The research mission of the space shuttle Columbia continues today, despite the tragedy that befell the astronaut crew and their spaceship in February 2003.
At the Kennedy Space Center in Florida, debris from Columbia was carefully wrapped and secured on pallets and then shipped last month to The Aerospace Corp. in El Segundo, Calif. The pieces are on loan to the nongovernmental group for research purposes.
Aerospace was one of 20 organizations to express interest in borrowing components associated with Columbia's propulsion system. The parts are made of a graphite/epoxy composite and range in size from the dimensions of a large beach ball to the length of a couch.
This is the first time space shuttle debris has ever been released to non-NASA researchers. NASA notified the families of the Columbia crew about the loan before making the items available for study.
Gleaning data from the Columbia mishap is considered preferable to simply entombing debris, as was the case following the fiery, catastrophic explosion of Challenger shortly after liftoff in 1986.
In looking over select pieces of recovered wreckage from Columbia, specialists hope to shed light on the forces encountered during the space plane’s fatal plunge to Earth. Those studies may well help experts design and build safer, more robust components for the spacecraft of tomorrow.
Analysts at The Aerospace Corp. will be subjecting the Columbia debris to various tests. Those investigations should help calibrate analytical models for predicting the re-entry behavior of composites — material used on the space shuttle fleet and elsewhere in the space business.
The shuttle tanks were initially internal to Columbia at various locations within the spacecraft, but separated during shuttle’s breakup. A section from the payload bay door is included in the delivery to The Aerospace Corp. This would be in the category of external surface material.
A few articles from one of the experiments carried on Columbia’s last flight are still to come, said Gary Steckel, senior scientist of The Aerospace Corp.’s Space Materials Laboratory. He is leading the analysis of the Columbia hardware in the labs.
"It’s a unique opportunity," Steckel told Space.com. "Up to this point, we’ve never retrieved any composite materials. That’s not to say that others haven’t re-entered, falling into the ocean where there’s no chance for recovery."
Hazards to people and property
Steckel said that careful analysis of the Columbia debris can show how composite materials responded to various heating and other loads as they slammed through Earth’s atmosphere. The findings could help enhance computer models that predict hazards to people and property from hardware falling from space and striking terra firma.
For instance, Steckel said that if a U.S. Air Force upper stage carrying a large composite tank were launched, later to re-enter, "chances are it’s not going to entirely burn up."
"So using this material from Columbia, we can hopefully predict what that tank is going to do, and whether it’s a danger … hitting a populated area," Steckel said.
Aerospace will have the debris for one year, Steckel said, to perform analyses to estimate maximum temperatures during re-entry based upon the geometry and mass of the recovered composite. "One of these that we got weighs 360 pounds [164 kilograms]. It’s pretty massive," he added.
A trajectory prediction analysis of the debris is also being done. That effort is meant to determine the paths taken by the components after they separated from Columbia — how they "flew" after they broke off and what the environment they experienced was like.
"All the pieces that we have, we know where they were found. Based on the mass of those articles and their geometry, our people will do a trajectory analysis to try and figure out exactly where it was when it broke free," Steckel said. "Once they’ve got that, the thermal history of the debris can be predicted. I’ll be looking at what peak temperatures were seen, how much heating the debris saw and how that jibes with what other people predict."
The Aerospace Corp. has conducted studies on the breakup and re-entry of spacecraft for more than 35 years. In 1997, the organization created a Center for Orbital and Re-entry Debris Studies, or CORDS. This center is gathering information and delving into what happens to human-made objects and the materials they comprise as they slice through Earth's thin to thick atmosphere.
For example, CORDS research teams focus on several key questions:
- Do some materials burn up or break apart, and when might this occur in the reentry process?
- What items do or don’t survive re-entry, and how are materials affected by specific temperature levels?
- How can designers best "enhance" the breakup process to lower the hazards associated with re-entering space objects?
Quite a bit is known about metals, such as stainless steel and titanium commonly used in satellites and other related space hardware that has taken the plunge from Earth orbit over decades of launchings.
Out of the sky
CORDS experts have inspected a number of tanks and spheres from launch stages that have fallen to the ground from space. That includes a stainless-steel propellant tank from the second stage of a Delta launch vehicle that fell onto a Texas ranch in January 1997 after nine months in orbit. Associated parts landed elsewhere in Texas and in Oklahoma. The group also analyzed a light fiberglass fragment that struck, but did not injure, a woman in Tulsa, Oklahoma.
On the international front, CORDS has studied a titanium sphere from the third stage of a Delta launch vehicle that plopped down near Riyadh, Saudi Arabia, in January 2001 after seven years in orbit.
The results of that work have helped in crafting computer models of how objects from space behave when they re-enter Earth’s atmosphere. Good modeling adds to the design of launch vehicle stages and spacecraft, paying off in terms of reducing the chances of harming people or property from a re-entry.
In the 1990s, The Aerospace Corp. also conducted — in collaboration with NASA’s White Sands Test Facility in New Mexico — extensive testing of pressure vessels that made use of composites. Tagged as the Enhanced Technology for Composite Overwrapped Pressure Vessels Program, components similar to these are included in the Columbia debris shipment.
Scarcity of data
NASA and the U.S. Air Force, as well as the European Space Agency, are interested in orbital debris breakup, said Richard Baker, senior engineering specialist within The Aerospace Corp.’s Fluid Mechanics Department.
The ability to analyze the composite material recovered after the Columbia accident is unique, Baker said. "It’s the first opportunity that we know of to look at the re-entry response of this particular material," he told Space.com.
Research findings from the Columbia debris assessment, Baker said, will extend currently used computer models of re-entering space items. "There’s a scarcity of data" concerning space-rated composites, he said.
Very little work has been done on composites, ceramics, and resins that are widely used in constructing orbiting spacecraft and structures, as well as rocket boosters, Baker explained.
Improve safety and reliability
"NASA's mission includes the development of technologies that improve the safety and reliability of access to space," NASA Deputy Administrator Fred Gregory said in a press statement regarding the release for study of recovered Columbia hardware.
"By allowing the scientific community to study Columbia debris, researchers will have the opportunity to gain unprecedented knowledge about the effects of re-entry," Gregory noted.
In time, more pieces of Columbia are expected to be lent for testing and used to help better appraise the rigors of space travel experienced by both piloted and automated spacecraft.
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