
Decades-Old Mystery Put to Rest: Why Are There X's in the Desert? - aaron987
http://www.npr.org/2016/10/11/496567104/decades-old-mystery-put-to-rest-why-are-there-xs-in-the-desert?utm_source=facebook.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=2037
======
grkvlt
Also interesting are the resolution targets, using sets of black and white
bars at varying widths in both X any X orientation, to determine the spatial
resolution i.e. how high frequency a component could still be imaged
separately as lines, similar to TV test cards. These are discussed in various
blogs [1][2] with some amazing picures. I think these were for both satellite
imaging and spy-plane (U2 and SR-71 plus less exotic surveillance systems) and
not just the USA. This article [3] shows some satellite test targets in the
Gobi desert, presumable for Chinese (PRC) spy satellites, and also has a cool
picture of the world's largest compass rose, at Edwards dry lake bed, as well
as explaining the crosses from the original article, and talking about radar
altimeter targets (another dry-lake bed) that are mapped to centimetre
accuracy in altitude for calibrating GPS and other systems.

I find it a really interesting area of industrial/scientific archaeology, with
some fascinating stories.

[1] [http://www.clui.org/newsletter/winter-2013/photo-
calibration...](http://www.clui.org/newsletter/winter-2013/photo-calibration-
targets) [2] [http://www.bldgblog.com/2013/02/optical-calibration-
targets/](http://www.bldgblog.com/2013/02/optical-calibration-targets/) [3]
[http://www.atlasobscura.com/articles/landscapes-made-for-
sat...](http://www.atlasobscura.com/articles/landscapes-made-for-satellite-
eyes-calibration-targets-resolution-tests-and-giant-desert-compasses)

~~~
toomanybeersies
Those tri-bar patterns are fascinating. I'd imagine that American surveillance
equipment would be able to discern all but the smallest couple of squares.

They'd easily be able to read registration numbers on aircraft, probably
almost be able to discern specific small arms (e.g. count the number of RPGs
and AK-47s sitting on some tarmac somewhere). Amazing.

~~~
rangibaby
USSR "trolled" the US by painting windows on top of a plane or helicopter
while it was under development. I can't remember the exact one will have a
look around.

~~~
grkvlt
I'm sure I've also read about this, but can't find any links at the moment.
The art of Maskirovka [1] (deception and camouflage) is still part of Russian
military doctrine. Interestingly, the US also does something similar with
planes like the A-10, which has a 'fake cockpit' painted on its underside, so
that it is hard to determine the orientation of the aircraft visually. This is
actually patented [2] and has been applied to various different aircraft, see
the pictures accompanying this answer [3] on stackexchange.

[1]
[https://en.wikipedia.org/wiki/Russian_military_deception](https://en.wikipedia.org/wiki/Russian_military_deception)
[2]
[https://www.google.com/patents/US4448371](https://www.google.com/patents/US4448371)
[3] [http://aviation.stackexchange.com/questions/2078/what-is-
the...](http://aviation.stackexchange.com/questions/2078/what-is-the-dark-
spot-visible-below-the-cockpit-on-a-10s)

~~~
rangibaby
According to wiki the one I was thinking of was the Ka-50

> The single-seat configuration was considered undesirable by NATO. The first
> two Ka-50 prototypes had false windows painted on them.[19] The "windows"
> evidently worked, as the first western reports of the aircraft were wildly
> inaccurate, to the point of some analysts even concluding its primary
> mission was as an air superiority aircraft for hunting and killing NATO
> attack helicopters.[20]

------
CoryOndrejka
My dad was project photogrammetrist on Corona when he worked at Itek in the
60s. Lots of stories around focus and aiming challenges, since Corona was used
to build maps of inaccessible regions of the world (e.g. Soviet Union ICMB
sites). Focus targets gave high contrast, known images to detect what kind of
focus problems were being encountered -- ranging from image smear from forward
motion compensation failing or stretching the film; film sticking, stretching
and/or lifting off of the focal plane; star camera inaccuracies; thermal
distortion of camera, spacecraft, star camera, or film; etc. A few good books
on Corona ([https://www.cia.gov/library/publications/intelligence-
histor...](https://www.cia.gov/library/publications/intelligence-
history/corona-between-the-sun-and-the-earth)) and Itek
([https://books.google.com/books/about/Spy_Capitalism.html](https://books.google.com/books/about/Spy_Capitalism.html))
out there. Same teams worked on subsequent KH projects (Gambit, Hexagon/Big
Bird/BMF), as well as Apollo and Viking camera systems.

