Mt. John Satellite Tracking Station

This station is intended to track all satellites orbiting the earth. It is run by Detachment 1, 18th Surveillance Squadron, 14th Aerospace Force of the USAF Aerospace Defence Command. Presence of the base in N.Z. is covered by 'An Exchange of Notes Constituting an Agreement' between the U.S. and N.Z. dated 9 July 1968. According to this agreement the purpose of this station is "to facilitate space flight operations contributing to the advancement of scientific knowledge through the optical observation of earth orbiting space vehicles, the application of this knowledge to the direct benefit of man, and the development of space vehicle, of advanced capabilities, including manned space vehicles".

However according to a USAF publication on the Aerospace Defence Command Mt John is one of a worldwide network of optical sensors which feed data into a Spadats (Space Detection and Tracking System) computer in the USAF underground Combat Operations Center in Colorado where orbital elements of all satellites are calculated so that if it is deemed necessary any one of them can be shot down by the Aerospace Command's anti-satellite defence system, a suite of Thor missiles based at Johnson Island in the U.S. Pacific Trust Territories. Other work being pursued includes satellite geodesy (the accurate measurement of the size shape and gravitational field of the earth) and calibration of Other instrumentation involved in space programs.

Tracking of satellites is carried out by a Baker Nunn camera which possess immense light-gathering power, and yields photographs of the satellite against a background of stars. These photographs are timed to a ten-thousandth of a second, and after processing, the satellites position can be read off them accurate to 4 seconds of arc (10 microns as measured on the film) The resultant data is relayed back to Spadats by teletype machines kept in a high security communications centre guarded by a heavy steel door, thick concrete walls, and a built-in self destruction device. The base has its own electric generator, 20,000 gallons of water stored on the base, and quantities of emergency food supplies in the form of one-day man packs, and appears to be designed to function independent of the rest of New Zealand in the event of an emergency.

In a subsidiary base at Washdyke north of Timaru, the Detachment employs 15 men in office work, logistics, etc. associated with the satellite tracking.