Can a spy satellite detect a submarine's nuclear reactor from space?

[Gary Compton]

Okay, in my WIP, I have a sub that has a cloaking device. The system bends sound waves around the hull and allows them to travel in their original direction, thus making the boat invisible to sonar.

I need a spy satellite to pick her up. Either a radar, infra-red or system that can track a nuclear reactor.

Any ideas chaps and chapesses?

I've done the usual research but nothing jumps out

 

[Gumboot]

There's nothing that currently exists... (at least that we know of...)

 

[Gary Compton]

There's nothing that currently exists... (at least that we know of...)

Does that mean I can make it up and get away with it?

 

[Abernovo]

The reactor should be shielded, both by the reactor lining (protecting the crew) and depth of water. The one thing that I thought of (not sure how realistic) is a complex algorithm to detect variance in temperature, salinity and plankton phosphorescence caused by the passage of the sub through the different strata of the sea. By the time it reached the surface it would be small, but you could have a very accurate satellite.

The data would also be old, having come up from the depths, so you would only have a projected path for the sub, creating a box to search and then home in on. Not sure how helpful that is, but use it if you want.

One thing about sonar - the biggest risk would probably not be active sonar (the ping type) which you could perhaps redirect, but passive sonar detection. That listens out for sounds, such as the sub screws, especially cavitation as they churn the water. I'm sure you've thought of this, but you'll also want a disguising effect for sound of water displacement.

As gumboot says, this doesn't exist, and possibly isn't truly feasible, but you could bluff it out.

 

[Gary Compton]

I already know that stealth subs are probably patrolling the seas, as we speak. See here

Just need to track her from space. Is it possible to completely hide a nuclear reactor. How do they do it?

 

[ctg]

Yes, it's possible to hide to a reactor, and it wouldn't be reactor that they are as they're looking where it comes up to the surface, or drive just under the waves. But then again, they wouldn't be needing satellites as they can do that with a Nimrod fleet.

However, if you're taking this to SF high-tech level then suddenly you have a plethora of methods available, and you only need to reach your imagination to bring them out.

 

[iansales]

Okay, in my WIP, I have a sub that has a cloaking device. The system bends sound waves around the hull and allows them to travel in their original direction, thus making the boat invisible to sonar.

Isn't that what the anechoic coating effectively does?

 

[kaal]

If the satellite was using very long wavelength, low power radio waves to penetrate the ocean surface and bounce off the ocean floor (not sure it's possible, but perhaps feasible), to create a sonar-like map it might be possible to build a map of discrepancies. Added to a map of surface discrepancies, such as the surface wake from a sub moving underwater and possibly the temperature/phosphorescence suggested by Abernovo, might all give you a chance of detection.
If the sub's "cloak" extends to bending the radio waves around itself, then you'd possibly have to build a model of return time discrepancies.

All told, it'd be a tough job...

K

 

[iansales]

I need a spy satellite to pick her up. Either a radar, infra-red or system that can track a nuclear reactor.

Magnetic Anomaly Detector - tho I've no idea if it'll work from LEO.

 

[Gary Compton]

Magnetic Anomaly Detector - tho I've no idea if it'll work from LEO.

What's LEO Ian?

 

[Vertigo]

Low Earth Orbit

 

[Gary Compton]

Low Earth Orbit

Thank you TFOAK

 

[ctg]

There's no spy satellites on LEO, as most are on MEO and maybe on HEO.

Altitude classifications

• Low Earth orbit (LEO): Geocentric orbits ranging in altitude from 0–2000 km (0–1240 miles)
• Medium Earth orbit (MEO): Geocentric orbits ranging in altitude from 2,000 km (1,200 mi) to just below geosynchronous orbit at 35,786 km (22,236 mi). Also known as an intermediate circular orbit.
• High Earth orbit (HEO): Geocentric orbits above the altitude of geosynchronous orbit 35,786 km (22,236 mi).

