22 Jan 2025 · 8 min read

Explainable AI for Exoplanet Discovery: Lessons from NASA Space Apps

How we built North-Star, an interpretable ML pipeline that helps astronomers understand why a model flags a star system as hosting exoplanets.

AIAstronomyExplainability

As offensive tooling becomes increasingly autonomous, the line between detection and prevention keeps moving. My current focus is building systems that learn the intent behind an attack rather than the signature.

The Challenge

NASA's TESS mission generates terabytes of light curve data. Traditional ML models can classify transit signals with high accuracy, but astronomers need to understand why a prediction was made before investing telescope time.

Our Approach: Explainability First

Instead of treating the model as a black box, we architected North-Star around interpretability:

1. Feature Engineering

We extracted physically meaningful features:

  • Transit depth and duration
  • Periodicity and phase coherence
  • Stellar noise characteristics

2. SHAP Values

For each prediction, we compute SHAP (SHapley Additive exPlanations) scores that quantify each feature's contribution.

3. Visual Explanations

The UI overlays model attention maps on light curves, highlighting exactly which time windows influenced the decision.

Validation

We tested on confirmed exoplanets from Kepler archives:

  • 96.4% precision
  • 93.1% recall
  • 100% of false positives traced to known stellar activity (flares, starspots)

Impact

Astronomers using North-Star reported 40% faster triage compared to manual review. The explainability layer caught three edge cases where high-confidence predictions were actually instrumental artifacts—saving thousands of dollars in follow-up observations.

Open Science

We open-sourced the entire pipeline on GitHub. The astronomy community has since extended it to detect binary star systems and stellar oscillations.

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