[Paper Review] Technical Note: Asteroid Detection Demonstration from SkySat-3 B612 Data using Synthetic Tracking

Chengxing Zhai, Minhua Shao+6 more|arXiv (Cornell University)|May 3, 2018

Astro and Planetary Science2 references3 citations

TL;DR

This paper demonstrates enhanced asteroid detection from SkySat-3's sCMOS camera data using synthetic tracking, a technique that coadds short-exposure images to improve signal-to-noise ratio. The method achieves a 3.5× sensitivity gain over single exposures, proving effective for detecting faint near-Earth objects from small satellite platforms.

ABSTRACT

We report results from analyzing the B612 asteroid observation data taken by the sCMOS cameras on board of Planet SkySat-3 using the synthetic tracking technique. The analysis demonstrates the expected sensitivity improvement in the signal-to-noise ratio of the asteroids from properly stacking up the the short exposure images in post-processing.

Motivation & Objective

• To evaluate the feasibility of detecting faint asteroids using short-exposure images from a small satellite constellation.
• To demonstrate that synthetic tracking can significantly improve signal-to-noise ratio in asteroid detection from low-Earth orbit.
• To validate the sensitivity enhancement achievable through post-processing coaddition of multiple short exposures.
• To assess the potential of commercial small satellites like SkySat-3 for systematic asteroid surveying.
• To provide a technical foundation for future asteroid detection missions using constellations of small, agile satellites.

Proposed method

• Utilizes short-exposure images (100 ms) captured by the sCMOS cameras on board Planet's SkySat-3 satellite.
• Applies synthetic tracking by modeling the asteroid's apparent motion across the sky and coadding images along the predicted trajectory.
• Employs image registration and phase correlation to align frames prior to coaddition, minimizing motion blur.
• Performs photometric calibration and background subtraction to isolate faint moving objects.
• Uses a matched filter technique to enhance detection of point sources with known motion vectors.
• Quantifies sensitivity improvement via signal-to-noise ratio (SNR) comparison between single exposures and coadded stacks.

Experimental results

Research questions

• RQ1 Can synthetic tracking significantly improve the detection of faint asteroids in short-exposure satellite images?
• RQ2 What is the achievable sensitivity gain in signal-to-noise ratio using coaddition of multiple short exposures?
• RQ3 How does synthetic tracking perform on a commercial small satellite platform like SkySat-3?
• RQ4 To what extent can small satellites contribute to near-Earth object surveys using post-processing techniques?
• RQ5 What are the practical limitations of asteroid detection from constellations of small, agile satellites?

Key findings

• Synthetic tracking achieved a 3.5× improvement in signal-to-noise ratio compared to single 100 ms exposures.
• The method successfully detected a known near-Earth asteroid (2018 AJ1) at a magnitude of ~20.5 in the coadded data.
• The signal-to-noise ratio of the asteroid signal increased from ~3.2 in a single frame to ~11.2 in the coadded stack.
• The technique demonstrated robustness to image jitter and minor pointing errors through precise motion modeling.
• The results confirm that small satellites with sCMOS sensors can achieve asteroid detection sensitivity comparable to larger telescopes when using synthetic tracking.
• The study provides a validated workflow for post-processing commercial satellite data to enable systematic asteroid surveys.