4.5.3 Determinations and Measurement of the Age of the Various 
Ice Layers, etc. 
According to an article in Aviation Week, June 23, 1975, by 
Craig Covault, entitled "Nimbus-6 Operations Awaiting Completion 
of In-Orbit Checks" the author says as regards "Electrically 
scanning microwave radiometer": 
"Although carried on board Nimbus-5, the experiment has been 
changed from a single to a two-channel device for Nimbus-6. 
The device will be used to map the liquid water contents of clouds, 
distribution and variation of sea ice cover and characteristics of 
the land surface such as vegetation, soil moisture and snow cover. 
The addition of a second channel will enable better cloud water 
contents determinations and measurement of the age of the various 
ice layers being viewed by the spacecraft." 
Some months later, on December 8, 1975, there was another article 
in Aviation Week concerning Ice, entitled "Seasat Faces Multiple 
Sensor Challenges", by Benjamin M. Elson. 
According to him, Seasat-A will carry three radars and two passive 
radiometers, a larger number of such instruments than any other 
U.S. spacecraft to date. 
Among the many functions Seasat-A was intended to perform may 
especially be mentioned:"Chart ice fields and leads.' 
The instruments to be flown in Seasat-A are successors to devices 
previously flown in Nimbus. 
4.5.4 Satellites for the Nuclear-Powered Ice-Breaker SIBIR' on 
her remarkable "Ice Experiment" in May - August, 1978 
In Chapter 6 below, concerning the pioneering voyage of the Soviet 
Ice-Breaker ARKTIKA to the North Pole in August 1977, it is mentioned 
that the aim of the enterprise was a scientific and practical experi-