If anyone has questions about SAR as a tool for tracking human activity - movement of ships or otherwise - I'm happy to answer questions. Mark's work here makes great use of our open data archive, now over 20TBs of openly licensed data free for research or even commercial use: https://aws.amazon.com/marketplace/pp/prodview-ybjvekte4hg7o...
Can you estimate how much cargo a ship is transporting by measuring how tall it is compared to the sea? Is this something that would be feasible with a constellation of tandemSAR-like satellites?
Wow, that's a cool idea. I bet you absolutely can. When you image a ship broadside, it gets projected onto the surface in a flattened way we call "layover" - here's an example of how nicely ships pop out on a flat sea: https://x.com/umbraspace/status/1797970305798816030
Depends on the ship as well, not all ships change their draught ("depth") that much according to what they carry, but ships like bulk carriers and oil carriers certainly do. They report it via AIS data as well, but as its manually input it is often unreliable. An other idea that has been utilized is to look at the vake patterns (wave patterns) to estimate the speed of the ship.
This is really interesting. I have worked a lot with AIS data (messaging system that relays information such as the position of a ship), but the AIS data can some time lack information (and sometimes can be spoofed). However I have never got around working with imagery data. This seems like a great starting point for that :)
It's cherry-picked, but it's a combination of commercial tasking and discretionary tasking. There isn't much to read into in terms of the distribution, it's just one person's best guess at where there's likely to be a lot of diverse types of ships.
Be forewarned, there is also a ton of other data to wade through, but if you find and click all the right boxes the results can be pretty interesting (island wind wakes, ocean current visualizations, etc):
One night in the late 1990s, lying on the grass in a garden in Palo Alto, CA, I saw, with the naked eye, three satellites flying in formation. I believe what I saw was: https://www.satobs.org/noss.html#NOSS2
Seeing through clouds and smoke is impressive. What options do people have at this point to protect their own property from being seen from above? Massive tarps? Is full tree cover enough? Some kind of reflective glass dome? It'd be a shame if it's now impossible for people to have any view of the sky, day or night and rain or shine, without risking being watched and recorded from space.
SAR = Synthetic-Aperture Radar. Radar bounces off of metal very well. Some strategically-placed radar reflectors, or a metal-lined fabric, could do it easily. It would also show up _very_ brightly on the resulting images.
The US Navy operates under the assumption that the position of their ships, excluding submarines, is known at all times by adversaries. This has been the case for decades.
I see some asking about capabilities and such - well there's a bunch of (satellite-borne) sensors for detecting ships
- SAR
- Optical
- NRD
- LIDAR
- AIS / VMS / LRIT
etc.
Truth be told, detection tends to be a fusion of sensors. When it comes to non-cooperative objects, sensors like SAR, Optical, NRD, LIDAR are often used. NRD sensors detect ship navigation radar on S- and X-band, while LIDAR detects light from ships. Optical and SAR everyone knows.
It's not that it doesn't work, it is just prohibitively hard. The other comments here pointed out GEDI which is a LIDAR payload on the ISS. But it's resolution is only 25 m. This is compared to the resolution of the Umbra satellites of ~0.5-1m. So with something like GEDI you could see large ships. But you would need a larger telescope and/or more powerful laser to get better resolution.
If 16cm through clouds and rain has been publicly available for three years, what does military have and for how long? And with that capability, and in a post-9/11 world, how could an entire rogue airliner not be traced to within sqm's of impact/landing?
The finer the resolution, the more narrow the scanner path is (and in any case satellite scanner paths aren't that wide, also for low-resolution optical scans). The Umbra satellite swath is a tiny 4km wide. And then along-track as well.
The total area a radar satellite (or an optical one) can scan at any particular time is very limited. A satellite, even multiple ones, will only see an airliner if it happens to be in the right spot at the right time.
