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Building a Space Age Stethoscope - Biological Monitoring Challenge
06.06.02
 
If you were playing word association, your first response to the word "astronaut" wouldn't likely be "fetus." But in fact, it's a better answer than you might think. An astronaut, or for that matter any living thing, floating in a spacecraft or on a space station has a good deal in common with a fetus developing in the womb.

A fetus depends entirely on its mother for survival. The womb provides a mechanism for oxygen and nutrient delivery, thermal control, and waste disposal, as well as protection from the outside environment. For an astronaut, the situation is remarkably similar. While the members of a Space Shuttle crew can feed themselves, they rely on the spacecraft for breathable air, a climate-controlled environment, waste processing, and protection from the vacuum of space.

Living things in space require sophisticated systems to monitor their health, safety, and to collect scientific data. Image above: Living things in space require sophisticated systems to monitor their health, safety, and to collect scientific data.

One critical difference between the astronaut and the fetus is that the fetus is part of a naturally occurring system that has evolved over many thousands of years to regulate itself. During space flight, living organisms become part of an artificial system that has evolved over only a few decades. Within this man-made life support system, there must be a mechanism for monitoring the plants, animals, cells, and, of course, astronauts that are part of it. A critical element of that mechanism consists of biosensor systems.

Biosensors are instruments that take biological and physiological measurements. They can be implanted internally, worn externally, or mounted throughout a spacecraft. They monitor a wide range of data encompassing the health and well-being of the crew and research subjects, experimental parameters, and the status of the living environment. The data signals generated by the sensors are gathered, processed and stored. The use of wireless biotelemetry is desirable when monitoring living organisms so that subjects can go about their business while data is being collected.

Listening to Life in Outer Space

Developing biosensor systems is a high priority for NASA. The virtual absence of gravity during space flight affects living organisms in ways that are not fully understood. Monitoring the health of astronauts is essential for safety reasons, and monitoring experimental parameters in astronauts and other research subjects offers insight into the short- and long-term effects of space flight.

Common measurements to assess overall health include heart rate, blood pressure, and body temperature. These measurements are also important for research purposes but provide only the most basic information. A variety of blood chemistry measurements are necessary to better understand the various ways organisms adapt to space flight. They include acidity, calcium, potassium, carbon dioxide, and oxygen.

Photo of adult holding tiny newborn baby's hand between her fingers. Image to right: NASA is developing a system for monitoring fetuses following surgery to treat congenital birth defects.

Developing implantable biosensors to support these science goals is a significant technological challenge. Sensors must be miniaturized so as to be safe in humans and unobtrusive to animal health and behavior. The body's immune system treats implanted sensors like foreign invaders, sending white blood cells to surround and kill them. The implants must be able to withstand these attacks for periods of up to a month or more. All associated hardware must also meet strict size, weight, reliability, and power specifications.

NASA's demanding size and performance requirements are pushing the technology envelope and opening up new scientific possibilities. The agency is creating biosensors and transmitters approaching the size of an ingestible pill, as well as systems to monitor air quality in sealed plant growth chambers, nutrient delivery in cell culture systems, and bacterial contamination of drinking water. In fact, one NASA-developed system has even given the womb a leg up.

Listening to Life in Inner Space

NASA is working with the University of California at San Francisco (UCSF) to develop a system to monitor human fetuses with life threatening congenital defects. Doctors at UCSF have pioneered surgical procedures to treat certain defects prior to birth.

Graphic suggests how a fetus in the womb is part of system much like that of an astronaut in a spacecraft or spacesuit. Image to right: A fetus in the womb is part of system much like that of an astronaut in a spacecraft or spacesuit.

The operation is generally performed when the fetus is 6 months old. This disruption of the birth process increases the likelihood of premature labor, but serious consequences can be avoided with early detection. NASA developed a compact telemetry receiver and fetal implant to allow for home monitoring of these at-risk fetuses.

This procedure saves up to $1 million per child over conventional treatment, boosts survival rates, and allows the mother to spend most of the remainder of her pregnancy at home rather than in the hospital. NASA is currently developing a pill-sized implant that will provide more sensitive early warning of fetal distress.

Fetal monitoring is just one example. These and the other monitoring technologies that support NASA's biological research help open a window on the inner workings of life in space while reducing the costs and improving the effectiveness of health care. Before long, the fetus floating in the womb and the astronaut floating in space may have something else in common–NASA–developed biosensor systems that monitor their health and well-being.