Fixing satellite radiation pressure to measure thermosphere winds more precisely

What is it about?

Accelerometers on board satellites such as GRACE-FO, which orbit 500 km above Earth, can measure the force of sunlight and heat radiating off their surfaces. If these "invisible nudges" are not properly accounted for, they interfere with our ability to accurately separate atmospheric winds and air density from the measurements. This study uses temperature sensors on the solar panels of GRACE-FO to track how heat builds up and radiates. The new radiation pressure model considers the effect of solar panel efficiency (as panels convert sunlight into electricity rather than just heat) and fine-tuned surface properties (e.g. the reflectivity or absorbency of materials). The work also corrected errors caused by satellite self-shading and heat glow during orbital day/night transitions. Consequently, the cross-track acceleration error has been reduced by approximately 87%. The refined datasets have been made publicly available (ftp://thermosphere.tudelft.nl). The study also compares these data with global upper atmosphere models.

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Photo by National Cancer Institute on Unsplash

Photo by National Cancer Institute on Unsplash

Why is it important?

This paper matters. Climate Science: more accurate thermosphere wind measurements help us to better understand the ionosphere-thermosphere dynamics. Satellite Safety: the data can be used to build better models. And better models help prevent orbital miscalculations (e.g., space debris avoidance). Space Weather: the data can reveal how solar storms disturb Earth’s upper atmosphere. These lessons can be applied to future satellite mission planning.

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