the Alligator Rivers Uranium Field. The mine commenced operation in 1980, reaching full production of uranium oxide in 1981. Owing to the environmental sensitivity of the site, a special statutory authority, the Supervising Scientist, was created to provide oversight of the operation and conduct environmental research in the region. Ranger mine covers two of a line of uranium orebodies that extend from near Nourlangie Rock in Kakadu north-eastwards to Koongarra, underneath Mount Brockman, then northwards through the Ranger One line of orebodies (in order Number 2, Number 1, and Number 3), then via Hades Flat, where there is uranium mineralisation, to Jabiluka where the line turns westward through the Barote and Ranger 4 orebodies. The mine covers No 1 Orebody and No 3 Orebody. No 2 orebody was excluded from the mining lease at the request of the traditional owners and included in Kakadu National Park. From Ranger 4 the line again turns northwards and then swings westward round an Archaean basement dome before turning south towards Nourlangie Rock again. Uranium mineralisation is known at several other places along this line but has never been explored in detail because of the creation of Kakadu. The name 'Ranger' for the series of discoveries made by Geopeko, the exploration arm of Peko-Wallsend, in the period 1969 to 1972, was thought up by Judy Ryan, the wife of the geologist in charge of the program. Koongarra and Jabiluka were retained by the companies that found them: Noranda Australia and Pancontinental Mining respectively, although since sold to other parties. The other discoveries were enclosed in the National Park. ERA was named Explorer of the Year at the sixth annual Australian Mining Prospect Awards held in Sydney in November 2009. During 2008, ERA's exploration programme identified a significant mineral resource adjacent to the operating Ranger 3 pit. The area, known as Ranger 3 Deeps, ranked among the world's most significant new uranium discoveries of recent years. Ranger 3 Deeps ERA constructed a $120 million Ranger 3 Deeps exploration decline to conduct close spaced underground exploration drilling and explore areas adjacent to the Ranger 3 Deeps resource. The Ranger 3 Deeps mineralised zone contains an estimated resource of of uranium oxide, comprising measured, indicated and inferred categories totalling 11.9 million tonnes of ore grading 0.274% U3O8. In parallel with the construction of the exploration decline, ERA began a $57 million project to prepare a Prefeasibility Study