NASA · MetDetect · planetary defense

Sensor fusion & radar meteorite detection

Working toward fusing radar, optical, infrasound and seismic data into one estimate of a falling body, so an event can be followed from the first telescopic detection through to the meteorite on the ground.

Schematic of the many sensors that observe a meteorite fall: telescope, fireball cameras, infrasound array, seismometer, Doppler weather radar, lightning-mapper satellite and casual footage
The many ways a single fall is recorded: an asteroid caught pre-impact, the luminous fireball and its fragmentation, then ground and space sensors (fireball cameras, infrasound arrays, seismometers, Doppler weather radar, lightning-mapper satellites and casual footage). Illustration: P. Shober.

MetDetect: meteorites in weather radar

At NASA Johnson Space Center (ARES) I’m building MetDetect, exploiting the U.S. NEXRAD Doppler weather-radar network, a continent-scale, openly-available mesh that can detect falling meteoritic debris. Working with Paul Abell and Mark Fries (who pioneered the Doppler-radar meteorite method), the goal is to turn that network into an automatic, physically-interpretable detector of fresh meteorite falls.

The detector ingests volumetric radar scans, suppresses weather noise, clusters spatio-temporal echoes with unsupervised machine learning, and applies consistency tests (altitude–time slope, fall-consistent apparent velocities, alignment with winds, multi-scan persistence). Candidates get a confidence score, and the strongest are flagged for rapid follow-up. A planned next step is a radar-fall simulator to generate annotated synthetic data, both to train a convolutional neural network for more robust detection and to provide a forward model for parameter inference. See live results at /acm2026 and the planned in-browser viewer at /detect.

Sensor fusion & sequential estimation

A single sensor only ever sees part of an entry. The real leverage comes from fusing them: optical astrometry and photometry from camera networks, Doppler radar (low-altitude debris, drift and terminal mass), infrasound and seismic records (total energy and fragmentation altitudes), and spectra / radiometry (composition and ablation regime). My research program aims to treat each significant bolide as a multi-sensor inverse problem, combining these heterogeneous streams with sequential Bayesian estimators (Kalman-type filters) that would update the meteoroid’s state (position, velocity, mass, density, fragmentation) and the ablation/fragmentation model parameters as each observation is assimilated.

The aim is full posterior distributions for pre-atmospheric mass, bulk density, strength and fragment size-frequency, with realistic uncertainties propagated to the predicted fall ellipse, rather than single best-fit values, with a forward model coupled to hierarchical MCMC so constraints can be inferred jointly across events.

Closing the decametric gap

Plot of peak dynamic pressure and albedo versus diameter showing meteors, fireballs and asteroids, with a 10-100 m gap in knowledge
The 10–100 m “decametric gap” between what fireball networks and telescopic surveys each sample. P. Shober; compiled from FRIPON, GMN, CAMS and NEO-survey data.

The 10–100 m size range is the worst-characterised in the whole small-body inventory: telescopic surveys become inefficient for objects this small and dark, while fireball networks only sample what actually hits Earth. Yet this regime dominates the impact flux responsible for Chelyabinsk-type events and probes the transition between rubble-pile asteroids and individual meteoroids, a core planetary-defense concern. Tying the multi-sensor bolide constraints to the decametric NEO population that upcoming infrared surveys will reveal (NEO Surveyor, NEOMIR) is the path to closing this gap.

From discovery to recovery

A small but growing number of asteroids have now been spotted before impact (asteroid 2023 CX1, which dropped meteorites over Normandy, among them). The endgame is full-chain, “telescope-to-ground” events: telescopic discovery and spectroscopy → predicted trajectory and impact energy → luminous flight in the camera networks → fragmentation from infrasound/seismic → dark flight in Doppler radar → prediction and recovery of the meteorites, with every step fused into one coherent, uncertainty-aware estimate. Building toward that pipeline, and helping prepare networks like FRIPON for this regime, is the goal of my sensor-fusion program.