photo credit: Callum Fairbairn
Scott Hunter
Northwest Nazarene University
Major: Engineering and Physics
Advisor: Dr. John Sample
Research Project: Hardware Development and Flight Systems for Space Science
BOOMS (Balloon Observations Of Microburst Scales) Instrumentation
A proposed experiment to measure the spatial size of relativistic electron microbursts from a high-altitude balloon. Relativistic electron microbursts are defined on the FIREBIRD mission webpage as:
"Relativistic electron microbursts appear as short durations of intense electron precipitation measured by particle detectors on low altitude spacecraft, seen when their orbits cross magnetic field lines which thread the outer radiation belt. Previous spacecraft missions (e.g., SAMPEX) have quantified important aspects of microburst properties (e.g., occurrence probabilities), however, some crucial properties (i.e., spatial scale) remain elusive owing to the space-time ambiguity inherent to single spacecraft missions. While microbursts are thought to be a significant loss mechanism for relativistic electrons, they remain poorly understood, thus rendering space weather models of Earth’s radiation belts incomplete."FIREBIRD website
The FIREBIRD mission uses cube satellites to directly measure the population of relativistic electrons in the Van Allen Radiation Belts. These measurements are constrained by time since the satellites move quickly through bursty regions and are also constrained by size, they are only point measurements in a region of microbursts. BOOMS would gather much different data because it would use a high-altitude balloon instead of an in situ measurement by a satellite. A balloon would not measure the electron population of a microburst directly, but would instead measure the X rays produced via bremsstrahlung when relativistic electrons are stopped by atmospheric particles. The information from the X rays corresponds to the energy of the precipitating electrons and their spatial location.
The proposed payload would measure X-rays collected through several Anger-type pinhole cameras. Together, these X-ray images could be used to determine the spatial size of microbursts when electrons precipitate into Earth's upper atmosphere, and could be further backcalculated to estimate the spatial size of microbursts at Earth's magnetic equator where these events start.
Primarily, materials were quoted for preliminary testing. Different options researched for scintillator crystals, photomultiplier tubes (PMTs), silicon photomultipliers (SiPMs), and PMT analysis microcontrollers are contained in the BOOMS Instrumentation document below.
LAFTR (Light And Fast TGF Recorder)Instrumentation
An experiment designed to measure TGFs (Terrestrial Gamma Flash) directly from a high-altitude balloon. A TGF is a burst of gamma radiation released upward, toward space during an electrical storm. They have only been measured a handful of times by satellites and sounding rockets. These research techniques potentially have lost the lower end of the energy range of gamma rays due to atmospheric scattering, over a large distance, the gamma radiation collides with atmospheric particles, either losing energy or changing direction and never reaching the spacecraft. The LAFTR instrument would gain important new low-energy data because of its close proximity to the origin of the TGF events.
A TGFs underlying mechanism is unknown, but the two main theories, the relativistic feedback model and the lightning leader tip model, differ by time profile. The balloon payload measures gamma radiation time and intensities with a goal of greater than 10 nanosecond precision. This information would begin to give evidence for the mechanism behind TGFs.
The LAFTR instrument comprised of a scintillator coupled with a Silicon Photomultiplier (SiPM) measure and record incident gamma rays, a PCB which would sort the TGFs by energy into bins which were converted into a digital signal, an FPGA harvested the digital data for speed, and an Arduino microcontroller took the data from the FPGA and stored it and GPS data to solid-state memory. There was a data bottleneck discovered at the beginning of the summer, and so a prototype using a Raspberry Pi 0 was tested to see if the faster processor, despite running a full OS, could compete for speed with the Arduino Due. The Raspberry Pi 0 completed the test, taking 1048 48 bit words from the FPGA, 40 times faster than the Arduino Due. To see the detailed results of experiments run, see the Raspberry Pi 0 Development document below.
Generated Documents
BOOMS InstrumentationLAFTR Raspberry Pi Zero Development
Final Presentation Slides