July 13, 2016

Aspera-3 Instrument

(Analyzer of Space Plasmas and EneRgetic Atoms)


Aspera-3 main unit and IMA

Aspera-3's main objective is to study the interaction of the solar wind with the Martian atmosphere, and to understand the mechanisms which caused the escape of water vapour and other light gases in space. The instrument uses a technique named ENA (Energetic Neutral Atom) to visualize the inert and ionized gas concentrations around Mars.

The instrument consists of four detectors destined to characterize the charged and neutral particles in the near environment of Mars:

  • the "neutral particle" imager (NPI), measures the total flux of neutrals with a high angular resolution (but without discrimination in mass/energy);
  • the "neutral particle" detector (NPD), measures the flux of neutrals with a good resolution in mass and speed, but a rough angular resolution;
  • the electron spectrometer (ELS);
  • the ionic mass analyzer (IMA).

It is completed by a data processing and housekeeping electronic (DPU). Apart from the IMA, all the subsystems are mounted on a mobile platform giving to Aspera a 4 coverage (sphere).

Instrument development was conducted under IRF prime contractorship (Swedish Institute of Space Physics) in Kiruna. The CESR (Centre d'Etude Spatiale des Rayonnements) in Toulouse contributed to Aspera by supplying the following subsystems:

  • Purchase, calibration and supply of the Micro Channel Plate (MCP) for the NPI subsystem. The main characteristics of these detectors are listed below.
  • Study, manufacture, documentation and tests of the low voltage DC/DC convertor card (prototype, electric model, flight model, and spare model).
  • Study, manufacture, documentation and tests of scanner command electronic cards (prototype, electric model, flight model, spare model).
  • Design and supply of test and control sets for the previous cards.
  • Numerical study for the design and the modification of the detection head of the IMA spectrometer and complete calibrations in ultra-vacuum chamber for this detector.

Detector MCP constituted of:
- 1 disk Ø = 99 mm with an interior hole Ø = 15 mm
- 2 half-disks superposed to the previous
Manufacturer Photonis
DiskØ
Thickness
99 mm
1.5 mm ± 0.05 mm
ChannelsØ
Inclination
25 µm
8° ± 1°
MetallizationTypeStandard NiCr
ResistanceDisk
½ disk
5 at 25 M
10 at 50 M
PolarizationNominal1200 V
Gain@ 1200 V 10000
MCP main characteristics