Space UV Experiment on Low Earth orbit (LEO)

Background

The ultraviolet spectrum (specifically, the range 0.12 µm and 10 µm) is singled out from the other wavelengths of sunlight irradiated on spacecraft because it contains 99.5% of the total energy of all electromagnetic radiation coming from the Sun. The energy intensity of UV radiation depends on the constitution of the ambient media and is at its highest in a vacuum. Equivalent Sun hours (ESH) per year is used to compare the stress due to UV radiation between various mission types in the table below.

where ESH stands for Equivalent Sun Hours

Experiment

The Ultraviolet Radiation at the surface of the Earth is directly proportional to the amount of radiation in free space, attenuated by the Earth atmosphere, primarily by the ion layer containing Ozone. Hence ability to determine the difference between the UV levels in space and at the ground level offers a direct insight into the level of the protection layers of the atmosphere. Hence the experiment will aim to perform simultaneous measurements of the space radiation from the sensor on-board of the pico-satellite traversing a polar orbit with an inclination of 80-90 degrees and apogee of approximately 280km over Europe, Africa, and Antarctic. Attenuation of UV radiation per kilometer of the atmosphere shall be determined, based on which distribution maps shall be produced over traversed areas of the globe.

Development

The sensor board has been developed by AmbaSat with onboard software developed by RFSAT. With the board measuring only 35 x 35 x 5 mm, the custom module can be considered as a femto-satellite or CHIPSAT. This is fitted into a stackable ‘Flight Tray’, while a stack of 25 trays fits inside the 3U CubeSat. This means up to 200 CHIPSATs like ours per launch. The open-case design of the 3U means that all CHIPSATs will function in exactly the same manner as if they were in free flight, fully exposed to the external space environment. The device is expected to remain in LEO orbit for approximately one month before entering and burning in the Earth atmosphere, with negligible environmental impact.

Each CHIPSAT is mounted on a modular Flight Tray and communicates its captured sensor data through an onboard low-power LoRa RFM95 radio transceiver to the core CubeSat controller, which together with data from other similar boards, ensuring reliable data transmission via onboard UHF to the 20,000+ ground stations of ‘The Things Network’. The telemetry data will also be transmitted via UHF-Band to the Ground Station. Results shall be made available via AmbaSat dashboard, as in the example below.

The current stage of development has completed ground-based programming and testing of both sensing and LoRaWAN communication functionalities to the RFSAT custom test ground base-station, as well as the integration with the core controller module of the AmbaSat 3D CubeSat. The example sensor data waveform from the dashboard is presented below.

Launch to space schedule

The expected launch vehicle will be Skyrora XL rocket developed by the Scottish company Skyrora Limited, expected to be launched to space in Q1 of 2026.