Down to Earth With: Neil Armstrong: First astrogeologist on the moon

by Barry E. DiGregorio
Sunday, August 4, 2013

Neil Armstrong — born Aug. 5, 1930, in Wapakoneta, Ohio — was the first man to walk on the moon. NASA

One year ago this month, Neil Armstrong died in Cincinnati, Ohio, at the age of 82. Armstrong will be forever remembered for that historic first step he took on the moon on July 20, 1969, but he also held another distinction: He was the first person to explore the geology of another planetary body.

President John F. Kennedy mandated in his famous 1961 speech at Rice Stadium in Texas that the primary goal of the Apollo program was to land humans on the moon and return them safely to Earth before the end of the decade. The science mission was an important, but secondary, goal.

In the early 1960s, almost nothing was known about the geology and origin of the moon. Geologists working at the U.S. Geological Survey (USGS) in Tucson, Ariz., and at NASA were commissioned with the task of training the astronaut crews, who were composed mainly of test pilots, to collect the most useful science samples. More than five years before the Apollo 11 moon mission launched, Commander Armstrong and lunar module pilot Edwin “Buzz” Aldrin had begun extensive geologic field training in various locales around the West — including Barringer (Meteor) Crater and the Grand Canyon in Arizona, Valles Caldera in New Mexico, and Marathon Basin and Big Bend Park in Texas — with such well-known USGS geologists as Eugene Shoemaker and Donald Wilhelms.

On the moon’s surface, the astronauts would have to work quickly. NASA estimated it would cost about $1 million per minute for Extra Vehicular Activity (EVA) for each astronaut working on the lunar surface.

Ultimately, Armstrong and Aldrin would only spend about two hours on the moon’s surface where, in addition to collecting rocks and soil, they set up a television camera, planted the American flag and installed three scientific instruments: a laser ranging retroreflectometer, a passive seismic experiment and a solar wind composition package.

The First Geological Observations of the Moon

Four days after the Apollo 11 mission launched on July 16, 1969, the Lunar Module, named Eagle, was scheduled to land in a relatively smooth, flat plain in the southwestern part of Mare Tranquillitatis (Sea of Tranquility). Mare Tranquillitatis was chosen by NASA, in part, for safety purposes, and in part for its interesting geology, including the presence of several impact ejecta rays. However, while at 600 meters above the lunar surface, Armstrong could see the lunar module computer was taking them toward a landing site about a kilometer away in a 180-meter-diameter crater filled with large boulders. Armstrong immediately took manual control and with only seconds of fuel remaining, landed the lunar module a few hundred meters west of their predetermined landing site.

An unanswered question at the time was how deep the lunar module landing struts might sink into the lunar soil. In fact, the astronauts' first task on the surface of the moon was to prep the lunar module ascent engine for possible immediate departure should the spacecraft start to tilt.

After completing that task and enjoying a brief meal, the astronauts decided not to take a scheduled rest period and instead get to the business at hand. A 16-millimeter time-sequence camera was set up inside the lunar module looking out one of the windows in the area where Armstrong would collect the first lunar samples. Armstrong and Aldrin donned their EVA spacesuits, depressurized the lunar module cabin and opened the hatch door.

As Armstrong backed down the lunar module (LM) ladder, he stopped at the second to last step and grabbed a D-ring on the outside compartment of the lunar module, called the Modularized Equipment Storage Assembly, which contained two aluminum Apollo Lunar Sample Return Containers (ALSRC) and a mounted television camera that would capture Armstrong’s historic first steps onto the lunar surface.

Before even stepping off the footpad, Armstrong made his first geological observation of the lunar surface: “I’m at the foot of the ladder. The LM footpads are only depressed in the surface about 1 or 2 inches, although the surface appears to be very, very fine grained, as you get close to it. It’s almost like a powder.”

