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Corona Calibration Targets, AZ
mini location map2017-02-22
40 by photographer avatarFLYING_FLIVER
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Corona Calibration Targets, AZ 
Corona Calibration Targets, AZ
Hiking avatar Feb 22 2017
Hiking16.00 Miles
Hiking16.00 Miles
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1st trip
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I went to the Casa Grande area and took photos of over thirty ‘Corona Calibration Targets’.
That’s a small number of targets compared to the total still out there.
(I took two hikes to do this, and I combined the hikes into this one HAZ upload).
Compared to my normal triplogs, this is a long one - Think of it as two hikes and one long triplog. :)

Many of you may already know about these “things-on-the-ground”.
I’ve known about the actual targets for a long time, but didn’t know the real reason for their placement. In 1995 the true, ‘top secret’ reason for the targets was declassified.

CORONA was the name of the USA’s first ‘Imaging Satellite Program’. They were spy satellites.
The program was top secret, with it’s cover story being the Discoverer satellite program.

Corona spy satellites were launched from 1959 thru 1972, to acquire reconnaissance photos of mainly, Soviet Union’s arsenal of military aircraft, airports, ICBMs, nuclear bomb plants, etc.
In the 1950s, President Eisenhower wanted to be able to know as much as possible about the Soviet Union’s war arsenal.
The CIA and the US Air Force were mainly in charge of the spy project. Alot of ‘firsts’ in satellite technology was tested and accomplished during the Corona program that enabled manned space flight later on.
One must remember, sending up satellites in the 1950s and 1960s was the fledgling era, with many satellite failures along the way.

Here’s a quote from a CIA web page, as to some of the challenges the Corona space program had to overcome:
“Corona’s goals were daunting - launch a large camera into earth orbit, photograph specific points and areas on the earth’s surface, jettison and parachute a capsule of exposed film to earth, snag the capsule in midair over the Pacific Ocean, develop the film, and search the images for answers to the USA’s pressing intelligence questions.”
(Note the word “film” - No digital stuff yet). The film was snagged in midair by C-119s and C-130s.

Actual Corona calibration targets:
The targets played a small role in the overall spy recon endeavor. They were used to calibrate the satellite cameras, and were used as a known ‘size-guide’, when trying to determine the size of objects on the ground in the Soviet Union and in Communist China.

In 1966 and 1967 (some in 1968), survey teams from the Army Map Service laid out a grid of normal benchmarks, with four panels surrounding each little disk. (The surveyors called the panels - ‘petals’) Most individual petals were made of thick concrete, and were in the shape of a maltese cross.
Those maltese crosses were HUGE.

From the tip of one petal of the maltese cross, to the tip of the opposing petal, measures 60 feet.
Each of the four petals of the maltese cross is about 26 feet long, 16 feet wide at its end, and about 3 feet wide near the disk. The space between the petals, where the survey disk is set, makes up the remaining 8 feet.
Their size was large enough for the satellite cameras to view, orbiting 100 miles overhead.

Accurate, hard facts are difficult to come by about the actual number of targets that were laid out in the grid. The government barely acknowledges the targets, as they were just a small part of the whole program. The cover story for the actual targets was - They were used for aerial camera calibrations of aircraft, like the U-2.

Wikipedia et al, has info that, in my opinion is just OK, concerning the targets, including the size of the land grid, number of rows and columns, and the actual number of targets set up. Some of the unofficial internet info conflicts with itself.

I’m certainly no expert, but I’ve done alot of research on the number of targets and the actual size & shape of the target grid. I’ve used Google Earth and a couple ‘GE’ add-ons, plus datasheets and something called ‘Control Marks’ to determine size, shape and numbers.

My findings are - There were 273 survey disks (and maltese crosses) laid out in a 17 mile by 17 mile grid. Except for the far western column (north to south) and the far southern row (east to west), the remaining 16 columns and rows had a ‘target’ each and every mile. The far west column and far south row had one target every ‘two miles’.
My guess is, the grid was set up this way so when the spy satellite flew over the grid, the film analysts could better determine (and confirm) direction and angle of the satellite orbit, along with knowing if the cameras had good focus and resolution. This grid was a known entity, for size comparisons of things in, what the CIA called, the “denied areas”.
Well over 100 of the targets are still easily viewed on Google Earth. Go take a look.

Although the majority of the targets were exact clones of one another, there are some target anomalies:
Not all maltese crosses are concrete. On, and near mountains, some crosses are made up of available rocks, with some only lined with concrete. (And some not lined with concrete). I know of one target that has a mix of petals, with three petals made of rock and one made of very thin concrete. One target, set in 1966, was moved almost 400 feet in 1968.
There’s one target (in pristine condition), viewable from your car, as you enter I-8 from I-10.

There’s also at least one maltese cross that is not only all rocks, but is physically smaller, possibly due to its location. That specific target location is thought by many ‘online contributors’ as being a location that the surveyors did not place a target. Trust me - the target is there.

A large number of targets are gone now. The Corona program was over in 1972, and the 273 targets weren’t needed anymore. Each target’s leased land was relinquished to its owner, and a cover story was made up as to why the survey disks were no longer needed.
Land owners were given a choice to have the huge concrete petals and disks removed, and alot of them had them taken away. Plus, many targets are out-of-sight now, below plowed fields, under desert sand, or obscured by vegetation.
With over 40 years of no-maintenance, some of the targets are still in perfect shape, and some are in real bad shape, due mostly to vandalism and nearby infrastructure changes.

It was fun and educational, hiking from one target to another and viewing these huge spy satellite artifacts up close.
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Casa Grande Mountains
Not All Those Who Wander Are Lost
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