A highly durable product-marking system approved for use by NASA in 2001 and currently being tested on the International Space Station would have helped investigators more easily identify debris from space shuttle Columbia, had it been available when the orbiter was built.
The 2-D marking system, known as Data Matrix, is based on compressed symbology technology patented by a Canton, Mass.-based company called RVSI and released for public use in the public domain.
The Data Matrix symbol is a checkerboardlike mark that's etched permanently onto a surface. The mark is scanned, like a bar code, using a charge-coupled device or optical reader, but is capable of storing up to 100 times more information than a bar code, company officials said.
Data Matrix symbols were designed to withstand extremely harsh conditions, said Donald Roxby, director of The Symbology Research Center, a Huntsville, Ala.-based unit of RVSI.
"Tests at Marshall [Space Flight Center] verified the mark would survive the 18,000-mile-per-hour slipstreams and temperatures in excess of 2,300 degrees" associated with orbiter re-entry, Roxby said. "The symbols could sustain up to 30% damage and still provide 100% of the [encoded] data."
Jerry Berg, a spokesman for the Marshall Space Flight Center in Huntsville, said the organization was unable to comment because the official in charge of the Data Matrix effort was not immediately available. But according to Roxby, since the 2-D etches are typically made during the product manufacturing process, none of Columbia's parts -- except for three tiles that were recently replaced -- carried the Data Matrix symbol.
The symbols would have made it easier for investigators to identify
parts of the Columbia orbiter that are now being recovered, he added.
A variety of Data Matrix symbols of various sizes and on different materials is being tested on the International Space Station to see how well they hold up in space. "The last photos we saw show these marks to be still in very good condition and readable," Roxby said.
The goal behind marking parts this way was to improve NASA's ability to readily check the specifications, manufacturing history and operational data of any of the parts that go into a shuttle, said Erin Binder, a director at Golden Valley, Minn.-based Veritec Inc., another company that worked with NASA to develop a compressed symbology standard for marking space shuttle parts.
"We had this code tested, from the outside of tires to individual tiles" on the orbiter, Binder said. "The intent was to mark everything so [NASA] had enough information to tie every part at the smallest component level back to a database."
Veritec's Vericode system was an early candidate for standardization at NASA before the space organization finally went with Data Matrix.
Unlike bar codes, which don't work on many types of surfaces and can peel off, compressed symbols such as Data Matrix can be applied permanently to a wide variety of surfaces, Roxby said. To mark the three newer tiles on Columbia, for instance, small recesses were first etched out of each tile and were then filled with a ceramic paint that would melt permanently into the tile from the heat on re-entry, Roxby said.
Since 1997, RVSI and NASA have been working on commercializing the technology and ruggedizing it for NASA's specialized needs.