CSAC Flight Experiment to Characterize OnOrbit Performance Authors
CSAC Flight Experiment to Characterize On-Orbit Performance Authors: Yashica Khatri, Aaron P. Aboaf, Daniel Dowd, Christopher Flood, Henry Dixon, Dr. Penina Axelrad Small. Sat Conference 2020 Project Sponsor : Air Force Research Laboratory (AFRL) Advisor: Dr. Penina Axelrad Presenter: Yashica Khatri 1
Presentation Overview 1. 2. 3. 4. 5. Motivation Orbital CSAC Experiment Definition Experimental Testing STK Simulation Schedule Outlook Microchip CSAC [1] MAXWELL [2] 2
CSAC Experiment Motivation ● Purpose ○ Characterize on-orbit performance of a Chip-Scale Atomic Clock (CSAC) ○ using a GPS receiver onboard a spacecraft. AFRL UNP-9 Mission - 6 U Cube. Sat: MAXWELL ● Motivation ○ ○ Low size/weight/power clock characterization Global Positioning System (GPS) Navigation: ■ ■ ○ Provides us with clock bias Coast through periods of interference or signal blockage Deep Space Network (DSN) Navigation: ■ ■ One-Way ranging opportunity Reduces ground support requirements Microchip CSAC [1] 3
Phase 4: (MO-5) CSAC Experiment Phase 3: (MO 1 -4) Communications Demonstrations Phase 5: (MO-6) TDa. GHR Deployment & Characterization Phase 2: Commissioning Phase 1: Release from the Launch Vehicle 4 Phase 6: Deorbit, End of Mission MAXWELL Mission Timeline [2]
CSAC Experiment Definition ● Global Positioning System (GPS) ○ ○ Constellation of 32 satellites Transmit position, clock data and ranging signals Satellite GPS receivers use multilateration solutions to determine location and clock bias Allows onboard clock steering or observation of external clocks ● The CSAC experiment will run onboard MAXWELL, with a Nov. Atel OEM 729 GPS receiver using the unsteered CSAC as an external clock. ● Data Acquisition: ○ ○ GPS Data: Position, Clock Bias and Rate, Pseudorange, Phase CSAC Physics Package Data: Temperature 5
MAXWELL Experiment Block Diagram MAXWELL Block Diagram [2] 6
Hardware and Software Testing 1. GPS Receiver Operational Testing 2. Breakout-Board Testing 3. MAXWELL Avionics Integration Testing 4. Thermal Chamber Testing 5. RF Simulator Testing 7
STK Simulation: Basic Setup MAXWELL Parameters ● MAXWELL orbit: 500 km, 40° inc ● Attitude description ○ Sun-pointing ○ Nadir-pointing Basic Setup ● GPS constellation for coverage ● STK DOP calculation plotting 8
STK Simulation: Directional Coverage Over Time 9
MAXWELL Schedule 10
Acknowledgements The authors would like to thank AFRL for CONTACT project support (AFRL Grant FA 9453 -19 -1 -0076). The authors also acknowledge the support provided by the MAXWELL team in hosting and supporting the development of this CSAC experiment. The contributions from other students and faculty at the University of Colorado Boulder are also acknowledged. These contributors include Margaret Rybak, Dr. Nicholas Rainville, Luci Schement, Quinn La. Barge, Tyler Morris and Alex Conrad. 11
Questions? Contact Information: yashica. khatri@colorado. edu 12
References 1. “Chip-Scale Atomic Clock, ” , 2020. URL https: //www. darpa. mil/aboutus/timeline/chipscale-atomic-clock. 2. MAXWELL, “Our Mission, ” , 2020. URL https: // www. colorado. edu/project/maxwellcubesat/ourmission. 13
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