------
mslev
I love stuff like this, I just think its so cool. Similar to this are the
large cement arrows across the US:

[http://www.cntraveler.com/stories/2013-06-17/transcontinenta...](http://www.cntraveler.com/stories/2013-06-17/transcontinental-
air-mail-route-maphead-ken-jennings)

~~~
Bronze_Colossus
Here is a few more picture more:
[http://www.messynessychic.com/2013/11/15/the-forgotten-
giant...](http://www.messynessychic.com/2013/11/15/the-forgotten-giant-arrows-
that-guide-you-across-america/)

I also find these kind of things cool. Forgotten structures that once served
an important roll but now are mostly forgotten.

~~~
nitrogen
Interesting story and cool photos. Couldn't get to the end due to website
design issues. Were these for horseback delivery or for airplanes?

Terrible, terrible UX in the form of a jittery delayed popover that fills the
entire phone screen. If you are going to do this (and I can't stand the fact
that it actually works on many people), make it so easy to dismiss and fast to
load that I close it instead of instictively hitting back.

~~~
Sanddancer
Air mail. These were the days before good roads crossed the country, and where
even an automotive trip was an Adventure which would take weeks. Horseback,
you're going slow enough that you'd be able to see much smaller signs, and
would be on a pretty well-trod path.

Shortly thereafter, though, a few things happened that made the arrows pretty
obsolete. Mapping of course, was a big one; you could now navigate a lot more
reliably through unknown territory. More importantly, a network of radio
beacons was set up. Charts had lists of radio beacons, with their frequencies.
Pilots could tune in to hear them repeatedly chirp their identification in
morse code, and use radio direction finders to set their heading accordingly.

There's one other feature that was developed in that time period which also
made pilots' navigation job a lot easier. The federal highway system meant
that there were good, very visible, roads, serving as routing beacons in their
own way. Pilots would, and still do for a lot of general aviation planes,
route close to highways, because they're also a very obvious landmark that
carves a path through the country.

------
strictnein
One of the most interesting things about the Corona satellites was that they
shot on film and that film was developed back on earth.

So how'd they get that film back down from space?

[https://en.wikipedia.org/wiki/Corona_(satellite)#Recovery](https://en.wikipedia.org/wiki/Corona_\(satellite\)#Recovery)

~~~
fizzbatter
Answered here:
[https://news.ycombinator.com/item?id=12695808](https://news.ycombinator.com/item?id=12695808)

~~~
ptaipale
Another question of course is that since it was impossible to load the cameras
with new film, how much film did they carry when deployed? After using it all
the camera was useless.

A modern digital camera would have been really valuable for these purposes.

BTW were those Corona satellites guidable, or did they just fly wherever they
flew and operators could ask them to photograph what was under?

A useful way to decommission a satellite that is about to run out of its film
storage would have been to guide it to a trajectory where it can take more
accurate pictures from a lower position -- because once the satellite goes on
such a trajectory, it will soon come down completely. But if you could use the
last bit of film that way, and eject it for retrieval, then the dying of the
satellite would at least have been utilized.

~~~
creshal
> Another question of course is that since it was impossible to load the
> cameras with new film, how much film did they carry when deployed? After
> using it all the camera was useless.

That's why both the US and Russians experimented with military space stations
(US MOL, Soviet Almaz), so they could both resupply the cameras with more
film, and in emergencies develop it directly in space and radio down scans of
them.

However, both eventually figured out how do automate the latter and eventually
developed fully digital cameras, rendering manned surveillance stations
obsolete. The US never launched any, and the Soviet program was cancelled
after three stations (that were masked as Salyuts).

> BTW were those Corona satellites guidable, or did they just fly wherever
> they flew and operators could ask them to photograph what was under?

