November 1972 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Ever since the advent of
Google Earth in 2001 (hard to
believe, non?), high resolution photos from orbiting satellites has become routine,
expected technology rather than awe-inspiring technology. In 1970 when this article
appeared, however, satellite imagery was still in its infancy. The
TIROS 1 weather
satellite, with a mere 78-day lifespan, had been launched just a decade earlier. Nations'
militaries had the biggest and best platforms, and pictures like those now routinely seen
on Google Earth were highly classified. If you recall, governments had conniption fits
over Google's photos taken of secret installations. Civilians eventually got space-based
images of Earthly weather systems on the evening news forecast segment, and some
commercial users could purchase high resolution photos from specially licensed private
companies. Nowadays, satellites carry not only optical sensors, but sensors covering a
broad span in the electromagnetic spectrum, gravity sensors, particle detectors and other
types of sensors.
Satellite Pictures Show Earth's Resources
One of the important sources of information obtained from the Earth Resources Technology Satellite (ERTS), launched last July by
NASA, is the multitude of photographs of the earth that are transmitted back daily. There
are more than 300 prime subscribers for the data and they represent 35 countries. The data
is available through negative and positive prints processed with Eastman Kodak Company equipment.
The ERTS photographic system has the capability of churning out as many as 300,000 photos
weekly. Since it photographs only a section of the earth each day, it takes the satellite
18 days to cover the entire world. There are seven sensors on the satellite-each relaying
separate data back to NASA ground stations located at Goddard Air Force Base; Fairbanks, Alaska;
and Goldstone, California. Data from the satellite are fed to computers at Goddard and then to
a photo laboratory; and a complete set of 61 prints is sent each day to Sioux Falls, S.D.,
where scientists, geologists, etc., can view areas of interest.
Posted October 2, 2017