of NASA’s Jet Propulsion Lab in Pasadena, California, have their hopes and dreams pinned on two spacecraft headed for the red planet. Aboard the spacecraft are two identical Mars Exploration Rovers that will investigate and photograph the planet’s surface. The six-wheeled vehicles will roll across the rocky, red soil of Mars, and examine rocks that could help scientists determine whether there ever was enough water on the planet to support life.
“It is really exciting to know that the wheels, suspension arms and other components we made for the rovers are going to Mars,” says Rodney Babcock, president of Next Intent. Most of the components for the rovers were produced in-house at JPL, but some parts, such as the wheels, were outsourced to local companies. “Back in 1997, when our other business areas were slowing down, I called up the guy in charge of manufacturing engineering at JPL, and he said come on in,” relates Babcock. “We started by doing a lot of fixtures and prototypes for them. As we gained experience with JPL, we got more and more complicated work. They visited our shop numerous times, and certified us for flight components. It was just good timing: When we needed work, they needed someone like us.”
The Mars Exploration Rovers are NASA’s latest attempt, and the agency is not alone in its quest for signs of life on Mars. The race to get back to the red planet is truly international. “It’s one of the most intensive explorations of another planet in history,” says Ed Weiler, associate administrator for NASA’s Office of Space Science. “Literally, the world is going to Mars.” The journey back to Mars has not been easy for anyone. Back in 1998, the Japanese space program launched “Nozomi,” with the intent of visiting Mars in 1999. The spacecraft’s first swing by Earth, however, did not provide it with enough speed to reach Mars as scheduled, so scientists decided to alter its orbit to reach Mars in December 2003, just ahead of the rovers from NASA. The European Space Agency is making its first visit to another planet as well, with the Mars Express orbiter and Beagle 2 lander. The Mars Express space probe was launched on June 2, 2003, from Baikonur Cosmodrome in Russia on a Soyuz-Fregat rocket. It was scheduled to arrive in December 2003, and deploy the Beagle 2 lander to examine the Martian surface in the Isidis Planitia region. Named after the ship that carried Charles Darwin to South America, the Beagle 2 weighs only 66 pounds and has no wheels. The Mars rovers from JPL, fully equipped with the wheels manufactured by Next Intent, were launched from Florida. The first Boeing Delta II rocket carrying the Mars rover Spirit left Cape Canaveral on June 10, 2003. But the second rover, Opportunity, waited on the launch pad for more than two weeks, as “everything that could go wrong did go wrong,” says NASA launch director Omar Baez. First, a fishing boat came too close to the launch site at Cape Canaveral, forcing a delay. Then, there were numerous weather delays, along with technical problems, that kept the Delta rocket grounded. It wasn’t until July 8 that the rover Opportunity was successfully launched.
“Gusev and Meridiani give us two different types of evidence about liquid water in Mars’ history,” says Dr. Joy Crisp, Mars Exploration Rover (MER) project scientist at JPL. “Gusev appears to have been a crater lake. The channel of an ancient riverbed indicates water flowed right into it. Meridiani has a large deposit of gray hematite, a mineral that usually forms in a wet environment.” The identical rovers can see sharper images, explore farther and examine rocks better than anything that’s ever landed on Mars. The rovers each have a panoramic camera, a rock abrasion tool to expose fresh surfaces, a miniature thermal infrared spectrometer, a microscopic camera, a Mossbauer spectrometer and an alpha-proton-X-ray spectrometer. There are nine cameras on each rover: six for navigation, two for geology and one for microscopic investigations. After past disasters, NASA budgeted resources to build and launch a pair of rovers, rather than one. With two, the chances of one making a successful landing are very high. “The rovers will use innovations to aid safe landings, but risks still remain,” says Peter Theisinger, MER project manager. One risk is the parachutes getting tangled and not opening properly. The rover wheels, however, were designed to withstand a rough landing, and anything else that might go wrong. “JPL designed a flat section on the inside of the wheel that has a large fillet radius to blend into the concave inside profile,” explains Babcock. “The wheel has to be able to absorb the landing impact of 30 to 50 g’s. Each rover is attached to the lander with a cable pulling 2,500 pounds of down force, holding the rover tightly to the lander. Strength and weight are critical, so when we machined the wheel, we had to control the wall thickness to a couple thousandths, all the way across.”
“We then took it over to the Haas VF-2 to machine the spirals on the hub of the wheel. It then went back on the lathe to create the convex OD profile. Finally, the VF-5 completed the outside profiling to create the unique tread pattern,” Babcock says. “It was a once-in-a-lifetime experience,” Babcock enthuses. “JPL is great to work with, because they know how hard it was to make the wheels. One of the best things about this project is that it stretched our capabilities and made us better. We weren’t just making a part with a part number, but a part going to Mars.” ~~ Next
Intent
|
||||||||||||||||||||||
On-line!