Wednesday, 14 December 2016

Dr. David Strangway's Work in Lunar Exploration

Dr. David Strangway in 2011 (CTBTO - Flickr)
Dr. David Strangway, who is well known as a leader in Canada’s advanced education system, died this week at age 82. Dr. Strangway first gained notoriety for his scientific work on lunar samples from the Apollo expeditions to the Moon.  

 I interviewed Dr. Strangway in February 1996 and wrote about him in my first book, Arrows to the Moon. The following is based on that interview:

Although several Canadian scientists worked on lunar samples, most of them with the Geological Survey of Canada, the best-known of their number was David Strangway, a native of Simcoe, Ontario. Aged 35 when Apollo 11 landed on the Moon in 1969, Strangway was a professor of physics at his alma mater, the University of Toronto, after work at the University of Colorado in Boulder and at the Massachusetts Institute of Technology.

As an expert on the magnetic properties of lunar samples, Strangway became well known to Canadians watching and reading media coverage of the first lunar landings. In 1970 he moved to NASA and became chief of the geophysics branch at the Manned Spacecraft Center in Houston, where he was involved in selecting experiments and landing sites, handling lunar samples and training astronauts for upcoming Apollo missions.

During lunar landing missions, Strangway worked in the scientific backroom next to the mission control center, and he was principal investigator on an electromagnetic sounding experiment flown aboard the Apollo 17 service module. After Apollo ended, he returned to the U of T in 1973, and he eventually became acting university president. From 1985 to 1997, he was president of the University of British Columbia, and he later served as president of the Canada Foundation for Innovation and founded Quest University in Squamish, B.C.

“My particular interest in the lunar samples had to do with two major areas,” Strangway told me in an interview in 1996. “One of them was the magnetic properties of the lunar materials, and the other had to do with the measurement of the electrical properties of the lunar materials. You can use magnetism to determine the composition of the metallic materials that are in the samples, such as iron. The other thing you can do is reconstruct ancient magnetic fields. So we were very interested in reconstructing the magnetic field at the time those lunar samples were formed.”

The pure metallic iron found in lunar samples differs from iron found naturally on Earth, which is usually compounded with oxygen, as in rust. “The second thing we found in terms of the magnetic fields and the preservation of them, was that there were very clear indications that they were very weak. There were indeed significant magnetic fields present in the lunar materials. The Moon was formed about 4.5 or 4.6 billion years ago. What we found where we had samples of 3.3 billion or 4 billion years of age, they still had a significant memory of some magnetic field that we believe must have existed at that time. So that tells us that unlike today, when there is no magnetic field on the Moon of any significance, that during that period of the Moon’s evolution, there was a magnetic field or possibly there was even a small core causing a small magnetic field.”

The lighter areas of the Moon, known as the highlands, were formed about 4 billion years ago, and most of the rocks there are breccias, created from the impacts that left the Moon covered by craters, Strangway said. The darker parts of the Moon, known as seas, appeared between 3 and 4 billion years ago and are made up of volcanic basalts.

At NASA, Strangway was involved in organizing many geological field trips for Apollo crews to various parts of the U.S. and some foreign sites. “We asked [the astronauts], ‘What would you sample, what would you pick up, what photographs would you take, what choices would you make to describe the nature of the [formation]?’ There were other trips that we went on, craters in Nevada and other places, trying to understand the dynamics of what happened in the cratering process. What kinds of samples should be taken, what features should be looked for, observations that should be made so that people could understand the nature of that crater.”

The last three expeditions to the Moon, Apollos 15, 16 and 17, were aimed at obtaining as much scientific information as possible, and the astronauts were equipped with Lunar Roving Vehicles for their exploration work. Strangway recalled simulations involving astronauts driving an Earthbound version of the lunar rover across a simulated Moonscape, while scientists watched by television from their backroom in Houston.

“They would be down there running a mockup of the lunar rover around, and the medical guys said we have 10 more minutes of science. What do you want to do in that time? So there were all kinds of simulations of that kind, which were very interesting exercises and actually forced you to look at your priorities and to think of what you wanted to do in that mission, so that you could get the maximum return after whatever crisis came up. What it did was force us to deal with the competing interests, the physicists, the chemists, the geologists, the astronomers, all of these people who wanted the maximum information return. What it really did was force us to exercise our minds as to what was really important. I think it had a real impact on the actual design and the actual layout of what happened in the missions.”

The results from Apollo’s research into lunar history have taught scientists a great deal about the early history of the Earth as well as that of the Moon, according to Strangway. Before Apollo, the Earth’s early history was obscured because of the Earth’s atmosphere and the forces that continue to change the Earth’s surface, he said. “The lunar samples that are 3 or 4 billion years old look as fresh as lavas that came out last week on the Earth. They are absolutely unaltered from the point of view of their chemical composition.

“What became very clear is that the rate of impacts taking place in the solar system was very non-uniform. It was very high up until 4 billion years ago, then slowed down immensely between 4 and 3.3 billion years ago. What this suggests is if you look at the period between the formation of the solar system, 4.6 billion years ago, and then the end of this most intense period of bombardment, 4 billion years ago, the solar system itself probably underwent an intense set of bombardment activity. And therefore, there was a whole piece of the Earth’s history that was probably the same as the early history of the Moon, but there’s no surface left of that age anymore, so we didn’t even know about that. We learned a lot about the Earth’s early history in a way that we hadn’t been able to record.”

Apollo 16 astronaut John Young doing geological fieldwork on the Moon, April 1972 (NASA)



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