NOTE: End date changed to 8/31/2023 per V. Lehman/JSC (Ed., 3/29/23)

NOTE: End date changed to 8/31/2022 per L. Barnes-Moten/JSC (Ed., 8/2/21)

NOTE: End date changed to 8/31/2021 per NSSC information/S. Huppman/HRP (Ed., 2/25/2020)

NOTE: End date changed to 2/1/2020 per NSSC information (Ed., 7/8/19)

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from nine ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from nine ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.

NASA Human Research Program (HRP) Student Augmentation Award (August 2021 report): For the Artemis missions to the lunar surface, NASA is planning for astronauts to employ a transfer vehicle to travel from the Gateway to low lunar orbit, a descent vehicle to land on the surface of the Moon, and an ascent vehicle to return to the Gateway. Since the Moon’s gravity is 6 times lower than Earth’s gravity, astronauts may pilot a lunar transfer vehicle in the standing posture similar to the Apollo missions, rather than a conventional seated posture. However, injury risks associated with different postures of astronauts under lunar spaceflight related dynamic loading conditions are not completely understood. There is a need to quantify and understand astronaut body kinematics and injury risks in the standing posture during vehicle launch, abort, and landing scenarios encountered on space missions.

This gap has been addressed under the current student award by carrying out computational assessment of different postures on astronaut response under lunar space-mission related dynamic loading conditions using full-body simulation with a finite element human body model. This study quantified injury risk associated with different postures for future lunar missions and will help in identifying critical regions for spacesuit and space-vehicle design to minimize astronaut injury risk for the future lunar missions.

NASA HRP Student Augmentation Award 2021 – The active muscles can significantly alter the kinematics response and hence the injury response of the subject for longer duration dynamic loadings. Since dynamic events associated with the lunar missions are of longer duration (~300 ms), we need an active muscle FE human model in the standing posture to predict astronaut kinematics and injury responses in lunar load events. Furthermore, we observed excessive knee-buckling and spinal slouching in of the model while simulating lunar launch and landing simulations with passive model for the 2020 HRP student augmentation grant.

This gap has been addressed under the student award by developing an active muscle finite element human body model in a standing posture. This study quantified injury risk associated with the standing posture for future lunar missions and compared it with the standing posture simulations from 2020 HRP student augmentation award study.

Objective 1. Publish retrospective analyses of the pre- and post-flight spinal muscle changes. Retrospective magnetic resonance imaging (MRI) scans of the lower back of six crewmembers were used to analyze the size and fat infiltration changes in the muscles that support the spine. Correlations between muscle change and onboard exercise were also analyzed. Results of this study were published this year, “Change in Lumbar Muscle Size and Composition on MRI with Long-Duration Spaceflight,” in the Annals of Biomedical Engineering.

Objective 2. Analyze prospective pre- and post-flight data to quantify spinal muscle and bone changes. Prospective quantitative computed tomography (qCT) and MRI data collection have been completed for all nine of the enrolled subjects. Bone and muscle morphology and quality measures are underway and will continue for all the subjects.

Objective 3. Develop methodology to develop astronaut-specific finite-element vertebrae models from prospective computed tomography (CT) scan data and analyze changes in spinal injury risk from pre- to post-flight. Different morphing methodologies to develop subject-specific finite-element vertebrae models from the prospective CT data have been compared, and optimum morphing methods for all the vertebrae have been identified. Pre- and post-flight subject-specific finite element vertebrae models are being developed using these methods. Vertebral compression test simulations are being conducted to assess the effects of space-induced changes on vertebral compression strength using these subject-specific vertebrae models.

Objective 4. Develop and validate a new modular deformable spine simplified finite-element human body model to study the effects of musculoskeletal changes on astronaut spinal injury risk. To study the effects of musculoskeletal changes on astronaut spinal injury risk, a modular deformable spine finite element human body model was developed by incorporating a deformable spine in the existing simplified human body model. This newly developed model has been validated against PMHS (post-mortem human surrogates) and volunteer test data from the literature to assess its biofidelity.

Objective 5. Develop an active muscle finite element human body model in the standing posture and assess the effects of active musculature on body kinematics and associated injury response for astronauts in the standing posture during lunar space mission-related dynamic loading conditions. (Human Research Program/HRP student augmentation award 2021). This year, an active muscle finite element human body model in standing posture was developed. This study quantified injury risk associated with standing posture for future lunar missions and compared it with the standing posture simulations from the 2020 HRP student augmentation award study.

