Fit, and on a Mission
Can the human body survive a lengthy Martian sojourn?
'They are huge!" exclaimed astronaut turned construction worker Joseph Tanner last week from a zero-gravity perch more than 200 miles above Earth's clouds. With millions of people sharing their views--via helmet-mounted cameras feeding ground control, the Internet, and TV networks--he and fellow NASA spacewalker Carlos Noriega had just attached a folded set of solar panels to the growing International Space Station and were watching a portion slowly stretch itself out from accordion-style stowage. Told that the electricity-generating expanse of gleaming silicon was only two-thirds extended, he could only marvel, "You mean there's more?"
There will indeed be lots more. The new solar panels span 240 feet, but when done the million-pound facility will stretch 356 feet. Astronauts on future flights must install three more sets of panels, six large laboratories, extensive trusswork, and living accommodations for crews of seven people at a time. Its first three modules have made up the spartan residence for American commander William Shepherd and Russian cosmonauts Yuri Gidzenko and Sergei Krikalev since early November. The shuttle Endeavour and its five crew members arrived last week with the new panels plus water and other basics. In February, the shuttle Discovery is to bring the first crew home and leave a second trio for the next four-month shift.
And so it will go for another five-plus years. It is a dazzling project, but sheer spectacle cannot stop some taxpayers from wondering what, exactly, this multibillion-dollar labyrinth of airtight corridors, cylinders, and gleaming, custom-designed research facilities is for. While scientists from 16 nations will pursue a variety of research projects, biomedical researchers are mostly interested in the bones, muscles, and organs of the station's long-term residents.
Feeble and flabby. For while Tanner and Noriega labored through three spacewalks--and just moving one's arms in a spacesuit inflated like a balloon is not easy--their muscles were steadily, slowly growing feebler, their bones flimsier, and their hearts flabbier. For billions of years, life on Earth has evolved to thrive in a steady gravitational field. Scientists are not surprised that from the cellular level up, things start going haywire without gravity. Brief shuttle flights pose few health threats, but cosmonauts and the several NASA astronauts who have spent months aboard the smaller, soon-to-be scuttled Russian space station Mir returned so weak they could barely stand. After floating freely, many wanted nothing more than the nearest, softest easy chair when they got back.
And the underlying motive for controlling the slow debilitation of the human body in very low gravity can be summarized in one word: Mars. NASA has not formally proposed a Red Planet expedition, but Administrator Dan Goldin recently declared flatly that the station gives the means to "ensure the continued health and safety of our astronauts, so that they will be able to leave low-Earth orbit to travel to Mars or beyond." It will be a long trip. NASA estimates it will take six months just to get people to Mars. They then might spend a year and a half in Martian gravity--38 percent of Earth's--and six months getting back. Without measures to counteract the effects of weightlessness, some experts fear the voyagers could die or never recover from debilitation once home.
By some estimates, astronauts could lose up to 20 percent of their bone mass on a trip to Mars and back. Thirty-year-olds could return as frail as people in their 80s. Heart and other muscles deteriorate in similar dramatic fashion, and even the immune system seems to stumble badly. NASA makes clear that medical studies of zero gravity take center stage. "We will have a baseline for a whole new biology up there," says the project's senior scientist, NASA physicist and two-time shuttle crew member Roger Crouch.
Gravity dreams. But there is growing debate, between top NASA managers like Crouch and the agency's own midlevel scientists, over whether to install a centrifuge on board big enough to whirl a person around and imitate the very thing the station gets away from: gravity. Long before the space age dawned, space dreamers were sketching ways to provide gravity in space. "It's not like on Star Trek, where you throw the artificial-gravity switch," said Charles Lloyd, manager of a NASA program to study "countermeasures" against the hazards of space, including low gravity. Back in the 1950s, rocket pioneer Wernher von Braun imagined a wheel-shape space station 125 feet across, turning fast enough to provide constant, simulated gravity along its rim. Nobody is thinking that big quite yet. "What we really want is a human-rated centrifuge," Lloyd says. It is possible, he contends, that just an hour or so a day exercising in simulated gravity would stem the body's decline--"but we will never know if we don't try it."
The present space station plan foresees--in 2006--a centrifuge only about 8 feet in diameter, enough for cell cultures or small rodents. "We are starting small and working our way up," says Crouch. Until more is known from simple living systems, he argues, there is no strong justification for one big enough for a person, one that might require about twice as much room.
Not everybody buys that argument. "There have been workshops, task force reports, and on and on, but we can't seem to get them [NASA officials] off the dime on this," said Kenneth Baldwin of the University of California-Irvine, leader of a NASA-funded research group studying muscle weakness from spaceflight. "It seems obvious. Let's put a centrifuge up there--and put people in it." He worries that if a Mars expedition is to get going within 20 years, work needs to start now to find how to keep the voyagers healthy.
Cycling epiphany. There is no shortage of ideas where to start. "This thing may do it all," said Arthur Kreitenberg, an orthopedic surgeon in Southern California who moonlights in a laboratory whose door reads "Space Cycle." Working with Baldwin and others at UC-Irvine and with a manufacturer of dirt bikes, he has invented and patented a "self-powered human centrifuge." The idea came to Kreitenberg in "an epiphany" in 1991, when as a would-be astronaut he toured a space station mock-up at Johnson Space Center. He rushed home and sketched out a bicycle seat mounted at the end of a rotating arm, with pedals and a chain drive so the rider sends the whole thing spinning. In Earthbound tests, riders have gotten spinning so fast their feet reached eight times the force of gravity (their heads, nearer the center, aren't weighed down nearly as much). Dizziness and nausea, remarkably, don't afflict riders if they don't speed up or slow down too fast and don't move their heads very much. The centrifuge would be about 15 feet across--and could be provided in an inflated space station module called TransHab that NASA has been considering as an eventual add-on.
"I think people will start thinking about this more seriously when the first crews come back from the station, and they're like jellyfish," Kreitenberg says. But he adds: "The great thing we found is that this is a lot of fun to ride."
Maintaining health in space
Muscles and bones atrophy after long periods without exercise and gravity. But this prototype "space cycle," currently housed at the University of California--Irvine Medical Center, could provide astronauts with both.
[Graphic is not available]
[Graphic labels]
The pedaling motion sets the cycle spinning, producing an artificial gravity.
Pedaling provides a muscular and aerobic workout.
Chair; Hub; Chair; Handlebars; Pedal
Sources: Dr. Arthur Kreifenberg, Center for Orthopedic and Sports Excellence; J.B. Witmer Co.; Rod Little--USN&WR
The Discovery Channel will rebroadcast Inside the Space Station at 6 p.m.(ET) on December 17, at 9 p.m. and 1 a.m (ET) on December 18, and at 6 p.m. (ET) on December 23.
This story appears in the December 18, 2000 print edition of U.S. News & World Report.