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A Balloon-Based Payload for Exposing Microorganisms in the Stratosphere (E-MIST)

David J. Smith
David J. Smith
, 
Prital J. Thakrar
Prital J. Thakrar
, 
Anthony E. Bharrat
Anthony E. Bharrat
, 
Adam G. Dokos
Adam G. Dokos
, 
Teresa L. Kinney
Teresa L. Kinney
, 
Leandro M. James
Leandro M. James
, 
Michael A. Lane
Michael A. Lane
, 
Christina L. Khodadad
Christina L. Khodadad
, 
Finlay Maguire
Finlay Maguire
, 
Phillip R. Maloney
Phillip R. Maloney
 e 
Nicole L. Dawkins
Nicole L. Dawkins
   | 05 mar 2022
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Article Category: Methods Article
Pubblicato online: 05 mar 2022
Pagine: 70 - 80
DOI: https://doi.org/10.2478/gsr-2014-0019
Parole chiave
© 2014 David J. Smith et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Labeled model of payload. Key design features of the Exposing Microorganisms in the Stratosphere (E-MIST) payload, which mounted onto the exterior of a large high-altitude balloon gondola. See text for details of labeled system and components. The mass of the payload was 36 kg.
Labeled model of payload. Key design features of the Exposing Microorganisms in the Stratosphere (E-MIST) payload, which mounted onto the exterior of a large high-altitude balloon gondola. See text for details of labeled system and components. The mass of the payload was 36 kg.

Figure 2

Modeled front view of the E-MIST payload with front panel removed. The key flight computer components, power source, and temperature/relative humidity (RH) sensors are shown.
Modeled front view of the E-MIST payload with front panel removed. The key flight computer components, power source, and temperature/relative humidity (RH) sensors are shown.

Figure 3

Model of the E-MIST skewers. Four independently-rotating skewers were embedded within the payload and controlled by the flight computer. A light seal and shield on each skewer ensured that the microbe sample exposure was restricted to the target altitudes. This design minimized the influence of the outside environment during other flight activities (e.g., launch, ascent, descent, and recovery). Panel A shows the front face, while Panel B depicts the motor and gear system on the backside of each skewer.
Model of the E-MIST skewers. Four independently-rotating skewers were embedded within the payload and controlled by the flight computer. A light seal and shield on each skewer ensured that the microbe sample exposure was restricted to the target altitudes. This design minimized the influence of the outside environment during other flight activities (e.g., launch, ascent, descent, and recovery). Panel A shows the front face, while Panel B depicts the motor and gear system on the backside of each skewer.

Figure 4

Distribution of Bacillus pumilus SAFR-032 spores on an E-MIST sample coupon. Each coupon contained approximately 1 × 106 spores and the aluminum coupon surface is visible in the circular gap of spores. The scale bar on the scanning electron micrograph is 10 μm.
Distribution of Bacillus pumilus SAFR-032 spores on an E-MIST sample coupon. Each coupon contained approximately 1 × 106 spores and the aluminum coupon surface is visible in the circular gap of spores. The scale bar on the scanning electron micrograph is 10 μm.

Figure 5

Test flight deployment on 24 August 2014 in the lower stratosphere over New Mexico. E-MIST payload in flight, with the four skewers rotated open, briefly (2 s) exposing the Bacillus pumilus SAFR-032 samples and other control coupons to the stratosphere. On Face-Up Coupons, the spore aliquots are visible as white dots in the center of each sample. One Inverted Coupon (protecting spores from sunlight) was included on each skewer base plate as well. A Negative Control (blank, sterile coupon) was also flown to verify payload seals prevented outside contamination.
Test flight deployment on 24 August 2014 in the lower stratosphere over New Mexico. E-MIST payload in flight, with the four skewers rotated open, briefly (2 s) exposing the Bacillus pumilus SAFR-032 samples and other control coupons to the stratosphere. On Face-Up Coupons, the spore aliquots are visible as white dots in the center of each sample. One Inverted Coupon (protecting spores from sunlight) was included on each skewer base plate as well. A Negative Control (blank, sterile coupon) was also flown to verify payload seals prevented outside contamination.

Launch, Ascent, and Float Profile.

Max.Min.Remarks
Atmospheric Pressure (mb)8374.26Altitude of Ft. Sumner, NM, 1.25 km ASL
Air Temp. (°C)23.3−67.5CSBF Free Air Thermistor
Payload External Temp. (°C)18.5−13.7HOBO measurements
Payload Internal Temp. (°C)Internal heaters pulsed during acent and descent
  Avionics22.3−4.10
  Proxy Coupon46.1−28.0
  Battery16.0−4.65
  Radiometer37.14.15
Payload Internal RH (%)65.0< 3.5Measurements below sensor sensitivity
Payload External RH (%)60.5< 3.5Measurements below sensor sensitivity
UV (W m−2)N/AN/AData were lost; see text for details

Most Probable Number of Viable Spores.

Sample CategoryTreatmentMPN (N, σ)
Lab Ground CouponsKept in the laboratory1.84 × 106 (1, N/A)
Transported Ground CouponsTransported to launch site but not installed1.93 × 106 (2, 3.74 × 105)
Face-Up Flight CouponsFlown, exposed for 2 s1.91 × 106 (4, 4.30 × 105)
Inverted Flight CouponsFlown, exposed for 2 s without sunlight1.66 × 106 (4, 5.96 × 105)
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