Infobox_Spacecraft
Name = Explorer 7


Organization = NASA
Major_Contractors = Jet Propulsion Laboratory
Mission_Type = Earth science
Satellite_Of = Earth
Launch = October 13, 1959 at 15:36 UTC
Launch_Vehicle = Jupiter-C
Mission_Duration = 2 years
NSSDC_ID = 1959-009A
Webpage = [http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1959-009A NASA NSSDC Master Catalog]
Mass = 41.5 kg
Eccentricity = .034693
Inclination = 50.27°
Orbital_Period = 101.38 minutes
Apoapsis = 1,073 km
Periapsis = 573 km

Explorer 7 (1959-009A) was launched October 13, 1959. It was designed to measure solar X-ray and Lyman-alpha flux, trapped energetic particles, and heavy primary cosmic rays.

Significantly, it also carried Verner Suomi's flat-plate radiometer, improved with the help of Robert Parent, that took the first earth radiation budget measurements from space and initiated the era of satellite studies of the climate. Using both satellite observations of the Earth's heat balance and atmospheric cooling rates measured by net flux radiosondes, Suomi established the important role played by clouds in absorbing radiated solar energy. These observations established that Earth’s energy budget varies markedly due to the effect of clouds, the surface albedo, and other absorbing constituents. Using these instruments, Suomi and his team discovered that the Earth absorbed more of the Sun's energy than originally thought and demonstrated that it was possible to measure and quantify seasonal changes in the global heat budget.

Launched by a Juno rocket from Cape Canaveral Air Force Station, it was in a 573 km by 1073 km orbit and inclined 50.27°.

The satellite weighed 41.5 kg, was 75 cm high and 75 cm wide. Powered by solar cells it also carried 15 nickel-cadmium batteries around its equator.

It transmitted data continuously through to February 1961 and went dead August 24, 1961. It is still in orbit. [cite web|url=http://usspaceobjectsregistry.state.gov/registry/index.cfm?fuseaction=home|title=U.S. Space Objects Registry|accessdate=2006-12-07]

References