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The International Space Station Meets TRIZ

| On 30, Sep 2007

Michael S. Slocum

The International Space Station is a massive undertaking coordinated by five national agencies (US, Russia, Japan, Europe and Canada) with participation from about a dozen other countries. In all, hundreds of companies and 100,000 people have been responsible for the building and operation of the Space Station, planned to be completed around 2016 at a cost of about $130 billion.

Some other facts about the International Space Station:

  • It will have a mass of about 500 tons when completely assembled and will measure the length of a football field (361 feet).

  • It will provide 46,000 cubic feet of pressurized living and working space-equivalent to the interior volume of one 747 jumbo jet.

  • The solar-powered electrical system is connected with 42,000 feet, or about eight miles, of wire.

  • The batteries, lined up end-to-end, measure 2,900 feet, more than ½ mile long.

  • Electrical and electronic parts include 1,900 different types of resistors, 500 types of capacitors and 150 types of transistors (note that this is not the part count; rather, it is a count of different types of hardware).

  • Fifty-two computers will control the systems on the International Space Station. There will be more than 400,000 lines of software for 16 of those computers which, in turn, talk to 2,000 sensors, effectors and embedded “smart” hardware controllers.

It’s the complexity of the Space Station – and its associated technical challenges – that initially drew TRIZ into the problem-solving mix. In many cases, typical “compromise” solutions would not meet the strict performance requirements the system demanded, and more creative solutions were needed.

For example, the Space Station is built by adding pressurized and un-pressurized modules to the system over time. Each module in the system exists to perform some specified scientific or research purpose. One such module, the Japanese Experiment Module, is a product of the Japanese Aerospace Exploration Agency, and is scheduled to make its trip to the International Space Station in February 2008.

A pressurized mating adaptor is needed to attach such modules to themselves as the space station is built over time. Just one technical challenge involved in building a pressurized mating adaptor (PMA) is that the heat generated by welding together its structural rings can damage associated sensitive electronics. In TRIZ terms, this is a physical contradiction that required the use of the separation, or isolation, principle to solve the problem of achieving proper welds but not damaging associated systems.

Initially, the electronics were attached to the internal wall of the PMA, and for good reasons that benefited the overall system. But the isolation principle behooved engineers to reconsider the spatial proximity of the electronic components, and decided they could isolate those components from the PMA structure using Fiberite™ bushings at attachment sites.

This worked very well, introduced little cost and complexity, minimized intrusion of the electronics into the internal volume of the PMA, and did not require any changes for the component suppliers.

Also, NASA engineers were challenged by the difficult procedure of attaching modules together in space – a task that required attaching well over a dozen power and signal couplings together. Imagine all those wires hanging or taped to the PMA need to be connected with similar wires on the space modules.

This was a difficult task in space that utilized a several-step, manual, module-interlock system. First two modules are brought together by an astronaut according to a “key system,” whereby their respective anodized aluminum fittings align. Next, the astronaut pushes the two fittings together until they snap in place. Finally, the astronaut uses a special aluminum tool to apply torque to the threaded sleeves of the two fittings until they lock down tightly.

Simulating conditions in space by working under water, this process was difficult and posed unacceptable mission risk. The design team, therefore, considered various TRIZ approaches and ultimately decided to use the Physical Contradiction technique.

The physical bi-polarity was this: they wanted the module interlock to ensure proper physical mating and powersignal distribution. At the same time, they didn’t want the interlock system because it was so difficult to perform.

The team applied the separation in time principle to compress the mating steps—combine all actions (align, connect, lock) into a single action instead of three. This required a re-design of the locking system whereby, upon pushing two keyed fittings together, the astronaut activates a mechanism that aligns, connects and locks the parts together in a simple, single motion.

This one solution yielded significant cost savings. One part, not many, for each necessary connection were now required. There was no longer a need to design and produce specialized tools. The time and cost of training astronauts was significantly reduced as well. And the new simplicity factor made the procedure safer and lowered overall mission risk to acceptable levels.

Still another formidable challenge was the extreme difficulty and variety of problems around the Space Station’s solar power array, a large system with a surface area of 27,000 square feet, or more than half an acre. The shear size of the structure posed extremely difficult problems. The surface finish on each piece of the mirrored tiles had to be near perfect. And assembling each of these panels into the overall structure posed difficulty as well.

During assembly, when panels and tiles were added to the system, adjacent pieces might be damaged, for example by tools or equipment falling on them. By applying the TRIZ principle of the other way around, designers inverted the solar panel structure for the assembly process so installers were looking up at the structure while working on it. This simple action dramatically reduced damage to tiles as others were added.

Also, the biggest reason for panel and tile damage was that many were removed, moved andor placed in other areas of the system; such transportation and turnover increased the opportunity to incur damage, and damage was in fact incurred more frequently than acceptable.

The reason panels and tiles were moved so much was that the system was vulnerable to heat differentials in different areas due to surface aberrations on certain panels and tiles. If such surface variation could be minimized or narrowed to the right extent, then no such heat differentials would occur, and the system would not be compromised or malfunction.

The engineering team measured and studied the problem, moving and replacing tiles in the system according to what the empirical data said. The more they did this, the more the problem just moved around from area to another. This was a serious problem because, in space, surface aberrations can cause one or another part of the solar panel system to overheat – or just create heat differentials that cause panels and tiles to break as they expand or contract according to those differentials.

A TRIZ technique called the System Approach was employed whereby the engineers studied their problem through the lens of the system, sub-system and super-system. It turned out that they had the system and the sub-system well covered in their consideration of solutions theretofore, but they needed to change their paradigm to include the super-system as well.

The System Approach forced the engineers to consider the larger system surrounding the solar panels and tiles, including the power distribution systems as well as the software that controls those systems. Ultimately, the engineers left all the panels and tiles where they were and solved the problem with software.

They determined that they could survey the panel array and record aberration information. They could then write correction algorithms for the analysis software that would adjust differences in performance based on surface imperfections. In other words, the software would make adjustments to how the system drew and distributed power from the various panels and areas of the overall panel assembly – thereby making the system robust to surface aberrations and fluctuations.

There were about 100 other problems encountered and solutions achieved using TRIZ on the International Space Station, each of which demonstrates that innovation is not typically robed in the fancy cloak of One Big Idea, like the Space Station itself. In practice, innovation is the ability to meet specific challenges and solve specific problems with specific tenacity over and over again until they add up to a whole that is greater than the sum of the parts.

(Excerpted from Insourcing Innovation, Francis and Taylor, 2007)