[0] https://x.com/hwtnv/status/2031326840519041114 [1] https://sentiwiki.copernicus.eu/__attachments/1672913/Revisi...
5-10 ships moving at speed across the ocean. Blasting the skies with radar.
Its as easy as anything is to find it in the ocean. And were pretty damn good at tracking ships at sea even small fishing vessels let alone a floating city.
The threat model to CSGs are basically nuclear submarines from nations that would simply tail the group if needed.
For the first one, just look at wikipedia lists of government says that fly as little triangular constellations, like Yaogan 9A, 9B, 9C on this list: https://en.wikipedia.org/wiki/Yaogan
Those are ELINT birds that use multilateration to spot emitters globally.
SAR can spot wakes far, far, larger than ships using the same techniques as SAR measuring ground erosion, etc.
https://www.youtube.com/watch?v=-GTpBMPjjFc is a good overview of what's up there so far, and what's coming as they really try to scale the technology.
Bandwidth and processing are substantial bottlenecks with SAR; Only targeted and stationary applications have been broadly useful so far, and more focus has been put on planes than satellites for this. SAR is not as simple as taking a static image with a fixed resolution, your sensing window has got a target velocity and distance in mind and the antenna and processing needs to be tuned for that.
I would think that medium and high orbit optical tracking (daytime, cloudless sky) is probably used, because with video you can reasonably track subpixel targets if they're high contrast, without a lot of data transmission requirements.
I'm not sure why you assume this, this is factually incorrect. Satellite based SAR has been successfully used for civilian ship detection applications (traffic management, illegal fishing, smuggling detection, etc) for over three decades. I am sure its military use goes back much further.
> SAR is not as simple as taking a static image with a fixed resolution, your sensing window has got a target velocity and distance in mind and the antenna and processing needs to be tuned for that.
No? SAR satellites take thousands of SAR images of stationary scenes every day. It's true that object motion in the scene introduces artifacts, specifically displacement from true position - this is often called the "train off track" phenomenon, as a train moving at speed when viewed with SAR from the right angle will look like it's driving through the adjacent field rather than on the track. However, this isn't a significant problem, and can actually be useful in some situations (eg: looking at how far a ship is deflected from its wake to estimate its speed).
I feel like there must be people at NRO whi are dedicated to sub tracking via satellite.
Aircraft carriers sail from home ports and are frequently visible to all. The Charles de Gaulle was previously in Denmark for instance, then obviously everyone can also see you crossing the English Channel and Straight of Gibraltar.
So from there it is only a matter of keeping an eye on it for anyone with satellites. So obviously all the "big guys" know where the other guys' capital ships are.
Not all of them.
So, you don't exactly "know" where the ship is, but you can draw a hypothetical geofence around where it's likely to be, and scan that area.
(of all "national security" reasons these is one of more reasonable ones)
It did not say if it had acted at the request of US authorities.
https://uk.finance.yahoo.com/news/leading-satellite-firm-hol...
For example nowadays Planet Labs [1] offers 30-50cm resolution imaging at a rate of one image or 120sec video stream every 90 minutes over a given 500 km^2 region. There is no situation where an aircraft carrier is going to be capable of evading a commercial satellite offering with that frequency and resolution. Once you know approximately where it is or even where it was in the semi-recent past, it's fairly trivial to narrow in and build a track off the location and course.
https://www.planet.com/pulse/12x-rapid-revisit-announcement/
Also nowadays they provide multi-spectal capture as well which can mostly see through cloud cover even if it takes a bit more bandwidth and postprocessing.
(of all "national security" reasons these is one of more reasonable ones)
So now you don't have to do the tracking, just find the hole.
And then you can use a non-US provider to get direct imagery now that you know exactly where to look.
The primary reason however for minimizing radar cross section and increasing radar scatter is to harden protections against radar based weapon systems during a conflict.
Even if the ship is still visible in peacetime operations, once electronic countermeasures/ECM are engaged, it gets an order of magnitude harder for guided missiles to still "see" the ship.
Depending on the kit, once missiles are in the air the ship and all of their friends in their strike group/squadron is going to start jamming radar, popping decoys, and trying to dazzle the missiles effectively enough for RIM-174/SM-6, RIM-66/SM-1, and RIM-67/SM-2s to intercept it without the missiles evading. And should the missile make it to close-in range then it's just praying that the phalanx/CIWS takes care of it.
And if everything fails then all that jamming and dazzling + the reduced radar cross section is going to hopefully result in the missiles being slightly off target/not a complete kill on the vessel.
So they still serve a purpose. Just not for stealth. Instead serving as compounding increases to survival odds in engagement scenarios.
Doesn't matter whether Estonia, Honduras, Laos, and Luxembourg can track their carrier, or not.
