The Roswell Report: Fact vs. Fiction in the New Mexico Desert

## Flight 78: Released from Alamogordo, New Mexico, 2038 MST, July 22, 1948 Not recovered

This flight was the first to be made with (white) thermistors exposed inside the .001" polyethylene balloon, inside the battery box and exposed to the air. The flight was at night and the balloon temperature was colder than the air temperature by about 50C during the short period of time that the temperature values were telemetered. The standard SCR-658 receiver and Friez radiosonde ground station were used to record this data which was transmitted by a T-69 radiosonde. A New York University AM-1 transmitter was used to send out pressure data.

An automatic ballast valve, activated by a mercury minimum-pressure switch, was used to control ballast flow but the cold temperature presumably caused the mercury to freeze and no ballast flow was evidenced. (A ballast-metering siphon was part of the equipment.)

On subsequent flights, the minimum-pressure switch used an electrolite which can withstand the cold nighttime temperatures of the upper air.

The evidence of the thermistor in the battery box is very encouraging, since after four hours of flight the temperature remained above $ 1 0^{\circ} \mathrm{C} $ . This was the first measurement obtained on the cooling of batteries and indicated that no special cold temperature batteries were needed if insulation is carefully made. The temperature data and the height-time curve of Flight 78 are shown in Figure 31.

Figure 31