KSEM & SOSMAG


Artist`s rendition of the deployed GK-2A satellite (image credit: KARI)

KSEM (Korean Space Environment Monitor) 

KMA in coordination with KARI selected KHU (Kyung Hee University) of Seoul to develop the KSEM suite of instruments and post-delivery support for the assembly and integration test, pre- and post- launch test of Geo-KOMPSAT-2A. The suite of KSEM instruments consists of particle detector (PD); magnetometer (MAG); and SCM (Satellite Charging Monitor). The sensors are used to monitor the space environment 6 the severe space weather information of high-impact space storms, the radiation environment hazardous to spacecraft, aircraft, and radio communication for 24 hours/7 days during 10 years mission lifetime.

KSEM configuration (image credit: KHU)

• PD (Particle Detector): The PD is of THEMIS SST (NASA) heritage. It consists of 3 detector heads and measures the differential energy flux of electrons and ions within the energy range of 100 keV and 2 MeV, which are trapped within Earth’s magnetic field.

• MAG, of THEMIS FGM (FluxGate Magnetometer) heritage, measures three components of near-Earth magnetic field within the range of ±350 nT and monitors those variations caused by space storm and high-speed stream.

• SCM (also referred to as CM) measures the satellite internal charging current within the range of ±3 pA/cm2 due to high energy particles and provides advance warning of a possible electrical discharge.

KSEM is the first Korean space weather instrument suite aboard a GEO satellite. Like the Galaxy 15 anomaly on 2010, GEO satellites are easily exposed to the risk due to severe space weather. It is expected that KSEM data will contribute to secure the satellite operation and the high-tech ground infrastructure.

KSEM

KSEM PD section view and figure (image credit: KHU)

SOSMAG (Service Oriented Spacecraft Magnetometer)

Monitoring the solar wind conditions, in particular, its magnetic field (interplanetary magnetic field) ahead of the Earth is essential in performing accurate and reliable space weather forecasting. The magnetic condition of the spacecraft itself is a key parameter for the successful performance of the magnetometer onboard. In practice, a condition with a negligible magnetic field of the spacecraft cannot always be fulfilled and magnetic sources on the spacecraft interfere with the natural magnetic field measured by the space magnetometer.

SOSMAG figure (image credit: ESA)

The “ready-to-use” SOSMAG (Service Oriented Spacecraft Magnetometer) is developed for use on any satellite implemented without magnetic cleanliness program. It enables detection of the spacecraft field AC variations on a proper timescale suitable to distinguish the magnetic field variations relevant to space weather phenomena, such as sudden increase in the interplanetary field or southward turning. This is achieved through the use of dual fluxgate magnetometers on a short boom (1m) and two additional AMR (Anisotropic Magneto-Resistance) sensors on the spacecraft body, which monitor potential AC disturbers. The measurements of the latter sensors enable an automated correction of the AC signal contributions from the spacecraft in the final magnetic vector. After successful development and test of the EQM prototype, an FM (Flight Model) is being built for the Korean satellite GEO-KOMPSAT-2A.

SOSMAG has the following basic features:

1) 2 fluxgate sensors (FG) on a short boom -the inboard (IB) and outboard (OB) sensor

2) 2 AMR sensors on spacecraft body

3) deployable boom of 1m length

4) a mounting interface for the boom, without specific requirements on the spacecraft structure

5) and the associated electronics.

Mass budget: sensor and electronics 2.0 kg; mounting plate and boom 1.1 kg. Power budget: 2.6 W.

All four sensors are operated continuously and simultaneously with a time resolution of at least 1 Hz or higher, depending on the type of effect to be characterized.

The operation shall be continuous and with higher time resolution in the early stages (commissioning phase) of the spacecraft flight, such that the typical operations of spacecraft subsystems and instruments are closely monitored and characterized in detail. The data of this early phase are studied on ground to detect and characterize the spacecraft AC effects and to determine correction factors for each specific AC disturbance. The correction factors are implemented in inflight algorithms, which then enable automated correction for these AC effects during further flight operation.