Space Shuttle Discovery blasts off in July for the International Space Station (ISS), with seven astronauts and 24 years of ergonomic innovation on board. The seven are packed, with the supplies and systems that make their mission possible, into the three-level cabin of a craft the size of a small airliner. Their efficiency and comfort depend on innovations built around the special demands of zero gravity.
This “Back to Flight” voyage will be Discovery’s 31st mission, and it comes after an enforced break. All NASA shuttles were grounded when Columbia disintegrated over Texas in 2003, killing the seven astronauts aboard.
Earthly ergonomic solutions don’t have to be built around the weightlessness, compact quarters and distorted night-day environment of any shuttle flight. A recent research paper published by the Canadian Space Program explains some of the design constraints. In “Advanced Human-Computer interfaces and Voice-Processing Applications in Space,” researchers note that the crew’s ability to execute tasks safely and efficiently is significantly improved if the controls are ergonomically placed, clearly marked and readily available. “Commonality” is a design theme: the systems and displays must cross cultural barriers to be comprehensible to astronauts of many nationalities.
One of NASA’s many information sheets describes “swizzle sticks.” Only practical in zero gravity, they are long rods with a hinged jaw for picking up items or manipulating toggles, push buttons, thumb wheels, press down and rotary switches and other devices aboard the orbiter. And wicket tabs — textured, extended surfaces — make controls easier to find in dim light.
The Canadian study talks about problems accompanying the advances in technology since 1981, when the first shuttle was launched. The crew’s workload has increased dramatically, and the cockpit is a marvel of complexity. A recent NASA technical paper describes the 2100 devices in the orbiter cockpit as “the most complex assortment of displays and controls ever developed for an aerodynamic vehicle.” Information streams in so constantly and in so many forms that astronauts now have to pair up to accomplish a task, according to the Canadian researchers. They see more automation and the introduction of alternative interfaces as potential solutions. Automatic recognition and understanding of speech is “the ultimate medium for human-machine interaction,” they say.
Crew comfort and efficient performance
Faced with such technological complexity and operating in an environment that is hostile to humankind, astronauts must be alert every waking minute. Their mental acuity depends on quality sleep, which eludes most astronauts.
Sleeping arrangements are very different in Space. Crews sleep practically anywhere they can anchor a sleeping bag. Adjustable straps stop the occupied bag from floating around the orbiter. Springs above the straps accommodate the sleeper’s movements, and restraints keep his or her arms from rising above the head. Eye covers and earplugs help to keep astronauts asleep in midst of noisy shuttle operations and sunrises that happen every 90 minutes in low-Earth orbit.
Ideal sleeping arrangements? No. And poor sleep is a safety issue. Researcher Laura Barger, a sleep specialist at the University of California-Davis, believes astronauts have trouble sleeping because their circadian rhythms might be upset. “Instead of 24-hour days, they have 90-minute light/dark cycles,” she told the The Davis Enterprise, the City of Davis newspaper in January 2005.
Working with principal investigator Dr. Charles Czeisler, director of the Division of Sleep Medicine at Harvard University, Dr. Barger has been working to develop counter-measures to help astronauts sleep better. Their experiment starts up again on Discovery in July. The NASA-funded research looks at the timing and intensity of light exposure while in Space and the possible effects on each person’s circadian rhythm – the “internal clock” that regulates biological processes in plants and animals over a 24-hour period.
Daily life aboard
In zero gravity a small movement continues until physically arrested, and something laid on a surface won’t stay there unless it is anchored. Designers have found ingenious ways to help astronauts cope. Cloth foot loop restraints secure crew members to the deck while they are working, and they have Velcro® strips sewn to their clothing so they can stick tools, meal trays, and other items there as needed. Handholds and ladders around the orbiter help them push off and move faster, or guide their way through portals.
Personal comfort requires ingenuity. There are no sinks and running water, so toothpaste and shampoo have been developed that don’t require rinsing. Moistened towelettes replace showers. A vacuum attachment gathers hair cuttings – drifting through the cabin, floating hair could be inhaled by an astronaut or find its way into the electronics that control life-support and other orbiter systems. Crumbs pose the same danger, so bread has been eliminated from menus.
By reusing water, the shuttle can carry a lighter load – a critical factor for space-bound vehicles. Urine passes through filters that remove all the wastes, leaving pure water behind. The filtration system must be judged a particular ergonomic success: it is so pure that some astronauts have complained the water has no taste at all.
How to pack for a trip and keep track of everything
Imagine the ergonomics of stowage on Discovery. For safe passage, every item on the orbiter must have its own custom-built space. NASA places a high priority on making sure everybody on a flight and controllers on the ground know where all items are at any given time. Innovative systems ensure that objects do not get loose and that crew members can find clipboards, cameras, experimental equipment, spare parts, and food and clothing in an instant.
