special scientific consultant. Its purpose was to determine whether a
party had a valid reason for entering the ground zero area. The board
functioned for three days.

Military police at Guard Post 4 and at three roadblocks set up along
Broadway controlled entry into the area. Guard Posts 3, 5, 6, and 7
were within 3,000 meters of ground zero and thus remained unmanned.
At the south shelter, the Medical Group set up a "going-in" station
where personnel were required to stop to put on protective clothing
(coveralls, booties, caps, and cotton gloves) and pick up monitoring
equipment before entering the ground zero area. Since it was not
known how much radioactive material might be suspended in the air, all
personnel entering the ground zero area wore complete protective
covering and respirators for the first three days after the
detonation. Figure 2-6 shows two Project TRINITY personnel wearing
protective clothing (1).

On the day of the shot, five parties entered the ground zero area.
One party consisted of eight members of the earth-sampling group.
They obtained samples by driving to within 460 meters of ground zero
in a tank specially fitted with rockets to which retrievable
collectors were fastened in order to gather soil samples from a
distance. This group made several sampling excursions on 16 and 17
July. The tank carried two personnel (a driver and a passenger) each
trip. No member of this party received a radiation exposure of more
than 1 roentgen (1).

Five other men from the earth-sampling group entered the ground zero
area in a second tank, lined with lead for radiation protection. The
tank, carrying the driver and one passenger, made five trips into the