Design and Analysis of Device to Capture Stratospheric Air Samples, 15-R8446
Inclusive Dates: 01/01/14 – Current
Background — This work is a collaborative effort between two SwRI technical divisions to design and analyze a device to collect atmospheric samples in the Earth's upper atmosphere. The purpose of this device is to address a serious gap in Earth atmospheric measurements needed to understand the energy balance, transport and chemistry in the upper atmosphere. The device will include two components. The first is the commercially available AirCore®, which collects columns of air during descent from high altitudes in a manner that preserves an altitude profile of constituents such as carbon dioxide, methane and nitric oxide. This device has been proven up to altitudes as high as ~30 km. The second component is a discreet sampling device that will collect air samples of 1L in volume for laboratory analysis of isotopic composition.
Approach — The project had four questions to address:
- What is the upper altitude (or lower pressure) limit of AirCore?
- What is the amount of fractionation that takes place as air enters and within the AirCore tube as a function of pressure?
- What is the upper altitude limit for collecting a discrete sample as a function of flight vehicle descent velocity?
- What other greenhouse gases can be measured using the device?
Accomplishments — We completed the initial setup of the system for evaluating the AirCore and conducted tests to characterize the system. In the process of characterizing the system, we found preliminary evidence for mass fractionation in the column and have determined the fill time for the column under static conditions. Further tests have shown signs of significant diffusion suggesting that there may be a lower pressure limit for use of AirCore. We are investigating this further.