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A New Satellite Can Peer Inside Buildings, Day or Night

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Re: A New Satellite Can Peer Inside Buildings, Day or Night

#41

Post by AlgorithmicTime »

jusssi wrote: post #24
leoedin wrote: post #20

Earlier quoted context omitted.

If you want to block SAR, just set up a big corner reflector near you. It'll completely blind the part of the image near you. It would also draw a lot of attention to you... So maybe not the best approach if you're trying to hide.

Big in home decoration fashion next year, upside down pyramids hanging from the ceiling. (edit: my bad, a corner reflector would have 3 corners at the base, not 4 as a pyramid would)

A pyramid is defined as any polygonal base with all vertices connected to an apex, so a triangular pyramid is possible.

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#42

Post by capekwasright »

arkh wrote: post #40

> Another innovation, he says, is the resolution at which Capella’s satellites can collect imagery. Each pixel in one of the satellite’s images represents a 50-centimeter-by-50-centimeter square, while other SAR satellites on the market can only get down to around five meters. When it comes to actually discerning what you’re looking at from space, that makes a huge difference. If that's what is available to civilians…

This is likely the best recent example (from last year):

https://www.thedrive.com/the-war-zone/29634/trump-tweets-int...

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#43

Post by ars »

leoedin wrote: post #20
motohagiography wrote: post #9

In the 9ghz range, does that mean a sub-1mm wire mesh could mitigate this? Asking for a hypothetical house renovator friend. Thompson's adage of when the going gets weird, the weird turn pro suggests that the tinfoil hat crowd could be able to corner the emerging domestic Faraday cage market.

If you want to block SAR, just set up a big corner reflector near you. It'll completely blind the part of the image near you. It would also draw a lot of attention to you... So maybe not the best approach if you're trying to hide.

Are you sure a corner reflector will work?

The entire premise of the synthetic aperture is that the transmission and reception are distant from each other, but a corner reflector will reflect back to the location of the transmission - i.e. it will entirely miss the receiver.

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#44

Post by garettmd »

raws wrote: post #17
a3n wrote: post #16

Earlier quoted context omitted.

Your linked article says that satellite's company is Finnish, not US.

I think he's just alluding to the fact that there's already better ones out there for other countries, maybe even better for secret military bodies.

And just because they have that capability, doesn't mean they can "legally" use it. The posted article says that it can do a better resolution than that 50cm, but didn't specify how much better.

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#45

Post by SoapSeller »

capekwasright wrote: post #42
arkh wrote: post #40

> Another innovation, he says, is the resolution at which Capella’s satellites can collect imagery. Each pixel in one of the satellite’s images represents a 50-centimeter-by-50-centimeter square, while other SAR satellites on the market can only get down to around five meters. When it comes to actually discerning what you’re looking at from space, that makes a huge difference. If that's what is available to civilians…

This is likely the best recent example (from last year): https://www.thedrive.com/the-war-zone/29634/trump-tweets-int...

It doesn't looks like SAR to me(there are shadows, for example).

More like standard optical image(the resolution and details are amazing, if it's a satellite, which is doubtful given the angle).

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#47

Post by madlag »

px43 wrote: post #34
leoedin wrote: post #19

Earlier quoted context omitted.

Power usage isn't necessarily huge. I worked on a SAR satellite a few years ago with a total RF power of It's pulsed as well - you send an RF "chirp" at a sub-1kHz pulse frequency. Depending on imaging mode the average power draw is probably in the 500W-1kW range. That had a much larger resolution (6m rather than 50cm), but the resolution is a function of frequency and antenna design as much as power. The SAR concept…

Great info, much appreciated. Still seems like kind of a lot of something that's supposed to live in space for years at a time. Presumably solar panels recharge a battery when it can, but continuous operations seem out of the question without some pretty large panels. Maybe I'm underestimating modern solar panels or something.

Efficiency of solar panels on satellites is about 40%. That means ~ 700W/m2 if correctly oriented. That's quite a lot of power, even if you stay 50% of the time in night while orbiting Earth. So no need for huge panels usually. (Updated : more like 40%, not 50%)

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#48

Post by abeppu »

> The satellite beams down a powerful 9.65 GHz radio signal toward its target, and then collects and interprets the signal as it bounces back up into orbit.

Years ago there were lots of articles about X-ray backscatter vans, owned by NYPD but probably also other jurisdictions. One of the concerns was you'd never know when they were scanning you and looking inside your car. But of course, though these active systems are invisible to human eyes, they do have to send out pretty strong signals. So I wonder if a kind of sousveillance is possible. Can we have devices that detect the signal being directed at the target, and alarm and publish that info? Both individuals could know if/when they are being imaged, and the public could see some patterns in who they look at. Anyone aware of how hard a detector would be to build?

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#49

Post by wlll »

motohagiography wrote: post #9

In the 9ghz range, does that mean a sub-1mm wire mesh could mitigate this? Asking for a hypothetical house renovator friend. Thompson's adage of when the going gets weird, the weird turn pro suggests that the tinfoil hat crowd could be able to corner the emerging domestic Faraday cage market.

I think this is a balance. Being the only house in the area that can't be seen into might get you more attention someone being able to see you in your underwear at a 50cm x 50cm resolution.

Re: A New Satellite Can Peer Inside Buildings, Day or Night

#50

Post by vorpalhex »

abeppu wrote: post #48

> The satellite beams down a powerful 9.65 GHz radio signal toward its target, and then collects and interprets the signal as it bounces back up into orbit. Years ago there were lots of articles about X-ray backscatter vans, owned by NYPD but probably also other jurisdictions. One of the concerns was you'd never know when they were scanning you and looking inside your car. But of course, though these active systems a…

9.65GHz would be outside the range of most common SDRs, but other than that it would be like detecting any other radio transmission. You would need a sample to know it's the satellite in question and not some other noise on that band, and it would be vulnerable to false positives unless the sample is unique.
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