NASA is simulating conditions typical of Space Shuttle
launch days to see what kinds of ice and frost form on the
foam insulation of the super-cooled External Tank. Engineers
are trying to understand better how much ice can safely
accumulate on the tank without becoming a debris hazard. The
tests are under way at NASA’s Stennis Space Center, Miss.
Because debris from the Space Shuttle Columbia’s External Tank
led to the loss of the orbiter, NASA initiated an effort to
determine sources of debris that could impact the Shuttle
orbiters and cause critical damage. Data from all the tests at
Stennis will be used in that analysis and, in turn, will also
be used in making launch day decisions, beginning with next
year’s Return to Flight mission, STS-114.
During preparations for Space Shuttle launches, at NASA’s
Kennedy Space Center, Fla., ice and frost can form on the
External Tank, depending on weather conditions, during pre-
launch cryogenic loading. That’s when super-cold liquid
hydrogen and liquid oxygen are loaded from storage tanks at
the launch pad into the External Tank. To simulate those
conditions, engineers at Stennis mount four 2-foot-by-2-foot
panels on a metal frame, then freeze them with liquid helium
or liquid nitrogen over an eight-hour period.
The experiment is being conducted in a facility specially
constructed for the tests. Just three weeks before foam test
panels were delivered Oct. 27, the facility was an empty
parking lot. An 8-foot-by-40-foot moveable building was
relocated to the site and then modified to accommodate
equipment to control the temperature and humidity and to
monitor the tests.
Lockheed Martin Space Systems Co. (LMSSC), Michoud Operations
is providing the panels and monitoring the tests to determine
whether ice and frost formations created during the test are
visually similar to those seen on the External Tank before a
launch.
The dimensions, hardness, quality (consistency and uniformity)
and density will be recorded. Nine sensors attached to the
back of each panel send data to a control center where LMSSC
personnel monitor.
“This is one series of many tests being performed throughout
the country to ready the External Tank for a safe Return to
Flight. Facilities at NASA centers like Stennis, as well as
many Defense Department and university facilities, are being
utilized to obtain timely and cost effective results,” said
Sandy Coleman, External Tank project manager at NASA’s
Marshall Space Flight Center, Huntsville, Ala.
Ice and frost samples of sufficient size (2 inches by 2 inches
by 4 inches) will be shipped to Dr. Erland Schulson at
Dartmouth’s Thayer School of Engineering in Hanover, N.H., for
testing and analysis. Schulson directs the Ice Research
Laboratory, which performs research on the physics and
mechanics of ice.
“This is a data-gathering exercise,” External Tank Foam Test
Project Manager Gary Benton said. “We’re trying to replicate
launch pad conditions,” he added.
Video of the testing and interview soundbites will be
available on the NASA TV Video File. NASA TV is available on
the Web and via satellite in the continental U.S. on AMC-6,
Transponder 9C, C-Band, at 72 degrees west longitude. The
frequency is 3880.0 MHz. Polarization is vertical, and audio
is monaural at 6.80 MHz. In Alaska and Hawaii, NASA TV is
available on AMC-7, Transponder 18C, C-Band, at 137 degrees
west longitude. The frequency is 4060.0 MHz. Polarization is
vertical, and audio is monaural at 6.80 MHz.
For NASA TV information and schedules on the Internet, visit:
For more information about NASA’s efforts to return Space
Shuttles to safe flight, visit:
