Television Infrared Observation Satellite (TIROS) was the first platform for space-based weather observation, both in visible and infrared wavelengths. All modern satellites have attitude and orbit correcting capabilities via gas jets, but there is only a limited supply of gas available so the lifetime of a satellite is limited as well. Scientists who monitored the performance of TIROS I noticed that the Earth's magnetic field affected the satellite's attitude as it orbited. They reasoned that attitude control coils could be installed and energized on TIROS II using electrical power from its solar panels rather than the onboard fuel supply. This article from a 1961 edition of Popular Electronics describes the effort.
|February 1961 Popular Electronics
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Tilting TIROS II
Magnetic "hand" tilts space satellite
The nation's latest "weather-eye" satellite, "Tiros II," has achieved a major "first" in space. By means of a remote-control system, ground observers can tilt the satellite in space for improved TV coverage of clouds above the earth.
Spherical "cage" designed to produce magnetic fields resembling those of the earth was used in pre-launching tests of Tiros II. Here, Warren P. Manger, of the RCA Astro-Electronics Division, takes reading of magnetic effect within the wired "cage," preparatory to rotating the satellite on its mount for study of the orientation system.
Magnetic orientation system being tested at RCA's Space Center in Princeton, NJ. Lights above and around the satellite are used to check operation of solar cells which surround satellite.
Developed by the Radio Corporation of America, the new orientation technique uses the effect of the earth's magnetic field to alter the "attitude" of the satellite upon command - without the need for special propulsion devices. This technique was the outcome of studies by RCA and government scientists of an unexpected gradual shift in the attitude of the first Tiros satellite under the influence of the magnetic field surrounding the earth.
In the first Tiros, which returned nearly 23,000 useful TV cloud pictures to earth following its launching last April, these magnetic forces caused the satellite to tilt gradually away from the predicted position of its axis in space. In Tiros II, the forces are being harnessed by a controllable magnetic field generated around the satellite itself by wire coils on the lower sides of the vehicle. Interacting with the earth's magnetic field, this controllable field gives ground observers an invisible "hand" to tilt the satellite on command, in order to obtain a more advantageous angle.
Equipped with the orientation-control system and with newly developed infrared instruments to measure the emission and reflection of solar heat by the earth and its atmosphere, Tiros II represents the second step in the experimental weather satellite program being conducted by the National Aeronautics and Space Administration to study the feasibility of regular satellite weather operations.
Among the major features common to both the Tiros I and II satellites are electronic clocks that control the timing of cameras, tape recorders, and infrared systems during each orbit; more than 9000 solar cells on the top and sides of the satellite to convert electrical energy for operation of the electronic systems; "yo-yo" weights which slow the satellite's spin from 120 rpm to 12 rpm as it enters orbit; and five pairs of solid-fuel spin-up rockets to restore spin momentum.
Wide-angled television camera on Tiros II is checked by
Sidney Sternberg, and Ralph Jordan at the RCA Space
Center. Tiros II, mounted on its side in this photo, is
identical in external appearance to Tiros I.