The PAGEOS project at Palmer Station

Above, in the backyard of Palmer Station in 1969, the Wild BC-4 camera enclosure for the PAGEOS project (NOAA original photo). More Palmer photos are below...but first, a discussion of this interesting bit of pre-GPS geodetic history.

The PAGEOS (PAssive Geodetic Earth Orbiting Satellite, as seen above during a 5 August 1965 test inflation in a blimp hangar at Weeksville, NC) was a 100'-diameter inflatable sphere made of 0.5-mil thick aluminized polyethylene terephthalate (PET) plastic. As a "balloon" it carried no instrumentation, and merely served as a reflective tracking and photographic target. It was in a near-polar orbit with an altitude of about 2600 miles, much higher than the more familiar and similar ECHO satellites. It was launched in 1966, and in 1975 it broke up into many small pieces (some of these are still in orbit, and useful for observing solar radiation pressure because of their extremely light weight).

Beginning in early 1966, the PAGEOS survey project, operated by the US Army Topographic Command, occupied 40+ worldwide sites, including 4 in Antarctica--McMurdo, Mawson, Casey, and Palmer. Other sites of interest included South Georgia, Invercargill, Easter Island, American Samoa, Thule, Diego Garcia, and the Seychelles...the USCG icebreaker Southwind was also involved with establishing the site on Heard Island. The goal was to take precisely timed photographs of the satellite against the stellar background; comparing the data to precisely determine the location of the stations. It used Wild BC-4 cameras which had previously been used with the more familiar ECHO 1A and 2 satellites which had been launched in 1960 and 1964. The ECHO satellites were about the same size as PAGEOS, but they were more general-purpose (such as their use for much- publicized transcontinental telephone and TV tests) and had orbits only about half as high as PAGEOS, which was more specifically intended for geodetic experiments.

The equipment was moved from station to station over the years, so that cameras were positioned so that at least 3 of them could see and photograph the satellite simultaneously. The project worked, but...it wasn't accurate enough for what folks really wanted. Traditional celestial navigation was accurate to +/- 400 meters, which was more than adequate for the open ocean, but not for (say) aiming of ballistic missiles. The PAGEOS project proved accurate to +/- 10 meters. The doppler satellite program (which came next) was accurate to about 5 meters, and the present GPS system has evolved to centimeter accuracy.

PAGEOS was slow, since the photographic plates had to be sent in to the headquarters office for processing. In addition, the system (unlike celestial navigation) was not generally accessible to the common user...that feature as well would have to wait for GPS.