Plants Survive Rapid Depressurization: Implications for Bioregenerative Life Support
Abstract
Understanding the risks and failures of life support technologies will be critical for future space missions. Among the possible system failures would be a loss of pressure in a habitat or containment vessel. Any damage to system components following a loss of pressure must be considered in terms of contingency, repair, or resupply. Plants are the centerpiece to bioregenerative life support approaches proposed for future missions, but have sometimes been criticized as being fragile entities and hence more prone to failure. To test this, we grew radish, wheat, and lettuce plants at two pressures, 97 and 33 kPa, for 21 days, then subjected them to a rapid pressure drop to 1.5 kPa where they were held for 30 min. Each test was repeated three times. Temperatures were maintained near 22 C throughout, although some adiabatic cooling occurred to depressurization. Thus the 1.5 kPa pressure was below the boiling pressure for water. Following this pressures were restored to the original levels and the plants allowed to grow for another 6 days. Immediate inspections of the plants via video camera and photosynthetic gas analysis showed no obvious damage following the low pressure event, with the exception a few wheat leaves that began to droop downward, suggesting a loss of turgor and mild water stress. Comparisons of fresh and dry mass values at final harvest for all three species showed no difference between controls and plants exposed to the rapid pressure drop, and this was true for plants grown either at 97 or 33 kPa. The results demonstrate a remarkable resilience of food crops to a catastrophic pressure loss that would be lethal to humans. Further testing should be conducted to determine how long plants could endure such low pressure to estimate required response times. Related testing should be conducted with all life support technologies, including physico-chemical components, to assess their risks under rapid pressure changes.
- Publication:
-
37th COSPAR Scientific Assembly
- Pub Date:
- 2008
- Bibcode:
- 2008cosp...37.3459W