Session
Flash Talks Session 3
Location
Salt Palace Convention Center, Salt Lake City, UT
Abstract
Launched into low-Earth orbit in 2016, the Cyclone Global Navigation Satellite System (CYGNSS) mission is a constellation of eight small satellites that studies hurricanes and soil moisture. The spacecraft orbit in a fixed orientation with the instrument pointed nadir and the main solar array pointed zenith. During high beta angle seasons – periods during which the magnitude of angle between the Sun vector and the orbit plane is large – the solar arrays generate less power, so mission operators roll the spacecraft 10-16° towards the Sun. This maintains the battery state of charge above the safe-mode threshold. After nine years of operating in space, the spacecraft have proved capable and resilient. However, the solar arrays and batteries are starting to degrade due to radiation and aging, causing the spacecraft to operate on thinner power margins. This amplifies the importance of understanding how external conditions impact the battery state of charge. Any unexpected dip in power generation could be enough to send the spacecraft to safe-mode – even eclipses by the Moon. In this paper, two models are created to help mitigate the impacts from lunar shadow eclipses on CYGNSS mission operations. The first uses past telemetry to model the future state of charge based on beta angle, distance from the Sun, and time since launch. The second develops a severity metric to predict the drops in battery state of charge due to future lunar shadow eclipses. Finally, the two models are combined and used to make state of charge predictions for the upcoming eclipses on August 12th, 2026, and February 6th, 2027. Overall, this work highlights the importance of considering drops in power due to eclipses by the Moon when operating small satellites in low-Earth orbit.
Document Type
Event
Presentation
Model to Predict Solar Eclipse Impacts on CYGNSS Mission Operations
Salt Palace Convention Center, Salt Lake City, UT
Launched into low-Earth orbit in 2016, the Cyclone Global Navigation Satellite System (CYGNSS) mission is a constellation of eight small satellites that studies hurricanes and soil moisture. The spacecraft orbit in a fixed orientation with the instrument pointed nadir and the main solar array pointed zenith. During high beta angle seasons – periods during which the magnitude of angle between the Sun vector and the orbit plane is large – the solar arrays generate less power, so mission operators roll the spacecraft 10-16° towards the Sun. This maintains the battery state of charge above the safe-mode threshold. After nine years of operating in space, the spacecraft have proved capable and resilient. However, the solar arrays and batteries are starting to degrade due to radiation and aging, causing the spacecraft to operate on thinner power margins. This amplifies the importance of understanding how external conditions impact the battery state of charge. Any unexpected dip in power generation could be enough to send the spacecraft to safe-mode – even eclipses by the Moon. In this paper, two models are created to help mitigate the impacts from lunar shadow eclipses on CYGNSS mission operations. The first uses past telemetry to model the future state of charge based on beta angle, distance from the Sun, and time since launch. The second develops a severity metric to predict the drops in battery state of charge due to future lunar shadow eclipses. Finally, the two models are combined and used to make state of charge predictions for the upcoming eclipses on August 12th, 2026, and February 6th, 2027. Overall, this work highlights the importance of considering drops in power due to eclipses by the Moon when operating small satellites in low-Earth orbit.
