Cajun Probe Preliminary Design Review. University of Louisiana at Lafayette Mark Roberts 11.5.2009. Table of Contents. Mission Overview Narrative Expectations Cosmic Rays Related Research Mission Requirements Mission Success Mission Benefits Expected Results Subsystems Layout
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Preliminary Design Review
University of Louisiana at Lafayette
Table of Contents
Expanding on RockOn 2008
Previous experiments have proven inconclusive with Geiger Counter circuit.
Therefore, a more robust circuit and improved Geiger-Muller tube is necessary.
Cosmic Rays (CRs)
Discovered by Victor Hess in 1912
Electrically charged particles that bombard Earth where the flux of the CRs will be different at different latitudes & altitudes.
When high energy cosmic rays collide with the atoms in Earth’s atmosphere a shower of secondary particles are produced, correspondingly the frequency of particles reaching Earth’s surface is directly related to the energy of the cosmic ray(s) which can be measured with a Geiger counter.
T-MAT H°600 film showing cosmic ray tracks
High Energy Particles (E > 250 MeV)
Low Energy Particles (E ≤ 250 MeV)
Measured fluence of high & low energy protons & electrons
Success for this mission is dependent on the performance of the Geiger counter. That is, an accurate measure of the total flux of the cosmic rays with respect to altitude.
With accurate Geiger data we will be able to reproduce similar curve
The power subsystem will supply 3.3 V, 5 V, and 9 V to respective components on the micro controller board. These specific voltages can be traced in the provided schematic of the micro controller board and will also be broken down in the following subsystems.
All subsystems will operate with the ambient temperature inside the rocket.
The requirements for the sensor subsystem is rather self explanatory via the title of each sensor.
The sensors are sampled by the MCU’s timer which is set to a finite amount of time; the sampling time must be greater then the dead time of the Geiger Counter otherwise sampling of the Geiger counter will continually return 0 because the counter is unable to function.
Command & Data Handling Subsystem (C&DH)
RockOn 2010 + RSPC Section
Payload Access Section
Team 1: RockOn 2010
Team 2: RockOn 2010
Team 3: RockOn 2010
Team 4: RockOn 2010/RSPC
Team 5: RSPC
Team 6: RSPC
Team 7: RSPC
Team 8: RSPC
Team 9: RSPC
1.) One optical and one pressure port in aft payload section.
2.) Four optical ports for each can in forward payload section.
3.) Three static ports for forward payload section.
4.) One dynamic (RAM) port for forward section.
Existing Atmospheric Port
Existing Optical Port
Functional Block Diagram
Schematic of RockOn 2008 AVR Board
Geiger Counter Circuit
Coronal discharge occurs in low pressure environments with high voltages present. The air around a high potential will become a conductor and emit a bluish glow (plasma). This plasma will cause adverse effects for the components as well as neighboring parts.
Corona is a process by which a current develops from an electrode with a high potential in a neutral fluid, air for instance, by ionizing that fluid so as to create a plasma around the electrode. The ions generated pass charge to nearby areas of lower potential, or recombine to form neutral gas molecules. In low pressure situations air is no longer a dielectric but a conductor thus allowing an electrical discharge or arching to occur.
Therefore a conformal coating to the board containing the high voltages is needed to prevent coronal discharge and will be applied to the Geiger counter circuit to prevent arching.
Top View of payload
Code Flow Chart
Code Flow Explanation
These actions are then repeated if activation is detected.
Data will be stored on the onboard flash memory which is located on the MCU board.
Data is collected from the sensors via the ADC channels of the MCU and then processed through the level translator and sent to flash memory.
The sample function is a strut which collects data from each sensor when called in the MAIN in conjunction with the MCU timer, the function samples data.
The MAIN then enters into a loop where it continuously flushes the sample strut to memory after the specified sample time; i.e. every 50 ms the sensors are sampled and flushed to memory.
Single-Axis, High-g MEMS Accelerometer: ADXL78
Single/Dual Axis Accelerometer: ADXL103/ADXL203
Dual-Axis, High-g: ADXL278
Pressure sensor ASDX series
LM50 SOT-23 Temperature Sensor
16-megabit data flash memory
LM2937 500mA Low Dropout Regulator
Maxim Low-Voltage Level translator
NPN Transistor: MPS2222A
Ultra Fast Diode: 1N4454
IRF9Z14PbF PNP Transistor
Absolute Maximum Ratings
Testing Protocol before Delivery
Testing pre-flight at delivery
The flight batteries will not be used during any/all testing. Flight batteries are only to be installed during final canister integration.
Logistics of Shared Canister
Timeline for project completion