The problem is that there aren't sensitive enough instruments to detect submarine sized magnetic anomalies in the seawater. Most of them are demagnetised and thus present almost non existent signature. However, it doesn't mean that there's a void in the magnetic field. Not unless Uncle Compton makes their sub to float in a demagnetized void. But that in my mind would make his neo-nazi's appear stupid. Well, maybe not stupid, but classically stupid in James Bond way. http://www.phys.unsw.edu.au/PHYSICS_!/SUBMARINES/subs.html

My concern is that you're going down the classical Speculative Fiction route rather than facing the problem. I have a problem with Bond movies, as they tend to often use something scientifically impossible to find out bad guys. And same goes to Star Trek "ion trails."

It's a cheap way to overcome the problem. However, if you look classical Tom Clancy books, and especially focus on the science behind the Hunt of Red October, you'll see that the "passive" sonar would be the way (to detect the "caterpillar" drive).

 

[iansales]

Good point. Subs only generally use active sonar to build targetting solutions. Detection is usually passive.

 

[TomS]

In a science fiction context....Only if you want it to, my friend. Only if you want it to.

 

[iansales]

Science fiction. There's a clue in the name.

 

[Gary Compton]

Does the actual act of producing energy from nuclear fission, not create some sort of detectable energy or field?

As long as it's possible in theory. I'm happy.

 

[Venusian Broon]

Hey Gary,

The nuclear sub's achilles heels are it thermal footprint - the reactor generates significant heat that it just can't hide, and it's noiser than a convential sub.

But after a bit of head scratching, I couldn't think of any way of a satellite to take advantage of either as the ocean is an effective blanket.

I see that modern Bathymetry is done by airbourne systems and use a LIDAR (or LADAR) system, bouncing wavelengths up and back again like a sonar system - but again may be again a step too far to contemplate for a satellite system. Plus you'd have to be constantly scanning a big area to see if something is moving real time and changing the effective depth/response of the system.

Finally satellites do their own bathymetric by measuring sea-level changes caused by the gravitational pull of masses under the sea...but to spot a sub and the tiny, tiny effect it would have...nah!

----

No, the only "sensible" SF option I can think of is to install a very sensitive neutrino detector in your satellite that can pick up the large flux of neutrinos pouring out of the reactor and flying unimpeded through shielding and the water.

Actually we're in the realm of near-future possiblity as I read somewhere that someone has built the first communication system that uses neutrinos as the carrier. Ok putting it into a satellite and making it scan the ocean, tough.

Actually, hell , why even put the detection system on a satellite? you can have it in a big network on the ground - easier to maintain and you can make it as big and complex as you desire, without the costly expense of sending something up into space. duh!

 

[MstrTal]

Why not Airships? Cheaper than satellites plus DARPA is or has been working on modernizing Airship technology for a number of purposes including cellular in atmosphere high altitude extended range communications, Wifi and if I am not mistaken recon. plus the surface area of a rigid airship is a lot of real estate to hook up all sorts of fun detection equipment. I would have to search around online (for which I am to lazy right now) to find it but there was a proposal submitted to DARPA and I think NYC back in the early 2000s for a wifi/cellular array attached to a high altitude airship that was supposed to cover the whole state with free or cheap wifi/ cell service and emergency 911 coverage.

Point is perhaps instead of satellites adapt the submitted proposals for airship tech and ideas suggested here?

 

[Gumboot]

I already know that stealth subs are probably patrolling the seas, as we speak. See here

As Abernovo has already pointed out, that only works for active sonar, it won't reduce a submarine's detection via passive sonar.

Just need to track her from space. Is it possible to completely hide a nuclear reactor. How do they do it?

I don't think the issue is so much "Can you completely hide a nuclear reactor?" but rather "How can you detect it?" The ocean is a pretty effective barrier to most methods of detection, particularly thermal (which would be the obvious signature a nuclear reactor would emit).