National Aeronautics and Space Administration

Glenn Research Center

Molly Townsend

Validation of Probabilistic Injury Models

Molly Townsend
Clemson University, NASA Glenn Space Academy 2011

Beth Lewandowski
NASA Glenn Research Center

In the case of a medical emergency on a low earth orbit mission, rather than treating the injury or ailment, the astronaut will be returned to the surface. In long-term space missions, such as a mission to Mars, this is impractical. Therefore, it is necessary to classify the probability of a mission-altering injury or illness occurring during various missions. In order to accomplish this, computational models were developed to model the biomechanics of the injury. Biomechanical models of lumbar spine fractures and thoracic impacts were created by the Integrated Medical Model team at NASA Glenn Research Center. The outputs of these biomechanical models were compared to experimental data in order to determine the accuracy of the models. Validation of the Bone Fracture Risk Model revealed favorable prediction results, while validation of the Thoracic Impact Model revealed a possible error in the biomechanical model.

Purpose and Background

In order to conserve space and resources on the International Space Station and to facilitate long-term space missions, it is necessary for NASA to determine the most probable accidents that will occur during normal missions operations. Once that is established, it will be possible to design and place microgravity-compatible medical devices tailored for the most probable injuries on the International Space Station. Many injuries being investigated do not have a recorded incident during a space flight mission and, therefore, it is necessary to determine the probability of injury based on a computer model.

One such injury is a bone fracture. With no documented cases of a bone fracture occurring during a mission, it was necessary to develop a computational model to determine this probability of a bone fracture. The Bone Fracture Risk Model was developed in order to examine the risk of a fracture while conducting day-to-day activities and mission activities in the wrist, femoral neck, and lumbar due to both a fall and a static lift. Unfortunately, due to a lack of microgravity studies, these models were developed largely from earth-based studies. However, data has recently been collected using the vertical treadmill in the Exercise Countermeasures Laboratory simulating a jump from a ladder in a lunar gravity environment.

Research Goals and Benefits

The goal of this project is to compare the data received from the Exercise Countermeasures Laboratory with the output from the Bone Fracture Risk Model in order to deduce the effectiveness of the lumbar fracture due to a fall simulation. In order to accomplish this goal, it will be necessary for the Research Associate (RA) to:

  • Manipulate the data into the correct form to be analyzed,
  • Calculate the peak force from the data, and
  • Compare this peak force with the output from MatLab.

The RA will learn to analyze and manipulate data in MatLab in order to draw conclusions based on the validity of its output. Specifically, The RA shall demonstrate understanding and mastery over the Bone Fracture Risk Model as well as its underlying biomechanical principles. The RA will combine knowledge from several fields, including, but not limited, to:

  • Biomechanics
  • Physiology
  • Physics
  • Computer Programming

Upon completion of the evaluation of the Bone Fracture Risk Model, the RA will then analyze a developing program designed to determine the chance of fracture after an astronaut has returned to Earth. This will entail incorporating the bone density lost while in orbit with the rate of bone remodeling and repair. The RA will be expected to:

  • Examine the most effective method of communicating results, and
  • Evaluate the efficacy of the model.