Ex Luna, Scientia: MeV Gamma-Ray Astrophysics with the Lunar Occultation eXplorer (LOX)

Astronomical investigations from the Moon afford new opportunities to advance our understanding of the cosmos. The Lunar Occultation Explorer (LOX) will leverage the power of a new observational technique to transform our understanding of the nuclear cosmos (0.1-10 MeV) and establish the Moon as a platform for astrophysics. LOX directly challenges traditional paradigms like Compton telescopes by mitigating mission complexity, technology development lifecycles, and cost constraints, while also delivering the sensitivity and continuous all-sky monitoring capabilities needed to transform nuclear gamma-ray (MeV) astrophysics. In its baseline configuration LOX is capable of surveying the entire sky at a bolometric sensitivity <10^-7 cm^-2 s^-1 MeV^-1, near-continuous monitoring of astrophysical light curves, and arcminute source localizations.LOX will operate from lunar orbit and use the Moon as a natural occulting disk to modulate astrophysical source signatures via repeated eclipses. Simplicity is a hallmark of this efficient and validated approach, and the resulting occultation ensembles contain all information necessary for source detection, characterization and localization. LOX’s lone instrument, the Big Array for Gamma-ray Energy Logging (BAGEL) is highly scalable, limited only by available mission mass and power resources, and data analyses rely only on detailed knowledge of the spacecraft ephemerides and a rigorous statistical framework rather than kinematic reconstruction. LOX’s deployment to the Moon and use of time series-based analyses benefits from 20+ years of successful lunar exploration using gamma-ray spectrometers and mimics the operational profile of planetary orbital geochemistry investigations. LOX is a mature, low-risk, and high-heritage implementation. Its viability as a competitive next-generation nuclear astrophysics mission, including in-situ validation of the technique from lunar orbit, and the benefits of the lunar environment, will be presented. Several high-priority science goals will also be reviewed to highlight the unique insights LOX can reveal about the lifecycle of matter and energy in our galaxy and beyond.