Space Ship Earth: monitoring space weather

Map detailing the location and viewing directions of the Space Ship Earth network of neutron monitors
The location (filled circles) and viewing directions (heavy lines) of the Space Ship Earth network of neutron monitors. The stations are: Apatity (AP), Cape Schmidt (CS), Fort Smith (FS), Inuvik (IN), Mawson (MA), McMurdo (MC), Nain (NA), Norilski (NO), Peawanuck (PE), Thule (TH) and Tixie Bay (T1).

Space Ship Earth is the brainchild of Prof John Bieber of the Bartol Research Institute, University of Delaware. The Earth is travelling through space in the inner part of the solar system and is the perfect platform for making measurements of the high-energy radiation environment of the region. Thus the name of the collaborative program. The consortium comprises Prof John Bieber and Prof Paul Evenson from Bartol, Dr Evgenia Eroshenko and Dr Anatoly Belov from IZMIRAN (Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation) in Russia and Dr Marc Duldig from the Australian Antarctic Division.

A network of polar neutron monitors will give real or near-real time measurements of the high-energy radiation environment surrounding the Earth. The polar monitors have been carefully selected to give narrow longitudinal bands of view at equatorial latitudes with a further two monitors viewing in polar directions (see figure). The Mawson and Inuvik monitors are crucial elements of the system because they have the narrowest longitude spread. They will characterise event arrivals more tightly than the rest of the network. Data will feed directly to Bartol for analysis and forwarding to industry and governments.

The near-real time 3-D monitoring of the radiation will greatly benefit spacecraft operators and will be one input to now-casting of space weather. It is hoped that studies with this unique linked system will lead to improved prediction of space weather and the space radiation environment. Of particular interest will be the rare 'Ground Level Enhancement', blasts of particle radiation arriving from the Sun. These can produce increases of several hundred percent at ground level but are much larger above the protective layers of the atmosphere. The higher dose but lower energy radiation arrives some 20 minutes or so later allowing predictions to be provided to relevant space authorities. Also of interest will be Forbush decreases that occur with geomagnetic storms. These decreases show evidence of precursors a day or more in advance and may be of value in space weather prediction. The Mawson cosmic ray observatory will be enlarged over the 2001-02 season and additional detectors installed the following summer in readiness for this exciting new program.

Marc Duldig
Cosmic Ray Physics Program Leader,
Australian Antarctic Division