
Ask HN: Which is the most powerful satellite camera directed towards earth? - o2l
Remember the scene from MIB where &#x27;K&#x27; zooms in on his wife and watches her live. How close are we to that ?<p>After a quick search, I found a few videos which showed scenes of an area with some traffic activity but it wasn&#x27;t that zoomed in. As far as images go, I haven&#x27;t found any other image source providing a better definition image than what Google Maps provide.<p>The American government had used live satellite feed while carrying out the Bin Laden operation ( Source of Information: Documentary | Correct me if wrong ).<p>Are there any images&#x2F;videos publicly available which demonstrate the limits of cameras in space directed towards earth ?<p>If not publicly available, can you describe how a possible image&#x2F;video might look like and what are the current limits for those cameras ?
======
luckydude
I worked a earth imaging system (EIS) back in the 1990s. I didn't have
security clearance (almost got it and realized it had no benefit to me but a
bunch of crap I'd have to do, or not do/say, so I passed).

I'm pretty sure that the satellites at the time could read 3 inch newspaper
print _under the right conditions_ which happened rarely.

I've got a tack sharp 600mm Canon lens and it's sort of useless for a lot of
stuff. If there is any haze, heat, dust, whatever, in the air, all that
expense glass sees is that instead of what you want to see.

That note aside, it was a fun project. I was the I/O guy, I did this work:

[http://www.nfsv4bat.org/Documents/ConnectAThon/1996/bds.pdf](http://www.nfsv4bat.org/Documents/ConnectAThon/1996/bds.pdf)

and I got Seagate to redesign part of their 9gb (I think, might have been 2 or
4g) barracudas. I've got a benchmark in lmbench that shows how the disk
performs as a function of seek distance, looks like this:

[http://mcvoy.com/lm/bitmover/disks/seek.gif](http://mcvoy.com/lm/bitmover/disks/seek.gif)

The lower edge of the band is what you get if you seek and get to the track
just as the sector you want is to about to pass under the head; the upper edge
of the band is what you get if the sector had just passed under the head; the
height of the band is a rotational delay; and those outliers? In this case I
think they were either bad blocks or I don't know.

But when you ran this benchmark on two drives, mounted in a rack right next to
each other, you got tons and tons of outliers which blew any chance we had of
meeting the performance metrics. I bitched at Seagate and they hemmed and
hawed and finally admitted there might be a problem with their internal
mounts.

The problem was that their mounts were so useless that the vibration caused by
one head moving vibrated the drive next to it enough that the other drive's
head didn't settle properly and you blew a rev waiting for it to get where it
needed to be.

Seagate redid the mounts.

Fun project.

~~~
eps
I remeber flipping through some spy tech book a while ago and one photo,
allegedly quite famous, stuck with me - it was of a wrist watch on a hand of
someone lying on a beach and while it was on a blurry side you could still
tell what the time was. From the context it was taken in the 70s and from what
I gathered it was a satellite snap.

Now thinking about it, it might've been a high-altitude plane (U2) photo
instead, but I'm not sure.

Has anyone else seen this photo?

~~~
anovikov
I seen it, but it is a famous fake. A few centimeters is the lowest bound for
resolution because of atmospheric distortion.

Also looking right from the top, at the best conditions, from 200km (a stable
orbit can't be lower), will give 4cm resolution for a Hubble-like mirror, or
2cm per pixel Niquist frequency.

------
CapitalistCartr
Satellites have had the ability to do that for decades. I was in the military
during the Reagan administration and we would roll $weaponsystem under cover
when the Russian satellites were passing over. They could see even small
details such as which model it was.

But more resolution isn't what's important. Other capabilities, such as deep
infrared, ultraviolet, radio, whatever scanning is more useful. Sats made
U-2s, SR-71s mostly obsolete; drones are doing a lot of what Sats did. Top of
the list though is refueling spy sats. That is the Holy Grail of reconnaisance
which the USAF X-37B totally experimental research craft totally doesn't do.

Refueling massively extends their use and lifespan. Its like have twice as
many for the money. Cuz, ya know, a hundred ain't enough.

~~~
edge17
what does "refueling spy sat" mean? (I know nothing about satellite power
sources)

~~~
CapitalistCartr
The problem with spy sats is they orbit too low, so the suffer from drag in
the trace atmosphere. Also, moving them in their orbit is super useful. Covers
more, plus confusing the opposition as to their location. But it takes too
much fuel. If you refuel them, both problems solved.

They have onboard fuel for "stationkeeping"; most low orbit sats do. That is
keeping them in their proper orbit and attitude in spite of drag.

~~~
sp332
I would expect a more elliptical orbit to be useful too. It would let you
swing down lower over your target while keeping your satellite out of the
atmosphere most of the time, and it would be even harder to track.

~~~
nickparker
The trouble with using elliptical orbits to get low and close is that you're
going incredibly fast at that altitude. This spells trouble both because you
spend a small fraction of your time above your target, and because drag is
proportional to the square of velocity, mitigating any savings there.

We do have uses for highly elliptical orbits, but they're usually used for
long residency times on their high side. The Molniya orbit is a prototypical
example.

