Explorer 7

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**Explorer VII**
Orbital elements

Organization:	Army Ballistic Missile Agency
Major contractors:	Jet Propulsion Laboratory
Mission type:	Earth Science
Satellite of:	Earth
Launch:	13 October 1959 at 15:36:00 UTC
Launch vehicle:	Jupiter-C
Decay:
Mission duration:	2 years
Mass:	41.5 kg
NSSDC ID:	1959-009A
Webpage:	[1]
Semimajor axis:	-
Eccentricity:	.034693
Inclination:	50.27°
Orbital period:	101.38m
Apogee:	1073km
Perigee:	573km
Orbits:	-
Instruments
Geiger-Mueller detector :	Detection of cosmic rays
Wire grid array :	Micrometeorite detection
Acoustic detector :	Micrometeorite detection

Explorer 7 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, 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.^[1]