SPACEDOS04 - Personal Active Dosimeter for manned deep space missions

SPACEDOS04 is currently under development. Parameters listed below are design targets and may change before the flight model is finalized.

SPACEDOS04 is a wearable radiation dosimeter for manned deep space and ISS missions, measuring ionizing radiation dose received by an astronaut using a silicon PIN diode detector combined with passive detectors (TLD and nuclear track detectors). It forms a Space Dosimeter Unit (SDU) together with a wristwatch-style Display and Data Unit (DDU) that provides real-time dose readout.

The device is being developed and flight-tested as part of the CZPAD experiment onboard the International Space Station (ISS), which serves as the qualification path towards a flight-proven, deployable instrument.

System overview

Each SDU consists of a SPACEDOS04 electronic dosimeter, a set of passive detectors (TLD and nuclear track detectors), and a Nomex pouch for mechanical protection and flame retardancy. The SDU can be attached to the cosmonaut’s body (waist strap, chest strap, thigh strap) or to the ISS structure (hook & loop adhesive pads).

Hardware

The SPACEDOS04 electronics consists of three PCBs:

  • Baseboard - MCU, Battery Management System (BMS), and a Bluetooth Low Energy RF interface to the DDU wristwatch display
  • Sensor board - silicon PIN diode detector and the analogue signal processing chain
  • Flex PCB - mechanical and electrical interconnect between the baseboard, sensor board, and the Li-ion battery cell

Parameters (design targets)

  • Silicon PIN diode detector, at least 28 x 28 x 0.5 mm³, with a full-area LiF neutron converter layer
  • Deposited energy range: 50 keV to 100 MeV (the 50 keV lower bound is set by the ²⁴¹Am 59.5 keV calibration line)
  • Aluminium shielding of the diode: 6 mm on the sides
  • Data storage device: SD card (~1 GiB), FAT filesystem, human-readable log format
  • Charging: USB-C
  • Battery endurance: at least 5 days
  • Dimensions (without pouch): approx. 80 x 70 x 20 mm (± 5 x 3 x 2 mm)
  • Mass: estimated 148 - 184 g (SDU including battery cell and shielding, excluding pouch)
  • Maximum temperature while charging: 45 °C
  • Vibration resistance per Crew Dragon / ISS JSC-20793 requirements