ESA Space Environments & Effects

Highlights

Soft Proton Fluxes in and around Earth’s Magnetotail

Analysis of 10 keV to 1 MeV proton environment (“soft protons”) in Earth’s neighbourhood beyond the radiation belts has been recently published in IEEE TPS. Soft protons are particularly interesting for X-ray space telescopes, since they pass through X-ray optics and cause background increase in the telescope instruments – affecting observations performed by Chandra and XMM-Newton. The second L-class (large) mission in ESA’s Cosmic Vision programme will be a large X-ray telescope named Athena, planned to operate at the L2 Lagrange point of the Sun-Earth system. There, the spacecraft would encounter protons accelerated both in the heliosphere and in the tail of Earth’s magnetosphere. Twin NASA Artemis spacecraft have measured proton fluxes in Earth’s magnetotail at the distance of the Moon’s orbit (about 60 Earth radii) – these data serve as proxy for proton rates in the still more distant environment near the L2 point (about 235 Earth radii).

 

In the first plot below, the proton spectrum measured by Artemis in Earth’s magnetotail is compared to the spectrum measured by NASA ACE spacecraft at the Sun-Earth L1 Lagrange point, which sees only protons of heliospheric origin. The spectra show proton fluxes which are not exceeded 90% of time, in a 9 month period in 2010 and 2011. Above 100 keV, the spectra show good agreement, indicating that heliospheric proton fluxes were dominant. However, protons in 30 to 80 keV energy range are most critical as background for the instruments of Athena. At these lower energies the Artemis data show an increase in flux contributed by the Earth’s magnetotail.

 

The second plot shows the background spectra in Athena instruments, derived using Monte Carlo simulations from the source proton flux as measured by Artemis in the magnetotail. Athena space telescope will use magnetic deflectors, not included in our simulation, to further suppress the proton fluxes in order to achieve the low background required for the most demanding astrophysical observations.

FORecasting Solar Particle Events and Flares

Rosetta SREM Solar Particle Event

Rosetta SREM Awakes

EPT first results

JUpiter Icy moons Explorer

March Solar Proton Event

10 Years of Proba-1 SREM data

SEPEM release

The 2011 Draconid meteor shower

First Solar Particle Event of Solar Cycle 24

First SREM data from Herschel/Planck

GIOVE-B

DEBIE-2

Rosetta Fly By

CHAMP/SWARM Modelling Using SPIS

Solar Wind Shock simulation