It's the middle of the night at JPL, and the usual dozens of deer are on their nightly foraging rounds across the campus. Mars is up. So is the Moon. And so are nine machinists in the lab's high-precision fabrication shop, working the second shift that ends between midnight and 3 a.m. They are part of the round-the-clock team turning out odd-shaped pieces of metal that will become robots destined for Mars.
Night shift supervisor Gary Keel holds in his hand an improbable mix of geometric shapes that somehow meld smoothly together. Finely machined out a solid, 25-pound brick of titanium, the part looks like a mechanical dog's leg as dreamed up by a computer. In a way, it is.
Only this is a leg for a rover of a different kind - it's a wheel strut for one of the two twin Mars Exploration Rovers now being built for launch in 2003. This part is one of thousands that will comprise the rovers.
The part displays a mathematical complexity made possible only through the speedy calculations of computer-aided design. Rendering it into a real part from a drawing falls to Keel and his colleagues in the fabrication shop.
About eighty percent of the rover parts are of a more routine sort that will be made by machinists outside of JPL. Some parts, like the launch vehicle adapter that connects the spacecraft to the rocket, are huge - the size of a round banquet table. Others are smaller than the diameter of a pencil. Large or small, the most exotic pieces stay at JPL with staff machinists, now available 24 hours a day, seven days a week through the crunch time of the rovers' assembly and test phase.
"We Get the 'Oh No!' Parts"
"We get the 'Oh No!' parts" says Keel. "The 'Nobody Else Wants to Touch This' parts." Engineers often want to keep the most complicated and challenging machining in-house, he says. That way, they can check the progress with the machinists who are bringing the new parts into being, and have an opportunity to make adjustments if needed. The relationship is known as "concurrent machining and engineering."
Mike Mangano, the Mars Exploration Rover mission's mechanical systems project element manager, explains the value of being able to communicate with the machinists on site: "You can do the design, you can put it on paper, but until you start to actually make it, you don't know what kinds of problems you're going to run into."
Because of the very strict constraints on size and weight, the spacecraft, landers and rovers are compactly layered inside of one another like Russian dolls, says Mangano. "We call it configurationally challenged," he says. The geometric complexity of some of the parts reflects the creative design that packs a lot of engineering and science capability into a relatively small spacecraft system.
The rover and lander systems require some three dozen gears and motors. Some of these help open and unfold the landers to release the rovers, some deploy scientific and communications instruments, and some are part of the rover's mobility and steering system. Building those and other parts for the project is driven by "a pretty ambitious schedule," says Mangano. Hence, Keel and other JPL machinists are burning the midnight oil.
"We interact a lot with the engineers," says Keel. Working against the project's tight deadlines, "If we have a question, they're going to get out of bed and come in and help us."
Keel, who grew up in Southern California's Simi Valley with a passion for science fiction and dreams of a baseball career, instead set out on a path that would lead to Mars when he took vocational machine shop classes at Royal High School. His shop teacher recommended him for an apprenticeship at a local shop making general industrial parts for autos, computers and safes. He later worked at Rocketdyne on parts for the Space Shuttle launch system. Ten years ago, he joined JPL.
"Mars Pathfinder was my first project where I worked from the start to finish," said Keel. Then he worked on parts for the Cassini spacecraft now enroute to Saturn. "Those were the first missions I felt part of."
For a machinist, Keel says, "this is the best place in the world to work. It's not the same thing day in, day out. There are challenging opportunities and a chance to advance your career. And this is the only place I know of where you work on a part for something and see it on the front page of the Los Angeles Times making history a few years later."