The tools for the job

The Baltimore Sun

At home, you might find Matt Ashmore reaching into his tool chest for the right socket wrench to speed up the restoration of his 1969 Dodge Polara.

But at the Goddard Space Flight Center, the 30-year-old aerospace engineer has spent the past several years developing a sleek new power screwdriver for spacewalking NASA astronauts. They'll need it to pop the hoods of two broken-down scientific instruments on the orbiting Hubble Space Telescope.

Ashmore heads a team of more than 35 in Goddard's Crew Aids and Tools Development office in Greenbelt. Their job is to invent and build tools for Hubble servicing missions. For the fifth and final repair call on Hubble, set for May, the astronauts will carry 140 custom tools into orbit - a record.

"More than any other tool we've built for the crew in the past," he says of his screwdriver, "we really tried to concentrate on ergonomics: How well can you see what you're working on? How comfortable is it in your hand?" Carefully designed tools are critical for work in space, says astronaut John Grunsfeld, who will be on the mission. "Hubble repairs are all about the tools," he says.

Some tools, like Ashmore's "mini power driver," have been in development since Hubble's Space Telescope Imaging Spectrograph broke down in 2004. Others have been crafted since September, when a key science data computer stopped working.

When problems arise, Grunsfeld points out, "we overcome those difficulties by making better tools. ... Humans are master tool-builders."

Grunsfeld was in Goddard's 1.2 million-cubic-foot "clean room" to practice with tools designed to repair Hubble's Advanced Camera for Surveys, which shut down early in 2007 because of an electrical failure.

Dressed in a dust-free "bunny suit," he rehearsed each step of the repair, standing inside a full-scale replica of the telescope's instrument bay - identical except that when he drops things, they clang to the floor instead of floating off into space.

With Ashmore's mini power driver, he turned dozens of screws to open an electronics box. The screws were captured by another Goddard-designed tool - a plastic tray, more or less. Holes allow the screwdriver's bits in, but loose screws are trapped so they don't drift into space.

"We put a lot of emphasis on making sure we have the right tools, and making sure they're easy to use," says Grunsfeld, who will be making his fifth shuttle flight and his third to service Hubble. "They are works of art."

Led by Jill McGuire, the tool shop at Goddard draws on NASA's own engineers and engineers with contractors such as Lockheed Martin and ATK Space Systems. Their task: to figure out what's needed and how to build it so the job gets done, with minimal risk to the spacewalkers and the telescope.

The engineers work with machinists in building custom tools, some of which have a single task to perform. Others may function much like their consumer-market counterparts, but require materials and designs compatible with the harsh conditions of outer space and the limitations of weightlessness and bulky space gloves.

Toolmakers also work closely with the astronauts. Some even dive with the shuttle crew into the simulated weightlessness of NASA's Neutral Buoyancy tank, a giant pool at the Johnson Space Center in Houston where astronauts train with waterproof versions of their tool kit.

Until now, servicing the Hubble Space Telescope has been a comparatively simple matter of unbolting and replacing failed or outdated hardware. "The telescope was pretty much designed to be all 7/16 -inch bolts, just like you use at home for your car," says Mark M. Jarosz, a spacewalk and crew systems manager for Hubble at Goddard.

For that, Goddard's tool guys developed a pistol-grip tool much like a do-it-yourselfer's cordless screwdriver, except for its heft - 14 pounds.

But it clearly wouldn't do for this mission, when spacewalking astronauts must open and repair two highly sensitive scientific instruments. They'll have to turn scores of delicate screws, and cut and remove components never designed to be touched.

One of their targets is a failed power supply board deep inside Hubble's imaging spectrograph. On the ground, it would be easy, Jarosz says. Grab a screwdriver, remove 112 little screws and open the cover.

But this is space. The mechanic - astronaut Michael Massimino - will work in a bulky spacesuit, with no gravity and the sun rising or setting every 45 minutes. One at a time, he'll remove 39 No. 4 flat head screws; 56 No. 4 socket head cap screws and 17 No. 8 socket head cap screws. Each type requires changing the screwdriver bit.

Ashmore's mini power driver was invented for this mission because NASA's standard-issue pistol-grip tool is too slow and too powerful for 112 tiny STIS screws. Astronauts needed something with a lighter touch and faster speed, that's easier to operate in a spacesuit.

Michael L. Weiss, deputy program manager for the Hubble mission at Goddard, said he's often asked why NASA doesn't just buy its tools at the local hardware store. In fact, a set of clamps on this mission was purchased from an automotive catalog, and modified for the Hubble job.

But in the near-vacuum of space, where the temperature can range from minus-112 degrees Fahrenheit to plus-176 degrees, most consumer products would fail, or endanger the crew or the telescope.

Even so, Goddard's toolmakers frequently do begin a project at the hardware store, to see how commercial toolmakers have addressed similar problems. Ashmore bought cordless drills at local stores and asked a dozen astronauts what speed would be optimal for the task. They settled on 200 rpm. To avoid snapping off the screw heads, they needed a torque rating of less than 5 foot-pounds - a fraction of the power on NASA's big pistol-grip tool.

Ashmore asked a contractor for a "revolutionary" new motor, "custom made for high output in a very small package." Then he designed the driver's stainless steel skin to wrap tightly around it.

Astronauts also asked for better lighting. The mini power driver was planned with six LED bulbs on the end, shining evenly across the work space, but Goddard toolmakers adjusted the design to focus all six bulbs on the screw head.

When Hubble's Advanced Camera for Surveys broke down early in 2007, the Goddard toolmakers found they could use the same mini power driver on the new job, and devised smaller versions of the fastener capture plate and extraction tool.

But Grunsfeld's access and view of the camera's work space is much more restricted. To spare him removing more screws, Goddard designed a guillotine-like device to cut out a metal grid that blocks access to electronics boards that need to come out before the camera can be fixed.

Cutting metal is risky in a spacesuit, so the cutting tool will retain the severed grid so the spacewalker never has to handle it.

Goddard officials could not provide the cost of any new tool, insisting the numbers are buried in the personnel costs for the 35 to 40 engineers on the development team. Compared to that, Weiss says, the actual cost of fabricating tools is "almost negligible."

But while custom-designed, space-qualified tools must be extraordinarily expensive, Weiss points out that an astronaut's time in orbit is priceless. "Every second of time you have ... has to be efficiently used. That's why we put so much effort into making sure the tools are optimized."

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