Researchers from Dartmouth College’s Thayer School of Engineering and Dartmouth Medical School have teamed up to design sophisticated computer software, called mobile agents, to help astronauts monitor bone loss during long space flights.

Bone loss begins as soon as astronauts enter space, mainly due to the weightless environment, and after about a month, the loss becomes significant. Considering that a roundtrip journey to Mars could last about two and a half years, bone loss poses a serious health issue for the astronauts. A successful, healthy mission depends upon crew members treating this problem as it happens, instead of recovering from the condition after their mission is over.

Mobile agents, migratory computer programs, are utilized in this project because of their ability to jump from host to host in a computer network as needed. The first step in the team’s long-term research project is a six-month feasibility study to map out their plan to develop a mobile agent-based information management infrastructure. Their system will, in part, measure urinary calcium, monitor atmospheric conditions inside the spacecraft, keep track of each astronaut’s diet and exercise, and continually analyze all the data to provide feedback.

Principal Investigator George Cybenko, the Dorothy and Walter Gramm Professor at Dartmouth’s Thayer School of Engineering, is working on this project with Sue McGrath, a Senior Research Engineer also at Dartmouth, and Jay C. Buckey, Jr., a Research Associate Professor at Dartmouth Medical School. The work is supported by the NASA Institute for Advanced Concepts.

“The inherent nature of mobile agents, moving among the different equipment in an integrated, methodical way, makes the data capture process less of a burden for the astronauts,” said Sue McGrath. Mobile agents are a developing field in computer science, and “it’s a natural extension to use them to help monitor people.” Computer networks with mobile agent architectures are already being developed to monitor information sources on the Internet, detect airborne threats for military intelligence systems, and provide timely tactical information and analysis to soldiers in the field through wireless networks.

“Without the weight loading usually provided by gravity, bones start to lose calcium,” said Jay Buckey. “Dim lighting and high levels of carbon dioxide, both of which also occur during space travel, also have an adverse effect on the skeleton.” Calcium-deficient bones are weaker, heal slowly and can’t adequately support weight once gravity is restored. Bone loss in some areas of the body, recorded during recent space flights, was as high as one and a half percent per month. Dietary calcium supplements aren’t an effective treatment, as the problem isn’t a deficiency of calcium, but rather a lack of loading on the bones.

The current method for monitoring bone loss in astronauts involves measuring the loss after the flight, correlating it to activity during the flight and adjusting the exercise and nutrition programs for subsequent voyages. Treatment to correct the bone loss begins after the astronaut has completed his or her mission. This approach would not be wise for an extended space journey.

The new proposed system monitors bone loss as it occurs so the crewmember can take immediate action. The challenge lies in creating the elaborate system of data collection, management and interpretation. The mobile agents that Cybenko, McGrath and Buckey are designing will:

  1. measure urinary calcium of each crewmember (bone calcium is the key source of urinary calcium);
  2. keep track of each crewmember’s diet;
  3. monitor the exercise routine of each crewmember;
  4. continually collect data on ambient carbon dioxide in the spacecraft;
  5. store and retrieve medical history of each crewmember as needed;
  6. analyze all of the above data and provide diagnostic feedback in a timely manner.

Once excessive calcium loss is detected, the mobile agents can recommend a prescription to the crewmember that might include increased exercise, pharmaceuticals or dietary intervention.

As part of this long-term project, the researchers will also evaluate other applications for this mobile agent technology. Non-invasive measuring of calcium loss in osteoporosis patients or in people suffering from kidney stones, and connecting that to daily exercise, food and other personal and environmental information, might lead to better diagnosis, an improvement to the quality of life, and cost-saving prevention measures.

After the feasibility study, the researchers will progress to running simulations to determine if the proposed model is valid, and if the agent architecture can perform the required tasks. “While development of an integrated onboard calcium loss system for a Mars flight would follow NASA’s program schedule, commercial application of the technologies could develop sooner, maybe in about five years, ” said McGrath.