EDIT: In confined waters (like the Mediterranean), many more countries could track the carrier if they cared to. Even back in the 1950's, the Soviets got quite adept at loading "fishing boats" with electronic equipment, then trailing behind US Navy carrier groups.
I just ran some googled numbers over my envelope, and I get that the Mediterranean sea (great circle distance between Gibraltar and Beirut is 2300mi) is about 14000x larger than the bow-to-stern length (858') of the carrier.
That's... not that terribly difficult as an imaging problem. Just a very tractable number of well-resolved 12k phone camera images would be able to bullseye it.
Obviously there are technical problems to be solved, like how to get the phones into the stratosphere on a regular basis for coverage, and the annoyance of "clouds" blocking the view. So it's not a DIY project.
But it seems eminently doable to me. The barriers in place are definitely not that the "empty space is just too big". The globe is kinda small these days.
That's why satellites use radars and scientific instrumentation magnetometers to find stuff like ships or even subs underwater.
Identifying a ship is harder, but not insurmountable. In particular, large ships like aircraft carriers tend to have very identifiable radar signatures if your resolution is high enough.
Most naval vessels move in groups/squadrons. Carriers basically always travel with a "carrier strike group"/CSG of a dozen other ships and destroyers often travel in "destroyer squadrons"/DESRONs. So any time you see a cluster of hits, just by the relative responses of each hit you can narrow down and guess the entire CSG/DESRON in one go and then work out which responses map to which ship in the CSG/DESRON once you have a good idea of which group you are looking at.
This is especially true because ships even within the same class have varying ages, different block numbers, and differing retrofits. So each one has a unique signature to it.
But also if you aren't completely certain you can always come back with a second high resolution pass and then it's trivial to identify each ship just visually.
EDIT: the sibling comment already provided a high quality answer: https://news.ycombinator.com/item?id=47458766
Consider shooting a ray at the ocean at an oblique angle from a satellite: it bounces off and scatters away from you. Hardly any of the energy scatters back towards you.
Now, put a ship there. The ray bounces off the surface of the ocean and scatters up into the side of the ship, and from geometry, it's going to bounce off the ship and come straight back towards its original source. You get tons of energy coming back at you.
A ship on the ocean is basically a dihedral corner reflector, which is a very good target for a radar.
> I'm having a hard time imagining a sufficiently high radar resolution for such a wide sensor swath width at such an extreme range. Is the idea that you locate it with the wide sensor swath and then get a detailed radar signature from a more precise sensor?
That's one approach, there are so-called "tip and cue" concepts that do exactly this: a lead satellite will operate in a wide swath mode to detect targets, and then feed them back to a chase satellite which is operating in a high resolution spotlight mode to collect detailed radar images of the target for classification and identification.
However, aircraft carriers are big, so I don't think you'd even need to do the followup spotlight mode for identification. As an example, RADARSAT-2 does 35 meter resolution at a 450 km swath for its ship detection mode. That's plenty to be able to detect and identify an aircraft carrier, and that's a 20 year old civilian mission with public documentation, not a cutting edge military surveillance system. There are concepts for multi-aperture systems that can hit resolutions of less than ten meters at 500 km swath width using digital beamforming, like Germany's HRWS concept.
tl;dr: Radar works very well for this.
This is why the Zumwalt and other low observable designs are going back to roughly tumblehome hulls:
https://en.wikipedia.org/wiki/Zumwalt-class_destroyer#/media...
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If only it could actually do anything. I genuinely don't understand how we refused to retrofit any weapon system to the gun mounts. We have 5inch guns. They aren't the magic cannon it was designed for but do they really not fit? Apparently we are now putting hypersonic missiles in those mounts instead.
Can't exactly make a Carrier that shape though.
They're putting hypersonics on it because they've got 3 hulls and might as well get some value out of them, but not because it's what you'd design for from scratch.
The Zumwalt program was dumb from day 1. It was driven by elderly people on the congressional arms committees that have romantic notions of battleships blasting it out.
The reality is since the development of anti ship missiles, sitting off the coast and plinking at someone is suicidal, even if you have stealth shaping and uber guns of some sort.
It was a DoA mission concept.
Just do a youtube search and you'll find plenty of talking head explainer videos. Ignore the talking head and just look at the imagery and data they share.
I mean fuck, I can pretty easily find the strait of hormuz on the map, pretty sure intelligence agencies can too and just look there for the carrier. If I can't find the carrier there, then I can plot the course between France and hormuz and do a brute force search over that course taking into account such a ship's relative velocity, since it's not like the carrier is gonna zig-zag through south america and the north pole on its way there to avoid detection. Is what I'm saying something sci-fi?
Seems to have come as a shock to the US government.