Speakers
Description
The OWL system is a beacon signal transmitter capable of determining the location of the satellite post-deployment in case of a shared launch and communicating that location towards the Ground Station. The major aim of OWL unit development was to create a platform and mission-independent in-orbit tracking equipment that is easy to integrate into every CubeSat and fulfils its major purpose even if the host satellite is in trouble. The unit is built up of 3 major subsystems: an EPS (Electrical Power Supply), an OBC (OnBoard Computer) controls a GNSS antenna, which determines the unit’s position, and a COM/ANT (Communication, Telecommand, Telemetry, Antenna) module, which makes the system functioning independently from the host satellite. The OBC also controls a GNSS antenna, which determines the unit’s position.
The unit fits inside the standard tunacan volume defined for CubeSats (⌀64x36[mm]), which enables the use of this system for satellites that have occupied payload bays, requiring only an electrical interface connector and a total of 4 fasteners as mechanical interface. As simple as the unit seems at first mechanically, just as complicated are its launch and in-orbit thermal environments. The purpose of this unit is to function even - or rather, especially - on Dead-On-Arrival satellites, so it has to be extensively analysed and tested. Vibration testing within a large acceleration spectra, as well as a high number of mechanism tests in different temperatures shall be conducted, to make sure that there is very low risk of unit failure.
As an optional, external unit that is planned to be mounted on satellites of different size - or even the fairing or third stage of launcher systems -, the thermal environment can vary greatly, thus, at first a research was conducted to determine possible thermally worst-case orbits. As this showed that a considerable number of satellites inhabit all the different orbits, from LTDN 0h to 12h, the worst cases can indeed be on the most and least illuminated orbital planes around Earth. Thus, 2 orbits were determined as to be analysed: dusk-dawn (LTDN 6h), and noon-midnight (LTDN 12h). The altitude of orbits was set to be 400[km], as it increases time spent behind the Earth during cold case orbit, or Albedo heat received from the Earth for the hot case orbit. Lastly, orientation was set as random thumbling for 2 cases; and as ’True Sun pointing’ for a 3rd also hot case, where the OWL was pointed towards the Sun for maximal solar radiation.
After the unit and its orbital parameters are explained, the detailed Thermal Mathematical Model and its creation process is described in this paper, together with the planned Thermal Vacuum Chamber tests.