NOTE: End date changed to 8/31/2021 per NSSC information/S. Huppman/HRP (Ed., 2/25/2020)

NOTE: End date changed to 2/1/2020 per NSSC information (Ed., 7/8/19)

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from nine ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from nine ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.

NASA Human Research Program (HRP) Student Augmentation Award (August 2021 report): For the Artemis missions to the lunar surface, NASA is planning for astronauts to employ a transfer vehicle to travel from the Gateway to low lunar orbit, a descent vehicle to land on the surface of the Moon, and an ascent vehicle to return to the Gateway. Since the Moon’s gravity is 6 times lower than Earth’s gravity, astronauts may pilot a lunar transfer vehicle in the standing posture similar to the Apollo missions, rather than a conventional seated posture. However, injury risks associated with different postures of astronauts under lunar spaceflight related dynamic loading conditions are not completely understood. There is a need to quantify and understand astronaut body kinematics and injury risks in the standing posture during vehicle launch, abort, and landing scenarios encountered on space missions.

This gap has been addressed under the current student award by carrying out computational assessment of different postures on astronaut response under lunar space-mission related dynamic loading conditions using full-body simulation with a finite element human body model. This study quantified injury risk associated with different postures for future lunar missions and will help in identifying critical regions for spacesuit and space-vehicle design to minimize astronaut injury risk for the future lunar missions.

Objective 1. Publish retrospective analyses of the pre- and post-flight spinal muscle changes. Retrospective quantitative computed tomography (qCT) scans from 16 crewmembers were analyzed to characterize back muscle geometry, volume, and fat infiltration changes in crewmembers of long-duration spaceflight. Results of this study have been published in a paper titled “Trunk Skeletal Muscle Changes on CT with Long-Duration Spaceflight” in the Annals of Biomedical Engineering journal.

Retrospective magnetic resonance imaging (MRI) scans of the lower back of six crewmembers were used to analyze size and fat infiltration changes in the muscles that support the spine. Correlations between muscle change and onboard exercise were also analyzed. Results of this study have been submitted for publication.

Objective 2. Acquire, process, and begin analyzing the prospective pre- and post-flight data to quantify spinal muscle and bone changes. Prospective qCT and MRI data collection has been completed for all nine of the enrolled subjects. Bone and muscle morphology and quality measures are underway and will continue for all the subjects.

Objective 3. Develop methodology to develop astronaut-specific finite-element vertebrae models from prospective CT scan data and analyze changes in spinal injury risk from pre- to post-flight. Different morphing methodologies to develop subject-specific finite element vertebrae models from the prospective CT data have been compared and optimum morphing methods for all the vertebrae have been identified. Pre- and post-flight subject-specific finite element vertebrae models are being developed using these methods. Vertebral compression test simulations are being conducted to assess effects of space-induced changes on vertebral compression strength using these subject-specific vertebrae models.

Objective 4. Develop and validate a new modular deformable spine simplified finite-element human body model to study the effects of musculoskeletal changes on astronaut spinal injury risk. To study the effects of musculoskeletal changes on astronaut spinal injury risk, a modular deformable spine finite element human body model is being developed by incorporating a deformable spine in the existing simplified human body model. This newly developed model has been validated against PMHS (post mortem human surrogates) and volunteer test data from the literature to assess its biofidelity.

Objective 5. Assess effects of different postures on astronaut body kinematics and injury risk for future lunar missions. (HRP student augmentation award 2020). This year, the standing and seated postures of astronauts for future lunar missions have been simulated using full-body finite element human body models. From these simulations, kinematics and injury metrics for different body regions have been extracted and compared between the different postures and also against the injury assessment reference values from the literature.

NOTE: End date changed to 2/1/2020 per NSSC information (Ed., 7/8/19)

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from nine ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from nine ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.

Objective 1. Analyze retrospective pre- and post-flight medical images to quantify spinal muscle changes. Retrospective quantitative computed tomography (qCT) scans from 16 crewmembers were analyzed to characterize back muscle geometry, volume, and fat infiltration changes in crewmembers of long-duration spaceflight. This year, an additional analysis was added to examine abdominal muscle changes. Crewmember dual-energy x-ray absorptiometry (DXA) reports were also obtained from Lifetime Surveillance of Astronaut Health (LSAH) and used to compare skeletal muscle indexes between CT and DXA modalities.

Retrospective magnetic resonance imaging (MRI) scans of the neck and lower back of six crewmembers were used to analyze size and fat infiltration changes in the muscles that support the spine. Correlations between muscle change and onboard exercise were also analyzed.