It's also not imaging all the time. The SAR imaging takes A LOT of power, so they can't run it constantly. If you look at the image in the article showing where the images were taken they are all near geopolitical hotspots, coastlines, high shipping areas, etc. It's not just a swath scan of the whole world.
also, by the physics of synthetic aperture radar, UMBRA (or any other satellite operator for that matter) can only collect 16 centimetres data at an angle equal or greater than ~45 degrees off-nadir (and for UMBRA, less than ~60 degrees off-nadir). this further restricts the footprint of feasible data collection.
> If 16cm through clouds and rain has been publicly available for three years, what does military have and for how long?
It is my understanding that phased-array antennas, of the type Starlink satellites carry, are also excellent for phased-array radar.
It's known that Starshield covers both military use of the civilian Starlink network, as well as military-dedicated satellites for communications and other functions. I suspect that during wartime Starlink will be the world's most comprehensive (and, thanks to its scale, most survivable) space-based radar system.
Phased array antennas are indeed usable antennas for radar purposes and many modern radars use them. That said just having a suitable antenna is not enough for having a radar system, you also need sophisticated equipment for both transmitting powerful enough pulses and receiving the (extremely weak) reflections. The power of the reflections drops with the fourth power of the distance to the target. From a quick look at the starlink satellites I very much doubt they could effectively function as a radar system. There's just not enough solar panels to power a big radar on there.
Background: I used to be an weapons engineering officer working on future radar systems back in my Navy days.
> how could an entire rogue airliner not be traced to within sqm's of impact/landing
Because nobody is looking. Umbra doesn't provide realtime global coverage, any location is only visited once per week. The chances of a specific location being captured right as a rogue airliner is flying over it are basically zero.
I also wouldn't be surprised if it didn't record any data over the open ocean. The vast majority of it is just waves, and nobody is ever going to pay for petabytes of empty images, so why bother? Same with capturing airlines at all: they are essentially always image artifacts, so I would expect them to be deliberately filtered out quite early in the pipeline.
I wouldn't be surprised if the US military had the capacity to track airplanes from space. But tracking every single commercial airliner, on the extremely remote chance that one of them goes rogue over a remote ocean? Not a chance, it'd be extremely expensive and provide zero strategic benefit.
This kind of makes sense, but to me, in a post-9/11 world, the US military would definitely be scrambling whatever they have to track a rogue airliner that's gone completely dark, yet is still verifiably flying (sat pings).
They kinda do, via sattelite pings, radar, etc. Whether they have radar coverage is another matter. I'm confident they have coverage all along the US coast and military bases, but other areas are temporary, like the AWACS flying over UN territory looking into Russia and Ukraine to provide the Ukrainians with intel (one from the French air force flying over Romania: https://apnews.com/article/ukraine-russia-surveillance-defen... and another over Poland: https://www.cbc.ca/news/world/flying-with-nato-awacs-1.66194...)
You know what’s huger? The Indian Ocean. Add to that the lack of blue-water competition in it and it’s totally reasonable that any birds we have in the area are craning their necks north, not down.
“Nearby” is doing a lot of work there. The presumed flight path of MH370 went tens of thousands of kilometres from Diego Garcia, certainly outside the range of even the latest over-the-horizon radars. Meanwhile the tracking stations on that base are mostly focused on space activity and missile launches.
No amount of money can break the laws of physics and, like any sensor, radar has fundamental limits in range and resolution. MH370 flew into one of the most remote parts of the ocean it’s possible to reach, it would’ve been a miracle if it was tracked by any radar.
The presumed flight path at the time it went missing is perhaps relevant, and that was within the vicinity of Diego Garcia, as the flights last few known turns were heading toward it. It seems odd the US would not care nor have tracking ability.
I've seen analysis that showed the flight was within range of several over-the-horizon radars at the time of disappearance and for hours after, ie - someone should know more than we do. As often with such things, I can't find it again.
OTH radars are not operating all of the time, given the cost to operate them, and are not just covering large areas of ocean all over. They're typically focused specifically on areas of most importance which, for Diego Garcia, would be north toward China, not East toward Malaysia.
Nor do OTH radars always operate at maximum efficiency: They achieve their longest ranges by bouncing signals off the ionosphere, which is severely affected by prevailing space weather.
