This week, NASA celebrates the 15th anniversary of the International Space Station (ISS) and the valuable science results the orbiting laboratory continues to reveal. NASA’s Marshall Space Flight Center played a pivotal role in station design and construction and continues to support thriving science operations.
On Nov. 20, 1998, the Russian’s launched the Zarya control module. A few weeks later on Dec. 4, the space shuttle STS-88 mission delivered the first U.S. element of the space station, the Unity module, built in an advanced manufacturing area at NASA’s Marshall Space Flight Center in Huntsville, Ala. by The Boeing Company, the station’s prime contractor.
“When astronauts joined Zarya and Unity on Dec. 6, a dream long held by space pioneers and science fiction writers became a reality,” said Teresa Vanhooser, Marshall Center Deputy Director. During station construction, Vanhooser led the team that provides around-the-clock support for station science. “We are proud of Marshall’s advanced manufacturing capabilities that enabled the construction of station elements and facilities, including the U.S. Destiny laboratory and the station’s life support system.”
The 22-foot-long, 18-foot-diameter Unity serves as a passageway between the station living and working areas, and station crews often gather there to eat or relax. Today, the space station, including its large solar arrays, spans the area of a U.S. football field, including the end zones, and weighs 924,739 pounds. The complex has more livable room than a conventional five-bedroom house, and has two bathrooms, a gymnasium and a 360-degree bay window. NASA and its international partners completed station assembly in 2011, and now the focus is on conducting science in space.
“Our role at Marshall’s Payload Operations Integration Center has now taken center stage,” said Jay Onken, the director of Marshall’s Mission Operations Laboratory. “We help the crew pack as much science as possible into their work day, and even into their weekends when possible. We staff the control center 24/7 operating facilities and experiments 365 days a year because space station science facilities and major systems operate continuously. Station science experiments never sleep or take a break.”
In 1998 when Unity was launched, Marshall was constructing and readying the operations center for business. Full-time operations support began in 2000 just before delivery of the Destiny laboratory in early 2001.
The Marshall team provides sustaining engineering support for critical parts of the station constructed and/or tested at the center: the Environmental Control Life Support System, the Microgravity Science Glovebox, the Materials Science Research Rack, eight EXPRESS (EXpedite the PRocessing of Experiments for Space Station) racks that provide support for station science investigations, and the Window Observational Research Facility that enables the Marshall-managed ISERV Earth observations camera and all other Earth observing investigations.
“Our team ensures these facilities operate as planned,” explained Annette Sledd, who manages Marshall’s ISS office. “We monitor facility operations, provide replacement parts, help develop procedures for crew maintenance, and assist investigators building experiments to work in station racks and facilities.”
Marshall’s ground-based engineering units–replicas of station facilities–help with these tasks. Sledd estimates about 15 to 20 investigators, or payload developers, visit Marshall each year to test their equipment before it heads to station. This involves trying out power connections and software operations to ensure successful operations on ISS. Others perform remote tests to ensure their experiment can communicate with the experiment racks that will provide them with power and other critical utilities.
It all started 15 years ago with an aluminum module called Unity. While Unity may look simple, Brian Mitchell, a Marshall engineer who served as one of the leads for Unity, said, “It is one of the most complex modules on the station because it has six berthing ports that align and capture adjoining modules during assembly and motorized bolts that attach the modules tightly together.”
The station elements all connect because of the common berthing mechanism found on all the U.S., Japanese, and European modules as well as on the SpaceX Dragon and Orbital Cygnus spacecrafts. To berth pieces together, the crew uses station remote manipulator arm and in a carefully choreographed sequence, connects two parts of the station or a visiting ship to the station. More than 40 berthings and 31 unberthings have been completed. The berthing mechanism was designed, built, and tested in a unique six-degrees of freedom simulator at Marshall where crews also trained.
The Unity Node contains more than 50,000 mechanical items, 216 lines to carry fluids and gases, and 121 internal and external electrical cables using six miles of wire. In addition to connecting to the Zarya module, Unity currently connects to the U.S. Destiny Laboratory Module, the Z1 truss, a pressurized mating adaptor that serves as a docking port, the Quest Joint Airlock, also built at Marshall, and the multi-purpose logistics module Leonardo permanently attached to the ISS during STS-133.
“I am proud to be part of the international team that built the space station and keeps this space research complex operational,” said Mitchell. “It is amazing that people almost anywhere in the world can go outside and see space station crossing the night sky with the naked eye as a reminder of our collective accomplishment. Every time I see it, it takes my breath away.”
Today, Marshall Center engineers are using the same systems engineering skills and capabilities that keep the station operating to build advanced life support systems and the Space Launch System, a launch vehicle that can send humans on missions farther away from home.
See the International Space Station! As the third brightest object in the sky the space station is easy to see if you know when to look up:
http://spotthestation.nasa.gov/
Download video b-roll of station activities at the Marshall Center:
http://av.ndc.nasa.gov/content/download.php?video=ISS_Broll_Rev_B
For ISS video b-roll and other media resources:
http://www.nasa.gov/stationnews
For more information on the International Space Station:
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