TIROS 4 (also called TIROS-D and A9) was a spin-stabilized

meteorological satellite A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting (covering the entire Earth asynchronously), or g ...

. It was the fourth in a series of

Television Infrared Observation Satellites Television, sometimes shortened to TV, is a telecommunication Media (communication), medium for transmitting moving images and sound. The term can refer to a television set, or the medium of Transmission (telecommunications), television tra ...

Launch

TIROS 4 was launched on February 8, 1962, by a

Thor-Delta The Thor-Delta, also known as Delta DM-19 or just Delta was an early American expendable launch system used for 12 orbital launches in the early 1960s. A derivative of the Thor-Able, it was a member of the Thor family of rockets, and the first ...

rocket from

Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the statio ...

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

. The spacecraft functioned nominally until June 30, 1962. The satellite orbited the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

once every 1 hour and 30 minutes, at an inclination of 48.3°. Its

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

was and

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

was .

Mission

The satellite was in the form of an 18-sided right prism, 107 cm in diameter and 56 cm high. The top and sides of the

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...

were covered with approximately 9000 1- by 2-cm

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

solar cell A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.

s. It was equipped with two independent television camera subsystems for taking cloud cover pictures and three radiometers (two-channel low-resolution, omnidirectional, and five-channel scanning) for measuring radiation from the earth and its

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

. The satellite spin rate was maintained between 8 and 12

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...

by the use of five diametrically opposed pairs of small solid-fuel thrusters. The TIROS-4 spin axis could be oriented to within 1° to 2° accuracy by use of a magnetic control device consisting of 250 cores of wire wound around the outer surface of the spacecraft. The interaction between the induced

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

in the spacecraft and the earth's magnetic field provided the necessary torque for attitude control. The flight control system also optimized the performance of the

s and television cameras and protected the 5 channel infrared radiometer from prolonged exposure to direct sunlight. With the exception of the degraded response of the 5 channel scanning

radiometer A radiometer or roentgenometer is a device for measuring the radiant flux (power) of electromagnetic radiation. Generally, a radiometer is an infrared radiation detector or an ultraviolet detector. Microwave radiometers operate in the microwave w ...

, the spacecraft performed normally until May 3, 1962, when one camera failed. On June 10, 1962, the other camera's tape recorder failed. The scanning radiometer provided usable data until June 30, 1962.''Journal of the British Interplanetary Society'', Vol. 19, pags. 386-409, 1963-1964

References

External links

TIROS
Encyclopedia Astronautica
Real Time Satellite Tracking - TIROS 4
N2yo.com. Weather satellites of the United States Spacecraft launched in 1962 {{US-spacecraft-stub