Because each mission has unique requirements and carries a different crew, stowage solutions for each flight are singular. Planners take as much as a year to determine how best to utilize the available space. Each object is analyzed for space optimization, crew habitation and ergonomics, mission objectives and safety. Space experiments often require bees, ants, plants and other living things, and these also demand inventive stowage solutions.
“Everything has to be packed to make optimal use of available stowage volume while balancing the shuttle for flight,” notes Debbi Boettger, stowage-integration system developer and software development supervisor at Johnson Engineering Corporation in Texas. Interviewed in 1999 for a Product Design and Development article, she explained that planners have to know the exact dimensions of every item to be packed as well as its center of gravity. “Plus, we have to factor in special requirements for each item,” she said, “for example, what needs electricity, what has to be refrigerated, and so on.”
Kimberly Campbell, a spokesperson for SpaceHab, a company allied to Johnson Engineering, told The Ergonomics Report™ that the Discovery Mission will see a brand-new stowage solution. The External Stowage Platform 2 (ESP2) is a modified version of SpaceHab’s Integrated Cargo Carrier system. ESP2, designed and built by SpaceHab, will be permanently attached to the ISS airlock, and will house critical replacement parts. The new palette brings ergonomic advantages to the loading and unloading operation, introducing new efficiency and removing the hit-and-miss problems of the previous methods.
Spacesuits — under development
Some operations require spacewalking in suits that have evolved from the earliest NASA designs — essentially pressure suits designed for pilots of high-performance jet aircraft. According to NASA, most spacesuit improvements have been to the gloves – they are more flexible and comfortable, with finger joints that provide new dexterity.
There will be plenty of work for suited-up space walkers on the Discovery mission. At least three spacewalks are planned while the orbiter is docked at the ISS.
When the first shuttle launched in 1981, its astronauts were using some of the most advanced electronics available in the aerospace world. Then shuttle avionics fell behind, and when commercial airlines moved on to sophisticated displays, astronauts were still coping with a crude cathode ray control panel. All that changed in 2000 when Shuttle Atlantis blasted off with the first “glass cockpit,” the nickname for the Multifunction Electronic Display Subsystem (MEDS).
MEDS has 11 full-color, flat-panel screens that replace 32 gauges and four cathode-ray tube displays. Ergonomic principles are incorporated in the design to make it simpler to comprehend. Dr. Jeffrey McCandless, a human factors engineer at NASA’s Ames Research Center in California, notes that human attention is attracted by changes in patterns. Writing for a February 2005 NASA report, he said engineers want the astronaut’s attention only when it’s needed. On the flight deck, he explained, “we make colors as distinct from one another as possible, using enough to distinguish from each other but not too many to confuse the astronaut.” Cultural factors enter into choices, too. Red is used for warnings and yellow for caution, just as they are on Earth. Contrast helps reduce chances for misunderstandings. Controllers don’t want astronauts to miss critical data even if it’s not an emergency, he said.
Discovery will have a “glass cockpit” for the first time when it blasts off in July, said Dr. William Langdoc. The head of the Habitability and Environmental Factors Office at Johnson Space Center, he confirmed in an interview with The Ergonomics Report™ that “the basic crew accommodations and habitability for the upcoming mission are the same as they were on previous flights.”
Many futuristic ergonomic solutions await future shuttle missions.
Spacesuits are better now, but they still have limitations. The integral boots keep the crucial air and pressure inside the suit, but they’re too stiff and heavy to walk in – suited-up astronauts use handholds on the spacecraft to move themselves around. Astronauts can look forward to spacesuits that provide better mobility and dexterity. Fingers and thumbs will have more tactile capabilities, and there will be tiny heaters to the gloves for more comfort in cold Space.
The MEDS cockpit is an interim step to the “smart cockpit,” which will reduce the crew’s work load during critical operations like ascent and entry. The advanced cockpits will be able to “think,” helping future astronauts solve problems.
Scientists at Ames Research Center in California are experimenting with visor technology that could allow astronauts to undertake outside inspections from inside the cabin. The visor would be used in conjunction with free-flying inspection satellites now in development at Johnson Space Center. Called Mini-Autonomous Extravehicular Robotic Cameras, they are likely to be used with the visors to improve the accuracy of inspections — by making astronauts feel as if they are actually outside the shuttle while the examination is under way.
NASA employs scores of human factors specialists, so astronauts can expect ergonomic improvements until the very last day of shuttle flight — in 2010, or sooner.
Sources: Nasa.gov; The Davis Enterprise; Product Design and Development, SpaceHab Inc.; Johnson Space Center
This article originally appeared in The Ergonomics Report™ on 2005-06-01.