Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces
Mars spacecraft encounter numerous <i>g</i>-loads that occur along the launch or landing vectors (called axial vectors) or along lateral off-axes vectors. The goal of this research was to determine if there was a threshold for dislodging spores under brute-force dynamic shock compression...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-09-01
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| Series: | Microorganisms |
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| Online Access: | https://www.mdpi.com/2076-2607/11/10/2421 |
| _version_ | 1827720350445600768 |
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| author | Andrew C. Schuerger Adriana V. Borrell |
| author_facet | Andrew C. Schuerger Adriana V. Borrell |
| author_sort | Andrew C. Schuerger |
| collection | DOAJ |
| description | Mars spacecraft encounter numerous <i>g</i>-loads that occur along the launch or landing vectors (called axial vectors) or along lateral off-axes vectors. The goal of this research was to determine if there was a threshold for dislodging spores under brute-force dynamic shock compressional impacts (i.e., henceforth called shock-impacts) or long-term vibrationally induced <i>g</i>-loads that might simulate spacecraft launches or landings profiles. Results indicated that spores of <i>Bacillus subtilis</i> 168 and <i>B. atrophaeus</i> ATCC 9372 were dislodged from ChemFilm-coated aluminum coupons during shock impact events of 60 <i>g</i>’s or higher. In contrast, the threshold for dislodging <i>B. pumilus</i> SAFR-032 spores was approx. 80 <i>g</i>’s. Vibrational <i>g</i>-loading was conducted at approx. 12–15 <i>g</i>’s (z-axis) and 77 Hz. All three <i>Bacillus</i> spp. exhibited very modest spore dislodgement at 1, 4, or 8 min of induced vibrational <i>g</i>-loads. However, the numbers of spores released depended on the Earth’s <i>g</i>-vector relative to the bacterial monolayers. When the experimental hardware was placed in an ‘<i>Up</i>’ orientation (defined as the spores sat on the upper surface of the coupons and the coupons pointed up and away from Earth’s g-vector), zero to only a few spores were dislodged. When the experimental hardware was inverted and the coupon surfaces were in a ‘<i>Down</i>’ orientation, the number of spores released increased by 20–30 times. Overall, the results of both assays suggest that spores on spacecraft surfaces will not likely be dislodged during nominal launch and landing scenarios, with the exception of jettisoned hardware (e.g., heat shields or backshells) during landing that might hit the Martian terrain at high <i>g</i>’s. However, off-nominal landings hitting the Martian surface at >60 <i>g</i>’s are likely to release low numbers of spores into the atmosphere and regolith. |
| first_indexed | 2024-03-10T21:03:06Z |
| format | Article |
| id | doaj.art-ecb3efacc3cb4d12878aa6a61b21573b |
| institution | Directory Open Access Journal |
| issn | 2076-2607 |
| language | English |
| last_indexed | 2024-03-10T21:03:06Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Microorganisms |
| spelling | doaj.art-ecb3efacc3cb4d12878aa6a61b21573b2023-11-19T17:26:29ZengMDPI AGMicroorganisms2076-26072023-09-011110242110.3390/microorganisms11102421Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft SurfacesAndrew C. Schuerger0Adriana V. Borrell1Department of Plant Pathology, University of Florida, Space Life Sciences Lab, 505 Odyssey Way, Exploration Park, Merritt Island, FL 32953, USADepartment of Plant Pathology, University of Florida, Space Life Sciences Lab, 505 Odyssey Way, Exploration Park, Merritt Island, FL 32953, USAMars spacecraft encounter numerous <i>g</i>-loads that occur along the launch or landing vectors (called axial vectors) or along lateral off-axes vectors. The goal of this research was to determine if there was a threshold for dislodging spores under brute-force dynamic shock compressional impacts (i.e., henceforth called shock-impacts) or long-term vibrationally induced <i>g</i>-loads that might simulate spacecraft launches or landings profiles. Results indicated that spores of <i>Bacillus subtilis</i> 168 and <i>B. atrophaeus</i> ATCC 9372 were dislodged from ChemFilm-coated aluminum coupons during shock impact events of 60 <i>g</i>’s or higher. In contrast, the threshold for dislodging <i>B. pumilus</i> SAFR-032 spores was approx. 80 <i>g</i>’s. Vibrational <i>g</i>-loading was conducted at approx. 12–15 <i>g</i>’s (z-axis) and 77 Hz. All three <i>Bacillus</i> spp. exhibited very modest spore dislodgement at 1, 4, or 8 min of induced vibrational <i>g</i>-loads. However, the numbers of spores released depended on the Earth’s <i>g</i>-vector relative to the bacterial monolayers. When the experimental hardware was placed in an ‘<i>Up</i>’ orientation (defined as the spores sat on the upper surface of the coupons and the coupons pointed up and away from Earth’s g-vector), zero to only a few spores were dislodged. When the experimental hardware was inverted and the coupon surfaces were in a ‘<i>Down</i>’ orientation, the number of spores released increased by 20–30 times. Overall, the results of both assays suggest that spores on spacecraft surfaces will not likely be dislodged during nominal launch and landing scenarios, with the exception of jettisoned hardware (e.g., heat shields or backshells) during landing that might hit the Martian terrain at high <i>g</i>’s. However, off-nominal landings hitting the Martian surface at >60 <i>g</i>’s are likely to release low numbers of spores into the atmosphere and regolith.https://www.mdpi.com/2076-2607/11/10/2421planetary protectionastrobiologyspacecraft microbiologymarsspecial regions |
| spellingShingle | Andrew C. Schuerger Adriana V. Borrell Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces Microorganisms planetary protection astrobiology spacecraft microbiology mars special regions |
| title | Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces |
| title_full | Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces |
| title_fullStr | Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces |
| title_full_unstemmed | Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces |
| title_short | Shock-Impacts and Vibrational <i>g</i>-Forces Can Dislodge <i>Bacillus</i> spp. Spores from Spacecraft Surfaces |
| title_sort | shock impacts and vibrational i g i forces can dislodge i bacillus i spp spores from spacecraft surfaces |
| topic | planetary protection astrobiology spacecraft microbiology mars special regions |
| url | https://www.mdpi.com/2076-2607/11/10/2421 |
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