Authors: Ben Bova
Battle Station (18 page)
Moreover, the Power Tower allows designers to place Earth-observing sensors at the “downward”pointing end of the station, and astronomical instruments at the end pointing skyward.
Remote manipulator arms, similar to the Canadarm that has been so useful aboard the shuttles, will run on trolleys along the length of the Power
Tower's spine and out along the 200-foot-long crossspar that will hold the station's solar panels.
Tower's spine and out along the 200-foot-long crossspar that will hold the station's solar panels.
The pressurized habitation modules will be at the “bottom” of the station. These will include two working laboratories, one module for crew quarters, one for logistics (a combination pantry and hardware storehouse), and a mission module from which the station is operated.
The station will need a minimum of seventy-five kilowatts of electrical power, which means that it will generate more electrical power in its first month of operation than all the manned spacecraft NASA has flown, from the first Mercury to the latest shuttle mission.
In all likelihood this power will be generated by solarvoltaic panels which convert sunlight directly into electricity. Solar panels have been thoroughly tested for years, and they work quite reliably. On shuttle mission 41-D in September 1984, a 102-foot array of solar cells was unfolded from the shuttle payload bay. The test showed that such large arrays can be deployed and remain stable in orbit.
Hutchinson, however, recognizes that sooner or later the power requirements for the space station will grow even larger, and there is a limit to how big a “farm” of solar panels the station can manage, and how much drag it can afford. He is interested, therefore, in “solar dynamic” electric power generators. These are generators that use mirrors to focus the sun's heat, which boils a working fluid that spins a turbine to generate electricityârather like the steam turbogenerators used by commercial power plants on Earth, except that orbiting “solar dynamic” generators would be smaller, more efficient, and would most likely use a working fluid like liquefied sodium, rather than water.
NASA's Lewis Research Center, at Cleveland, is
directing the development of electrical power systems for the station.
directing the development of electrical power systems for the station.
The station will house six to eight people, who will probably stay in orbit for ninety-day periods. The jobs they will do will include:
Scientific, medical, and industrial experiments that will take advantage of zero-gravity conditions for indefinitely long periods.Observations for astronomical and geophysical research.Servicing and repairing malfunctioning satellites so that they can be returned to useful life in orbit.Running manufacturing facilities for zero-gravity processing of medicines, plastics, crystals, metal alloys, and other materials.Assembling, checking out, and launching complex spacecraft carried to the station in modules by the space shuttle.The Marshall Space Flight Center, at Huntsville, is responsible for the habitation modules in which the crews will work and live, and the station's environmental control systems. Huntsville was the lead NASA center for the Spacelab program. Like the Spacelabs (which were designed and built by the European Space Agency), the habitation modules will be “aluminum cans” sized to be carried aloft by the shuttle.
Johnson Space Center is taking charge of the station's superstructure, the radiator panels that will get rid of excess heat, the data management system, and the overall integration of all the station's components. Mock-ups of station modules are already being built at Johnson, and engineers are beginning to try out various configurations for crew quarters and station operations.
The station will not be alone in orbit. It will be accompanied by “free flyers,” smaller unmanned
platforms that will be released from the station for specific experiments or observations. One “free flyer” that is already a definite part of the program will be inserted into polar orbit, where it can observe every part of the Earth twice each day with sensors that can seek out natural resources and monitor pollution.
platforms that will be released from the station for specific experiments or observations. One “free flyer” that is already a definite part of the program will be inserted into polar orbit, where it can observe every part of the Earth twice each day with sensors that can seek out natural resources and monitor pollution.
There will also be orbital maneuvering vehicles (OMVs) aboard the station. Developed from the manned maneuvering units already flown aboard the shuttle, the OMVs will allow astronauts to fly out and reach satellites or free-flying platforms and bring them to docking facilities at the station, where they can be repaired and serviced. The OMVs will be capable of being operated remotely, guided from the station's command center.
The station will be highly automated, according to Al Wetterstroem, lead engineer of the Space Station Crew Control Mock-Up. The mock-ups his team has built at Johnson Space Center are already more sophisticated than the famed bridge of
Star Trek's
U.S.S.
Enterprise.
With a crew of only six or eight aboard, perhaps none of them trained as astronauts, the station needs highly automated systems to run its life-support equipment, logistics, and other facilities.
Star Trek's
U.S.S.
Enterprise.
With a crew of only six or eight aboard, perhaps none of them trained as astronauts, the station needs highly automated systems to run its life-support equipment, logistics, and other facilities.
Typical of the problems the space station will face is the need for an excellent computer program in the area of logistics, to keep track of all the equipment, clothing, food, and other supplies brought aboard. Each item may be marked with a computer code symbol, like canned goods in a supermarket, to help the computer system keep track of them.
“We'll have plenty of computer power aboard,” Wetterstroem said confidently. “There's no good reason not to carry sixteen megabytes.” That is 250 times more computer power than the space shuttle carried on its first flights and twice the power of the Cray 1 supercomputer. Wetterstroem believes the
station's computer needs will grow to thirty-two megabytes easily.
station's computer needs will grow to thirty-two megabytes easily.
Computer screens line the walls of the control center mock-up. Touch a screen with your finger and a complete schematic of the life-support system appears. Point to a symbol depicting a valve and it will be closed. Or opened. Functions that now require an astronaut to flick a dozen switches in precisely the proper sequence will be automated so that the touch of one fingertip will do the job.
Or maybe not even a fingertip will be needed. “We're pushing hard on voice-actuated systems and artificial intelligence,” Wetterstroem said.
There will be moments when a station engineer literally has his hands full. Imagine standing at a work station in the control center, watching through the window as you handle the controls of the remote manipulator arm. Perhaps you are trying to place a recaptured satellite gently in a servicing cradle, where your crewmates will go out and repair it. Or maybe you are placing a new sensing system at the far end of the Tower, where it has an unobstructed view of the celestial sphere.
There may come a moment when you need a third hand. “Move the power pack ten centimeters to the left,” you say. And the voice-actuated control system built into the station's command center hears and obeys, like an electronic genie.
After a hard day's work, crew members will want some comfort and privacy. Chris Perner, chief of the Man-Systems Division at JSC, is responsible for the crew's safety and living conditions.
“We've got to think about fifteen hundred meals at a time,” said Perner, an affable avuncular Texan, discussing the problems of feeding six crew members for ninety days.
On earlier space missions, including the shuttle and
even
Skylab,
precooked meals were carried aboard the spacecraft. “But now we're thinking about home cooking, dishwashers and clothes washers and a lot else.”
even
Skylab,
precooked meals were carried aboard the spacecraft. “But now we're thinking about home cooking, dishwashers and clothes washers and a lot else.”
“Personal hygiene is important,” Perner said, pointing out that the station will need a better shower facility than the one on
Skylab
, which he regarded as “not satisfactory.”
Skylab
, which he regarded as “not satisfactory.”
And the occasional problems with the toilets on the space shuttles will have to be solved. Thinking about having six or eight people living in the station for ninety days at a time, he said, “We certainly need
that
system to work extremely well.”
that
system to work extremely well.”
Water will be recycled in the station. Frank Samonski, chief of environmental control and life-support systems, said, “I believe we can go with a system where the water is completely recycled, with no replenishments necessary.”
Six to eight pounds of potable water per man-day are needed aboard the station, plus another thirty pounds per man-day for personal hygiene and washing clothes and dishes. Samonski foresees a twoquality system: potable water for drinking and cooking, and “gray” water for the rest. Among the unknowns: “We don't know how much water will be used for showering.”
Samonski's team is building a testbed system at JSC for ninety-day trials of various water-recycling equipment.
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