JSC News Release Log 1990/90-025
Shuttle Trash Compactor to Serve as Extended Duration Flight Treasure
When Fred Abolfathi and J.B. Thomas work on one of their many projects at Johnson Space Center, a detailed test objective scheduled to fly on STS-35 in May, they don't have any problem finding material to test it out - they just reach for the nearest trash can.
Abolfathi, a Lockheed Engineering and Science Corp. project engineer, and Thomas, a subsystems manager in JSC's Man-Systems Division, have spent the past year working on a trash compactor for the Space Shuttle. They've crushed hundreds of pop cans, squished thousands of memos, mutilated pounds of flight food containers, and even thrown in a couple of cans full of cat food, just to test odor containment. "So far we haven't had any trouble generating trash,” Abolfathi said.
The experimental shuttle trash compactor is scheduled to fly on STS-35 for the first time as detailed test objective (DTO) 0534. The compactor will become an important part of shuttle hardware as NASA begins flying extended duration orbiter flights (EDO), said project managers. EDO missions mean more trash in a vehicle where stowage space already is extremely limited. The first 13 day EDO mission currently is scheduled in 1992. Plans call for the first 16 day EDO mission to occur in 1994.
"The goal of the EDO Trash Compactor is to reduce the trash to a manageable volume for EDO missions," said Thomas. "Each crew member generates about one-half cubic foot of trash per day."
Current projections indicate about 56 cubic feet of trash will be generated on the first 16 day EDO flight and those working on this project would like to reduce that number to 14 cubic feet, said Abolfathi.
The 48-pound compactor fits in place of middeck locker and is operated manually. Trash is placed inside a polypropylene bag which, when full, is placed inside the chamber of the compactor.
One bag holds a volume equivalent to one-half cubic foot. A metal compactor door is closed securing the bag inside the chamber. A crew member then uses handles on either side of the compactor in a garden shear-type movement to engage gears which push a piston from the back of the chamber to the front, compressing the trash to a volume four times smaller. The piston compresses the trash using a force of about 60 pounds per square inch.
After the piston is moved as far forward as it was designed to go, the crew member retracts the piston, opens the compactor door, and pulls a strap to remove the bag from the chamber. The bag has a lid which houses a charcoal filter to contain odors, fluids and bacteria. A one way air valve in the lid allows air out of the bag, relieving pressure built up during compaction. Next, the entire package is placed inside the orbiter trash stowage compartment. The bags fit through an eight inch diameter hole in the middeck floor. This compartment, known as Volume F, normally is used for wet trash stowage.
Operating the EDO Trash Compactor could provide a type of exercise for the crew, Thomas said.
About 10 years ago Johnson Engineering Corp. in Boulder, Colo. began working on a concept for an orbiter trash compactor that could be developed commercially for recreational vehicles. Using that experience, the company bid on a contract in July 1989 to design a shuttle trash compactor.
The design has been tested and certified using a variety of items, including: food, water, flight trash, plastic and metal food containers, and teleprinter pages.
The current shuttle rehydratable food package, which does not crush well in the compactor, is being redesigned for EDO missions, Abolfathi said.
"The DTO is flying as a proof of concept for the compactor," said Abolfathi. "We'll prove the concept will work and results will be used to build two flight units."
During STS-35, crew members will experiment with various types of lids and bags, Abolfathi said. Thirty bags and lids will accompany the compactor into space.
The hardware is scheduled to be shipped to KSC March 19 to support the Crew Equipment Interface Test), said Hamid Tabibian, Man-System's Systems Development Section manager.
"We've always been interested in designing a trash compactor for the shuttle but we just couldn't justify flying it until extended duration flights began coming along," Tabibian said. "EDO missions will last up to 16 days and can have as many as seven people. The trash compactor will become essential for those types of missions."
Photos available through JSC's Still Photo Library, (713) 483-4231. Photo numbers: S90-31435, S90-31434, S90-31433.