Technicians make final check of Explorer XIX payload which
mountedon fourth stage of Scout launch vehicle.
Scientists theorize that increased solaractivity warms the upper atmosphere and thatas the atmosphere warms, it swells and liftsdenser layers to higher altitudes. As the sunquiets down, the upper atmosphere cools andcontracts, becoming less dense at any altitude.
DESCRIPTION OF EXPLORER
Explorer XIX is essentially a 12-foot diam-eter inflated sphere weighing about
so large and so light in weight, it
markedly affected even by the sparse airatoms and molecules of the upper atmosphere.Scientists calculate air density in the satellite'spath by comparing the spacecraft's orbit with atheoretical orbit based upon the absence of air.Explorer
constructed of a four-plylaminate, consisting of alternating layers of-mil-thick polyester plastic film and '/2-mil-thickinum foil. The aluminum foil forms theouts~de urface; and the plastic, the inside sur-face. (A mil
one-thousandth of an inch.)Whitecircles (resembling polka dots)painted on the satellite's outer surface contributeto temperature balance by absorbing less of thesun's heat than the aluminum skin. Temperaturebalance
required for operation of the space-craft's electronic equipment.Mounted inside of the satellite
a smallradio that transmits a tracking signal. Its power
rechargeable storage batterywithin the sphere and a bank of solar cells onthe satellite's outer surface. Solar cells convertsunlight to electricity.They contain silicon, amaterial that emits electrons when struck bylight. The electrons are channeled into wiresand, thus harnessed, become an electric current.
A principal purpose of the Explorer XIXexperiment
to extend measurements of airdensity in the upper atmosphere to the polarregions. Prior experiments have furnishedmeasurements of the atmosphere over otherareas of earth. The various measurements