Electric Field Sensor for the ExoMars mission

Ref-Nr:

Micro-ARES antenna and electronics.

Technology abstract

Micro-ARES is an electric field sensor developed in France by LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales) for the ExoMars mission. The sensor was designed to measure and characterize the Martian atmospheric electricity.
Thanks to its small size, low volume and real time filtering capabilities, the instrument could be embedded as a payload, for example in robots or drones.

Technology Description

Micro-ARES is an electric field sensor that was developed for the ExoMars mission in order to observe:

  • the electric conductivity, its diurnal and seasonal variations and  its  perturbations following  solar events;
  • the quasi DC E-field, which reflects the nature and role of the various charging mechanisms at work on the surface of Mars;
  • the ELF/VLF radio-electric emissions that may originate from atmospheric as well as from ionospheric processes and the AC signals from dust particle impacts on the sensors or on the lander structure.

Micro-ARES is a single probe E-field instrument consisting of a spherical electrode installed on a stiff metallic support and a single electronics board. Micro-ARES measures the amplitude of the vertical component of the E-field in the atmosphere, using the lander potential as a reference. A high impedance (1014Ω) preamplifier is mounted in a voltage follower configuration yielding a precise measurement of the surrounding atmospheric potential in a medium whose resistivity shall be typically >10 smaller than the instrument impedance, as expected for average Martian conditions.
The instrument has a sensitivity in DC mode of 10 mV/m and can sense potential values between -90 to +90 V (the expected corresponding E-fields are +265 and -265 V/m, once averaged between 0 and 25.5cm above the ground) and up to > O(1)kV in high voltage mode.
This instrument could be used on earth in order to:

  • measure under water electric fields produced by marine energy devices and cables
  • measure electric fields in remote or inaccessible environments requiring the use of embedded sensors in drones or robots

Innovations & Advantages

The sensor was originally developed as a double probe with 2 cylindrical electrodes placed at the extremities of a meteorological antenna. Because of mass constraints, the design was changed to a configuration including a single spherical electrode. As a consequence, the total mass of the device is only 200 grams, for an average power consumption of 350mW. 12 800 samples per second can be collected by the instrument, producing several Gigabits of data in less than a day. The volume of data can however be reduced in real time by a factor of 100 thanks to the embedded Digital Signal Processor.
The small size, low volume and real time filtering capabilities of the instrument therefore allow it to be embedded as a payload in robots or drones for example.

Further Information

  • The potential of the electrode can be measured with a precision of ±1,5 mV in the range [-100 ; +100 V]
  • In “High tension” mode, the instrument can measure E-fields until 30 000V/m. This induces a 3-fold increase of the energy consumption

Current and Potential Domains of Application

Micro-ARES was developed for the ExoMars mission in order to observe:

  • the electric conductivity, its diurnal and seasonal variations and its perturbations following solar events;
  • the quasi DC E-field, which reflects the nature and role of the various charging mechanisms at work on the surface of Mars;
  • the ELF/VLF radio-electric emissions that may originate from atmospheric as well as from ionospheric processes and the AC signals from dust particle impacts on the sensors or on the lander structure.

 
The small size, low volume and real time filtering capabilities of the instrument allow it to be embedded as a payload in robots or drones for example.
This instrument could be used on earth in order to:

  • measure under water electric fields produced by marine energy devices and cables
  • measure electric fields in remote or inaccessible environments requiring the use of embedded sensors in drones or robots