Objective 2. Continue consenting crewmembers for the prospective arm of the study. Additional crewmember briefings took place this year and a total of nine crewmembers are currently enrolled to participate in the prospective portion of the study.

Objective 3. Acquire, process, and begin analyzing prospective pre- and post-flight medical images. Prospective qCT and MRI data collection has continued for all nine of the enrolled subjects. Bone and muscle morphology and quality measures are underway and will continue as additional data become available.

Objective 4. Prepare the prospective data for integration into human body finite element models. This year, a sensitivity analysis was conducted with the study’s finite element human body model to investigate the effects of muscle activation on astronauts’ kinematic and injury response under complex multi-directional loading conditions associated with spaceflight launch and landing. Considering the results of this sub-study, the available prospective qCT and MRI images are being used to create 3D computational models of the spine representative of each subject. With the help of computational algorithms, these subject-specific models are being used to customize existing finite element models of the spine to represent each crewmember.

NOTE: End date changed to 2/1/2020 per NSSC information (Ed., 7/8/19)

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from nine ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from nine ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in 900 dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.

Objective 1. Analyze retrospective pre- and post-flight medical images to quantify spinal muscle changes.

These retrospective analyses were continued from the previous year and completed. Retrospective quantitative computed tomography (qCT) scans from 16 crewmembers were received in March and July 2017. Pre-flight and post-flight qCT scans were used to characterize back muscle geometry, volume, and fat infiltration changes in crewmembers of long-duration spaceflight. Retrospective magnetic resonance imaging (MRI) scans of the neck and lower back of six crewmembers were received in June 2017. Pre-flight and a post-flight scans were used to analyze size and fat infiltration changes in the muscles that support the spine.

Objective 2. Continue consenting crewmembers for the prospective arm of the study.

Eleven crewmember briefings took place this year and a total of seven crewmembers have consented to participate in the prospective portion of the study.

Objective 3. Acquire, process, and begin analyzing prospective pre- and post-flight medical images.

Prospective qCT and MRI data collection has begun for five of the enrolled subjects. Preliminary measures of muscle size and fat infiltration are underway and will continue as additional data becomes available.

Objective 4. Prepare the prospective data for integration into human body finite element models.

The available prospective qCT images are being used to create 3D computational models of the C3, T3, and L1 bones in the spine representative of each subject. With the help of computational algorithms, these subject-specific models of the bones are being used to customize existing finite element models of the spine to better represent each crewmember.

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from nine ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from nine ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in 900 dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.

Objective 1. Acquire and analyze retrospective pre- and post-flight medical images to quantify spinal muscle changes.

Retrospective quantitative computed tomography (qCT) scans from 16 crewmembers were received from the LSDA (Life Sciences Data Archive)/LSAH (LSAH (Lifetime Surveillance of Astronaut Health) in March and July 2017. Pre-flight and post-flight qCT scans were available for 16 subjects, and the psoas, paraspinal, and quadratus lumborum muscle groups were segmented and analyzed from the retrospective qCT scans to characterize muscle geometry, volume, and fat infiltration changes in crewmembers of long-duration spaceflight.

Retrospective magnetic resonance imaging (MRI) scans of the cervical spine and lumbar spine of 6 crewmembers were received from the LSDA/LSAH in June 2017. All crewmembers underwent both a pre-flight and a post-flight scan. The psoas, paraspinal, and quadratus lumborum muscle groups were segmented to characterize full-length volume changes in these lumbar muscles. Select cervical muscles were measured at pre-determined axial slices in order to characterize changes in the cross-sectional areas of the cervical muscles.

Objective 2. Modify a finite element human body model to mimic the musculoskeletal changes seen in imaging.

Using the outputs from the MRI scans, a finite element model has been modified to better represent the back and neck musculature of crewmembers both before and after spaceflight. A total of 10 models have been generated to date (pre- and post-models for 5 crewmembers).

Objective 3. Create an injury risk prediction post-processor for the spine.

Cross sections were implemented in the finite element models along all cervical, thoracic, and lumbar vertebrae. This allowed us to extract information on stresses, strains, axial forces, and bending moments experienced at each vertebra to calculate injury risk.

Objective 4. Begin running simulations of landing conditions.

A total of six 10G deceleration simulations were created by varying loading direction. Each astronaut model was subjected to this test matrix creating a total of 60 launched simulations. Of these 60 simulations, the clear majority have completed without errors.

Objective 5. Continue consenting crewmembers for the prospective arm of the study.

