Characteristics of the SPADUS Instrument


Dust Particles

Single sensor: 36 cm², 6 µm thick PVDF copolymer.
Particle mass (10 km/s): 5*10-12 g (Dp = 2 µm) to 1*10-5 g (Dp = 200 µm).
Particle velocity: 1 to 10 km/s with 1 to 4% error. Greater error for velocity > 10 km/s.
Particle trajectory: mean angular error of 7° for isotropic dust flux.
Sensitive area of D1 array (16 sensors): 0.058 m².
Geometry factor for isotropic dust flux: a) D1 array -- 0.18 m² sr.
b) D1,D2 arrays -- 0.04 m² sr.
Field of view (full cone): a) 180° for flux.
b) 120° for trajectory.
Low resolution Pulse-Height-Analysis: 32 channels for each of 32 dust sensors.
High resolution Pulse-Height-Analysis: 2000 time points, 8-bits/point, each of 4 channels.
Expected impact rate: a) ~2/day to 20/day (flux).
b) ~0.2/day to 2/day (trajectory.


Physical

  1. Estimated total power: 6.5 W.
    Estimated total weight: 18 pounds.
  2. thermal: operating temperature range -40°C to +50°C for dust sensors and electronics.
  3. mounting: dust sensor normals along spacecraft velocity vector.
  4. data readout: readout at an average bit rate of ~4 bits/s.
  5. commands: CALIBRATE and CONTINGENCY commands occasionally.
  6. attitude: spacecraft attitude (~1° accuracy) and velocity (~1° accuracy) required.


The addition of an energetic nucleon telescope to SPADUS would provide measurements of electrons (20 keV to 2.5 MeV) and ions (20 keV to 20 MeV) and would add ~3 pounds and ~3.5 Watts to the SPADUS weight and power values listed above.


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