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

------
jdhawk
41cm/pixel available to the government & 50cm/pixel available to Google
through GeoEye-1

[https://en.wikipedia.org/wiki/GeoEye-1](https://en.wikipedia.org/wiki/GeoEye-1)

31cm/pixel through WorldView-4

[https://en.wikipedia.org/wiki/WorldView-4](https://en.wikipedia.org/wiki/WorldView-4)

~~~
astrobase_go
take it for what it's worth, but according to this bbc article published in
2014...

> "The latest US spy satellites, in comparison, are reported to be able to
> pick out objects less than 10cm (4 inches) across."

[http://www.bbc.com/future/story/20140211-inside-the-
google-e...](http://www.bbc.com/future/story/20140211-inside-the-google-earth-
sat-lab)

~~~
jdhawk
Wow - I figured they were ahead, but 3x...

------
aw3c2
Some links for you:

[https://space.stackexchange.com/questions/3868/is-
photograph...](https://space.stackexchange.com/questions/3868/is-photography-
from-a-satellite-good-enough-to-make-out-a-person-on-the-ground)

[http://boards.straightdope.com/sdmb/showthread.php?t=627617](http://boards.straightdope.com/sdmb/showthread.php?t=627617)

[https://everything2.com/title/Spy+satellites+can%2527t+read+...](https://everything2.com/title/Spy+satellites+can%2527t+read+your+license+plate)

 _A perfect 2.4-meter mirror observing in the visual (500 nm) would have a
diffraction limited resolution of around 0.05 arcsec, which from an orbital
altitude of 250 km would correspond to a ground sample distance of 0.05 m.
Operational resolution should be worse due to effects of the atmospheric
turbulence._

[https://en.wikipedia.org/wiki/KH-11_Kennen](https://en.wikipedia.org/wiki/KH-11_Kennen)

------
antognini
I'm assuming this is all pretty well classified, but I would be shocked if the
US government hasn't had the ability to do that for a long time. Consider that
back in 2012, the National Reconnaissance Office donated two surplus
telescopes to NASA that were substantially better than the Hubble telescope.
If those are the sort of telescopes that the government has no need of
anymore, imagine what the state-of-the-art is!

As an aside, that donation has actually put NASA in a bit of a bind. For
political reasons they can't very well turn down the offer. But the telescope
itself is only about one third of the total cost of space telescope, with the
rest being due to the cost of the instruments and the launch itself. Unlike
the US military, NASA does not have an unlimited budget so this unexpected
expense threw a wrench into their long-term plans. Furthermore, the telescopes
were designed to look down instead of up, so they're not optimized for
astronomical observations.

~~~
palunon
Hubble was launched in 1990, is it surprising that 22 years later, NRO
telescopes are substantially better ?

~~~
dasmoth
The donated telescopes were build for the Future Imagery Architecture project:

    
    
       http://www.space.com/16077-nasa-space-telescopes-failed-nro-program.html
    

They're substantially newer technology than Hubble (which is older than the
1990 launch date suggests -- it was delayed several years after the Challenger
disaster).

That said, I don't think they'll give an appreciably better resolution --
given good fabrication techniques, optically a 2.4m mirror is a 2.4m mirror,
and everything I've read suggests that US IMINT satellites have been (in good
seeing conditions) close to diffraction-limited for a long time now.

I'm sure the capabilities of the satellites have improved a great deal, but in
other directions than resolution. More communications bandwidth? Faster
repointing (giving more flexibility about which targets get imaged on a given
pass? Better multi-spectral imaging? I'm sure there will be some surprises
when the program is eventually declassified. (And I'm optimistic it will be --
there's lots you can read now about the film-return satellites).

------
dotancohen
There is a question on the Stack Exchange network which asks about publicly-
viewable satellite cameras:
[https://space.stackexchange.com/questions/4485/which-high-
re...](https://space.stackexchange.com/questions/4485/which-high-resolution-
earth-facing-satellites-transmit-data-to-the-public-in-rea)

Disclaimer: I'm the OP on that question.

------
Const-me
High-rez satellite cameras don’t film videos.

Satellite cameras don’t have a 2D sensor you can find in a traditional camera.
Instead, they feature a long narrow sensor. As the satellite flies over the
earth, the sensor records a single row below the satellite. That row is
oriented perpendicular to the satellite’s velocity. As the satellite flies, it
scans a long strip of land underneath.

It works similar to a flatbed scanner. Can you film a video with the scanner?
I don’t think so.

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

About Bin Laden, the live satellite feed was not filmed from space. The feed
was recorded by an on-body camera of an American soldier, transferred to a
telecom satellite, then back to Earth, at Obama’s place.

~~~
dasmoth
Video from space has been done by civilian spacecraft, e.g.:

    
    
        https://terrabella.google.com/
    

We know that the film-return satellites were working in push broom mode (or
"whisk-broom", as I've seen the KH-9 cameras described). I have little doubt
that the primary observation mode of the follow-on electro-optical systems is
also push-broom. But not sure I'd want to rule out the possibility that the
more recent blocks might also have some kind of staring mode (which could
plausibly give video of small-ish areas). They're still pretty secretive
birds.

