It is a common custom to send an innocent messenger on a fool's errand on April 1st. Some might have seen the launch of TIROS-1, 40 years ago today, in such a light. However, the arrival on the scene of the first dedicated weather satellite opened a new era in the history of meteorology; it was the day when, as one contemporary practitioner of the science put it, "meteorology went from rags to riches".
TIROS, the Television and Infra-Red Observation Satellite, came less than three years after the cosmic trail-blazer, Sputnik I, in 1957, and was considerably less sophisticated than the satellites we know today.
The pictures, for example, instead of being available in "real time", were recorded and stored aboard the satellite, and then transmitted to Earth some hours later when the spacecraft passed over a conveniently located and suitably equipped groundstation. Nonetheless, a mere five hours after the launch, President Eisenhower was gazing at the first image ever received from an orbiting weather satellite.
Nearly 23,000 pictures of the Earth's ever-shifting cloud patterns were received from TIROS-1, and getting these to forecasters around the world was a considerable challenge. The data were translated into a numeric code, using a technique similar to "painting by numbers", and the encoded message was then sent by teleprinter line to forecasting offices throughout the five continents. Finally, after 78 days, TIROS-1 expired.
This was a pitifully short life compared to today's spacecraft, which are expected to remain functional for five years or more. With experience, those elements which were found to be most liable to failure have been improved, prolonging the useful life of a satellite.
However, they still do not last for ever; among the factors that limit the lifetime of a spacecraft are shortage of the fuel needed for stabilising it and controlling its position, a diminution of the power output from its solar cells because of bombardment by high-energy particles from space, and the number of charge-discharge cycles that the on-board storage batteries can stand.
There have been hundreds and hundreds of weather satellites since TIROS-1 was launched. One sometimes hears it said that if the meteorologist's "eye in the sky" can see exactly what is happening to the weather all around the globe, there must surely be no excuse for the forecaster ever to be wrong.
Alas, satellites are not a panacea: they show the weather as it really is, but on the future development of the atmospheric systems, TIROS and its successors have always been discreetly silent.