ESSA 3 (or TOS-A) was a spin-stabilized operational meteorological satellite. 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).

Operation

The satellite's skeleton was made of aluminum and stainless steel and had the shape of a prism with an eighteen-sided base. Power was supplied by 12,000 1x2 cm

photovoltaic cells A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect.

arranged on its sides, which were used to charge 21 NiCd batteries. Stabilization in orbit was provided by rotational movement at a speed of 9.2 revolutions per minute, maintained by a magnetic

attitude control system Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...

(MASC, ''Magnetic Attitude Spin Coil''). Its actuator was a coil, and the torque necessary for position control was generated by the interaction of the

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...

with the magnetic field induced in the satellite. An additional stabilization system was provided by five constant-current engines mounted on the circumference of its bottom. A single

monopole antenna A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. The current from the transmitter is applied, or for rece ...

placed at top was used for communication with Earth. Two

dipole antenna In radio and telecommunications a dipole antenna or doublet is one of the two simplest and most widely used antenna types, types of antenna; the other is the monopole antenna, monopole. The dipole is any one of a class of antennas producin ...

s (4 rods protruding from the bottom) were used to transmit

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', 'far off', an ...

. Cameras were triggered automatically when Earth entered the field of view. The pictures were transmitted directly to Earth or recorded onboard. The satellite was equipped with two twin independent wide-angle

Vidicon Video camera tubes are devices based on the cathode-ray tube that were used in television cameras to capture television images, prior to the introduction of charge-coupled device (CCD) image sensors in the 1980s. Several different types of tubes ...

television cameras. These could work simultaneously or alternately. The satellite was also equipped with a Flat Plane

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 micro ...

(FPR) used to measure solar energy reflected from the Earth.

Mission

ESSA-3 was launched on October 2, 1966, at 10:34

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 ...

. It was launched atop a

Delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...

rocket from

Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg S ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. The spacecraft had a mass of at the time of launch. ESSA-3 had an inclination of 100.9°, and an orbited the Earth once every 114 minutes. Its

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

was and its

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

was . One of the first images taken by ESSA 3 was of Category 4

Hurricane Inez Hurricane Inez was a powerful Category 5 major hurricane that affected the Caribbean, Bahamas, Florida, and Mexico, killing over 1,000 people in 1966. It was the first storm on record to affect all of those areas. It originated from a tropical w ...

over the

Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...

and

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 satellite operated without failures until January 20, 1967, when its FPR radiometer stopped working. On September 29, 1967, one of the cameras stopped working. On October 9, 1968, the second camera failed. The satellite was decommissioned on December 2, 1968.

References

{{DEFAULTSORT:Essa-3 Spacecraft launched in 1966 Weather satellites of the United States Television Infrared Observation Satellites