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Comment by ricardobeat | Hacker News Reader

Planet Labs already has full coverage of the Earth, and with the latest SkySat (another 3 launched earlier today) they will have the ability to image the same point on earth 12x a day.

I think it's very unlikely that the USA and maybe others don't have this capability already.

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The USA does not. The NRO does not operate large fleets of small satellites. They have just a few big ones. The optics are way better though.

>> optics are way better though

That was going to be my question. Doesn’t the NRO need big optical lenses for their missions? Are there any “telescopic” advancements that can fit into small sats that can meet their mission objectives?

Yes. My understanding of these things based mostly on trolling through the various digital imagery company websites, is that many of the small satellites can generate detail as good as the "big guys" (at least as far is known in open sources) by using a telescopic lens. The difference however is aperture. Given the size of the optics on a small satellite the amount of area it can cover at 1 meter per pixel resolution is much smaller than something with a very large aperture could. As a result if you take a 10 Mpixel image with 1 meter per pixel accuracy that is a region roughly 3.2km on a side. Not a particularly large area.

Do the small sats have an advantage by being closer to the target, needing less zoom?

Higher orbits are much more expensive to launch a satellite into. I think partially because of this, commercial imaging satellites will be in the range of 600-800km altitude unless there's a really good reason otherwise. So I don't think that distance would account for a very large factor.

Yes. The difference between 100k-400km in LEO is far different from 22000km in GEO. Planet Labs updated their licenses for a few satellites a couple of months back to gain double digit percentage resolution quality increases by dropping the orbit (I think it was somewhere about by 50km to the lower end of that range) for example. The trade off is that you hit more atmosphere in that lower orbit and will reenter the atmosphere much sooner. So that increases the number of launches you need to do to replenish your fleet. Which is $$$.

Also, they have greater relative velocities so require better targeting and command & control technology to compensate.

Nothing open source can take images anywhere near the capability of spy satellites.

We learned this when Trump tweeted an image of the Iranian missile/launch vehicle disaster.

Maybe [1] https://en.wikipedia.org/wiki/Superlens &

[2] https://en.wikipedia.org/wiki/Negative-index_metamaterial

can change that? Also I'm sometimes wondering what happened to Holography, and if something like

[3] https://en.wikipedia.org/wiki/Invention_Secrecy_Act came into play?

There's also rules on launching a satellite with capabilities below 10m per pixel on the basis of national security. At least if you're an American company anyway, can't vouch for elsewhere but they're a bit behind the tech curve (at least in the private sector) in this field (but not by much) so it hasn't really come up yet as an issue so far.

There was an image that Trump tweeted a satellite image about something in Iran a while back, I forget the actual reason. But it was a declassified image of something and some keen eyed observers did some analysis on it and concluded the resolution was better than what is "Officially" out there. So it's safe to say there's better out there that we just don't know about yet.

Rocket blew up on pad during launch.

[1] https://www.thedrive.com/the-war-zone/29634/trump-tweets-int...

Made me think of the movie "Enemy of the State" from 1998, and another action/sci-fi B-Movie from before 1980 which I can't remember the title anymore because forgettable, except of the FLIR inserts they made. Which were as good as anything you can personally buy today as private person.

In a B-Movie! From before 1980! (Maybe even 1975/76) W-T-F?

I really can't remember the title anymore, because "loading, looking, lösching!" (loading, watching, erasing)

In 2012 the NRO turned over two satellites to NASA [0] for research purposes. The scientists who have examined them (they have not been launched yet) described them as being better than Hubble even though they are comparable in size (designed to fit in the Shuttle bay). Given the unlimited funds available to them, I expect they're a decade ahead of industry.

The NRO is probably going for larger lenses in future satellites to increase their field of view. Could they use a series of smaller sats orbiting in a cluster to form a virtual lens, much like the multiple mirror telescope in Arizona [1]? Maybe.

[0] https://en.wikipedia.org/wiki/2012_National_Reconnaissance_O...

[1] https://en.wikipedia.org/wiki/MMT_Observatory

Probably. At least it works for RADAR in

[1] https://en.wikipedia.org/wiki/TerraSAR-X

[2] https://en.wikipedia.org/wiki/TanDEM-X

edit: optical [3] https://en.wikipedia.org/wiki/Sentinel-2 but with rather low resolution.

To clarify what they turned over were lens and optics assemblies that are a sort of cousin to the hubble space telescope's structural body and lens, not whole satellites. No power systems, no control electronics, no batteries, no comm systems, etc.

There are proposals[0] for mirror-fleet based exoplanet detecting and imaging, as well as for resolving the purported 20 km neutron star seen/known as the Crab Pulsar.

But accurately controlling such a swarm seem like a still-untested concept.

[0]: https://www.researchgate.net/profile/Olivier_Lardiere/public...

Ultimately, the diffraction limit means that--all else held equal--larger optics will always beat smaller optics for image quality.

Any tricks used to aid small optical platforms will have as much, or more, of an improvement if applied to large optical platforms.

Don't forget the NGA.

[1] https://en.wikipedia.org/wiki/National_Geospatial-Intelligen...

We have no idea whether that's true since such capabilities are incredibly classified.

Except Trump tweeted a picture taken by one of these satellites, so we do in fact know their capabilities.

Yes, that puts the lower bound for spy satellites at one. Who could have known that before?

Don't forget that many of those images will be of cloud.

do they all work in the visible spectrum?

Companies like Capella Space and ICEYE operate in the RF/radar spectrum

A person I know at ISRO mentioned that Planet labs did the launches from India in violation of US accords. Not sure exactly which ones.

No that’s Swarm Technologies.

https://qz.com/1226962/an-unauthorized-satellite-launch-in-i...

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