Ten crewmember briefings have taken place this year and four crewmembers have consented to participate in prospective portion of the study. Additional consent briefings are tentatively planned for the Fall of 2018.

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from nine ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from nine ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in 900 dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.

Objective 1. Obtain study approvals for the retrospective and prospective arms of the study.

Approvals for the retrospective and prospective arms of the study were obtained this year, including LSAH (Lifetime Surveillance of Astronaut Health), IRB (Institutional Review Board), and Flight Investigation approvals.

Objective 2. Acquire and analyze retrospective pre- and post-flight medical images to quantify vertebral and spinal muscle changes.

Retrospective quantitative computed tomography (qCT) scans from 16 crewmembers were received from the LSDA (Life Sciences Data Archive)/LSAH in March and July 2017. Pre-flight and post-flight qCT scans were available for 16 subjects, with follow-up qCT scans at 1, 2, 3, and 4 years for select subjects. The 16 pre-flight,16 post-flight, and 27 annual follow-up qCT scans of L1 and L2 vertebrae were segmented using a semi-automated process to create 3D models of the vertebrae. Each qCT scan was processed with an algorithm to quantify the cortical thickness of the L1 and L2 vertebrae, mapping these thicknesses onto the 3D vertebral surface models. Analysis of the cortical thickness data is ongoing.

The psoas, paraspinal, and quadratus lumborum muscle groups are in the process of being segmented and analyzed from the retrospective qCT scans to characterize muscle geometry, volume, and fat infiltration changes in crewmembers of long-duration spaceflight. Segmentation of the psoas, paraspinal, and quadratus lumborum muscles, including fat infiltration, has been completed for 16 of the 59 qCT scans. Analysis of muscle geometry, volume, and fat infiltration changes for pre-flight, post-flight, and follow up scans is in progress.

Retrospective magnetic resonance imaging (MRI) scans of the cervical spine and lumbar spine of 6 crewmembers were received from the LSDA/LSAH in June 2017. All crewmembers underwent both a pre-flight and a post-flight scan. Analysis of these scans to quantify spinal muscle changes from pre- to post-flight is in progress.

Objective 3. Prepare the medical image protocols and procedures for the prospective arm of the study.

A parametric experiment with a cadaver was conducted to vary qCT scan parameters and examine the resulting image quality and radiation dosage. The objective was to determine a set of scanning parameters that produced adequate image quality to measure bone outcomes, while reducing the radiation exposure to the research participant. The cadaver underwent 14 qCT scans of the C1-L5 region and the following scan parameters were varied: tube voltage, tube current, and pitch. Volumetric bone mineral density measures from each of these scans were compared to a qCT scan acquired with standard parameters that are used clinically to assess accuracy. Using this data, we have finalized a qCT protocol to scan the C3, T3, and L1 vertebrae that produces accurate volumetric bone mineral density measurements with minimal radiation exposure (<1 mSv).

The MRI scan protocol was also finalized for the prospective arm of the study. T1 and T2 weighted MRI scans of the cervical, thoracic, and lumbar spine regions will be acquired to capture the spinal musculature surrounding the vertebral column.

Objective 4. Begin consenting crewmembers for the prospective arm of the study.

Consent briefings for potential crewmembers for the prospective arm of the study began in July 2017 and we are actively enrolling participants. To date, four consent briefings have been held or are scheduled.

Changes in pre- and post-flight vertebral geometry, volume, cortex thickness, and bone mineral density will be measured from existing lumbar quantitative computed tomography (qCT) scans, as well as from planned qCT scans of the cervical, thoracic, and lumbar spine from six ISS crewmembers. Likewise, the pre- and post-flight spinal muscle volumes will be analyzed using both existing magnetic resonance imaging (MRI) scans and planned MRI scans from six ISS crewmembers. The qCT and MRI scans will be analyzed to determine structural and material changes in the cervical, thoracic, and lumbar vertebrae and the spinal muscles that indicate damage which could weaken these tissues.

Our unique engineering approach will measure the loss of vertebral strength during spaceflight conditions and predict the risk of failure during traumatic, dynamic loading conditions such as launch or landing. Vertebral strength and risk for vertebral fracture and injury will be quantified in 900 dynamic simulations using a full human body model that is constructed using structural and material data gathered from the pre- and post-flight medical images for each astronaut.

This study has significance in quantifying and addressing risks of long-duration spaceflight, including vertebral injury from dynamic loads, vertebral fracture, early onset vertebral osteoporosis due to spaceflight, and impaired performance due to reduced spinal muscle mass, strength, and endurance.