University of Luxembourg LunaLab

Source: [1]. CC BY 4.0.

LunaLab is an indoor lunar analogue built to reproduce light, not soil. Its design case is the high-latitude lunar visual environment: a sun a few degrees above the horizon, almost no atmospheric scattering, and a scene dominated by long moving shadows. The operators chose coarse basaltic gravel over regolith simulant deliberately, on cost and health grounds, and that choice is what bought them an 11 by 8 m field instead of a small bin [2]. The field has also been reproduced as a photogrammetric digital twin inside an open-source lunar simulator, so work that starts on the physical terrain can continue in simulation without rebuilding the scene [3].

Laboratory data

Parameter	Value
Operator	University of Luxembourg, SnT, Space Robotics group, with ispace Europe
Location	Esch-sur-Alzette, Luxembourg [2]
Commissioned	Constructed 2019 to 2020, reported October 2020. No formal date published
Type	Indoor analogue terrain field at 1 g, built for optical and vision-based navigation
Floor area	88 m2, 11 x 8 m ; 77 m2, 7 x 11 m, in the construction paper . See below
Capabilities	Terrain field, sun simulator, motion capture
Simulant or terrain	Coarse basaltic gravel and sand, 20 t, 0.2 to 4 mm. Not a simulant
Instrumentation	12 OptiTrack PrimeX cameras at 25 Hz. No load cells described
Ground truth	Motion capture position and quaternion attitude at 25 Hz
Fidelity limits	Grain size 0.2 to 4 mm against 40 to 130 um lunar; no opposition effect . See below
Access	Not published. The dataset is public on Zenodo, code on GitHub
Cited by	None. Published users are fictionlab Leo rovers [4]

Capabilities

Terrain field

Parameter	Value
Working volume	11 x 8 m; 7 x 11 m in the construction paper [2]. Bed depth not published
Test article limits	Articles run are Leo rovers, about 359 x 296 mm, masts to 550 mm
Vacuum	Not applicable. Ambient pressure
Temperature	Not applicable. No thermal capability
Illumination	See sun simulator
Simulant or terrain	Basaltic gravel and sand, 20 t, 0.2 to 4 mm, with placed rocks and shaped craters [2]
Gravity offload	Not applicable
Instrumentation	Ceiling OptiTrack; walls and ceiling painted black

A rectangular field of loose basaltic material with rocks and shaped craters on it, inside a room whose walls and ceiling are painted black. Every element of that is an optical decision.

The soil choice is the most consequential and the operators explain it directly. Regolith simulant was rejected because of its cost and because its fine fraction is a carcinogenic inhalation hazard, and rejecting it is what allowed the field to be built at 20 t and tens of square meters rather than as a small enclosed bin [2]. The material is chosen for its reflectance and its ability to hold a shaped crater rim, not for its mechanical behavior under a wheel: basalt sand at 0.2 to 1 mm plus gravel at 2 to 5 mm, and a separate ispace lunar yard of 8 by 8 m holding 3 t was built alongside it [2]. Bed depth and relative density control are not published.

Black paint on the walls and ceiling is the shadow-contrast measure. The operators record it as a mitigation rather than a solution: lunar shadows are darker than the room can produce, and the paint reduces but does not remove the bounce that fills them.

Sun simulator

Parameter	Value
Working volume	One movable head on the short side of the field
Illumination	Aputure LightStorm 600c Pro, 600 W, 69 to 51,100 lux, 2300 to 10,000 K
Slope	Solar elevation 8 degrees at 80 cm lamp height, 4 degrees at 40 cm
Instrumentation	Lamp position adjustable vertically and horizontally

The lamp is a single source and its height is the control variable. At 80 cm above the floor it subtends 8 degrees at the field center and at 40 cm it subtends 4 degrees, which brackets the elevations a polar site sees across a lunar day [1]. Color temperature is set to 6000 K to approximate the solar spectrum. Four standard cases were defined for the published dataset: a reference case at 200 lux, a noon case at 100 down to 1 lux, a dawn and dusk case at 25 down to 1 lux, and a night case at 0.1 lux [1].

The earlier configuration used a 2000 W and a 1000 W tungsten bulb with a focusing lens, reaching about 100,000 lux at 1 m, run in flood mode with barn doors [2].

Motion capture

Parameter	Value
Working volume	Ceiling mounted over the field
Instrumentation	12 OptiTrack PrimeX cameras, logging at 25 Hz
Illumination	Emits infrared tracking light and status LED rings into the scene

Accuracy is stated by the operators only as sub-millimeter, with no numeric figure published [1]. A validation of the same class of array, a 16-camera OptiTrack rig at NASA Glenn’s SLOPE facility, found the software’s self-reported mean error of 0.17 mm was honest as an aggregate but understated error in regions where test hardware occluded cameras, and that more cameras were needed to close the occluded regions [10]; an unvalidated sub-millimeter claim here should be read the same way. The system pollutes the scene it measures, which is treated below as a fidelity limit rather than as an instrumentation note.

