
Satellites Taking Pictures of Rockets Carrying More Satellites - privong
https://www.planet.com/pulse/satellites-taking-pictures-of-rockets-carrying-more-satellites/
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oelmekki
Each time I'm sad we're not exploring galaxy star trek style yet and the space
conquest made a flop, I remember how many commercial satellites are around
here.

It really has this regular taste of things you think just died after being
hyped (the moon landing) and which you suddenly realize has got slowly,
steadily, discretely omnipresent since then without anybody noticing much
(granted, satellites are not as cool as visiting other celestial bodies, but
that's still growth, and going the right direction).

I would love to see a graph of the amount of satellites in activity over time.

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tenpies
It has basically fallen into a classic hype cycle -
[https://en.wikipedia.org/wiki/Hype_cycle](https://en.wikipedia.org/wiki/Hype_cycle)

This is partly why I'm skeptical of technologies when the media is talking
about them. It probably means we're somewhere on the peak of inflated
expectations.

~~~
valuearb
The peak of inflated expectations was the Saturn V. Custom built, massive,
cost around $10,000/lb in present day dollars to low earth orbit.

The trough of disillusionment was the Shuttle. Much smaller payload capacity,
trapped in LEO so it ended manned deep space exploration, and cost around
$50,000/lb to LEO.

The Falcon Heavy is the highest capacity launch system since the Saturn V, and
will cost $1,000/lb to LEO. I think the plateau of productivity approaches.

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natch
Would love to see an actual speed version of this... what's the hurry?

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ChuckMcM
Think about the system[1], you've got to take a picture, store it, and then
downlink it. If you take too many pictures your downlink is overloaded and you
run out of memory. Assuming that an HD frame is about 2 megabytes once it is
compressed, that is a 2 - 5 mbs downlink speed (depending on error
correction). The satellites they launch are tiny and low power so they will
have a limited budget for down link bandwidth.

That said, it makes me wonder about things like NROL76 which was a classified
DoD payload that SpaceX launched and had no upper stage video from. At what
point are there so many of these tiny satellites in orbit that they can pick
up the fairing deploy and satellite separation independently? Or have them
watch the X37 as it maneuvers around in orbit?

[1]
[https://www.planet.com/company/approach/](https://www.planet.com/company/approach/)

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jessriedel
If bandwidth were the main limiting factor, they would just take video
intermittently and downlink it over a long period of time. This would be
useful for documenting real-time changes on the ground during important
isolated events (e.g., rocket launches). But they apparently don't have this
capability, and I think it's because the hardware for taking many frames per
second just isn't worth the cost and complexity.

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andrewstuart2
As mentioned in parent, the rate you can capture depends on the resolution
(i.e. image size in bytes), downlink speed, available memory, and length of
the event.

As the length of the event approaches infinity, the framerate you can capture
is basically bandwidth / image size. `(mb/s)/mb = 1/s` (aka hz). Beyond that
limit, the memory size / image size gives you a hard limit for the number of
additional frames you can buffer. To get a constant frame rate, you want to
spread that quantity over the duration of the event.

~~~
natch
The playback speed can also be adjusted by changing the frame rate of
playback. Each frame just stays on the screen for a longer time. Similar to
the -delay <n> parameter when creating a GIF in ImageMagick.

~~~
andrewstuart2
That's not in question. Yes, playback framerate is independent from recording
framerate.

The question is the availability of resources (memory and bandwith) to the
satellite and how many frames it can store without needing to transmit them
over its slow downlink.

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natch
The frames are already back on earth now, as evidenced by the video being on
Youtube. Adjusting the playback rate of those frames is what I'm talking
about...

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siscia
Any of you have any idea of how much the images from planet.com cost?

~~~
notahacker
Satellite image prices through a broker, including Planet's RapidEye
constellation

[http://www.landinfo.com/satellite-imagery-
pricing.html](http://www.landinfo.com/satellite-imagery-pricing.html)

Prices are per square kilometer, but there's a minimum order of 500 square
kilometers, and you're paying for a licence for a certain number of people to
use them in a certain way.

TLDR: best have at least a few hundred dollars handy even if you're only
wanting to look at one city.

A lot of lower resolution satellite data is free and open though

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jessriedel
Any idea why the minimum area requirements exist? It completely kills
localized applications like a single farm. It seems like a minimum price,
which you could also reach by committing to buy regular photos for a period of
time, would be a lot more flexible.

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nine_k
I suspect it's related to the need to possibly re-orient the satellite to have
a particular place visible by the camera. It must be relatively slow, and
possibly even cost reaction mass, thus the commitment to shoot more of the
same area.

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jofer
Rapideye and SkySat aside, Planet primarily operates a monitoring
constellation, rather than a tasking constellation. The doves (satellites used
to take this and the satellites being launched) are focused on imaging the
land surface of the Earth with an approximately daily cadence. They don't
target a particular area, try to reorient, or even have active propulsion
(just reaction wheels).

This is an exception -- the satellite was tasked to try to capture this and
did reorient itself to do so.

For the most part, though, the doves just point straight down and capture
images whenever they're over land and it's not forecast to be completely
cloudy. There are over a hundred of them imaging the earth like a line scanner
as it rotates beneath their orbit.

The Rapideye satellites operate completely differently, though. They are
tasked, and do have to reorient as you mentioned, thus the minimum area
requirement for acquisition of Rapideye imagery.

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vonuebelgarten
Their strategy is particularly awesome: a hundred of small short-lived
satellites (really small, they're 3-unit cubesats, 30x10x10 cm) operating in a
swarm. No big deal if a single one is lost: operation can continue with other
ones once they are in position. Also, costs are spread due the possibility of
servicing several customers simultaneously in separate locations around the
globe.

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dopeboy
Kind of offtopic but I figured I'd ask: how close are we to enemy of the state
style satellites that can track movement like a overhead CCTV camera?

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Iv
20 years ago they pretended it was good enough to differentiate between Saddam
Hussein and his decoy lookalikes.

It is possible however that they made that up to not reveal an internal source
of intel.

I, for one, think we have been there for a while. The tech is not hard: camera
with huuuuge optics will bring you there.

The military have secret satellites with undisclosed specs, that's what they
have been doing since Sputnik. You bet they are good at it by now.

~~~
jsmthrowaway
The tech might not be hard, but stationkeeping an orbit on top of a target is,
unless you have optics that can handle 36,000 kilometers of distance
(geosynchronous). All other, lower, orbits involve the satellite hauling ass
across the ground, usually at 5+ kilometers per second. The video would be
great for about five seconds.

Real spy satellites have time windows and image like hell within the window,
then adjust for the next orbit and wait 90 minutes. They’re often in polar
orbit, too, because then you get different parts of Earth as it rotates under
you. Satellite surveillance is quite tedious, and the enemy knows where and
when they are.

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MR4D
With this kind of video, it would be interesting to see how the North Korean
rockets actually do.

Something tells me the CIA/NSA have already used this to get an answer. And at
military resolution too.

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the_d00d
Vampires pretending to be humans pretending to be vampires

