Production of Photographic Records Photofacsimile

It has become customary to use the term photofacsimile although the machine which gave its name to the product is no longer in use. 

To reconvert the picture transmitted from the satellite, the analog tape controls a beam of light that scans photographic paper under control of the scanning conditions of the mirror on board the satellite. The photographic paper unwinds at a speed synchronized with that of the satellite. The intensity of the light beam is directly controlled electronically by the analog tape. Thus, a picture is reproduced, line by line, on 70 mm film. 

As the sensitivity of the detector is 1 K, it would theoretically be possible to reproduce pictures incorporating all of the tonal shades recorded on board the space vessel. It does not work out this way in practice. Due to the number of spurious signals (static, noise) if every signal were to be reproduced on the picture, it would be distorted out of all recognition. Also, although the system I have just described has been improved by utilization of a cathode ray tube, the inertia factor has to be allowed for. 

Despite the reduction at ten temperature levels that we will take a look at below, the inertia factor distorts the pictures especially when a thermal gradient, for example a land-sea boundary, extends in the flight direction of the satellite - a very roughly north-south oriented boundary. In this case, the inertia factor usually shows up as a narrow, light strip along the coastline. I point this out because errors have already been committed in the analysis of photofacsimile when some interpreters have discovered non-existent features. 

At Goddard, the first film obtained serves to make a negative master) from which the records requested by users are produced the original film is kept in safe storage. 

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