Radiation Conditions in Interplanetary Space Became Worse

    Since April 16, 2018 Liulin-MO aboard ExoMars Trace Gas Orbiter operates successfully on TGO science orbit – a circular orbit at 400 km above Mars with a period of two hours. Solar activity decreases, the 24th Solar Cycle is at its minimum now. Liulin-MO measures the GCR flux and the radiation doses they deliver since TGO began its journey to Mars. Figure 1 presents the development of Solar Cycle 24 and the intervals of Liulin-MO operations. MCO indicate the initial highly elliptic Mars Capture Orbits.

 

    With the decreasing of the solar activity the flux of the highly penetrating and ionizing galactic cosmic rays (GCR) increases. The particle radiation environment gets worse. The table below demonstrates the increasing of GCR fluxes and dose rates measured by Liulin-MO at 1.5 a.u during June 2019 in comparison with those measured during the different TGO phases.

Increase of radiation parameters

June 2019 to :

22.04 – 15.09. 2016

Cruise

1.11.2016–17.01.2017

MCO1

24.02– 7.03.2017

MCO2

May 2018

Science phase

Flux

11.6 %

7.3 %

7 %

3.5 %

Dose rate

18 %

9.4 %

8.7 %

6.5 %