ESSA-6

{{Infobox spaceflight

| name = ESSA 6

| names_list = TOS-D

| image = ESSA general view.jpg

| image_caption =

| image_size =

| mission_type = Weather

| operator = NASA

| COSPAR_ID = 1967-114A

| SATCAT = S03035

| website =

| mission_duration =

| spacecraft =

| spacecraft_type =

| spacecraft_bus =

| manufacturer =

| launch_mass = {{cvt|145|kg}}

| dimensions =

| power =

| launch_date = November 10, 1967, 18:00 UTC GMT

| launch_rocket = Delta

| launch_site = Vandenberg Air Force Base

| launch_contractor =

| entered_service =

| deactivated =

| last_contact =

| decay_date =

| orbit_reference = Geocentric orbit

| orbit_regime = Low Earth orbit

| orbit_eccentricity = 0.00498

| orbit_periapsis = {{cvt|1410|km}}

| orbit_apoapsis = {{cvt|1488|km}}

| orbit_inclination = 102.12°

| orbit_period = 114.82 minutes

| apsis = gee

| instruments =

| programme = ESSA program

| previous_mission = ESSA-5

| next_mission = ESSA-7

}}

ESSA 6 (or TOS-D) was a spin-stabilized operational meteorological satellite.{{Cite web |title=ESSA 6 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-114A |website=NSSDCA}} Its name was derived from that of its oversight agency, the Environmental Science Services Administration (ESSA).

Details

File:ESSA 6 Typhoon Shirley 11.21 a.m. on August 21,1968.jpg on August 21, 1968|left]]

ESSA 6 had a mass of {{convert|299|kg|lb}} at the time of launch.

The satellite's electrical power was supplied by about 10,000 1x2 cm solar cells on the cover and 21 nickel-cadmium batteries.

Two redundant wide-angle APT (Automatic Picture Transmission) cameras, mounted on opposite sides and perpendicular to the spin axis, captured images. This subsystem was a camera-transmitter setup, designed to transmit real-time daylight images of cloud cover to ground stations. It included two 2.54-cm vidicon cameras with {{not a typo|108° F/1.8}} lenses, mounted 180° apart. Each orbit, the cameras captured four or eight images, with picture taking lasting 8 seconds and transmission 200 seconds. The 800-line images were transmitted at 137.5 MHz to local APT stations, with reticle marks on the images to assist with geographical alignment. Each picture covered a 3100 x 3100 km area with 4 km resolution at nadir, with a 30% overlap to ensure complete coverage.{{Cite web |title=ESSA 6 Automatic Picture Transmission (APT) System |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-114A-01 |website=NSSDCA}}

The base featured crossed-dipole antennas for command reception, while a monopole antenna provided telemetry (136.500 MHz) and tracking (136.770 MHz) from the top.

Spin rate was regulated to 10.9 rpm using a Magnetic Attitude Spin Coil (MASC), which interacted with Earth's magnetic field to maintain a stable spin axis normal to the orbital plane, within ±1 degree.

Mission

File:ESSA 6 lifts off Spac0230.jpg

ESSA 6 was launched on November 10, 1967, at 18:00 UTC, atop a Delta rocket from Vandenberg Air Force Base, California, USA.

ESSA 6 had an inclination of 102.12°, and orbited the Earth once every 114.8 minutes. Its perigee was {{convert|1,410|km|mi|sp=us}} and its apogee was {{convert|1,488|km|mi|sp=us}}.{{Cite web |title=Launch/Orbital information for ESSA 6 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1967-114A |website=NSSDCA}}

The satellite performed normally after launch.

The APT camera system was successful, operating nearly continuously until November 4, 1969 when the spacecraft was deactivated.

References

{{NASA|article=ESSA 6|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-114A|access-date=June 4, 2018}}

Category:Spacecraft launched in 1967

Category:Weather satellites of the United States

Category:Television Infrared Observation Satellites