Battle Station

by Ben Bova

  This much seems clear: the station will be “shuttle compatible”; that is, each component of the station will have to fit inside the shuttle’s cargo bay. The station will be assembled in an orbit between 250 and 280 miles high. Its orbit will be inclined 28.5° from the equator, the latitude of the Kennedy Space Center, from which the components of the station will be launched.

  This orbital inclination takes advantage of the Earth’s spin to give the shuttle an extra bit of velocity, like a broad jumper getting a running start. That not only gives more boost per pound of rocket propellant, it also means that it will take less energy to send satellites from that orbit onward to the geosynchronous orbit, 22,300 miles above the equator.

  The task of actually running the space station program and making it work was started in an unprepossessing cinder-block office building a few miles outside the Johnson Space Center, near Houston. The placard taped onto the rented building’s glass door said “Space Station Program Office.” But the engineers inside the place called it “the Skunk Works.”

  (A note on aerospace etymology: the Skunk Works was, and still is, an elite group of Lockheed engineers in California. This small, tightly knit, highly secret cadre designed such extraordinary aircraft as the U-2 reconnaissance plane and Mach 3 SR-71. The term was originally borrowed from A1 Capp’s comic strip, Li‘l Abner.)

  Strangely enough, NASA had space problems. The Johnson Space Center, the sprawling complex at Clear Lake, Texas, where all the manned space programs have been directed, did not have enough room to handle the ongoing shuttle program and the space station as well. So the fledgling space station offices were temporarily housed in the Skunk Works.

  Neil Hutchinson, manager of the Space Station Program, is a “second generation” NASA man. At the age of forty-four, he cut a figure of youthful vigor, despite the fact that he had been with the agency since getting his bachelor’s degree in math and physics from Willamette University, in Oregon. Tall, intense, his hair and full beard just starting to turn salt-and-pepper, Hutchinson had been a flight director for the final three Apollo missions, all three Skylab missions, the Apollo-Soyuz program, and the first two shuttle flights.

  The Space Station Program is being handled differently from earlier NASA projects, Hutchinson pointed out. There will be no prime contractor. No industrial corporation will receive a contract from NASA to design and build the entire station.

  “We’re really trying to avoid the ‘prime contractor syndrome,’” said Hutchinson. “We don’t want to get into a position where, for the next twenty-five or thirty years, NASA’s beholden to a single contractor.”

  Hutchinson’s office will be responsible for integrating all the studies and designs and coming up with the final selection of systems and contractors. “We have broken the station program into chunks,” he said, “and given primary technical responsibility for those chunks to different NASA field centers.”

  The various NASA centers started out by proposing different designs for the station, but by early 1984 Hutchinson’s group had narrowed the possibilities down to three, all of them developed at Johnson.

  The Planar concept called for an A-frame type of structure 300 feet long, with four large sets of solar panels mounted at each end of the framework and the pressurized habitation modules and laboratories located in the middle of the structure.

  The Delta design was an inverted pyramid, its point facing the Earth, with its array of solar panels at the top and the living quarters at the bottom.

  The Power Tower, however, was the design that Hutchinson favored. It is based on a central spine, a 400-foot-long aluminum “strongback” that holds all the station’s pieces together. Compared to the Delta and the Planar concepts, says Hutchinson, the Power Tower offers advantages of lower drag and easier stabilization.

  Even 250 miles high, the space station will encounter some drag from the wispy outermost fringes of the Earth’s atmosphere. To counter this, the station will carry cold-gas thrusters capable of nudging it to higher altitude when necessary. The thrusters will squirt out a gas such as nitrogen, which can generate the thrust needed for attitude adjustment. Since the Power Tower design gives the least drag, it will save on the amount of propellant gas the thrusters must carry.

  Because the Power Tower is rather like a long, lean pole, it can take advantage of the Earth’s gravity to stabilize its attitude in orbit. This is called gravity-gradient stabilization: the more massive end of the Tower, where the habitation modules are clustered, will be attracted by the Earth’s mass and will point solidly toward the center of the planet. This means that the Tower will be less inclined to wobble in space than the Planar or Delta configurations, which are “fatter” and less adapted to gravity-gradient stabilization.

  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.

  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 electricity—rather 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.

  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 superst
ructure, 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.

  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.

  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.

  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.”

  “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.”

  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.”

  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.

