TIROS-1

A camera in orbit

TIROS, the Television Infrared Observation Satellite, grew from US military research on observing the Earth from space. NASA took over the programme in 1959, and TIROS-1 was launched on 1 April 1960 on a Thor-Able rocket into a low orbit. It was a drum about 1 metre across, covered in solar cells, spun for stability, and carried two television cameras, one with a wide-angle and one with a narrow-angle lens.

The first picture, a few hours after launch, showed bands of cloud over the north-eastern United States. Within days the pictures revealed storm systems that no ground station could have seen as a whole, including a vortex of clouds off the New England coast.

What the weather forecasters learned

Meteorologists worked from a few thousand surface stations, none in the oceans. TIROS showed them the pattern of weather over those empty areas in one picture, and it showed the organised cloud structures around cyclones. More than 19,000 pictures were returned. Morris Tepper at NASA headquarters led the meteorological programme.

Useful transmissions ended after a power failure on 15 June 1960. Nine more TIROS satellites followed, and by 1965 the system became operational, as ESSA satellites and then NOAA's polar-orbiting satellites.

An observatory with a life of weeks

TIROS-1 had no scientific goal beyond showing that it could be done, and showed it in eleven weeks. Its real product was a method: images from space, received on the ground, interpreted by forecasters. That chain, from sensor to image to forecaster, is still how weather satellites are used. The satellite remains in orbit as space debris.

From pictures to forecasts

The first TIROS pictures did not immediately improve forecasts, because forecasters had to learn to read them and numerical models could not yet ingest them. The step that mattered was the training of meteorologists in the interpretation of cloud patterns and the development of tools to map pictures to the Earth's grid. Later satellites added infrared sensors and temperature soundings, which models could use directly. The pattern is familiar: a new sensor produces data first, then knowledge, then, after further effort in assimilation and training, a better product. TIROS shows how long that chain can be.

Instruments and technologies

• Wide-angle television camera A vidicon tube behind a wide lens covering about 1,200 kilometres on the ground, with images recorded on tape and played back over a ground station.
• Narrow-angle television camera A similar camera with a longer lens, for detail.
• Tape recorders and command link On-board recording stored pictures over areas out of range of a ground station.

The people

• Morris Tepper NASA meteorologist who led the programme.
• Edgar Cortright NASA engineer who managed the weather satellite programme.

Timeline

• 1959 NASA takes over the satellite programme.
• 1960 Launched on 1 April; first TV image shows cloud bands over the United States.
• 1960 Useful transmissions end after a power failure on 15 June.

Key lessons for observation today

• A proof of concept is a legitimate mission A short-lived pilot made the case for a lasting system. Demonstrators are how new observing modes enter practice.
• The chain matters, not only the sensor Sensor, downlink, processing and a trained user together made weather satellites work. Ground segment and users are part of the observatory.
• See the whole to understand the part One image of a storm system outdid thousands of point readings for some questions. Combine area and point observations.

Sources

• NASA, TIROS, the Nation's First Weather Satellite
• NOAA NESDIS, Celebrating the World's First Meteorological Satellite: TIROS-1
• Wikipedia, TIROS-1