IGY Bulletin, Number 8, February 1958 - Thule neutron monitor station

One last short article from this issue of the IGY Bulletin.

The Thule (Greenland) neutron monitor station was built for the IGY in 1957 by the Bartol Research Foundation. It was operated by the U.S. Army Signal Corps, which is in charge of communications and information systems support for the armed forces. Martin Pomerantz, president of the Bartol at the time, provided the material for this article.

The Bartol Research Institute is a research center in the Department of Physics and Astronomy at the University of Delaware (a 90-minute drive from my location in Lancaster, PA). The Bartol Research Institute currently operates 10 neutron monitor stations as part of the Neutron Monitor Program. Thule, which was put into operation on 27 Aug. 1957 during the IGY, is still running.

Thule neutron monitor, oldest of the monitors operated by Bartol Research Institute. The neutron detector tubes are inside the four white boxes (photo by J Roth, Bartol).

As a reminder of what was in an earlier post, the Bartol says: A neutron monitor is an instrument that measures the number of high-energy particles impacting Earth from space. For historical reasons these particles, mostly protons and helium nuclei, are called "cosmic rays." Because the intensity of cosmic rays hitting Earth is not geographically uniform, it is important to place neutron monitors at multiple locations in order to yield a complete picture of cosmic ray influxes. The neutrons are secondary spallation products derived from cosmic rays interacting with molecules in the atmosphere.

The article goes on to say that the Thule station, 1500 miles from the North Pole, was important because it was closer to the geomagnetic pole than any other neutron monitor. Cosmic rays can more easily funnel in towards the Earth's surface through the openings at the magnetic poles.

The secondary protons and neutrons produced in the atmosphere by cosmic rays are stable, so they provide much information about the distribution of cosmic rays and the geomagnetic field. The neutron fluxes vary with cosmic ray intensity; on the one hand they correlate with flares on the sun which emit cosmic rays, but on the other hand are inversely related to the solar cycle and solar magnetic fields when high (low) heliomagnetic fields shield (don't shield) galactic cosmic rays from reaching the Earth. Bartol gives a thorough explanation.

Thule has a fascinating history as: the home to indigenous Inughuit; the site of a secret U.S. airbase; the main staging point for the construction of Camp Century; the site of a Ballistic Missile Early Warning System (BMEWS) outpost, with radar in order to warn North America of a transpolar missile attack from either the USSR mainland or of submarine-launched missiles from the Arctic and North Atlantic oceans.

A philatelic aside on Thule: I was looking at eBay to see if I could find any relevant stamps or covers. I found listings of five 1937 stamps from Thule. Apparently, stamps for regular mail were not issued from the town of Thule (now Qaanaaq) until 1938. The 1937 "local" stamps were privately printed by the Thule Committee in memory of polar explorer Knud Rasmussen (1879-1933) on the 25th anniversary of the establishment of the most northerly trading post in the world, the Thule Trading station. These stamps are not listed in the Scott catalogue, but you can find them in Colnect.

Thule stamps, not in my collection (Quora)