Space based active optical sensors for maritime surveillance

Question

I am designing a CubeSat. The size is yet to be decided as it is based on the sensor. The mission is maritime surveillance (illegal fishing). The payload should be capable of detecting the vessels. The operation should not be interrupted by the time of the day (Meaning, the payload detection capability should be active both during day & night). It should not be interrupted by the weather. Based on these constraints, the only options for the sensor are an active optical sensor or the SAR sensor. I cannot go with a SAR sensor as my orbit is a circular 12-degree inclined LEO orbit and so it will go through ~45 minutes of eclipse each orbit making continuous solar power impossible. Is there any laser sensor that I can use for this purpose? Or any other optical sensor that would be suitable here? Kindly please advise.

EDIT:

This is my course project however, I need to design it using the realtime subsystems/payloads.

Thanks everyone for the response. Some of the points I would like to highlight here. uuv & Leonardo are based on AIS data. We have been intrigued about what if the AIS radio on the boat/ship is turned off as they intend to do illegal fishing.

Also, with respect to my project, my satellite sensor intends to do only the surveillance on the particular region of the sea. So, If I use the ADCS attitude sensors, would I have the ability to turn on SAR only for the region needed and when the satellite went past that area if the SAR sensor is turned off, can the power be an issue?? Can this (SAR sensor turn ON/OFF) be even done?

Also, this is not a single satellite. I am designing a 3 x constellation of satellites to assess that particular area for better coverage and decent revisit rate.

Possible worth mentioning if this is a course project or a serious proposal? The former can use blue sky tech, the later will restrict you to things that actually exist and your launch provider will accept. — GremlinWranger, Sep 25 '21 at 13:27
Worth noting that continuous SAR operation is not practical even in SSO, for instance RCM can only use its SAR for ~20% of the time per orbit. — BrendanLuke15, Sep 25 '21 at 16:57
@BrendanLuke15 the application for this particular satellite might simply be detection of the presence of a ship, not necessarily imaging it at 1 x 3 meter resolution. Once a ship is noticed that does not have its ears on they just call Leonardo DiCaprio to investigate (maybe with a bigger SAR system or a coast guard) https://usa.oceana.org/IUUVesselTracker — uhoh, Sep 25 '21 at 17:11
@geetha this is a great question! I am wondering if you need to rule out SAR so quickly. As mentioned above, perhaps you only need to detect ships and not really image them at high resolution. That may be doable with a lot less power, and therefore with battery power instead of needing continuous sunlight. SAR (and radio in general) goes through clouds and light simply does not. I think you may have to find a way to make lower power, lower resolution SAR work as a ship detector but not imager, and then ground software can compare to AIS or IUU — uhoh, Sep 25 '21 at 17:15
just for fun, some images of ships in the Suez Canal when it was blocked — uhoh, Sep 25 '21 at 17:21
The USGS hopes to complete collection of lidar data for all of the U.S. and its territories by 2022 (status map). Due to high cloud cover and remote locations, Interferometric Synthetic Aperture Radar (IfSAR)—rather than lidar—is being used in Alaska. From what I can tell, a modest sized satellite (but perhaps bigger than 6U cubesat) could detect ships at sea via LIDAR, if it knew where to point it's beam, but over a single pass probably could not cover a large area. — uhoh, Sep 26 '21 at 02:53
I think for a given amount of power SAR can detect ships over a larger area than LIDAR because radio can be converted to electrical signals directly and processed whereas the returning individual photons must be converted to electron-hole pairs in a photodetector and that current has to be amplified for detection. https://space.stackexchange.com/a/55116/12102 but I'm not sure yet so I've just asked Given 10W and a 100 square meter target to look for, which can search a larger area; SAR or LIDAR? (back of spherical cow-shaped envelope question) — uhoh, Sep 26 '21 at 03:29
Re: Edit > This mission architecture is sounding a lot like Canada's RADARSAT Constellation Mission, where the SAR is only used when over the target of interest (i.e., SAR can be turned ON & OFF). Another thing to consider is the prevalence of wooden vessels (wood + RADAR = poor results) — BrendanLuke15, Sep 27 '21 at 13:37
@BrendanLuke15 With your previous comment, the application for this particular satellite might simply be detection of the presence of a ship. How do you detect the ship whose Radios are turned off. Are you aware of any RF scanners (COTS CubeSat compatible) to detect shipe — geetha, Sep 28 '21 at 06:31
Unfortunately I am not familiar with real/specific commercial CubeSat hardware — BrendanLuke15, Sep 28 '21 at 14:25
You can subdivide your options into "active" or "passive" detection. With passive, you rely on the target's inherent emissions (radio links, radars, heat, ...). You must know the characteristics of your targets' emissions. With active, you rely on the target's reflection properties of illuminations of your choosing (or natural ones =sun light). If you have a power constraint with the illuminator, you may consider dedicating sats/orbits to the illumination jobs and other sats/orbits to the detection job. Finally, you can combine active and passive in some sequential CONOP. — Ng Ph, Sep 29 '21 at 16:45
@NgPh With respect to the target emissions, radio links, radars are ruled out considering those would be turned off but to detect heat, what kind of sensors can be used for small satellites? — geetha, Sep 30 '21 at 00:48

score 3 · Answer 1 · answered Sep 30 '21 at 16:37

This is not an answer, but additional information on sea fishing and observation from space.

One of the projects that the cosmonauts were engaged in at the Mir orbital station was the observation of plankton on the surface of the ocean. Сosmonauts tracked large yellow spots on the surface of the oceans - an accumulation of plankton, near which there are usually many shoal of fish. And they passed this information to fishing ships.

Thus, ships in the plankton area are most likely to be fishing vessels.

Space based active optical sensors for maritime surveillance

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