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To achieve appropriate link budget and system engineering analyses of capability-based small satellites missions, an objective assessment and computation of the component-, subsystem-, and system-levels parameters requirements must be carried out. This paper presents the measurement-derived parametric models for the system engineering analysis of communication, meteorology, planetary, and other small satellite programs with recourse to the initial mission, conceptual design, and postmission objectives. Mass and power margins are the critical resources under investigation besides the link contingencies and operational times. The case study spacecraft systems engineering analyses indicate a transmit power for data transmission uplink and downlink of at least 33 dBm for the generic communication, meteorology, and planetary missions applications. The presented parametric models also reveal a signal-to-noise ratio of at least 16 dB per radio communication link for worst case noise floor and path loss. For a 30-W power utilization, a two-power communicationoverpower mode mission operates for an extra 8.3 min compared with a three-power payload-overpower mode mission. This holds a great promise for the development of adaptive subsystems for reconfigurable multiband, and multistandard transponders for multipurpose missions and postmission applications.

The success of the satellite subsystems engineering depends on the optimal design, modeling, simulation, and validation of the deliverables of the conceptual and mission design objectives. This paper presents the operational times analysis of the thermal control subsystem onboard a 97-kg microsatellite in low-Earth orbit during an eclipse period. Power-storing, communication downlink and uplink, payload processing, and thermal control overpower modes were implemented for a communication mission under worst-case orbital patterns. An embedded digital temperature and lighting controller circuitry was designed and practically validated to effect a desired logic. For an average eclipse period of 34.4 mins, the operational times of the thermal subsystem at altitudes of 400 km, 500 km, and 600 km are 38.6 mins, 38.1 mins, and 37.7 mins respectively. Moreover, the thermal control subsystem simulation reveals that reducing the operational times of non-thermal control subsystems during the eclipse period by 50 % can result in an operational factor of safety of over 1.5. At least 10 dB data link transmission margin can be achieved. The reported findings show that the operational times of spacecraft subsystems overpower modes can be reconfigured in orbit to reliably sustain the operating conditions of the capability-based satellite components for ubiquitous communication.

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