PoSAT-1 Cosmic-Ray Experiment Monitors Massive Solar Particle Event

SOLAR SCIENCE

PoSAT-1 poster

Guildford - Nov 04, 2003
The 10-year-old PoSAT-1 microsatellite, built by SSTL for Portugal in 1993 and still operational in orbit, has been monitoring the recent massive solar storm that has affected both satellites in orbit and ground-based power distribution systems.

The Cosmic-Ray Experiment (CRE) has been monitoring the changes in the low-Earth orbit (LEO) ionising radiation environment related to changes in solar activity in virtually continuous operation since launch on the PoSAT-1 microsatellite built at SSTL over a decade ago.

Currently the Sun is in a very active state with many large Sun-spot groups, and in the last week a number of massive solar storms (known as coronal mass ejections - CMEs) have erupted, ejecting large numbers of particles (protons and other ions) out into space. As these particles reach Earth they temporarily fill the outer magnetosphere, greatly affecting the ionising radiation environment of Earth-orbiting spacecraft.

Such events are known as solar particle events (SPEs). The geostationary Earth-orbit (GEO) (36,000 km altitude) is greatly affected. However, these same particles follow the magnetic field lines down towards the Earth's polar regions where they can affect LEO satellites (typically 700-1500 km).

The PoSAT-1 CRE proton data for the last few days are shown below. The regular thin spikes are due to the passage of the spacecraft through the protons in the inner Van Allen belt. Note that the vertical scale is logarithmic, with particle fluxes exceeding 100,000 protons in the 3cm x 3 cm detector per integration period (150 s).

SOLAR SCIENCE

We're Going To Get Hit Again!

Cambridge - Oct 31, 2003
Just when we thought we were through the worst of it, a second gigantic solar flare has erupted, sending another coronal mass ejection directly towards Earth. The X10-class flare was detected by an orbiting GOES satellite at 3:37 p.m. EST on Wednesday, Oct. 29th and peaked at 3:49 p.m., according to the National Oceanic and Atmospheric Administration.