[HN Gopher] Satellites Spotting Ships
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Satellites Spotting Ships
Author : ingve
Score : 172 points
Date : 2024-06-18 10:29 UTC (2 days ago)
(HTM) web link (tech.marksblogg.com)
(TXT) w3m dump (tech.marksblogg.com)
| robxorb wrote:
| 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?
| TMWNN wrote:
| > 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.
| RF_Savage wrote:
| At least the civilian Starlink sats will not be able to do
| that. The transmit and receive frequencies are different and
| limited by hardware filters.
|
| They would be most useful for communications and possibly
| enable interference mapping.
|
| Or finding Ku-band VSAT terminals of other users.
| WJW wrote:
| 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.
| Tor3 wrote:
| 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.
| m2fkxy wrote:
| 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.
| dr_orpheus wrote:
| 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.
| crote wrote:
| > 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.
| robxorb wrote:
| 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).
| 14u2c wrote:
| In Southeast Asia? The US military probably didn't even
| hear about it until after it was missing for a bit.
| robxorb wrote:
| As is often the case almost anywhere in the world,
| there's a major US military base nearby. In this case
| it's Diego Garcia, and is absolutely huge:
|
| https://veteranlife.com/military-history/diego-garcia/
|
| "The base is home to thousands of American troops,
| sophisticated radar, space tracking, and a communications
| facility."
| JumpCrisscross wrote:
| > _it 's Diego Garcia, and is absolutely huge_
|
| 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.
| _djo_ wrote:
| "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.
| robxorb wrote:
| 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.
| _djo_ wrote:
| 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.
| robxorb wrote:
| 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.
| _djo_ wrote:
| 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.
| ianburrell wrote:
| Not tens of thousand of kilometers. Diego Garcia to tip
| of Indonesia is 2800km and 3000km to Australia. But the
| rest of your post holds.
|
| Also, the over the horizon radars are in Australia. I
| think they could have picked up the flight but were
| offline that day.
| _djo_ wrote:
| Appreciate the correction, I meant thousands.
|
| Yes, that's the JORN system. The western sector might've
| picked it up if it went near western Australia as
| presumed, but it wasn't operating.
| Cthulhu_ wrote:
| 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...)
| ianburrell wrote:
| 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.
| mytailorisrich wrote:
| 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.
| dist-epoch wrote:
| This is one of the reasons in any real war, all the aircraft
| carriers will be far far away from the conflict region.
|
| Now your average Joe can track them from their desktop for free.
| scanny wrote:
| 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.
| dist-epoch wrote:
| Sure, I was over simplifying it. China will already have a
| good idea where the carrier roughly is - the previous
| position.
|
| And they will also have their own satellites.
| Cthulhu_ wrote:
| 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.
| JumpCrisscross wrote:
| > _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].
|
| [1] https://phillipspobrien.substack.com/p/war-and-
| deterrence-in...
| badpun wrote:
| It's mainly being tested in the Black Sea, where Ukrainians
| are methodically sinking Russian ship after Russian ship,
| with cheap drones.
| ceejayoz wrote:
| 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.
| paganel wrote:
| 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.
| ceejayoz wrote:
| > 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.
| paganel wrote:
| > 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.
|
| [1] https://en.wikipedia.org/wiki/Fleet_in_being
| ceejayoz wrote:
| > Not sure about that, plane-launched FABs are creating
| havoc on the Ukrainian front-lines.
|
| The Patriots aren't on the front lines, and weren't
| allowed to even shoot at the planes lobbing bombs from
| Russian airspace until just recently.
|
| Attempts to knock them out have failed. The same is not
| true for the Russian equivalents deep in Crimea.
|
| The idea of the US Navy as a "fleet in being" is simply
| absurd at the present time.
| ianburrell wrote:
| 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.
| FuriouslyAdrift wrote:
| Wake seeking long range semi-autonomous torpedoes are a major
| threat and are already deployed.
|
| Currently they have about a 100km range.
|
| The subs can fire from far away, move and fire again from
| different angles.
|
| A ship could have dozens coming from all directions.
| Mikhail_K wrote:
| Neural networks are statistical in nature and their results are
| inherently unreliable.
| jgrahamc wrote:
| 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
| quercusa wrote:
| Thank you! Saw those about 92-93 while camping in the Ventana
| Wilderness and have always wondered what they were.
| ravivyas wrote:
| Damn... I was hoping to read more about ships that could spot
| satellites :)
| WJW wrote:
| 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.
| dzhiurgis wrote:
| How about RTL-SDR detecting SAR signal?
|
| I just wonder how many SAR sats we don't know about.
| KeplerBoy wrote:
| Won't work with a regular RTL-SDR.
|
| 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.
| TrackerFF wrote:
| 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.
| dzhiurgis wrote:
| I don't think LIDAR works from satellite, the distances is just
| too high.
| is_true wrote:
| https://gedi.umd.edu/instrument/instrument-overview/
| dr_orpheus wrote:
| 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.
| b_emery wrote:
| You can also see ships in the SAR data available here:
| https://ovl.oceandatalab.com/ (eg from the ESA satellites).
|
| 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):
|
| https://ovl.oceandatalab.com/?date=2024-02-13T12:00:00×...
| campchase wrote:
| 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...
| KeplerBoy wrote:
| 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?
| campchase wrote:
| 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
| stefan_ wrote:
| Does the commercial tasking feed into the open dataset? Or is
| it more a case of once the satellite is up, might as well keep
| it busy?
|
| Just wondering since the distribution of locations shown in the
| blog post seems particular.
| campchase wrote:
| 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.
| itissid wrote:
| 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".
| wongarsu wrote:
| 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.
| Qworg wrote:
| A direct use of work like this is to detect and stop illegal
| fishing, an enormous environmental problem and human trafficking
| contributor.
|
| For example: https://www.skylight.global/
| kylehotchkiss wrote:
| How does the US DoD feel about this? It was my understanding the
| exact location of different fleets was something that wasn't
| public info
| dr_orpheus wrote:
| Probably pretty good since the NRO is buying data from Umbra:
|
| https://spacenews.com/nro-signs-agreements-with-six-commerci...
| jandrewrogers wrote:
| 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.
| pyuser583 wrote:
| Future positions are a different matter, which is why the
| Navy is quiet about scheduled port calls.
| Animats wrote:
| Now for something that takes this data and detects ships with no
| AIS data, or which changed AIS identity.
| toomuchtodo wrote:
| https://insights.spire.com/maritime/dark-shipping-detection
|
| 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.
| Animats wrote:
| 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.
| toomuchtodo wrote:
| 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.
|
| Maybe there is a variable I'm missing?
| autoexec wrote:
| 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.
| tony_cannistra wrote:
| 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.
| banish-m4 wrote:
| 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.
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