Formation of RAAN-Spread CubeSat Constellations Utilizing Onboard Low-Thrust Propulsion
| Autor: | Gagnon, Amelia T. |
|---|---|
| Rok vydání: | 2022 |
| Druh dokumentu: | Diplomová práce |
| Popis: | Internal gravity waves are waves in the atmosphere caused by the interaction of air with differing buoyancy. This instability can cause weather phenomena to occur as the wave travels vertically and horizontally over large distances. To characterize these internal gravity waves, radio occultation sampling must occur within a timeframe and distance that allows for adequate capture of the horizontal wave vector. Receivers used in radio occultation have been successfully used on CubeSats. A CubeSat constellation of satellites in the same orbital plane with varying right ascension of the ascending node (RAAN) will satisfy the internal wave gravity sampling requirements. Called a RAAN-spread constellation, the separation in argument of latitude of the clusters will allow for and the separation in RAAN will allow samples to be captured with adequate resolution in the horizontal directions. This work focuses on 2-2-200 and 3-3-300 RAAN spread constellations, comprised of 2 clusters of 2 satellites and 3 clusters of 3 satellites, where clusters are spread by 200 s and 300 s, respectively. Two maneuvers are required to form this constellation from an assumed deployment orbit. To conserve propellant during the constellation formation, differences in RAAN nodal precession and argument of latitude angular momentum are used to spread the CubeSat orbits. Maneuver 1 is an orbit-raising maneuver, where argument of latitude is spread by having satellites drift at different altitudes to obtain needed spacing before rejoining an altitude identical among the satellites to lock in the final argument of latitude spacing and prevent further drift. Maneuver 2 is an inclination-changing maneuver where RAAN separation is induced by differences in nodal precession for satellites at different inclinations. When the appropriate RAAN spacing is achieved, the satellites rejoin at the same inclination to stop further RAAN drift. The thrust durations and drift durations are calculated analytically for these maneuvers for three thrust cases to first estimate the fastest formation time and associated change in velocity (deltaV), second estimate 1/2 of the maximum deltaV, and third for a thrust case that is longer in drift duration. Analytical thrust durations and drift times are subsequently simulated with high-fidelity orbital propagation software called Systems Tool Kit (STK). This orbital propagator takes into account the effects of orbital perturbations including atmosphere, solar radiation pressure, and Earth-oblateness perturbations including J2. Simulation results generally agree with the analytical time and deltaV estimations that formation can occur within 45 days for all constellation configurations examined. Additionally, simulation data shows that a RAAN-spread CubeSat constellation with 2 satellites per cluster at a high starting inclination will have most efficient use of deltaV of the maneuvers explored. Results for a 2-2-200 constellation in a sun-synchronous orbit show that the constellation can be formed in 17 days with 50.471 m/s of deltaV. Propellant left over from the constellation formation will be used to maintain the constellation over time and increase orbital lifetime. The work in this thesis is also applicable to maneuver planning for other similar constellations. S.M. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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