The only radar that it likely did pass through was Australia's JORN, but the western sector was not operational that night and isn't on 24/7 because of cost constraints.
Good points but neither of them rule out being reconfigured and used in an emergency, potential hijack situation to locate what could be a significant security threat. Airliners were used for the biggest attack on US ground since WW2. Priority number one.
Only if there’s enough forewarning, the radar is operational, the aircraft is within its range given prevailing space weather conditions, and that it’s pointing in the right direction. The latter is important because OTH radars are almost all fixed and can’t be steered.
Yes, governments would love to have global 24/7 coverage even over the open ocean. In practice that’s neither possible nor practical.
Given their strategic advantage, you can bet the military will have prioritised steerable.
I disagree with the general premise regarding global coverage. With the US military, capabilities, especially in surveillance, have historically been shown to be decades ahead of what the public thinks is possible.
Personally, if a post appeared tomorrow showing some HN had figured out how to trace the movements of any airliner, without using its adsb and relying instead on anything and everything else that's publicly available, from satellite imagery, to radio frequency data, to radar, even weather data (contrails are often detectable), it would seem cool, sure - but, not unbelievable.
That hypothetically believable scenario would be one person, with no budget, in likely a few weeks or months of their spare time.
The US military has trillions of dollars, the best talent in the world, and decades of dedicated effort in exactly this area, and a propensity to keep such advances secret for decades (as shown recently enough by the Trump photo).
> Given their strategic advantage, you can bet the military will have prioritised steerable.
This is not something you can really prioritise. OTH radar designs are a trade-off between range, angular resolution, frequency, and mobility. For the longest-ranged systems with good angular resolution you can't steer them outside their set beam pattern, because their sheer size makes that kind of steering impossible. So if you want steerable radars you necessarily have to compromise on range, angular resolution, etc.
> I disagree with the general premise regarding global coverage. With the US military, capabilities, especially in surveillance, have historically been shown to be decades ahead of what the public thinks is possible.
Again, there are fundamental limits here. As much money as the US military has, it can't break the laws of physics. We also have a good sense of what types of assets it has and where they are, including satellites.
> Personally, if a post appeared tomorrow showing some HN had figured out how to trace the movements of any airliner, without using its adsb and relying instead on anything and everything else that's publicly available, from satellite imagery, to radio frequency data, to radar, even weather data (contrails are often detectable), it would seem cool, sure - but, not unbelievable.
Doing so over the vast open ocean would indeed be unbelievable. Even doing so for an individual over an ideal location would not be believable, as available resources don't make this possible at any real scale with the necessary granularity.
> The US military has trillions of dollars, the best talent in the world, and decades of dedicated effort in exactly this area, and a propensity to keep such advances secret for decades (as shown recently enough by the Trump photo).
See my point above. As for the Trump photo, by which I presume you're referring to the satellite image of the failed Iranian launch, the displayed resolution was within what experts had already presumed was within the capabilities of deployed US satellites given all available information. The photo didn't display surprising capabilities, it merely provided an official confirmation about what was already widely assumed.
What is the point of tracking rogue airliner in the middle of the ocean? It isn't a threat to anything except itself. Regular radars can track it when gets close to land, and scramble fighters.
Also, tracking has gotten much better. There are ADS-B receivers on satellites that can cover the whole globe. But nothing helps if plane turns off its transceivers.
If military capabilities are secret then whatever they might be able to detect will not be passed on to the public because that would obviously inform adversaries about those capabilities. Remember Trump's gaffe when he shown satellites pictures of some Iranian facilities taken by a secret satellite...
As others have commented, there is also a difference between ultra-high definition pictures of precise locations and sweeping entire oceans.
This was a really nice post, using imagery to confirm the positions of ships is really useful when the normally used data source, AIS data, has lacking data or may be spoofed. I have mostly worked with AIS data, but might incorporate these data as well to see what can be found.
