ESSA-9, also known as TOS-G, was a meteorological satellite.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 government, United States Federal executive agency created in 1965 as part of a reorganization of the United States Department of Commerce.

(ESSA). ESSA-9 replaced the ESSA-7 satellite.

Launch and orbit

ESSA-9 was launched on a three-stage

Delta rocket The Delta rocket family was a versatile range of American rocket-powered expendable launch systems that provided space launch capability in the United States from 1960 to 2024. Japan also launched license-built derivatives (N-I (rocket), N-I, N ...

from

Cape Canaveral Cape Canaveral () is a cape (geography), cape in Brevard County, Florida, in the United States, near the center of the state's Atlantic Ocean, Atlantic coast. Officially Cape Kennedy from 1963 to 1973, it lies east of Merritt Island, separated ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

. The launch occurred at 07:47

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

(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 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 ( UK/IUPAC) or aluminum alloy ( NA; 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 ...

and

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

. The shell of the craft was covered with 10,020 solar cells.NASA Science page
, ESSA-9 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 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 (sometimes called B-field) is a physical 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 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 Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible light perceptible to the human eye as well as invisible infrared (typically p ...

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 meteorology, meteorological research and development. The spacecraft were designed to serve as stabilized, Earth-oriented platforms fo ...

Gallery

File:Launch of ESSA 9 Spac0044.jpg, File:ESSA-9 satellite photo mosaic.PNG, File:Hurricane Agnes.jpg, Part of a ESSA-9 image showing

Hurricane Agnes Hurricane Agnes was the List of costliest Atlantic hurricanes, costliest hurricane to hit the United States at the time, causing an estimated $2.1 billion in damage. The hurricane's death toll was 128. The effects of Agnes were widespread, ...

on June 19, 1972 as it approaches Florida.

References

External links

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