Instrumentation

Ground truth is the twelve-camera ceiling-mounted OptiTrack rig described above.

The instrumentation that matters here is the payload rather than the facility. The published campaign carried a monochrome camera, a stereo-inertial sensor and, for the first time in a planetary exploration setting, a single-photon avalanche diode camera, alongside wheel odometry and an inertial unit [1]. A single-photon detector is the natural instrument for a scene whose interesting cases are at 1 lux and below, and the facility is built to produce those cases.

What it does not reproduce

Regolith. Grain size is 0.2 to 4 mm against 40 to 130 um for lunar regolith, a difference of one to two orders of magnitude [1]. The real material also carries bulk density rising from about 1.30 g/cm3 at the surface toward 1.92 g/cm3 by 60 cm depth [6] and shear strength that climbs with it, above 2 kPa at 1 m depth, none of which loose basalt gravel at 1 g is built to match [9]. Nothing measured here about wheel sinkage, slip, dust lofting or adhesion transfers to the Moon, and the facility does not claim it does. The operators’ rejection of simulant is itself consistent with the wider record: NASA’s own simulant-scoring work finds that even purpose-built lunar simulants rarely exceed a composition figure of merit around 0.6 against an Apollo reference, because none but the NU-LHT series contain anything standing in for lunar agglutinates [7][8], so a graded basalt that makes no claim to compositional fidelity is not obviously worse placed than a simulant that claims it and falls short. The same workshop that set NASA’s simulant framework also tabulated the geotechnical envelope a simulant is expected to reproduce, cohesion 0.1 to 1 kPa and friction angle 30 to 50 degrees among the targets [8], a bar the facility’s coarse gravel does not attempt to clear.

The opposition effect. The operators state plainly that the backscatter surge lunar regolith shows near zero phase angle cannot be reproduced in the facility at all [1]. The opposition surge is a first-order term in lunar photometry, so a photometrically calibrated perception algorithm cannot be validated against it here.

Regolith reflectance. The soil is less reflective than real regolith, which the operators offer as a worst-case optical scenario rather than as a match.

Collimated sunlight. The lamp is close to the field relative to the field’s size, so illuminance falls off as the inverse square across it, producing uneven illumination and inconsistent exposure along a long trajectory [1]. Real solar illumination is effectively collimated and uniform across a rover’s traverse.

A dark scene that is only dark. The measurement system contaminates the measurement. Status LED rings and the infrared illumination the motion capture cameras emit act as secondary light sources, producing faint glows, ghosting and lens flares in the dark cases, an effect the operators describe as overlooked and unavoidable. Any perception result at 0.1 lux [1] carries it.

Lunar shadow contrast and full solar illuminance. The lamps reach about 100,000 lux in the earlier configuration against a lunar solar constant equivalent of about 135,000 lux, and shadows are not as black as lunar shadows even with black walls and ceiling [2].

Dust discipline. The fine material still lifts and has to be allowed to settle between runs, and it ingresses into mechanisms [2].

Campaigns run there

SPICE-HL3 dataset, recorded 2024 and published 2026. Two fictionlab Leo rovers, 88 sequences and 1.3 million images across seven trajectories and four illumination conditions, at 5 cm/s and 50 cm/s, with and without headlights [1]. Measured: stereo RGB-inertial, monocular monochrome and single-photon imagery with wheel odometry and inertial data, all against motion capture ground truth. The single-photon camera produced tighter and more stable image quality distributions clustered around the mean, while the conventional cameras reached lower absolute minimum and mean quality scores because of their higher resolution; visual SLAM pipelines were run to their failure points under the dark cases. The dataset is the facility’s principal published output.

Facility construction, 2019 to 2020. The construction paper is itself a lessons-learned report on lighting, surface material and shadow contrast for two indoor lunar analogues, the LunaLab and the adjacent ispace yard [2].

Terrain-induced vibration prediction. LunaLab is one of three test environments, along with a lakeshore and a disused mine, used to validate a lightweight method that predicts rover vibration from LiDAR terrain roughness corrected with IMU data on a Leo Rover [4].

Downstream simulation. The photogrammetric digital twin of LunaLab is one of the environments distributed with an open-source lunar robotics simulator, and a separate terramechanics campaign on a 20 m sand bed has since fitted slip and sinkage models for that same simulator, an effective-radius correction for grousered wheels among the results [3][5].