  Then there is the question of health. Perner wants to make sure that each crew aboard the station includes a medical doctor. Even so, there are problems to be faced. How do you administer an intravenous solution or a blood transfusion in zero gravity, where fluids do not flow the way they do on Earth?

  Far from being dismayed by these problems, Perner is enjoying the challenges they present. “The space station is gonna be fun,” he chuckled.

  Privacy is important for crew morale and work efficiency. Each crew member will have private quarters in the habitation module. Mock-ups have been built at Johnson Space Center to test out different possible configurations for individual crew quarters.

  In the mock-ups a crew member’s private quarters looks only slightly larger than a telephone booth. A college dorm room seems enormous by comparison. Even a submarine begins to look spacious. But in zero gravity, Perner pointed out, where you can use all six surfaces of an enclosure and even float in the middle of it, space seems to expand. A telephone booth can seem almost roomy. Almost.

  Each private compartment in the JSC mock-ups has a zero-gravity bedroll attached to one wall. The bedroll includes a head strap. Astronauts have learned that it is more comfortable to be zippered in while sleeping, rather than floating freely. And once the body relaxes in sleep, the pressure of blood pumping through the carotid arteries in the neck tends to make the head nod back and forth, often awakening the sleeper. Hence the head strap.

  Early studies of the space station considered the idea of “hot beds”: that is, sharing one living compartment between two crew members, one sleeping while the other is on shift. Perner was firmly opposed to that. “It’s an absolute must that each crew member have his or her own private quarters,” he insisted.

  Although it will be possible to operate the station on a three-shift, twenty-four-hour-a-day basis, Perner saw NASA’s thinking moving to one or, at most, two shifts per day, with the entire crew (except for the computers) sleeping at the same time. That is the way the flight-support teams on the ground work, and it makes sense to have the station crews follow the same routine.

  Then there is the trash problem. “People are the dirtiest animals on Earth,” Perner said, without a trace of malice. He and his human factors engineers are trying to determine how many shredders and trash compactors the station will need.

  There are literally hundreds, perhaps thousands, of other problems that must be faced by a space station intended to remain on orbit for a quarter century or more. Exactly what construction techniques will be used to assemble the 400-foot-long aluminum “strongback” of the Power Tower? Will it be folded into the shuttle’s cargo bay and then unfolded and locked rigid in orbit? Or will it be carried up in sections and bolted together by astronauts in EVA? Tests at Langley Research Center showed that the sections could be connected as quickly as one strut every thirty-eight seconds. But that was a test done on the ground, not in
zero-gravity space. And there are some six hundred struts to the total station structure.

  How will the habitation modules be attached to the strongback? How much will the constant fine, sifting infall of cosmic dust erode the structures? Must they be covered with protective coatings?

  “There’s a good chance that sometime during the station’s lifetime it’s going to get hit” by a piece of man-made space debris, according to Donald J. Kessler, an engineer at JSC. It may be necessary to place a “free flyer” satellite up with the station to monitor the amount of man-made clutter accumulating in orbit. Computers would then assess the likelihood of any individual piece striking the station, and astronauts would ride out to the threatening pieces and remove them from orbit.

  But while NASA and the aerospace industry draw their plans for a space station that will remain active in orbit for at least twenty-five years, opposition on Earth continues to criticize the decision to build a manned station at all.

  The OTA report, in particular, was seized upon by opponents to the station and by the media. The New York Times editorialized, “Indeed, the Office of Technology Assessment experts say that everything NASA proposes can be done with an automated space station, if we’re willing to wait the five years it would take to develop the necessary equipment.”

  Most space engineers disagree strongly. All the experience of space exploration and development to date shows that human beings are necessary for the success of complex space missions. The more complicated the equipment placed in space, the more needed are humans to operate and, often, repair the equipment or adapt it to be used in ways it was not originally intended.

  Arthur C. Clarke, replying to the Times editorial, wrote that OTA’s concept of building an automated space station “showed uncanny timing … in the very month when astronauts brilliantly improvised the salvage of two stray communications satellites.”

  While a small but vocal group of space scientists argue that the station will take funds away from their own programs, history shows that space science budgets tend to follow the size of the total NASA budget; big manned programs such as Apollo and the shuttle have usually been accompanied by increased budgets for space science. And a survey conducted in late 1984 by Research and Development magazine showed that 69 percent of the scientists polled said they would like to fly on the space shuttle and an overwhelming 79 percent said they would like to conduct their research in the space station.