where is the wgs84 datum used for measurements
Geodetic datum The Global Positioning System (GPS) uses the World Geodetic System 1984 (WGS 84) to determine the location of a point near the surface of the Earth.
Radar astronomy The next easiest target is Venus. This was a target of great scientific value, since it could provide an unambiguous way to measure the size of the astronomical unit, which was needed for the nascent field of interplanetary spacecraft. In addition such technical prowess had great public relations value, and was an excellent demonstration to funding agencies. So there was considerable pressure to squeeze a scientific result from weak and noisy data, which was accomplished by heavy post-processing of the results, utilizing the expected value to tell where to look. This led to early claims (from Lincoln Laboratory, Jodrell Bank, and Vladimir A. Kotelnikov of the USSR) which are now known to be incorrect. All of these agreed with each other and the conventional value of AU at the time.[2]