San Marco 1 was an Italian flight test of the satellite to furnish
data on air density and ionosphere characteristics. The Scout-X4 launch vehicle was provided by NASA and
was launched with an Italian launch crew from Wallops Island.
San Marco 2 was a 66-cm-diameter spherical satellite with two
experiments, one designed to make direct measurements of air density below 350 km, and the
other an ionospheric beacon experiment developed to observe electron content between the
earth and the satellite. The spherical shape of the spacecraft was important to the air
density experiment in that it provided a constant satellite cross section to the
decelerating effects of the air. This simplified data interpretation and eliminated the
need for satellite attitude control. A 5-m dipole antenna was extended along the spin axis
only when the beacon experiment was turned on. Four 48-cm telemetry and command antennas
extended symetrically outward from the satellite equator. The satellite had black and
white longitudinal sections painted on its surface for thermal control. The satellite
mission was to study density and its small-scale variations and to study equatorial
electron density irregularities and ducted radio propagation above 200 km. The satellite
was powered by four battery packs, and rough measures of satellite attitude were provided
by four solar cell sensors. The satellite performed as expected until 5 August 1967. By
August 14, power had decreased so that satellite command was no longer possible. Reentry
occured on 19 October 1967, during orbit 2680.
Two suborbital tests of the San Marco satellite were flown on Shotput launch vehicles.
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