MRO Magazine

Out of this world

"So there I was, upside down in the middle of nowhere, no gravity, my tools were floating all over the place ..." This sounds like the beginning of a real Friday-night whopper, but if it was an International Space Station (ISS) astronaut doing the


December 1, 2003
By Carroll Mccormick

“So there I was, upside down in the middle of nowhere, no gravity, my tools were floating all over the place …” This sounds like the beginning of a real Friday-night whopper, but if it was an International Space Station (ISS) astronaut doing the telling, he would just be warming up to another strange but true story of maintenance in outer space.

For example, consider the story Canadian Space Agency astronaut Dr. Dave Williams told Machinery & Equipment MRO recently. It was back in April 1998 that he was partway through a 10-million-km, 256-orbit mission on the Space Shuttle Columbia, performing life science experiments in the Neurolab. “One of my friends was working on a large cable. He let it go for 30 seconds and when he turned back, it had disappeared. He said to me, ‘What did you do with my cable.’ I said, ‘I didn’t do anything with your cable.’ We spent 20 minutes looking for it. It had become intertwined with a bunch of other cables.”

That’s why there’s a key parts rule for maintenance work in outer space: During assembly and disassembly, tether or stick the bits and pieces to something. “If you remove four screws from a panel, they will eventually float away. We do the reverse gray tape trick. This is a great temporary restraint mechanism,” says Williams. Bend a bit of tape into a circle with the sticky side out. Stick it to a wall and then stick your screws and such to the tape, like flies on flypaper.

Then there’s the tool rule: Don’t leave them lying — or actually — floating around. “There is the whole issue of tool management,” says Williams. “If you release a tool in space, the tool will stay there for a moment, but the air currents will take it away.”

Advertisement

They do not want wrenches and stuff floating away during a space walk, which is why the fronts of astronauts’ spacesuits are so cluttered with exotic thingamajigs. They’re like portable tool chests.

The first astronauts were fighter pilots on a really fast ride. Mission commanders are still test pilots, but the men and women associated with the ISS program are specialists. They are responsible not only for assembling the 100 different components that will eventually make up the 453,600-kg ISS, but also for doing all the MRO (maintenance, repair and overhaul) work during its service life — all while floating 400 km above earth.

Astronauts mated the first two components of the ISS, the Russian-built Zarya control module and the United States-built Unity connecting module, on Dec. 8, 1998. They were separately launched on a Proton rocket from Kazakhstan, and on the Space Shuttle Endeavour from Cape Canaveral, Fla.

Inhabited since Nov. 2, 2000, this orbiting laboratory and test bed for twenty-first century technology will eventually host up to seven long-duration astronauts at a time. July 29, 2003, marked the 1,000th consecutive day of people living and working aboard the ISS.

As of September 2003, after 37 U.S. shuttle and Russian rocket launches and 51 space walks, the ISS assembly has grown to 14 major components (and lots of minor ones) measuring a total of 73 by 44.5 by 27.5 metres, with 425 cu m of habitable volume and a total weight of 187,000 kg.

‘Complex’ is an inadequate label to describe the space station, its support staff and its supply chain. Earthside, over 100,000 support personnel and contractors in 500 facilities in 37 U.S. states, 16 countries (Canada among them) and five space agencies are involved in the ISS.

The Unity module alone has more than 50,000 mechanical items, 216 fluid and gas lines and 121 internal and external electrical cables using 10 km of wire. The 399-page ISS Familiarization Manual prepared by the National Aeronautics and Space Administration (NASA) mentions that there are over 300 heaters in the U.S. orbital segments alone. And then there are all those systems: electrical power, communications, thermal control, environmental control, life support, navigation and robotics … the list goes on and on.

The space station’s equivalent of plant maintenance and engineering managers are the Operations Support Officers (OSO) who work in NASA’s Front Room at the Mission Control Center in Houston, Tex. It’s also where the flight director and 13 other mission controllers monitor the ISS and direct the crew’s activities.

The OSO is responsible for the station’s structures, mechanical systems, maintenance, and supply chain management. They are like maintenance managers at warp nine. Whatever the problem, they either have the answers, or know who is responsible for getting them.

“Operations Support Officer (OSO) is the designation of the flight controller in the Mission Control Center responsible for ISS structural issues as well as mechanical systems,” says OSO Lisa Marszalek. “OSOs are responsible for the operation of attachment systems used during station assembly. OSOs also train the crew with necessary on-orbit maintenance skills.”

Bill O’Hara is an OSO who works in Space Station Mechanisms and Maintenance Operations. “We write ISS assembly and maintenance procedures and train crew members with the skills to perform them,” he says. “We also support real-time activities in the ISS Mission Control Center.”

Notwithstanding their skills and those of the others who monitor and control the ISS systems, it’s the on-orbit astronauts do the hands-on work as they whirl around the earth — everything from the ISS assembly to scheduled maintenance and emergency repairs.

Last June 27, for example, Russian cosmonaut Yuri Malenchenko had to replace a pump. On Sept. 5, Malenchenko and his NASA partner Ed Lu spent most of the day doing annual spacesuit maintenance, which included emptying and refilling the suit’s water tank and loops, cycling relief valves and running the suit’s fan for two hours to lubricate it.

Mission status reports frequently refer to housekeeping maintenance and “jar jobs” — odds and ends of work ready to fill any spare moment.

The key to success for the ISS is timely and effective maintenance, according to NASA. Key tenets guiding its maintenance philosophy are that the ISS cannot be brought into the shop for repairs (obviously) and that repairs should be permanent (cannibalization of parts and temporary fixes are strongly discouraged). The goal is to return affected systems to their original configuration and efficiency.

