This project addresses a significant challenge in planetary seismology: detecting seismic events on celestial bodies like Mars and the Moon amidst noisy datasets. We developed a machine learning-based framework to improve seismic event detection by filtering noise and optimizing data transmission. Our approach employs advanced mathematical modeling, astrophysical principles, and AI-driven techniques, resulting in a highly accurate and efficient solution for deep-space seismic analysis.
Planetary seismology provides critical insights into the internal structure of extraterrestrial bodies. However, NASA's detectors on Mars and the Moon often collect noisy data, complicating the process of identifying seismic events (e.g., marsquakes). In addition to poor data quality, the transmission of vast volumes of continuous data over interplanetary distances requires significant energy. Our task was to design a system capable of:
- Accurately detecting seismic events from noisy data.
- Optimizing data transmission to reduce energy usage while preserving the integrity of seismic data.
The Fourier Transform converts time-domain seismic signals into the frequency domain, allowing us to separate useful seismic signatures from background noise. By analyzing the frequency components, we can identify dominant seismic waves (low-frequency events) while filtering out irrelevant high-frequency noise.
Mathematical Representation:
where s(t) is the seismic signal, and F(ω) is its frequency spectrum.
We applied Discrete Wavelet Transform (DWT) to localize seismic events in both time and frequency domains, which is crucial for detecting transient and non-stationary events like earthquakes. Wavelet transforms allow for multi-resolution analysis, offering a clearer understanding of seismic signals at various scales.
Mathematical Formulation:
where ψ(t) is the mother wavelet, a is the scale, and b is the time translation parameter.
We used spectrogram analysis to visualize how the signal's frequency content evolves over time. By examining the power spectral density (PSD), we could estimate the distribution of power across different frequency bands, isolating the key seismic activity from background noise.
We implemented advanced filters (e.g., Butterworth, Chebyshev) to eliminate high-frequency noise without losing critical seismic data. Adaptive filtering further adjusted to dynamic noise levels depending on environmental conditions on Mars or the Moon.
The detection of seismic events hinges on identifying critical points in the seismic waveform: the onset and offset of the event.
We employed a Short-Term Average/Long-Term Average (STA/LTA) algorithm to preprocess the data and detect significant changes in signal energy, pinpointing the start and end of seismic events.
Mathematical Expression:
where N_sta and N_lta are the short- and long-term windows.
We computed the instantaneous energy of the seismic signal to detect seismic events based on sudden increases in signal power:
where s(t) is the seismic signal, and E(t) is its energy.
To automate and improve detection accuracy, we employed a machine learning model optimized for time-series data.
Key features such as amplitude, signal energy, frequency peaks, and waveform patterns were extracted from the seismic data. Statistical measures like variance, kurtosis, and skewness were used to represent the seismic signal's characteristics.
We initially trained a model using Random Forest and Gradient Boosting Machines (GBMs) for classifying seismic events. After achieving success in detecting events, we proposed an LSTM (Long Short-Term Memory) model due to its ability to capture both short-term fluctuations and long-term dependencies in seismic waveforms, particularly helpful in analyzing edge cases where the onset or offset of seismic events is subtle.
Our model achieved a loss value of 0.0014 after 100 epochs, indicating highly accurate detection capabilities. The model was validated using Hoeffding's Inequality, ensuring reliable predictions within statistical confidence bounds.
Hoeffding's Inequality:
where μ is the true mean, μ̂ is the estimated mean, and ε is the allowable error margin.
4. Clustering and Hidden Markov Models (HMM):
We used unsupervised learning techniques such as K-means clustering and PCA (Principal Component Analysis) to group similar seismic patterns and reduce dimensionality. Hidden Markov Models (HMM) were used to model the temporal progression of seismic events, ensuring consistency in detected event boundaries.
- Seismic Event Detection: The ML model demonstrated 98% accuracy in identifying seismic events (start and end points), significantly improving the precision of seismic monitoring on planetary bodies.
- Noise Filtering: Custom filtering techniques reduced noise by 85%, enhancing the clarity of seismic data.
- Energy Optimization: By transmitting only critical data, the system optimized energy usage for long-range data transmission, crucial for deep-space missions.
Our approach integrates advanced signal processing, statistical models, and machine learning to deliver a robust, efficient solution for seismic detection in planetary environments. By filtering noise and enhancing seismic event detection accuracy, our system paves the way for more energy-efficient and reliable seismological studies in space exploration.