SMITH Payload
Sampling Microbes In The High atmosphere


     The main purpose of SMITH is to take biological samples at a range of altitudes in the mid-stratosphere. Since HASP (High Altitude Student Platform) will float at 120,000 ft, this will be the targeted altitude for this flight. The payload will consist of a sample chamber and a flight control chamber. The flight control chamber measures the background contamination throughout the flight without actively sampling. The sample chamber actively samples at the target altitude. Both chambers will be physically identical, but the flight control chamber will remained sealed. In the event the sample chamber fails to operate during flight it will be possible to use the flight control chamber to actively sample as the sample chamber. Since we would lose our flight control, this will be done only as a last resort.

     Before flight, both chambers will be sterilized and sealed. They will remain in this state until HASP reaches float. Before float if the temperature of the payload becomes too low, two commands will be sent to the payload to enable the sample chamber heaters. This will ensure the motors are in operational temperature range before use. Once at float, a command will be sent to begin sampling. This command opens the sample bay and begins the sampling procedure. Confirmation of a successful opening will be relayed to the ground station. Data on all sensors will be relayed to the ground station throughout the flight.

     Shortly before descent, a command to stop sampling will then be uplinked to the payload. This will seal the sampling bay again. Confirmation of a successful closing will be relayed to the ground station. The payload will then remain in this state until recovered. If for some reason the sample bay fails, commands can be relayed to the flight control bay that follow the same procedure as stated above.

Original Design Concept:

     This design incorporated a Yo-Yo system that used a Rotorod chamber suspended below the payload. The rod chamber is lowered and reeled back up repeatedly throughout the flight to provide the necessary flow. When HASP entered the float stage of the flight, the heaters, controlled by HASP's discrete lines, would be turned on and would remain on while the sampling takes place. To begin sampling the command would be sent to open the sample bay door and the rod chamber in the sample chamber bay would be reeled in and out.

     There were a considerable number of environmental sensors on this design of the SMITH payload. These include: humidity, ozone, UV-A, UV-B, UV-C, pressure, and temperature.

SMITH HASP-2011 Design:

     Drastic changes were made to the original design and the yo-yo system was replaced with pumps and motors. The sampling chamber was altered from rotorods to a filter system. The filter system contains the filter used to capture microbiology and is kept sealed until HASP reaches float, at which the command is sent to open the solenoid valves on either side of the filter housing. Then the sampling motor is turned on allowing air to be pumped through the filter. The state of the valves, temperatures, and rotations per second of the motor are observed at the ground station to ensure there are no complications. The state of the valves is known by magnetic hall-effect sensors located on top of each solenoid. The rotations per second of the motors are calculated using logic photo-gate sensors.

     This payload flew on the HASP-2011 flight. Environmental data collected included: temperature, pressure and humidity. Results can be found on the Technical Documents page.