Solar Particle Alert Network

The Solar Particle Alert Network (SPAN) observatory, installed early in 1965, was critical to the safety of the Apollo astronauts. The study of the relationship between sunspot activity and intense solar flares would hopefully enable NASA to predict radiation hazards to astronauts on Apollo missions.

The three NASA multiple-telescope observatories (Boulder, USA; Canary Islands; and Carnarvon) were spaced at approximately 120° intervals around the world. They maintained continuous 24-hour monitoring of the sun with real-time reporting of flare activity, assisted by an observatory at Houston and four other observatories contracted to NASA. Several other observatories, associated with the Solar Forecast Centre, also contributed data to SPAN Control.

The SPAN site hosted two other facilities relatively unimportant to the main work of the station: a Riometer (Relative Ionospheric Opacity Meter)and a Jupiter Monitor.

SPAN also shared a role in the Carnarvon Location Project. A Satellite Tracking Camera was briefly located there and a Mobile Laser Tracking System at Range and Range Rate.

SPAN Site at the height of the Carnarvon Location Project: behind the Security Hut (on the left) are the Riometer antenna back-plane masts; centre is the SPAN building with Razdow telescope dome on the roof; to the right front is the Satellite Tracking Camera dome; just behind is the Radio Telescope radome; and near distant right, the Mobile Laser sat just to the left of the RARR VHF antenna. The Town of Carnarvon can be seen on the far distant horizon.

We are indebted to Dave Gardiner, Jim Gregg, David Johns, and Hans Lemmens for their contributions to the SPAN pages.