Satellite orbits are largely fixed – changing your orbital plane is the single
most expensive manoeuvre you can do, and too expensive in practice. (Even if
we wanted to, we couldn't tilt the ISS' orbit by more than a degree or two,
and if we did, Soyuz rockets couldn't reach it any more.)

That's why we instead just launch a whole lot of satellites that focus on
different areas.

> A useful way to decommission a satellite that is about to run out of its
> film storage would have been to guide it to a trajectory where it can take
> more accurate pictures from a lower position

Even just lowering your orbit is expensive, fuel-wise, but the more important
problem: The lower you go, the faster you are. This means lower exposure times
and _less_ image quality, not more.

Additionally, as far as I can tell, the film buckets were really dumb and used
solid boosters hand-tuned to their original orbit. Launching them from a
different trajectory would likely make them burn up during re-entry.

------
dredmorbius
The Corona project. A/K/A the KeyHole satellites. If my count is right, 135
satellite launches, though not all were successful.

Fun fact: this was the early 1960s. CCD technology and IP transmission
bitrates were a bit primitive[1], so the _film_ cameras would eject capsules
after they'd been shot, which would re-enter the atmosphere and be recovered,
most through mid-air retrieval. The project was active from 1959 to 1972.

[https://en.m.wikipedia.org/wiki/Mid-
air_retrieval](https://en.m.wikipedia.org/wiki/Mid-air_retrieval)

[https://en.m.wikipedia.org/wiki/Corona_(satellite)](https://en.m.wikipedia.org/wiki/Corona_\(satellite\))

Video of recovery: [http://petapixel.com/2014/08/31/us-spy-satellites-used-
drop-...](http://petapixel.com/2014/08/31/us-spy-satellites-used-drop-photos-
film-buckets-space-airplanes-catch-mid-air/)

______________________________

Notes:

1\. Well, technically they didn't exist.

~~~
tjohns
Nitpicking here, but I think even most modern satellites don't use IP for
their downlinks.

I suspect something like X.25 is used instead for digital data, if not
something even more bespoke... and many satellites still send analog data.

For example, this is the protocol used for NOAA weather satellites (and
actually was developed in the 60s):
[https://en.wikipedia.org/wiki/Automatic_picture_transmission](https://en.wikipedia.org/wiki/Automatic_picture_transmission)

~~~
dredmorbius
That was a flip bit of stage-setting.

I know little about space data transmission (though I vaguely recall some good
discussion around the time of the New Horizons Pluto contact), but yes, it's
been a mix of analog transmissions (initially) and digital, of various
descriptions. I believe there _is_ an IP-based transmission support for the
ISS, though I wouldn't swear to that.

One of the zaniest image transmission protocols was for the early Soviet lunar
missions, Luna 3. Again, film cameras, _an in-spacecraft photo processing lab_
, and a TV camera to read off the film image and transmit it back to Earth.
The image quality wasn't much, but it _was_ the first imagery of the Lunar
farside ever received.

[https://en.m.wikipedia.org/wiki/Luna_3](https://en.m.wikipedia.org/wiki/Luna_3)

A few years back there was a story of the National Geographic lunar map timed
to coincide (well, a month late) with the December, 1968, Apollo 8 mission,
the first manned flight around the Moon (though without a landing). This gave
us the famous Earthrise photograph, and the Christmas Day broadcast from
Apollo. The story of the map, and how rapidly the Lunar far side went from
_terra incognito_ (well, _luna incognito_ ) to mapped in detail was pretty
staggering. I had that map as a kid, and just figured "we knew all that".
Sometimes it takes growing up to see things with childlike wonder....

The story:

[http://kelsocartography.com/blog/?p=1481](http://kelsocartography.com/blog/?p=1481)

[http://kelsocartography.com/blog/?p=1588](http://kelsocartography.com/blog/?p=1588)

(Pretty sure that's made HN at some point.)

------
LoSboccacc
"Those X where used to calibrate spy satellites camera" #stopclickbait

------
okket
The in the story linked movie about the Corona Project is an amazing document
of history.