The ISS stocks many Orbital Replacement Units (ORU), so when some component fails, a unit can simply be replaced. NASA feels this approach reduces the amount of crew training and leaves more time for doing science. The project’s international partners are responsible for the planning, training and execution of maintenance procedures and supply tools and deliver spares to the ISS.

Specialized skills

Training, methods and tools are a familiar trinity to anyone in the MRO business, but familiar is a strange concept when doing maintenance in space.

Take training, for which NASA is famously obsessive. All ISS crews receive basic and advanced on-orbit maintenance training. Some learn additional specialized skills. When we spoke with Dave Williams, he was training 40-50 hours a week for his next shuttle flight. “We are trained for our space walk and to take care of any contingencies in the ISS. We are also given training on the ISS, but as a visiting crew, we are trained to help the long-duration crew.”

In preparation for his 1998 shuttle flight, Williams spent time in NASA’s Neutral Buoyancy Laboratory (NBL). “On routine shuttle flights there is not a lot of maintenance that takes place if everything works OK. I was trained as a contingency EVR (extravhicular robotics) specialist in case there was a problem, like a payload door not closing properly,” explains Williams.

The NBL is a 24.6-million litre, 12-metre-deep pool in which astronauts can practice tasks in a fairly good simulation of the weightlessness of space. Here, crews train exhaustively for ISS assembly missions and any conceivable emergency. Outside of the NBL, specialists teach crews how to operate and maintain ISS equipment. NASA leaves very little to chance.

NASA has four ISS
maintenance categories:

Preventive, which includes systematic inspections, repairs and preplanned replacements

Corrective, which restores items to original condition

In-situ, in which repairs are performed at the hardware site, and

Contingency, which restores functions vital to crew safety or the integrity of the ISS — NASA terminology for life-threatening situations.

Any maintenance operation or failure that NASA can think of has been given a priority ranking. Core maintenance procedures, including a list of the required tools, safety steps (such as removing power or pressure) and access and removal instructions, also are spelled out.

Average ISS annual maintenance figures are: 2,536 crew hours doing maintenance inside the ISS; 777 crew hours doing robot-assisted maintenance outside the ISS from within the ISS; and 421 crew hours doing maintenance during space walks.

NASA has also identified different skill levels, ranging from those required for visual inspections and cleaning to replacing ORUs, to complex tasks, such as circuit board repairs, that can only be done on earth.

Tools include familiar items like ball peen hammers, pliers, wrenches and screwdrivers, and range to fibre optic repair kits and a sewing kit, as well as various diagnostic kits. The crew has a great deal of capability to diagnose and repair failed ISS ORUs and ORU components, according to NASA.

To help with work being done in zero gravity, the ISS has a portable worktable on which astronauts can restrain equipment. The setup includes a containment system, which resembles the gloveboxes chemists use to work with dangerous substances, to contain debris created during, say, cutting, drilling, filing or soldering. (On one Shuttle mission, a Canadarm wrist joint failed because a missed scrap of wire a couple of millimetres long floated into the wrong place and shorted it out.)

Regarding the selection of spares carried on the space-restricted ISS, the more critical the function of a part, the shorter the mean time between failures (MTBF) and the more of that specific part that is in use on board, the more likely the ISS is to have it in stores.

Replacement parts delivery is not on-demand. The shuttle fleet is currently grounded until at least late 2004. Although Russia is currently filling the gap with its launch vehicles, suffice it to say that deliveries are infrequent — not quite what was meant by those who coined the phrase ‘just-in-time.’

Although astronauts spend quite a bit of time doing maintenance — one source estimates that ISS maintenance could occupy one crew member full time — ground crews do support activities such as tracking ORU failures, generating maintenance procedures and updating maintenance databases.

Maintenance in outer space is clearly a topic that is death to the pace of science fiction novels. A recent article in a science magazine discusses which propulsion technology would get us across the galaxy the quickest, as though speed was the only impediment to space travel. Yet maintenance seems to be the Achilles heel in today’s hideously complex and maintenance-intensive manned spacecraft.

One can only wonder what on-board parts repair facilities, raw materials stores and unimaginably reliable technologies or self-repairing equipment will be needed for the multi-year space voyages of the future, let alone the training and expertise required of those maintenance professionals who must keep downtime at bay in a hostile environment that’s simply out of this world.MRO

Machinery & Equipment MRO senior contributing editor Carroll McCormick is based in Montreal.

INSIDE THE ISS

Since the first crew arrived in November 2000, the International Space Station has grown into an unparalleled space laboratory whose size will eventually more than double. The living and working area increased by 168 cu m during the first 1,000 days. Now, the station’s 425 cu m volume is larger than a three-bedroom house.

The seven Expedition crews, 10 Americans and 10 Russians, have conducted 12 space walks from the ISS, welcomed 11 visiting shuttles, 10 Russian Progress cargo vehicles and four Soyuz taxi crews. Additions to the station include the first space railway, stretching more than 40 metres and a science facility more sophisticated than any ever flown in space. Canada provided a new generation of space robotics with the unmatched capabilities of the Canadarm2.

Inside the orbiting complex, crews have created a home as well as a laboratory, with living quarters, a kitchen and exercise equipment to keep them strong and healthy.

Aboard the station, research has been conducted in human life sciences, physical sciences, fundamental space biology, space product development and earth science. Experiments conducted by station crews may provide insight that could lead to improved crops, better braking systems, advanced spacecraft materials and petroleum industry advancements.

Expansion of the ISS will continue in the future. The European Columbus Laboratory will expand the station’s size to that of a five-bedroom house. A European Automated Transfer Vehicle will serve as an additional spacecraft for transporting supplies to the station. The “Kibo” Japanese Experiment Module will be added to further increase the station’s science capabilities.

As NASA says, today’s space station “is only the beginning.”