Abstract

The International Space Station is up and running, although it will be more than a year before the biological research facilities are in place. There's still plenty of controversy over whether a space station is necessary or cost-effective for much of the proposed research.

What weighs 470 tons, is made up of 35 linking parts, and, after taking years to get where it's going, will float 250 miles out in space? No, not the first herd of elephants shot 'round the world. It's NASA's International Space Station (ISS), a cooperative space effort among 15 nations, with the United States leading the way and, critics lament, footing most of the bill.

When ISS is completely assembled, on-board biomedical experiments using microgravity promise to make news. The experiments will also continue to generate controversy in some scientific orbits.

The first ISS component, the Unity node, which will lay the foundation for the other components, lifted off December 4, 1998. It rode on space-shuttle mission STS-88. The component that will house the Human Research Facility (HRF), where astronauts will do space-related physiology experiments, and the Biotechnology Facility (BTF), for microgravity experiments, won't be in orbit until the spring of 2000. Or so. Both facilities are still being constructed by Boeing in Huntsville, Alabama.

Even as Boeing technicians race to get the components finished so that new space history can be forged, another space biomedicine event on Earth recently made no headlines at all.

A National Academy of Sciences (NAS) study, funded by NASA and titled "A Strategy for Research in Space Biology and Medicine in the New Century," blasted off the presses precisely on schedule in late October. It spells out what NASA's space-science role should be. NASA-friendly, but pulling no punches, the NAS report, prepared by the Committee on Space Biology and Medicine of the National Research Council (NRC), says that NASA should assign a lower priority "to areas of basic and applied research that are relevant to fields of high priority to NASA but are extensively funded by other agencies," fields in which NASA has "no obvious unique capability or special niche."

The statement appears to be a softer version of what other scientists are telling NASA: Don't get too carried away with doing science in space, where it is much more expensive.

"NASA is such a small player in this arena, compared to NIH funding," says Sandra Graham, the study's director. "NASA needs to be selective and focus on what they have to offer, which is microgravity."

And Microgravity It Will Be

According to scientists at the Marshall Space Flight Center (MSFC), experiments aboard ISS will include growing protein crystals in microgravity, an environment that, they say, makes for larger and more perfect crystals. By unlocking and improving the crystal's structure in microgravity, scientists gain a better understanding of crystal function and are able to create better designer drugs.

MSFC scientists in charge of the crystallography experiments to be carried out aboard the BTF say that gravity influences attempts to grow protein crystals on Earth. Protein crystals grown in microgravity can "yield substantially better structural formation than can be obtained from crystals grown under the full influence of Earth's gravity."

While the recently released NRC report was fully supportive of doing experiments to investigate how microgravity affects bone and muscle mass, blood pressure, sensory orientation, and movement, the NRC suggested that NASA aim most research funding at "ground-based experiments which are less costly to conduct." The report does not comment on the microgravity protein-crystallography experiments NASA touts, a program repeatedly bashed by the American Society for Cell Biology (ASCB). The ASCB says "biology should not be used to justify a space mission" and characterizes the ISS as "an engineering temple in search of science."

The ASCB fired shots at ISS during a July press conference, saying that NASA's microgravity experiments in crystallography serve no purpose other than to "make use of the engineering temple." The plant and crystal experiments, says the ASCB, can be done on Earth more cheaply and efficiently. An ASCB "blue ribbon committee" stated that "there is no justification for a NASA protein-crystallization program" and recommended that "no further funds be spent" on the project, because the parameters for obtaining good crystals of proteins and protein complexes are "harder to control in space than in a conventional laboratory."

U.S. Representative Tim Roemer participated in the ASCB press conference on July 15 and issued his own press release saying that ISS should be canceled. Costs, said Roemer, have "spun out of control," and ISS lacks "scientific merit." He called promises of great medical research results "closer to fantasy than reality."

Long-time ISS critic Robert Park, a columnist for the American Physical Society, agrees. According to Park, the NAS report went out of its way not to comment on the controversy surrounding the crystallography program. "In every hearing about the space station, NASA trots it [the crystallography program] out as a bottom-line example," says Park, who has been railing against ISS since 1984. "ISS has no scientific value and is enormously expensive," charges Park.

While crystallography bashing continues, long-space-trip impacts on astronaut physiology is a major research focus of ISS that no one seems to be attacking (at the moment, that is).

Bone and Muscle Experiments

"Once we leave gravity behind, all systems of the body have been shown to be perturbed by being in space," says NRC committee member Danny Riley, professor of cell biology at the Medical College of Wisconsin. "Changes in bone and muscle physiology in microgravity need to be looked at." Riley also sees a bigger question for understanding microgravity's effect on living organisms. "How do cells see gravity as raw material?" he asks.

