LUMIO (space mission)

Did You Know?

• The spacecraft platform is manufactured by Argotec, which previously designed LICIACube and Argomoon.
• Extendable solar arrays and an X-band transponder are produced by IMT.
• The propulsion system enables space maneuvers and station-keeping corrections.

Background

Near-Earth meteoroids, fragments of asteroids and comets ranging from micrometers to meters, impact the Earth and Moon daily. About 33 tons of these fragments enter Earth's atmosphere each day, but most burn up before reaching the surface. Because the Moon lacks an atmosphere, lunar impacts are more frequent and pose a constant hazard to surface operations. When a meteoroid strikes the ground, its kinetic energy converts to heat, vaporizing part of the mass and scattering debris; if the impact occurs in shadow, it appears as a bright flash detectable by Earth-based optical telescopes. Flash intensity reveals the meteoroid's kinetic energy. Earth-based observations are limited to nighttime and are often disturbed by atmospheric conditions, and only impacts on the visible lunar face can be seen. LUMIO will have a constant, unobstructed view of the lunar far side from its orbit around the L2 Earth-Moon Lagrangian point. Because its observation periods (when the surface is shadowed) are opposite to Earth's, LUMIO will greatly expand the monitored lunar surface area. Combining spacecraft measurements with Earth-based data will yield more detailed statistics on the probability and distribution of meteoroid impacts on the Moon.

Mission profile

The L2 Lagrangian point is a gravitational equilibrium zone in the Earth-Moon system where a family of three-dimensional trajectories called halo orbits exists. LUMIO will fly one such trajectory, observing the lunar far side from a distance of 36,000 to 86,000 km. The mission has four phases. In the parking phase, the spacecraft is released into selenocentric orbit as a secondary payload and begins commissioning over 14 days. The transfer phase involves a stable manifold injection maneuver and a 14-day journey to L2. During the one-year operative phase, LUMIO performs a halo injection maneuver, conducts scientific tasks, relays data to Earth, and executes station-keeping maneuvers. At end of life, a final maneuver ensures safe disposal.

Scientific payload

LUMIO-Cam, the main scientific instrument, is being designed and manufactured by Leonardo at its Campi Bisenzio (Florence) facility. The camera has a resolution of 1024 x 1024 pixels and captures images in visual and near-infrared spectrums at 15 frames per second, detecting flashes as brief as 30 ms. Its focal length of 127 mm yields a 6.0-degree field of view, sufficient for full-disk observations when the Moon's apparent size is 5.6 degrees at closest approach. Surface monitoring is possible only when less than 50% of the Moon is illuminated, occurring in 15-day windows; during the other half of the time, the spacecraft performs station-keeping and secondary activities. The payload generates about 5 TB of data per day, but on-board processing sends only images with detected impact flashes to Earth, reducing transfer to roughly 1 MB per day.

Navigation experiment

A secondary objective is demonstrating fully autonomous navigation without ground-station communication. Images from LUMIO-Cam are processed by optical navigation algorithms to estimate the satellite's position relative to the Moon using full-disk navigation. Each image is processed to detect the Moon's edges, then an ellipse is fitted to reconstruct the lunar limb's projection. Because the camera characteristics and Moon ellipsoid dimensions are known, the ellipse points serve as state measurements in a Kalman filter. The technique is expected to achieve operational accuracy of less than 100 km.