Star-Bee · GEM in space

Space challenges & solutions

Patent pending

What changes when a concentrating GEM leaves Earth — vacuum, lunar night, radiation, launch loads, dust — and how each challenge is addressed and verified.

Values are min / std / max; «calculated by Bot» values are design estimates, not test results.

Challenges and our approach

Challenge	Why it matters	Our approach	How we verify
Radiator mass in vacuum	No convection: a stand-alone radiating panel needs ~38× the Earth area. Moon optics + free-standing radiator: 65.8 / 248 / 269 W/kg (dry)	Use the mirror back face as the radiator, so only the overflow area needs a panel: Moon 153 / 982 / 1,130 W/kg dry, 129 / 696 / 998 W/kg with one shared coolant loop + pump per GEM «calculated by Bot». Deployable / heat-pipe radiators for any extra area	Thermal-vacuum balance test of a GEM segment
Coolant loop in space	A pumped loop adds mass, freezing and leak risks	ONE shared loop and ONE pump per GEM (not per module); passive dry / heat-pipe variant where possible; redundant pump	Loop tests in thermal vacuum; freeze / thaw cycling
Lunar night and eclipses	A 14-day lunar night or orbital eclipses stop power	Polar sites with long sunlight; a survival load instead of full power; batteries for short eclipses; optional heat storage only where heat is needed	Site illumination analysis; cycling tests on the mission profile
Radiation on cells and electronics	Cells and controllers degrade	Space-qualified multi-junction cells with doped cover glass; radiation-tolerant controllers, shielding and redundancy	Electron / proton irradiation of cells; dose and single-event tests of controllers
UV and atomic oxygen on mirrors	Reflectance can drop	Space-heritage protected mirror coatings with protective overcoats; no bare polymers on exposed faces	Combined UV / particle exposure of mirror coupons
Launch loads	Thin mirrors are sensitive to vibration and noise	Fly compact, supported stowed packs; launch locks; stiff sandwich panels; assemble in space where possible	Sine, random, acoustic and shock tests of a stowed pack
Deployment and focus	Mirrors must keep their shape and alignment	Modular / robotic assembly with kinematic mounts; repeatable hinges; focus trim with the existing actuators	Deployment repeatability and surface-figure checks in thermal vacuum
Outgassing and contamination	Vapours can fog mirrors and cells	Low-outgassing materials (ASTM E595 screen) or adhesive-free joints; bake-out; vents away from optics	ASTM E595 tests; bake-out monitoring; witness samples
Lunar and Mars dust	Dust is abrasive and cuts power	Built-in cleaning concept; electrodynamic dust shields (flight-proven on the Moon); stow during Mars dust storms	Regolith-simulant tests in vacuum / low-pressure CO₂
Pointing accuracy	Concentrators need accurate sun tracking	Closed-loop sun sensors feeding the GEM actuators; pointing error budget	Sun-simulator tracking tests
Thermal cycling	Many hot / cold cycles in orbit	Matched-expansion materials, compliant mounts, brazed / welded joints	Thermal-cycling qualification of coupons
Complete mass budget	Frame, wiring and deployment mass are not yet counted, so space W/kg are lower-bound estimates	Full mass breakdown with growth allowance; sandwich panels as structure	Mass measurement of an engineering model

Context: space flat PV arrays reach about 30–100 W/kg (NASA Small Spacecraft Technology State of the Art). GEM design optics: Moon 1,482 / 2,035 / 2,557 W/kg before radiator and structure.

Watts per kilogram off Earth

GEM optics + radiator in vacuum (Moon, Mars) vs today's space arrays

The mirror is the radiator: Moon, mirror-back radiator, wet incl. shared loop + pump (696, up to 998 W/kg)

References

NASA Small Spacecraft Technology State of the Art (power) https://www.nasa.gov/smallsat-institute/sst-soa/power-subsystems/
NASA electrodynamic dust shield on the Moon https://ntrs.nasa.gov/api/citations/20250009407/downloads/EDS_ESA%20Newsletter%20paper%202025_Final_WithAuthors.pdf
NASA GSFC outgassing database https://etd.gsfc.nasa.gov/capabilities/outgassing-database/user-guide/
NASA ISAM https://ntrs.nasa.gov/citations/20250008988
NASA ISS active thermal control overview https://nasa.gov/wp-content/uploads/2021/02/473486main_iss_atcs_overview.pdf

Full numbers: GEM vs flat PV vs CPV .