After stepping onto the lunar surface and uttering his famous quote, “That’s one small step for [a] man, one giant leap for mankind,” Armstrong made his second geological observation: “The surface is fine and powdery. I can kick it up loosely with my toe. It does adhere in fine layers like powdered charcoal to the sole and sides of my boots. I only go in a small fraction of an inch, maybe an eighth of an inch, but I can see the footprints of my boots and the treads in the fine, sandy particles.”

Armstrong then began taking pictures with a 70-millimeter Hasselblad camera, but was reminded by the control room back in Houston to first gather the “contingency sample.” The contingency sample was needed in order to ensure that scientists on Earth would have at least a small sampling of lunar rock and soil in the event something went wrong and the mission had to be aborted. Armstrong was responsible for retrieving the contingency sample while Aldrin remained in the lunar module making sure the 16-millimeter time-sequence camera documented every sample Armstrong gathered.

Collecting Samples on the Moon

As Armstrong gathered the sample using a simple jointed aluminum handle with a Teflon bag attached to it, Aldrin commented: “Looks like it’s a little difficult to dig through the initial crust.”

Armstrong noted: “This is very interesting. It’s a very soft surface, but here and there, where I plug with the contingency sample collector, I run into a very hard surface. But it appears to be a very cohesive material of the same sort. I’ll try to get a rock in here. Just a couple.”

The first geologic samples collected on a body other than Earth totaled 1 kilogram, including soil and four rock fragments.

Armstrong put the folded sample bag in the pocket located on the left leg of his spacesuit and proceeded with some other tasks, including setting up a camera to document the EVA, photographing Aldrin coming down the ladder, and unpacking the science experiments.

Three main geological collection tasks remained: to collect as much of a wide variety of bulk samples as possible within 10 to 20 meters of the lunar module, drive two core tubes into the lunar regolith, and carefully document and photograph as many samples as possible before and after their collection — all before the scheduled EVA time elapsed. Both astronauts had a limited amount of oxygen and needed to be extremely efficient with their time on the surface.

Using a large scoop on an aluminum extension handle, Armstrong collected 16 more kilograms of soil and rock, carrying the samples back to the lunar module in nine trips. It took him 14 minutes to gather and seal the samples in the ALSRCs.

Armstrong also made a long traverse to a 33-meter-diameter crater east of the lunar module. He photographed the interior of the crater and noted that some smaller 1-meter rimmed craters in the area appeared to contain shiny spherules, which he referred to as “blebs” and said looked like drops of solder mixed in the lunar regolith. Unfortunately, in all the samples returned by Apollo 11, no samples of the blebs were found, although Armstrong obtained a number of photographs of them.

Meanwhile, Aldrin was busy gathering two core tube samples, which he hammered to a depth of 22 or 23 centimeters into the lunar regolith. Aldrin noted that none of the sample material fell out as the core tube was removed and that the holes left in the surface did not infill when the cores were removed. 

Placing the American flag, along with difficulties in setting up the three main scientific experiments left behind on the moon, drastically reduced the time for the documented sample portion of the EVA plan. With only 3 minutes and 35 seconds of EVA time remaining, Armstrong realized there was no time to obtain the before-and-after photos of rocks in their natural settings and make the traverse with samples back to the ALSRC. Instead, Armstrong and Aldrin began collecting as many “grab bag” samples as possible, gathering an additional 7 kilograms before time ran out. The EVA closeout activities included vacuum sealing the sample boxes on the lunar surface and using a flexible conveyor system designed to haul up the sealed ALSRCs for storage inside the lunar module.

The Legacy of the Apollo 11 Samples

On July 21, 1969, the lunar module left the surface of the moon. Once it reached lunar orbit and rendezvoused with the command module Columbia, the precious lunar cargo was transferred and stowed securely until Apollo 11 splashed down in the Pacific Ocean three days later.

The Apollo 11 samples were then transferred to the Lunar Receiving Laboratory in Houston, Texas, and studies on them continue today.

Neil Armstrong’s efforts were not only the first geologic steps on the moon, but they led to a giant leap in our understanding of the Earth, the moon and our solar system.

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