Thursday, February 04, 2016

Radar Bounced Off the Sun

 We are all familiar with the moon bounce, but the "sun-bounce" is much more obscure accomplishment.  The first successful attempt was transmitted on April 7th, 1959 at Stanford University. the radiomen on the job were Dr. Von Russel Eshleman, Lt. Col. Robert C. Barthle and Dr. Philip B. Gallagher, staff at Stanford University Stanford Electronics Laboratories. Their names appear together on a number of different astrological papers at Stanford:
1955 -  Regularly observable aspect-sensitive radio reflections...
1956 -  Analysis of a new type of radio scattering...
1957 -  Antenna array for studies in meteor and radio astronomy
1957 -  Meteor rate and radiant studies: experimental radio studies...
1958 -  Radio reflections from artificially produced electron clouds
1959 -  Theory of radar studies of the cislunar medium
1960 -  Radar echoes from the sun
The Stanford Electronics Laboratories group continued churning out white papers until 1961. It continued to make reports for NASA until at least 1973. It's notable that follows the departure of Gallagher. Barthe and Eschleman got all the press. Eschleman made the statement to the Stanford newspaper on Sputnik. Their quotes in Popular Mechanics weren't specifically credited.  [SOURCE] Sensibly Escheman and Gallagher went on to work for NASA and continued to write arcane papers that I barely understand for decades.

Their experiment required a 40,000 watt transmitter. The antenna consisted of 5 miles of wire spread over 11 acres of ground. To quote the Popular Mechanics article "...the sun was difficult to reach by radar because it was 93,000,000 miles away and because of the 'thunderous radio noise' arising from it's turbulent surface."  The signal's round trip took over half an hour.  The signal was a 30-second bursts of dots and dashes that was perceptible the random noise of the sun. The radar echo didn't come from the sun's visible surface but it's outer corona. The return signals were recorded to magnetic tape for further study with an IBM 707 computer.

The experiment was repeated on April 10 and April 12, and the data was published in the journal Science on February 5, 1960. Popular Mechanics wrote it up in May 1960. More here.