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One giant leap for map-kind

 May 16, 2022

Fifty years ago, in a brick ranch house off Lindbergh Boulevard in south St. Louis County, Dave Alspaugh sat quietly in front of his black-and-white TV screen, with his wife and 5-year-old daughter. It was the evening of July 20, 1969, and American Neil Armstrong was about to take his first step on the moon, with the help of machines and equipment designed for the task.

“I remember thinking, ‘I hope all this stuff works,’’’ says Alspaugh, then a cartographer with the Air Force Aeronautical Chart and Information Center. “Those guys had a lot of nerve to do what they did.”

The Apollo 11 astronauts surely did have nerve, but thanks to Alspaugh and his colleagues, they also had confidence in where they were and where they were going. The astronauts’ journey had been mapped intricately with the help of lunar cartographers, photo lab workers, artists and more from NGA predecessor organizations ACIC and the Army Map Service. Their efforts resulted in hundreds of lunar maps, charts and models in support of NASA’s mission to land an American on the moon.

Here’s a look back at some of the products produced by ACIC and AMS in the 1950s, ’60s and ’70s that helped Neil Armstrong — and 11 other Americans — take one small step on one large rock.

Mercury Orbit Charts (1959)

When the National Aeronautics and Space Administration was formed in 1958 to support American space exploration, it was prohibited from duplicating the capabilities of other federal agencies. So in 1959, NASA partnered with ACIC to create orbit charts for the Mercury missions, which were the first to send Americans into space. The charts would show landmarks on the Earth’s surface that could be seen from space, helping astronauts know their location while in orbit.

“The assignment posed several unique problems,” wrote U.S. Air Force Maj. Williams Rogers in ACIC’s newspaper, The Orientor, in 1962. “Since no one knew what the astronaut would be able to see from orbital distance, an educated guess as to what would be on the chart had to be made. What size city would show from 100 miles out during daylight? Would they show at all at night? Are mountains, rivers and lakes discernible and identifiable?”

In the end, the cartographers’ guesses turned out to be pretty good. “Best regards to ACIC,” John Glenn said after his 1962 Mercury mission. “The charts worked fine and were a big help.”

ACIC cartographers also supported the Gemini missions from 1961–1966 with charts that were used for astronaut training, plotting orbital paths and capsule recovery.

Lunar Reference Mosaic (1962)

One of the first lunar products created by ACIC was the Lunar Reference Mosaic, which depicted names of features, such as craters and plains, and showed the features’ latitude-longitude positions. To create the Lunar Reference Mosaic, ACIC personnel pieced together separate photographs of the moon’s surface to create one complete image of the moon.

The process was tricky, like putting together a puzzle. All the photos needed to show the same solar illumination — otherwise, shadows would be cast differently in different photographs.

Next, the photographs needed to be put in the right place on a selenographic reference projection, which is analogous to the geographic reference system of latitudes and longitudes used for maps of Earth, said Raymond Helmering, former lunar mapping technical manager for ACIC. The cartographers had to make sure all lunar features were continuous at the photo boundaries, and that each photo was in the right position on the lunar map reference grid, Helmering said.

Helmering also credited the expert work performed by the ACIC Photographic Lab and Reproduction Facilities. “The Lunar Mosaic was the result of the expertise of the photographic astronomy work from the observatories, cutting-edge photographic processing and skilled, advanced cartography,” Helmering said.

The Lunar Reference Mosaic was used by experts in all phases of the lunar program, from studies of lunar geology to potential human landing site selection, Helmering said.

Lunar Astronomical Charts (1962)

After being hired in 1962, Alspaugh’s first assignment at NGA was to the lunar branch. His job: assisting in the creation of a set of 44 topographic charts of different areas of the moon, which began known as the Lunar Astronomical Charts, or LAC.

The object of the charts was to help NASA scientists identify the best potential landing site on the moon’s surface, Alspaugh says.

Each of the 44 charts, 2 feet by 2 feet square, was mapped at a 1:1,000,000 scale and given the name of the most prominent feature in the area.

Alspaugh says he was among those who did the “grunt work” of measuring shadows and calculating the distances and depths of craters, plains and other moon features based on photos of the moon taken from an observatory in France. He had two primary tools to accomplish this: a comparator and a microdensitometer.

“If you knew the direction of the sun when the photo was taken, you could determine heights of crater rims from the shadows,” he says. “The comparator collected x-y coordinates, and densitometer collected image density profiles, and both were seeking shadow lengths to provide trigonometric elevations.”

Rectified Lunar Atlas (1962)

Rectified, in this context, means “corrected.” This book of photographs of the moon’s surface show how the moon’s surface would appear if viewed from above — this is, on a curved surface rather than a flattened surface.

“Rectification is important for photographs taken of the surface of the earth or moon,” says Gene Woodford, a physical scientist who worked in the ACIC Lunar and Planetary Branch. “Normally photos taken of the surface may be tilted causing distortions on the edges. The negatives were adjusted for tilt and reshot producing a rectified image that is square to the surface and not stretched on the edges.”

