ESSA-9, also known as TOS-G, was a

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 geo ...

.tbs-satellite.com Satellit Fact Sheet: ESSA-9
/ref> Its name was derived from that of its oversight agency, the

Environmental Science Services Administration The Environmental Science Services Administration (ESSA) was a United States Federal executive agency created in 1965 as part of a reorganization of the United States Department of Commerce. Its mission was to unify and oversee the meteorologica ...

(ESSA). ESSA-9 replaced the

ESSA-7 ESSA-7 (or TOS-E) was a spin-stabilized operational meteorological satellite. Its name was derived from that of its oversight agency, the Environmental Science Services Administration (ESSA). Launch ESSA-7 was launched on August 16, 1968, at 11 ...

satellite.

Launch and orbit

ESSA-9 was launched on a three-stage

Delta rocket Delta is an American versatile family of expendable launch systems that has provided space launch capability in the United States since 1960. Japan also launched license-built derivatives (N-I, N-II, and H-I) from 1975 to 1992. More than 300 ...

from

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type =Cape , map_caption = Location in Florida , location ...

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 launch occurred at 07:47 UTC (02:47 EDT) on February 26, 1969. The spacecraft was placed in a

sun-synchronous orbit A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

of 101.4° inclination. Immediately after launch ESSA-9 had a perigee of and an apogee of , giving it an orbital period of 115.2 minutes, or a mean motion of 12.5 orbits per day. ESSA-9 operated for 1,726 days before it was deactivated in November 1972.

Spacecraft

The ESSA-9 spacecraft was similar to the

TIROS TIROS, or Television InfraRed Observation Satellite, is a series of early weather satellites launched by the United States, beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth, enablin ...

series of satellites, having an 18-sided polygonal shape that measured in diameter and high. It weighed . The body of ESSA-9 was made of

aluminum alloy An aluminium alloy (or aluminum alloy; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal ...

and

stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...

. The shell of the craft was covered with 10,020 solar cells. The solar cells recharged the 63 nickel–cadmium batteries during the time the spacecraft was in sunlight. ESSA-9 employed the same cartwheel-style stabilization as the

TIROS-9 TIROS-9 (also called TIROS-I or A-54) was a spin-stabilized meteorological satellite. It was the ninth in a series of Television Infrared Observation Satellites. Launch TIROS-9 was launched on January 22, 1965, by a Thor-Delta rocket from Cap ...

satellite. The satellite used a magnetic attitude spin coil (MASC) to control its attitude while in orbit. The magnetic field induced by the MASC's current interacted with the earth's

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 ...

to provide the torque necessary to maintain a desired spin rate of 9.225 rpm.Spacecraft details
/ref>

Instruments

ESSA-9 carried two sets of two main instruments, the Advanced Vidicon Camera System (AVCS) and the Flat Plate Radiometer (FPR). The AVCS was used to collect imagery of cloud cover on earth. The cameras had a resolution of and covered an area of . The cameras took single images of a particular region of the earth's surface once a day. The FPR's were used to measure the global distribution of

solar radiation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...

reflected by the earth and the earth's atmosphere. They also measured long-wave emissions from the earth. The sensors used in the ESSA satellites were from the earlier

Nimbus program The Nimbus satellites were second-generation U.S. robotic spacecraft launched between 1964 and 1978 used for meteorological research and development. The spacecraft were designed to serve as stabilized, Earth-oriented platforms for the testi ...

. File:Launch of ESSA 9 Spac0044.jpg, File:ESSA-9 satellite photo mosaic.PNG,

References

External links

NSSDC ID: 1969-016A
{{DEFAULTSORT:Essa-9 Spacecraft launched in 1969 Weather satellites of the United States