Explorer 7
Encyclopedia
Explorer 7 was launched October 13, 1959 at 10:36 a.m. Eastern Time by a Juno II
Juno II
Juno II was an American space launch vehicle used during the late 1950s and early 1960s. It was derived from the Jupiter missile, which was used as the first stage.-Development:...

 rocket from Cape Canaveral Air Force Station
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...

 to an orbit of 573 km by 1073 km and inclination of 50.27°. It was designed to measure solar x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

 and Lyman-alpha flux, trapped energetic particles, and heavy primary cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s. Also Secondary objectives included collecting data on micrometeoroid penetration and molecular sputtering and studying the earth-atmosphere heat balance. The Explorer 7 micrometeorite impacts studies can be found under the NASA paper "RESULTS OF MICROMETEORITE PENETRATION EXPERIMENT
ON THE EXPLORER VII SATELLITE[1959 IOTA} LaGow and L. Secretan
Goddard Space Flight Center

Significantly, it also carried Verner Suomi
Verner Suomi
Verner E. Suomi was the father of satellite meteorology. He invented the Spin Scan Radiometer, which for many years was the instrument on the GOES weather satellites that generated the time sequences of cloud images seen on television weather shows.Together with Robert Parent, in 1965 Suomi...

's flat-plate radiometer
Radiometer
A radiometer is a device for measuring the radiant flux of electromagnetic radiation. Generally, the term radiometer denotes an infrared radiation detector, yet it also includes detectors operating on any electromagnetic wavelength....

, improved with the help of Robert Parent, that took the first Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 radiation budget measurements from space
Space
Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum...

 and initiated the era of satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 studies of the climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

. Using both satellite observations of the Earth's heat balance and atmospheric
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 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.

The satellite weighed 41.5 kg, was 75 cm high and 75 cm wide. Powered by solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....

s it also carried 15 nickel-cadmium batteries
Nickel-cadmium battery
The nickel–cadmium battery ' is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes....

around its equator.

It transmitted data continuously through to February 1961 and went dead August 24, 1961. It is still in orbit.
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