As part of a French-Argentinian cooperation, the CARMEN instrument was embarked, as technological passenger, on the SAC-D satellite (Satelite de Aplicaciones Cientificas-D) for a 5-year mission and for a launch initially planned in July 2009 (LEO 657 km, 96 °). It is the first CARMEN mission formally decided by CNES in COMEX on 14/12/2004.
Flight models of ICARE-NG (above) and SODAD #1 (below) of the CARMEN-1 mission
CARMEN-1 is composed of an ICARE-NG instrument and three external SODAD sensors. The ICARE-NG instrument performs the TM/TC interface of these sensors. They are dedicated to micro-debris and micro-meteorite monitoring.
The SAC-D satellite is dedicated to the observation of the oceanic circulation, climatic variations and environment. Developed as part of a US-Argentine-Italy-France cooperation (NASA-CONAE-ASI-CNES), this mission is based on the use of a SAOCOM's platform and embarks for the operational part, NASA's AQUARIUS. The platform is built by INVAP and CONAE is the prime contractor. The SAC-D satellite has been finally launched in June 2010. The chosen orbit is practically the same than the one of the previous satellite, SAC-C.
For the CARMEN-1 mission, CNES is the prime contractor and tasked EREMS with the ICARE-NG flight model development, and STEEL Electronique with the flight model development of SODAD detection systems.
The CARMEN-1 instrument has particular mission objectives as well as objectives related to the satellite:
- Scientific objectives: to allow the measurement of charged particle fluxes and their effects on test electronic components, and to ensure the counting and time-tagging of impacts due to micro-debris and micro-meteorites.
- SAC-D associated objectives: to allow the local radiative environment characterization and the evaluation of the potential drifts of the equipment in particular due to radiation from the South Atlantic Anomaly (SAA), and to interface the three SODAD sensors with the satellite.
|CARMEN-1 / SAC-D Mission||Performances|
|High Energy Environment||ICARE-NG|
Particle Flux Measurement
Fast counting ~3E5 cnts/s
250 keV - 4 MeV
8 - 100 MeV
|Radiation Effects on EEE parts||ICARE-NG|
~10 -¹ rad
some ev./d, @1 s
some ev./wk, @1 s
1 ev./d, @1s
CARMEN-1 mission performances
Description and Features
The ICARE-NG/CARMEN-1 instrument is composed of a data acquisition unit (SPECTRE) for the set of three radiation detectors and the component test bed (EXPERIENCE Module or MEX) identical to those of CARMEN-2. ICARE-NG performs also TM/TC interfacing for the three SODAD sensors.
CARMEN-1 functional description
The radiation detectors are made of silicon fully depleted solid state detectors used in single and coincident mode. The SPECTRE unit performs the radiation spectrum measurement on various energy ranges. The on-board measurements consist in accumulating energy loss spectra in the junctions over a programmable accumulation period.
The reference levels of the discriminators, the gain of the amplifiers and the accumulation time are programmable and provide a possible on-board tuning optimization. The reference values are preset before launch.
In addition to the on-board acquisition, the SPECTRE unit carries out the functions of power distribution and communication interface via a 1553 bus. It also includes an interface to control one or more external instruments. In the case of CARMEN-2, this capability is not used.
The objective of the EXPERIENCE module (MEX) is to measure the flight event rates and the parametric drifts of an advanced electronic component set. This module is slave of the SPECTRE unit of which it depends for power and data exchanges.
The main characteristics of the CARMEN-1 instrument are the following:
|Dimensions||200 x 118 x 96 mm|
|Power Consumption (according to operating mode)||6,3 W to 11,3 W|
|Telemetry Data Rate||420 bits/s|
|Data Volume||4,32 Mo/day|
|Dimensions||120 x 120 x 83 mm|
|Power Consumption||1 W|
|Data Volume Included||ICARE-NG data rate|
CARMEN-1 instrument main features.
Concerning SODAD sensors, four flight models have been initially developed: three of them were dedicated to the French-Brazilian FBM satellite and one to the MEDET experiment aboard the International Space Station. This last model has been mounted in orbit in February 2008. CNES put an end to the FBM satellite cooperation in 2004, which led to three almost complete SODAD flight models waiting for mechanical interface specifications and integration.
SODAD is dedicated to the in-orbit micro-meteorite and micro-debris detection. The measurement principle is based on the sampling of a MOS capacitor discharge. Its superior electrode is very thin and its surface is directly exposed to the impact of particles. An electric potential is applied to the device and a load is normally stored in the capacity. When a high speed particle passes through it with enough energy, a short circuit may occur and induce a discharge. The corresponding event is then measured and allows to characterize the particle's speed and mass. After a short time, the sensor is reloaded to the nominal value.
The electrode evaporation around the impact usually prevents any permanent short circuit. The sensitivity of the sensor depends on the dielectric thickness, on the material and the thickness of the top electrode, and on the applied bias. The device is optimized for the detection of particles with a diameter of 0.5 µm to a few µm.
ICARE-NG (above) and one of the SODAD sensors (below) mounted on their dedicated panels.