YOLO is amazing. When I first looked at the loss function in YOLO v1, I was stunned: You can do regression loss(Mean square error) instead of classification loss(categorical cross entropy) on class prediction probabilities, and it can still just "work".
I imagine the YOLO researchers would argue MSE is more "correct" in their case. Yolo has augmentations that combine images with different labels. If you make an image that's to 30% composed of the image of a train and to 70% the image of a car, you can argue it should be predicted as 0.3 train, 0.7 car, 0 everything else. But now you are suddenly doing a regression task.
Most modern military vessels could spot them, but typically the air warning radar has its filters configured such that satellites are excluded (as they are not interesting targets for most naval vessels). This also heavily depends on the exact orbit of course. Low orbit satellites like starlink are quite below the maximum altitude from ballistic missiles, geostationary orbit is usually too far away to still detect within the unambiguous range of the radar system.
Most SAR systems operate in X-Band (~10 Ghz). I guess it's fair to assume that every organization who has ever sent anything to space has also launched SAR satellites. The radar part is comparatively easy to getting things into orbit.
I'm wondering how long it will be before transponder data and satellite imagery will be correlated to look for suspicious activity like individual ships moving their transponders to small decoy ships while they commit crimes.
Your point is taken though, tons of remote sensing signal you can fuse to detect malicious marine activity (I'd argue in real time). If you can detect the ship from orbit, and the AIS doesn't align with owner, cargo, and previously expected route (or there is no AIS), strange things are afoot.
Spire seems to require that ships send AIS data. They're checking the self-reported positions AIS sends vs. distances measured from their the satellites.
They won't detect no-AIS ships.
Right, that’s what SAR is for: to subtract AIS reporting ships from radar detected ships. No AIS when there should be? Hello, we see you, can’t hide from the radar.
Carriers will also never be going alone; they're part of a battle group (https://en.wikipedia.org/wiki/Carrier_battle_group) with anti-air and -sea defenses to intercept any incoming counterattacks. In theory anyway, that wiki article has some criticisms about whether it's still viable today with hypersonic cruise missiles, u-boats, drones, etc. It hasn't come to a full on naval battle since WW2 though, so a lot of naval strategies and technology is theoretical. It is being tested nowadays with attacks on ships from the mainland from the Houhtis though.
> hasn't come to a full on naval battle since WW2 though, so a lot of naval strategies and technology is theoretical
Even then, aircraft carriers being unsinkable was a myth.
“In 1942 the US lost as many carriers as the Japanese—and a larger percentage of their overall carrier force” to the extent that it “was almost out of carriers in the Pacific in late 1942.”
“Why the US ended up winning the war in the Pacific was therefore not because of the fleet that they started the war with—it was the fleet that they ended it with—almost all of whose most effective and advanced warships were launched after the Battle of Pearl Harbor on December 7, 1941” [1].
Aircraft carriers were a key component of projecting power into the pacific. They've never been impregnable (obviously both sides lost carriers in the pacific, including at least one I can think of to a lone submarine).
> “Why the US ended up winning the war in the Pacific was therefore not because of the fleet that they started the war with—it was the fleet that they ended it with—almost all of whose most effective and advanced warships were launched after the Battle of Pearl Harbor on December 7, 1941”.
Considering that the tonnage of ships the US had was limited by treaty (treaties were expired, but it takes time to build ships) and that Japan's attack further reduced the fleet strength, one would expect that the US won with ships built after Pearl Harbor.
There was an 18 month period in which the US built more fleet carriers than Japan had in the entire war. In addition, Japan lost a huge fraction of their experienced pilots in 1942, which was arguably as deleterious as losing the carriers.
That's revealing a severe deficiency in Russian air-defense and close-in defense (tactics, equipment, probably a bit of both). People looking to smack the US Navy in the same way would be wise to look at how Kyiv's Patriot batteries have fared, though; quite a bit better, including against hypersonics.
