Skip to page content Mission Information


Digital Astronaut: Bone Remodeling Model (Bone_Model)
Principal Investigator
Research Area:
Biomedical countermeasures
Bone and calcium physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

Under the conditions of microgravity, astronauts lose bone mass at a rate of one to two percent a month, particularly in the lower extremities such as the proximal femur. The most commonly used countermeasure against bone loss in microgravity has been prescribed exercise. However, data has shown that existing exercise countermeasures are not as effective as desired for preventing bone loss in long-duration space flight. This space flight related bone loss may cause early onset of osteoporosis to place the astronauts at greater risk of fracture later in their lives. Consequently, NASA seeks to have improved understanding of the mechanisms of bone demineralization in microgravity in order to appropriately quantify this risk, and to establish appropriate countermeasures.

In this light, NASA’s Digital Astronaut Project worked to implement well-validated computational models to help predict and assess bone loss during space flight, and enhance exercise countermeasure development. More specifically, computational modeling is a way to augment bone research and exercise countermeasure development to target weight-bearing skeletal sites that are most susceptible to bone loss in microgravity, and thus at higher risk for fracture.

This study had the following specific aims:

  1. For individuals in the age range of the astronaut corps, predict changes in trabecular and cortical volumetric bone mineral fraction and density as a function of time since measurement, gravity level, and applied loads.
  2. Support the bone fracture standard by accepting and providing data in the same form as that of a Quantitative Computed Tomography (QCT) scan.

++ -- View more

Chang KL, and Pennline JA. Predicting bone mechanical state during recovery after long-duration skeletal unloading using QCT and finite element modeling. Cleveland, Ohio: NASA Glenn Research Center, 2013. NASA Technical Memorandum NASA/TM-2013-217842. [NTRS]

Pennline J, and Mulugeta L. Evaluating daily load stimulus formulae in relating bone response to exercise. Cleveland, Ohio: NASA Glenn Research Center, 2014. NASA Technical Memorandum NASA/TM-2014-218306. [NTRS]

Pennline J and Mulugeta L. A Computational Model for Simulating Spaceflight Induced Bone Remodeling. 44th International Conference on Environmental Systems, Tucson, Arizona, July 13-17, 2014. ICES Paper ICES2014-513-83. [NTRS]

Raykin J, Forte TE, Wang R, Feola A, Samuels BC, Myers JG, Mulugeta L, Nelson ES, Gleason RL, and Ethier CR. Characterization of the mechanical behavior of the optic nerve sheath and its role in spaceflight-induced ophthalmic changes. Biomechanics and Modeling in Mechanobiology. 2017. February; 16(1):33-43. [DOI]

Bone density
Quantitative computated tomography (QCT)

Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
Data Sets+ Request data

Aerial bone mineral density (aBMD)
Body weight
Bone formation
Bone mineral density (BMD)
Bone resorption
++ -- View more

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
Directed Research