We are reporting on the concept, design, construction, and critical operating parameters of a new photon-counting detector package. It was developed based on silicon SPADs manufactured using K14 technology. Four detection chips with an active area diameter of 25 microns are used. The active quenching electronics enable the detection chips' operation in a bias range of 0.5 to 2.5 Volts above their breakdown voltages in a continuous counting mode. The entire design and construction are prepared for long-term operation in space conditions. Our operation experience of K14 detection chips and all the electronics in numerous space missions was taken into account when designing the device. It can be operated in an extensive temperature range of −55 to +50°C without any active temperature stabilization. The built-in SPAD biase power supply voltage is following the SPAD breakdown voltage temperature dependence. This way, the detection chips are biased fixed bias above their breakdown voltage over the entire temperature range. The critical detector parameters depend on a selected bias above a breakdown voltage. For selected configuration, every single detector's parameters are as follows: photon detection probability at 800 nm is 30%, the maximum count rate is 2 MHz, the timing resolution is better than 80 ps FWHM, detection delay temperature drift is within the range of ±0.3 ps/K. The dark count rate is typically < 50 kHz at +25°C. It may be reduced one order of magnitude, lowering the operating temperature to 0°C. The entire detector package power consumption is well below 1 Watt; its mass will be below 100 grams.