ACIC personnel accomplished this by projecting an image of the moon surface onto a hemisphere, and then photographing it from a constant distance. This allowed users of the atlas to see a depiction of the moon with the highest possible positional accuracy.

Lunar Orbiter Landing Approach Simulator (1962)

To help prepare astronauts for what they would face when they actually landed on the moon, the Army Map Service created the Lunar Orbiter Landing Approach Simulator, or LOLA.

AMS cartographers made four models, meticulously formed and painted, of what the targeted landing site would look like from four distances, as if descending onto the lunar surface.

The first model showed nearly the entire visible lunar surface on a 20-foot near-sphere. From there, computer-driven cameras on roller coaster-like tracks moved to three other curved models of the lunar surface that showed the moon’s surface as if descending closer, and closer, and finally within 150 feet. A closed-circuit TV playing in a pilot capsule gave training astronauts a sense of what it would be like to actually descend on the moon’s surface.

“The flight of a spacecraft could be simulated by computer programming and switching of cameras,” said NGA archivist Lisa Wagner.

Moon topographic model (1963)

To help NASA decide where it might land a spacecraft, ACIC and AMS created 3-D plastic topographic maps of potential lunar landing sites.

This particular model was created in 1963 by ACIC based on Lunar Astronomical Chart №58.

A model like this might be printed from a 3-D printer today, or maybe even viewed on a monitor. But such technology was science fiction in the 1960s, says Woodford.

“Back then they were made by hand, with special tools to stretch the plastic into the shape of the surface to follow the contour lines,” said Woodford.

First complete map of the moon (1964)

While previous efforts to chart the moon’s surface focused on specific chunks of the moon, such as the Rectified Lunar Atlas, the Army Map Service was the first to publish a complete detailed topographic map of the visible surface of the moon in 1964.

To create the map, published on two sheets at a scale of 1:5,000,000, AMS mapmakers used lunar surface photographs showing two different angles to determine the actual contours — the heights and depths — of the moon’s exterior.

Lunar Orbit Chart (1967)

Seventeen Lunar Orbit, or ORB, charts were created by ACIC and AMS cartographers from medium- and high-resolution photography that came from NASA’s Lunar Orbiter. Five Lunar Orbiters were launched between 1966 and ’67 to take photographs of the moon’s surface from a closer distance than possible from earth.

These Orbiter photographs showed more detailed images of the lunar surface than was possible before, and lunar cartographers used the images to created charts for the selection of landing sites for the Surveyor probes, the first U.S. spacecraft on the moon, and the Apollo missions, which landed the first people on the moon.

“These were very large-scale, detailed and precise charts of the moon’s surface,” said Woodford. “They are stunning and beautiful, compiled by our talented lunar cartographers.”

This particular ORB chart, ORB-I-9–2g, was used to select the landing site for Surveyor I.

Lunar globe (1969)

This 16-inch globe, created by ACIC cartographer Howard Holmes and artist Jay Inge, was among the first batch of lunar globes ever produced. It depicts the entire surface of the moon — the near-side features drawn from ACIC’s Lunar Astronomical Charts, and the far-side drawn from photos taken during Lunar Orbiter missions.

ACIC employees could purchase a lunar globe for themselves for $50, which equates to about $350 in 2019 dollars. NGA has one, Woodford has one, Alspaugh has one — “still covered in the original plastic,” he said — and records show one was presented to the City of St. Louis.

While this globe currently functions as interesting display item for NGA and former ACIC employees — Alspaugh jokes his is a “trophy” — they also had a practical use during discussions or planning sessions.

“This is the very first detailed cartographic lunar globe with a latitude and longitude coordinate system,” said Woodford. “We could use the globe to quickly locate features and measure distances.”

Photography of the far side of the moon for the lunar globe and other products showing the far side of the moon came from NASA’s Lunar Orbiters, which captured images of far side of the moon for the first time, says Woodford. The far side of the moon is never visible from Earth.

“The first time we saw photography of the far side of the moon — it was absolutely unbelievable,” said Woodford.

Glass slides of lunar photographs (1972)

The photographs that NASA shared with ACIC and AMS to analyze and depict the moon’s landscape were converted to glass slides by ACIC. ACIC shared the slides, which could be projected onto a large screen, with NASA. This gave mission-planners and astronauts another way to present and understand the details of the lunar surface.

There are four of boxes of these slides sitting among the archives in the NGA Museum on the NGA St. Louis campus — alongside lunar charts, models and other products created by “grunts” like Alspaugh, scientists like Woodford, artists like Inge, and managers like Helmering. All conveyed critical information to American astronauts, scientists and engineers about a terrain that no human had yet visited.

And that insight gave American astronauts, visiting to a place humans had never been, the confidence to place one foot, and then another, into the not-so-totally-unknown.