Also, the Houthis attacking ships in Red Sea have shown that modern air defenses work. None of the warships have been touched. Two cargo ships have been hit. The warships have shot down a lot of missiles and drones. Which is really expensive and hasn't opened up the Red Sea. But shows that attacking warships is harder than the Houthis, who have proper anti-ship missiles and ballistic missiles in addition to drones.
The Black Sea is a de facto big lake, any big navy would have the same problems as the Russians now have against drones and land-based missiles. In a way the Americans are now experiencing the same problems in the Red Sea, hence why USS Eisenhower had to escape 200 miles North to Jeddah once it started being targeted a few weeks ago.
Which is to say that the Black Sea / Red Sea is not the Midway Atoll with its wide-open ocean.
> The Black Sea is a de facto big lake, any big navy would have the same problems as the Russians now have against drones and land-based missiles.
I doubt that; Russian land-based air defense is struggling in a similar fashion. Very little get anywhere near Ukraine's Patriots, while hand-me-down NATO-supplied weapons are happily taking out S-300 and S-400s in Crimea. As for drones, the US has been dealing with small-boat attackers for significantly longer; I'm sure they're using lessons learned in Ukraine to improve, but in jet ski versus CIWS in open waters, I'm betting on CIWS.
(That said, you would indeed avoid getting a carrier group stuck somewhere like the Black Sea.)
> hence why USS Eisenhower had to escape 200 miles North to Jeddah once it started being targeted a few weeks ago
Notably, it's not on the bottom like the Moskva.
Being able to pretty effectively take down threats doesn't mean you need to unnecessarily risk it, but Russia's difficulty a) defending against NATO missiles and b) striking back against NATO air defense in Ukraine should give folks like China some serious pause in their own planning.
> Very little get anywhere near Ukraine's Patriots,
Not sure about that, plane-launched FABs are creating havoc on the Ukrainian front-lines.
> Being able to pretty effectively take down threats doesn't mean you need to unnecessarily risk it
Of course, but that's how you get to the "Fleet in being" [1] situation, which I'm not sure it's the ideal solution for the US Navy, which (afaik) consumes about a third of the US military budget. I mean, how would the US Navy commanders be able to explain that they're spending that much money only for their magnificent warships to avoid direct battle contact?
> striking back against NATO air defense in Ukraine should give folks like China some serious pause in their own planning.
Neither China nor Russia depend on their fleets in order to win existential wars for them, as they're both continental powers, so not sure a Russian cruiser ending on the bottom of the Black Sea will make any strategic difference. Also, geographically speaking there's no sea between South Korea and both Russia and China, and the sea distance between the same China and Taiwan is pretty small, they'd be able to provide artillery/missile cover for it entirely from land.
> Neither China nor Russia depend on their fleets in order to win existential wars for them, as they're both continental powers
Chinese are hopelessly dependant on imports of raw commodities (most notably oil), a naval blockade would sent them back into Middle Ages in a matter of a couple of years. Hence, their continous existence is contingent on strong navy. Which they presumably get, seeing how much they invest in it.
That is false, which is why Romania, my country, has just approved sending one of its (only) two Patriot systems to Ukraine.
> The idea of the US Navy as a “fleet in being” is simply absurd at the present time.
It is absurd if you ignore the facts on the ground (on the sea?), and the facts show that the USS Eisenhower has chosen to avoid direct confrontation with land-based missiles shot by the Houthis.
More generally, people should try to look closer at the facts as they are happening (again, saying that Ukrainian Patriot systems have been unaffected this far into this war is just ignoring facts), that's good advice for any war, past, present or future.
That's not exactly how it works. The satellite operator will be taking paid orders to scan over specific areas of the earth, about 4km in width or so.
So you have to have a pretty good idea where the carrier is, and then you get an image delivered with some latency as the satellite will need to pass over a ground station that downlinks the data.
So it isn't free (although umbra has a CC BY 4.0 license for their data, much more permissive than other providers. Nor is it easy to search huge amounts of the ocean for the carrier.
What most entities probably do is tip and cue, which is use a sensor with coarser resolution to get an approximate location and then use a sensor with finer resolution to look closer.
