]
Wake Shield Facility is an experimental science platform that was placed in
low-earth orbitA low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
by the
Space ShuttleThe Space Shuttle, part of the Space Transportation System , is a spacecraft operated by NASA for orbital human spaceflight missions. It began operations in the 1980s and is scheduled to be retired from service in 2010 after 134 launches...
. It is a 3.7 meter (12 ft) diameter, free-flying
stainless steelIn metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel alloy with a minimum of 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel...
disk.
The WSF is deployed in the wake of the Space Shuttle at an orbital altitude of over 300 kilometers (186 mi), within the
thermosphereThe thermosphere is biggest of all the layers of the earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. The International Space Station has a stable orbit within the upper part of the thermosphere, between...
, where the atmosphere is exceedingly tenuous. The forward edge of the WSF disk redirects atmospheric and other particles around the sides, leaving an "ultra-vacuum" in its wake.
]
Wake Shield Facility is an experimental science platform that was placed in
low-earth orbitA low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
by the
Space ShuttleThe Space Shuttle, part of the Space Transportation System , is a spacecraft operated by NASA for orbital human spaceflight missions. It began operations in the 1980s and is scheduled to be retired from service in 2010 after 134 launches...
. It is a 3.7 meter (12 ft) diameter, free-flying
stainless steelIn metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel alloy with a minimum of 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel...
disk.
The WSF is deployed in the wake of the Space Shuttle at an orbital altitude of over 300 kilometers (186 mi), within the
thermosphereThe thermosphere is biggest of all the layers of the earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. The International Space Station has a stable orbit within the upper part of the thermosphere, between...
, where the atmosphere is exceedingly tenuous. The forward edge of the WSF disk redirects atmospheric and other particles around the sides, leaving an "ultra-vacuum" in its wake. The resulting vacuum is used to study epitaxial film growth.
The WSF has flown into space three times, on board shuttle flights
STS-60STS-60 was the first mission of the US/Russian Shuttle-Mir Program, which carried the first Russian cosmonaut, Sergei K. Krikalev, to fly aboard a Space Shuttle. The mission used Space Shuttle Discovery, which lifted off from launch pad 39A on February 3, 1994 from Kennedy Space Center, Florida...
,
STS-69STS-69 was a Space Shuttle Endeavour mission, and the second flight of the Wake Shield Facility . The mission launched from Kennedy Space Center, Florida on September 7, 1995.-Crew:-Mission parameters:*Mass: 11,499 kg payload...
and
STS-80STS-80 was a Space Shuttle mission flown by Space Shuttle Columbia. The launch was originally scheduled for October 31, 1996, but was bumped back to November 19 for several reasons. Likewise, the landing, which was originally scheduled for December 5, was pushed back to December 7 after bad...
. During STS-60, some hardware issues were experienced and as a result the WSF was only deployed at the end of the shuttle's robotic arm. During the later missions the WSF was deployed as a free-flying platform in the wake of the shuttle.
These flights proved the vacuum wake concept, and realized the space
epitaxyEpitaxy refers to the method of depositing a monocrystalline film on a monocrystalline substrate. The deposited film is denoted as epitaxial film or epitaxial layer. The term epitaxy comes from the Greek roots epi, meaning "above", and taxis, meaning "in ordered manner". It can be translated "to...
concept by growing the first-ever crystalline semiconductor thin films in the vacuum of space
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V1N-42GDGKN-9&_user=10&_origUdi=B6TW4-44D2CDR-5&_fmt=high&_coverDate=01%2F02%2F2001&_rdoc=1&_orig=article&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e30617536478ffd83bda0a133828e63a. These included gallium arsenide (
GaAs) and aluminum gallium arsenide (
AlGaAs) depositions. These experiments have been used to develop better photocells and thin films
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJ6-3YF9X43-1G&_user=10&_coverDate=02%2F29%2F2000&_alid=922552806&_rdoc=1&_fmt=high&_orig=mlkt&_cdi=5302&_sort=v&_st=17&_docanchor=&view=c&_ct=24&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=741571820de7edcf76644e030db89b85. Among the potential resulting applications are artificial retinas made from tiny
ceramicA ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
detectors.
Pre-flight calculations suggested that the pressure on the wake side could be decreased by some 6 orders of magnitude over the ambient pressure in low earth orbit (from 10
−8 to 10
−14 Torr). Analysis of the pressure and temperature data gathered from the two flights concluded that the decrease was some 2 orders of magnitude or 4 orders of magnitude less than expected
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TW4-44D2CDR-5&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=4850910b821748d877dc7963cb459fb8.
The Wake Shield is sponsored by the Space Processing Division in
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
's Office of Life and Microgravity Sciences and Applications. Wake Shield was designed, built and is operated by the
Center for Advanced Materials (formerly
Space Vacuum Epitaxy CenterSpace Vacuum Epitaxy Center is the of laboratory space in 3 buildings on the University of Houston campus. The SVEC facilities contains equipment dedicated to thin film deposition, processing and characterization of III-V compound semiconductor, high temperature superconductor and ferroelectric...
) at the
University of HoustonThe University of Houston is a public research university located in Houston and is the flagship institution of the University of Houston System...
—a NASA Commercial Space Center—in conjunction with its industrial partner, Space Industries, Inc., also in Houston.
External links