~~~
Const-me
The resolution is not that great, 1212 pixels / 2.5 km gives 2 meters / pixel.

The ground wind speed at the time of eruption was below 5 m/s, i.e. the video
plays much faster then real-time.

If you’ll download the video, pause it, skip between frames, you’ll notice
different parts were shot from different positions and with different
resolutions.

They probably abused the fact clouds move in very predictable manner. They
took several satellite images from whatever satellites happen to pass roughly
above the volcano, and used creative video editing to make a smooth video from
those several frames.

------
jlgaddis
I suspect the most powerful are classified NRO satellites. The public's
knowledge is likely a decade or two behind actual capabilities.

I recall reading somewhere about satellites being able to see license plate
numbers from space but I have no idea where I read that or if it's true.

~~~
luckydude
I'm pretty sure it was NRO that was our customer. Any idea if around the late
1990's the NRO was run by a woman? If so, that's the agency we were working
for (as mentioned in another comment).

------
jaggederest
KH-11 had a theoretical resolution in the inches. "Not quite good enough to
identify faces." Those were first launched in the seventies, so I assume they
are doing much better now. I think it's safe to assume 5cm or better
resolution on a minutely refresh.

~~~
glasz
makes you wonder why the imagery floating around with reporting on war zones
and incidents are of such bullshit quality.

even the supposedly recorded-with-mobile footage is always so bad. as if the
person is stumbling around not knowing their phone's cammera is rolling.

~~~
c22
I assume militaries don't provide news outlets with their highest resolution
spy imagery as to not disclose the extent of their capabilities.

I'd also suspect anyone recording a news-worthy "incident" on their mobile
phone in a war zone has other priorities than maintaining a stable image.

------
lucideer
> As far as images go, I haven't found any other image source providing a
> better definition image than what Google Maps provide

As many have alluded to here, there's likely to be a big difference between
publicly available imagery and what's currently possible. Sticking to publicly
available stuff though, while the resolution of all mapping services varies a
lot across the globe, [http://wego.here.com](http://wego.here.com) provides
satellite imagery that betters Google's in a lot of cases.

This is all somewhat moot if you're looking for MIB-esque video of course as
these still images are compiled rather than directly snapshotted

~~~
o2l
It's hard to compare Here Maps and Google Maps here. It's out of question that
Google Maps provide a superior experience as compared to Here maps. But all
the Google Maps imagery is processed, even while using the 2D option ( This is
true only for countries with street view, from my observation. It's brilliant
how they use street view along with satellite imagery to make a 3D model ).
For my country India, the quality of images are slightly better on Google
Maps, whereas when I check for other locations like Beijing, Here Maps seem
slightly better than Google. It's weird how image quality change from country
to country. It must have something to do with how they use their resources to
provide best quality to probable customers and also country specific laws
might apply for releasing satellite imagery.

------
KiwiCoder
I expect drones are now more relevant than satellites for localised imaging.

For example [http://www.cropcopter.co/uav-imagery-vs-
satellite/](http://www.cropcopter.co/uav-imagery-vs-satellite/)

~~~
hyperbovine
Yes. There was a piece on 60 Minutes a few years back where they had a big
(~20 ft. wingspan maybe), loud drone circling overhead a few thousand feet up.
It was inaudible and invisible. What's the point in solving a hard problem
like hi-res imagery from space when you can just fly one of these over the
target practically at will? (With a Hellfire missile attached, no less.) Range
and airspace issues notwithstanding, the drone future is a scary place.

~~~
planteen
> Range and airspace issues notwithstanding

Those are precisely the reasons satellites will remain relevant. Satellites
are the reason the SR-71 fell out of service. Russia can and will shoot down
US aircraft or drones in their airspace.

~~~
hyperbovine
SR-71 is about as far from a drone as you can possibly get. Politicians are
going to (pretend to) care a lot less about airspace sovereignty when
violating someone else's airspace does not involve risking pilots' lives.
Range and stealth are only going to increase. This is why I said the future
looks bleak.

------
zip1234
The problem is the distance involved and the orbits. For example, GeoEye-1 is
in a sun-synchronous orbit in order to be over the US at the same time each
day. However, it means that the satellite is moving quite rapidly across the
surface of the earth much of time. If you've taken a photo of a moving person
or car, you know how hard it is to get a non-blurry picture. Now, try doing
that at much higher speeds. If you put a satellite into a GEO orbit, it is
incredibly far away from the Earth and would require huge optics in order to
get good photographs.

------
Errorcod3
Commercial Imagery:
[https://www.ijircce.com/upload/2016/may/47_Estimation.pdf](https://www.ijircce.com/upload/2016/may/47_Estimation.pdf)

For the full NIIRS rating:
[https://fas.org/irp/imint/niirs.htm](https://fas.org/irp/imint/niirs.htm)

------
Zaak
[https://what-if.xkcd.com/32/](https://what-if.xkcd.com/32/)

