We went to Bandelier National Historical Park in the morning. It is an interesting place geologically and historically. The valley is in a layer of volcanic tuff, which is ash spewed from a volcano. The actual eruptions (there were two major ones) happened a little over a million years ago. The tuff layer is 2000 feet thick. It looks like sandstone but it is not layered. This was a place that was inhabited by the pre pueblo people over many years . In the end they developed a city built of rock (tuff) and utilizing the caves in the valley walls. It was a nice hike.

With our hike finished before 11:00 am, it was decided to head to Los Alamos to visit the Bradbury Science Museum. This Bradbury was director of the Los Alamos laboratories right after WWII. Its focus was on the many disciplines that have been under investigation at the labs. There was also historical information about the Manhattan Project and the two weapons dropped on Japan in 1945.

One display really caught my eye because I had never heard of it before. When the B-29 carrying the atom bombs went out on its mission it was accompanied by three other B-29s. One was called the Great Artiste (it went on both missions) which was an instrument plane tasked with determining the yield of the bomb. It carried three identical blast gauge cannisters which were parachuted as the bomb was dropped. It was a device that contained a "microphone" of special design to measure the strength of the sound waved generated by the blast. Remember that microphones are nothing more than pressure sensors. The data was relayed back to the Great Artiste where a rig consisting of a radio receiver, oscilloscope and movie camera recorded the data. There were no data loggers back in those days, so the movie camera filmed the signals on the oscilloscope which were later measured. It was determined that the blast was equivalent to 15 kilotons.

I just love it when I stumble upon some new (to me) technology. Today's photo is of a blast gauge cannister and an oscilloscope and radio receiver of the types actually used. The cannister parachuted to earth while doing its measurements. The actual explosive event probably lasted only a couple seconds.