핵심 개념

Machine learning techniques can be effectively leveraged to improve the accuracy of orbit estimation and atmospheric density modeling, which are critical for enhancing space safety and mitigating the risks of collisions between space objects.

초록

This survey provides an overview of how machine learning has been applied to tackle key challenges in orbit estimation and atmospheric density modeling:
Orbit Determination:
The Extended Kalman Filter (EKF) is the standard method, but has limitations due to linearization and Gaussian assumptions.
Machine learning approaches like Gaussian Mixture Models, Gauss-von Mises distributions, and Physics-Informed Neural Networks have been used to better represent the non-Gaussian nature of the orbit distribution.
These methods can propagate the orbit uncertainty more accurately compared to the EKF.
Orbit Prediction:
Analytical and numerical methods like SGP4 have errors due to simplifying assumptions and lack of information about space object characteristics.
Machine learning techniques have been used to correct the errors in physics-based propagators like SGP4, improving prediction accuracy.
Data-driven models like Latent Force Models and Neural Networks have also been explored as alternatives to physics-based propagators.
Thermospheric Density Modeling:
Empirical atmospheric density models like NRLMSISE-00 have limited predictive capability and uncertainty estimation.
Machine learning has been applied to improve space weather forecasting, which drives these density models.
Neural networks and other techniques have also been used to calibrate and combine multiple density models to reduce forecasting errors.
Overall, the survey highlights how machine learning can work in parallel with classical methods to enhance orbit estimation and space safety by better characterizing the uncertainty, improving prediction accuracy, and advancing atmospheric density modeling.

통계

The number of space objects larger than 1 cm is estimated to be around 1 million, with only 30,000 larger than 10 cm being tracked.
Orbit determination errors are in the order of kilometers for 7-day predictions, which is insufficient for space debris tracking.
Atmospheric density models have 10-15% one-sigma accuracy on average, and a 10% error in EUV light prediction can result in over 200 km uncertainty after 7 days.

인용구

"To avert a chain reaction of collisions, known as Kessler Syndrome, it is essential to accurately track and predict debris and satellites' orbits."
"Current approximate physics-based methods have errors in the order of kilometers for seven-day predictions, which is insufficient when considering space debris, typically with less than one meter."
"On average, these [atmospheric density] models have a one-sigma accuracy of 10-15%, depending on the model, solar activity, and location."

더 깊은 질문

Machine learning techniques can be extended to handle the challenge of orbit determination and prediction for unknown or untracked space objects by implementing unsupervised learning algorithms. These algorithms can analyze patterns and anomalies in the data to identify new objects or predict their orbits based on existing data. Clustering algorithms like K-means can group similar objects together, while anomaly detection algorithms can flag unusual behavior that may indicate a new object. Additionally, reinforcement learning can be used to continuously improve orbit prediction models by learning from new data and adjusting predictions based on feedback.

One potential limitation of over-relying on machine learning models for critical space operations is the lack of interpretability and transparency in the decision-making process. If the models make errors or unexpected decisions, it may be challenging to understand why. Additionally, machine learning models are only as good as the data they are trained on, so biases or inaccuracies in the training data can lead to incorrect predictions. To mitigate these risks, it is essential to have human oversight and validation of the machine learning models. Regular audits and testing can help ensure the models are performing as expected and identify any potential issues. It is also crucial to have fallback mechanisms in place in case the machine learning models fail or provide inaccurate results.

Machine learning can be leveraged to develop more robust and adaptive density models for accurate atmospheric density modeling in space. One approach is to use neural networks to analyze historical data and space weather patterns to predict future atmospheric conditions. By training the neural networks on a wide range of data, including extreme space weather events, the models can learn to adapt and make more accurate predictions in challenging conditions. Additionally, ensemble learning techniques can be used to combine multiple models and improve overall accuracy. Continuous monitoring and updating of the models with real-time data can also help ensure they are prepared to handle extreme space weather events effectively.

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