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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

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 2y ago
> 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 2y ago
  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 2y ago
  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 2y ago
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.
- dr_orpheus 2y ago
  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.
- m2fkxy 2y ago
  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.
crote 2y ago
> 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 2y ago
  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).
  - ianburrell 2y ago
    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.
  - 14u2c 2y ago
    In Southeast Asia? The US military probably didn't even hear about it until after it was missing for a bit.
    - robxorb 2y ago
      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/ https://veteranlife.com/military-history/diego-garcia/ "The base is home to thousands of American troops, sophisticated radar, space tracking, and a communications facility."
mytailorisrich 2y ago
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.

TMWNN 2y ago

> 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 2y ago
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 2y ago
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 2y ago

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.

dr_orpheus 2y ago
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.
m2fkxy 2y ago
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.

crote 2y ago

> 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 2y ago
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).
- ianburrell 2y ago
  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.
- 14u2c 2y ago
  In Southeast Asia? The US military probably didn't even hear about it until after it was missing for a bit.
  - robxorb 2y ago
    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/ https://veteranlife.com/military-history/diego-garcia/ "The base is home to thousands of American troops, sophisticated radar, space tracking, and a communications facility."

mytailorisrich 2y ago

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.