CANDLE

CANDLE (calibration using an artificial star with NIST-traceable distribution of luminous energy) is an on-orbit, NIST-traceable flux calibration source. The project will provide discreet laser diode sources, reflected sunlight, and programmable spectral sources that can be used by ground-based or space-based telescopes to improve their absolute flux measurement knowledge. This translates to increased accuracy in almost every observational field including a star's brightness, size, energy, and habitable zone calculations. Additionally, for cosmological studies, the standardization of supernova and other observations will help to understand dark energy, dark matter, and the time scale of the universe. This engineering test unit consists of three main components: (1) a single mode fiber laser suite (FLS), (2) a solar reflector (SR), and (3) a programmable spectrum system (PS).

Requirements:

Item	Requirement
SI Traceability	Knowledge of emitted flux is ≤0.4% with a goal of 0.2%
Exit Beam Profile	Must be smooth and stable so that flux ratios between wavelengths is the same at the receiving telescope's entrance pupil as at the on-board flux monitor(s)
Flux at Telescope	10 - 105 photons m-2 s-1 in a monochromatic line
Wavelengths	Minimum 3 wavelengths between 0.35 and 2.3 µm
Power	< 125 Watt
Mass	<10 kg
Volume	<24U with target <12U (1U = 10 cm × 10 cm × 10 cm)
Surface Contamination	Must be monitored and characterized
Risk	Low
Stray Light	Control sufficient to retire risks in achieving 0.4% flux knowledge
Radiation Tolerance	Net impact ≤ 0.2%