Lunar Trailblazer Spacecraft Tracking and Mission Recovery Attempt: Characterization of Status and Behavior of a Non‐Cooperative Object in Cis‐Lunar Space

Abstract

Unexpectedly following launch, the Lunar Trailblazer mission experienced software anomalies that led it to orient solar panels away from the sun and lose communication with Earth. This paper describes efforts to determine the spacecraft state and attempt recovery of the mission's science at the Moon. First, ground observatories at optical and radar wavelengths were engaged to maintain custody of the spacecraft and knowledge of its trajectory. Second, viability of recovery of the mission science objectives was established via testbed work to understand system behavior in fault conditions and determination of trajectories and maneuvers that would enable lunar orbit insertion. Third, optical photometry and radar doppler broadening were employed to determine Lunar Trailblazer's spin and orientation, using approaches similar to those in asteroid studies, to establish when solar panels might again receive sufficient power to boot the spacecraft and initialize its radio. Fourth, X‐band‐capable groundstations in addition to the NASA Deep Space Network were engaged to monitor for the spacecraft's radio carrier signal nearly continually, including crowd‐sourced monitoring and tip‐and‐cue style commanding. Lunar Trailblazer left the Earth‐Moon system and is in a 14‐year Earth return, heliocentric orbit. As it moved further away from Earth prospects for recovery became formidable; ultimately, the ability of the telecom system to return telemetry to Earth would have been insufficient to enable actions to recover the spacecraft, and the recovery attempt ended 6 July 2025. Lunar Trailblazer's mission recovery efforts illuminate capabilities in characterizing a 1–3.5 m ³ size non‐cooperative object in cis‐lunar space.