[https://archive.org/details/gov.archives.arc.1678526](https://archive.org/details/gov.archives.arc.1678526)

~~~
c0rtex
Same thing on YT:
[https://www.youtube.com/watch?v=k3bzHk_6yHM](https://www.youtube.com/watch?v=k3bzHk_6yHM)
For those who like to watch at 2x.

------
initram
Anyone know what's nearby there at about (32.92669, -111.922201)[0]? It looks
like some sort of strip mine a few hundred feet to the north, so I assume it's
related, but was just curious what it is. It looks like a painting!

[0]
[http://maps.apple.com/maps?ll=32.926699,-111.822201&spn=0.00...](http://maps.apple.com/maps?ll=32.926699,-111.822201&spn=0.006796,0.014104&t=k)

~~~
helb
As e2021 said, these are some kind of tailing dams to treat remaining water
from mining.

Google even has streetview photos from the nearby road, resolution is just
enough to read "[something] wastewater evaporation ponds" on the fence sign:
[https://goo.gl/maps/WZKbdPxs5sS2](https://goo.gl/maps/WZKbdPxs5sS2)

The mine itself looks cool, too:
[https://www.google.cz/search?q=Casa+Grande+Copper+Mine&safe=...](https://www.google.cz/search?q=Casa+Grande+Copper+Mine&safe=off&tbm=isch)

------
zerooneinfinity
Can someone explain to my dumbass how they helped calibrate the photos or
satellites?

~~~
mabbo
Okay, I just spent 20 minutes trying to figure that out and I'm still not very
far.

These were film cameras, so the computer on board can't look through the
camera and see if the objects are in focus, can they?

~~~
13of40
They took a whole series of images at different focuses, then dropped it to
earth and people radioed back the most in-focus setting....is how I'd do it.

------
sago
Here's a map of them. Corrections and additions welcome.

[https://drive.google.com/open?id=1bebA9E6kTb3G9g5GEeezYPzvwH...](https://drive.google.com/open?id=1bebA9E6kTb3G9g5GEeezYPzvwHo)

Based on the map from wikipedia, which had 84 locations, this has 120.

------
beamatronic
Could you infer the orbit of the satellite from the location of the X's?

~~~
pilom
If you had an image taken by the satellite and the time the image was taken,
then yes. Google maps doesn't make it obvious but not all satellite images are
taken from directly overhead. Most are off angle, so by calculating the
distance on the film between known points on the earth, you could have a
pretty good idea of the location of the satellite.when the picture was taken.

------
SCHiM
tl/dr: U.S. Military spy satellite camera calibration.

~~~
Animats
Right. Since each "mysterious" X was equipped with a "US Army Corps of
Engineers" brass plate, it was kind of obvious they were calibration targets
for something military. The article says "focusing", but they were probably
used to get more precise orbital elements for satellites. This was pre-GPS,
and calibration across geography on a planetary scale was tough.

~~~
planteen
> The article says "focusing", but they were probably used to get more precise
> orbital elements for satellites. This was pre-GPS, and calibration across
> geography on a planetary scale was tough.

My guess is that they served a function for calibrating ground control points
rather than orbital elements. Even today, NORAD publishes orbital elements
(TLEs) for spacecraft deduced by radar (and also optical means). I think other
radio ranging techniques were also used before GPS. Trying to point at Earth-
fixed point with only an inertial attitude (without a position/velocity) seems
really tough.

Today, lots of CubeSats don't have GPS, so they eagerly await getting TLEs
from NORAD. It seems like this Twitter is always the first with new data:

[https://twitter.com/TSKelso](https://twitter.com/TSKelso)

------
kahrkunne
I bet the Corona thing is just a cover story for pirate treasure

------
127001brewer
Interesting: I've submitted this story over a day ago
([https://news.ycombinator.com/item?id=12684118](https://news.ycombinator.com/item?id=12684118))
with a _clean_ URL, yet this submission got noticed?

Yes, good luck and good timing, but still - ha!

------
jlebrech
my guess was a marker for mexican drug cartels to drop packages.

------
vizzah
They could have embedded LOVE instead of X's and it wouldn't have created any
mystery and unneeded attention, as everyone would know it was hipsters.. no, I
mean hippies.. =D

