Active control of femtosatellite swarms for synthetic aperture rada 

  • Jianlin Cao

Student thesis: Doctoral Thesis


Recent developments in electronics and technology have pushed miniaturised satellites to the femto-scale, which feature a low mass between 10 to 100 g. Although femtosatellites have been proven as a feasible concept, most designs are limited by sensor capacity and mission lifetime due to the lack of environmental protection and onboard propellent. In this thesis, a novel concept of using femtosatellites for Earth remote sensing missions has been proposed. In particular, a novel femtosatellite concept based on the utilisation of solar radiation pressure is introduced together with an Earth remote sensing mission concept. The prototype femtosatellite design features a high area-to-mass ratio to maximise solar radiation pressure for orbit control. A flexible base material enables self-release when loaded with pre-applied tension to reduce the complexity of the carrier spacecraft release mechanism. Its flat-bubble design also provides basic thermal and radiation protection. In addition to an antenna for communication to the carrier spacecraft, the prototype design includes a separate antennae for radar applications, the design of which will vary depending on the mission requirement. A hardware design is also provided for such a femtosatellite concept and performance is evaluated for an Earth remote sensing mission. The mission concept utilises swarms of femtosatellites as receivers for enhanced radar mission. A 'dawn-dusk' Sun-synchronous orbit has been chosen to maximise solar radiation pressure for orbit control and power generation. The orbital dynamics of the proposed femtosatellite concept is investigated and a novel active orbit control strategy for relative motion control with solar radiation pressure is developed. This control strategy demonstrates the feasibility of using solar radiation pressure for swarm control, which can be modulated by using electrochromic panels, to achieve the active orbit control of individual femtosatellites. This will extend the femtosatellite swarm mission capability and lifetime. The femtosatellite swarm deployment evolution is also provided to demonstrate the active orbit control strategy. The performance of the femtosatellite swarm Earth remote sensing mission is evaluated and characterised by the number of femtosatellites, the receiver signal-to-noise ratio and the accuracy of positioning. These research results demonstrate the feasibility of using swarms of femtosatellites for Earth remote sensing. In addition, by adapting the radar signal processing algorithm, on-orbit targets could be detected. This is demonstrated by imaging the international space station and mock space debris for space situational awareness applications.
Date of Award1 Jun 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorJohn Soraghan (Supervisor) & Colin McInnes (Supervisor)

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