Session
Session I: Year In Review
Location
Utah State University, Logan, UT
Abstract
Planet is a leading provider of global, daily satellite imagery and geospatial solutions. Planet's mission is to image the world every day and make change visible, accessible, and actionable. To enable this mission, Planet operates the world's largest constellation of Earth Observation satellites (about 180 Doves and 20 Skysats) in the LEO environment of 400-550 km. However, this latitude regime became a challenging environment as we approached the solar maximum of the 25th solar cycle. The solar cycle describes an 11-year rotation period of the Sun's magnetic poles, which is characterized by several activities like solar flares and coronal mass ejections. These activities elicit thermal and magnetic responses in Earth's thermosphere (85-600 km), where several LEO satellites operate. The cycle has a period of maximum activity, called the solar maxima, where LEO satellites in particular experience the highest levels of drag, ultimately leading to shorter mission lifetimes. While solar cycles are periodic, the period around the 25th solar cycle saw higher levels of activity compared to the previous cycle. Specifically, during 2023-2025, we observed LEO satellites decay at a faster rate than what was predicted using the Schatten space weather model. The Schatten space weather model has been a reliable workhorse in forecasting the solar flux in the 10.7 cm wavelength range (f10.7), and Earth's geomagnetic indices. These forecasts are needed to predict the atmospheric densities experienced by the satellites. However, as we approach the solar maximum, the Schatten forecasts deviated significantly from the observations. Such discrepancies, if unaccounted for, can be catastrophic to satellites that operate in low Earth orbits. The risk is even more pronounced for small satellites due to their limited maneuverability. To address some of these risks, we adopted the Solar Cycle 25 model developed by the National Center for Atmospheric Research (NCAR). The NCAR model forecasts the f10.7 flux using the observations of the past sunspot cycles, in contrast to relying on modeling solar magnetic cycles alone. In the current work, we present an application of the NCAR model to predict the altitude decay of satellites operating in the 400-550 km altitude range and compare this against the Schatten model during the solar maximum. In both cases, the NRLMSISE 00 model is used to model the atmospheric density. In addition to this, we compare the predicted decay rates to the real data noted from our fleet of satellites that operate in these altitude ranges. The results indicate that during this period, the NCAR model predicts a faster decay compared to the Schatten model and is closer to the decay rates noted from the orbiting satellites. This suggests that the NCAR model can be used as a potential tool to forecast space weather, especially around the solar maximum. Such models can help us build and operate robust spacecraft missions that are better prepared to handle the challenges of aggressive space weather, ultimately leading to improved security and space situational awareness.
Improved Forecasting of LEO Satellite Orbital Decay During the 25th Solar Cycle Maximum
Utah State University, Logan, UT
Planet is a leading provider of global, daily satellite imagery and geospatial solutions. Planet's mission is to image the world every day and make change visible, accessible, and actionable. To enable this mission, Planet operates the world's largest constellation of Earth Observation satellites (about 180 Doves and 20 Skysats) in the LEO environment of 400-550 km. However, this latitude regime became a challenging environment as we approached the solar maximum of the 25th solar cycle. The solar cycle describes an 11-year rotation period of the Sun's magnetic poles, which is characterized by several activities like solar flares and coronal mass ejections. These activities elicit thermal and magnetic responses in Earth's thermosphere (85-600 km), where several LEO satellites operate. The cycle has a period of maximum activity, called the solar maxima, where LEO satellites in particular experience the highest levels of drag, ultimately leading to shorter mission lifetimes. While solar cycles are periodic, the period around the 25th solar cycle saw higher levels of activity compared to the previous cycle. Specifically, during 2023-2025, we observed LEO satellites decay at a faster rate than what was predicted using the Schatten space weather model. The Schatten space weather model has been a reliable workhorse in forecasting the solar flux in the 10.7 cm wavelength range (f10.7), and Earth's geomagnetic indices. These forecasts are needed to predict the atmospheric densities experienced by the satellites. However, as we approach the solar maximum, the Schatten forecasts deviated significantly from the observations. Such discrepancies, if unaccounted for, can be catastrophic to satellites that operate in low Earth orbits. The risk is even more pronounced for small satellites due to their limited maneuverability. To address some of these risks, we adopted the Solar Cycle 25 model developed by the National Center for Atmospheric Research (NCAR). The NCAR model forecasts the f10.7 flux using the observations of the past sunspot cycles, in contrast to relying on modeling solar magnetic cycles alone. In the current work, we present an application of the NCAR model to predict the altitude decay of satellites operating in the 400-550 km altitude range and compare this against the Schatten model during the solar maximum. In both cases, the NRLMSISE 00 model is used to model the atmospheric density. In addition to this, we compare the predicted decay rates to the real data noted from our fleet of satellites that operate in these altitude ranges. The results indicate that during this period, the NCAR model predicts a faster decay compared to the Schatten model and is closer to the decay rates noted from the orbiting satellites. This suggests that the NCAR model can be used as a potential tool to forecast space weather, especially around the solar maximum. Such models can help us build and operate robust spacecraft missions that are better prepared to handle the challenges of aggressive space weather, ultimately leading to improved security and space situational awareness.