The NRC agrees with NASA that the human skeleton is at risk during space flight. Bone loss is the most noticable effect of microgravity and may be one of the most limiting factors on long space flights. Lack of mechanical stimulation in microgravity is partly to blame.

The NAS report says that although NASA should not be involved in the task of looking at genetic risk factors for osteoporosis, "the information and methodology for identifying those individuals most vulnerable to osteoporosis is extremely important to NASA."

Kinesiologist Kathy Clark, chief scientist in charge of the HRF, says research protocols are still being collected from prospective principal investigators, but there definitely will be a battery of tests assessing low gravity's effect on human motion. Clark adds that muscle atrophy and mineral loss in weight-bearing bones occur in space at the alarming rate of one percent a month.

She is also concerned with astronauts losing flexibility across joints during a long flight, such as one to Mars. Consequently, an ultrasound machine on the HRF will periodically check astronaut bone density during six-week stays.

"We have a wonderful foot-ground interface system that measures postural changes," says Clark, who feels that the experiments on muscle mass and bone density have a significance and benefit beyond space flight. She hopes that learning more about muscle atrophy and bone loss can benefit those suffering on Earth.

"If we can solve those problems in space, where progression is rapid, there is a great deal of potential to solve the problems on Earth," she says with conviction.

Cardiovascular Systems in Microgravity

According to the NAS report, another major effect of a low-gravity environment is a reduction in gravitational body forces, thus decreasing buoyancy-driven flows, rates of sedimentation, and hydrostatic pressure. In microgravity, blood-pressure irregularities plague astronauts (remember John Glenn commenting on the Shuttle astronauts' swollen "Pillsbury doughboy" faces). So blood-pressure readings will be taken frequently in the HRF. Microgravity's effect on cardiovascular and pulmonary systems is pronounced because these systems are "gravity dependent." Thus, it is not surprising that humans exposed to microgravity show significant cardiovascular and pulmonary changes.

"The complexity of the cardiovascular system is driven by gravity," says Andrew Gaffney, a cardiologist from Vanderbilt University Medical Center, who served on the NRC committee. "Gravity has a big impact on where blood is in the body. In microgravity it appears that some of our compensatory mechanisms get lazy."

According to Gaffney, the cardiovascular system is remarkably plastic. It adapts extraordinarily well to microgravity, but the transitions between microgravity and full gravity may be difficult. "After a long space flight the cardiovascular system may be severely deconditioned, with a greatly reduced exercise capacity," says Gaffney. He emphasizes that what is learned from cardiovascular experiments in microgravity may well have a practical treatment application. Most of our medical advances, he says, come from better knowledge of how a system works. For Gaffney, the ability to look at the cardiovascular system's reaction to microgravity on ISS will be like turning up the magnification on a microscope. "You see things you didn't see before," says Gaffney.

Russell Rayman, executive director of the Aerospace Medicine Association, wonders if the ISS's HRF lab experiments will really tell us what to expect physiologically on a very long mission.

"Plans for the ISS call for a crew of four to six crew members each with an approximate six-month stay," says Rayman. "Is a six-month stay on ISS an acceptable analog for a two- to three-year journey to Mars?" He suspects not.

Gaffney disagrees, saying a six-month stay will yield some important answers. "In order of magnitude it would bring us closer to answers than a two-week stay," says Gaffney. "It could also show us the shape of the curve in the longer term."

The discussion over ISS's value may come down to whether it is a valuable tool for doing basic research in microgravity, a unique environment.

"I firmly believe that what we will learn in space is applicable to human health on Earth," says Riley. "The bottom line is that we have made a commitment to be permanently in space. In space we have an opportunity to work across the biological breadth, from molecules to man, to understand this novel environment."

Riley says that space is a very good place to do basic research. "There is not enough money spent on basic research," he says. "If technology is to advance and we [are] to grow and be competitive, we can grow by growing up into space."

Randolph Fillmore is a freelance medical technical writer and science journalist who has written for Faulkner and Gray, Prudential Health Care, Stars and Stripes, and The Baltimore Sun.

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Endlinks

Microgravity Research Program - provides details about the protein crystallization and other programs. From the NASA/Marshall Space Flight Center.

Microgravity News and Microgravity News and Research - two publications from the MSFC, covering topics of interest to researchers and the public, respectively.

Committee on Microgravity Research - another of the NRC's Space Studies Board committees. Has several online reports and links to member biographies.

ESA Microgravity Database - a searchable database listing all microgravity experiments carried out on European Space Agency and NASA missions since the 1960s.

Report on NASA Life Sciences Research to the ASCB Council - an online version of the report delivered July 1998.

American Crystallographic Association - includes information about the society, meetings, online resources, and other crystallographic organizations.