Quality of satelite imagery.

2 stroke

In recent days, we have seen poor quality satelite images relating to the search for MH 370. What has happened to those satelites that can focus on the words in the book we are reading? or is this a load of bull?
I think possibly the best satelite images I've seen are on google earth. I would have expected spy satelites to be much better. Is it even worth launching cameras into orbit, if they haven't the resolution to distinguish aeroplane wings from floating pallets and 40 foot containers.

Stuxnet

Nations don't want to show their capabilities I assume.

eta google maps are aerial photos, not satellite

AlmightyCushion

2 stroke wrote: »

In recent days, we have seen poor quality satelite images relating to the search for MH 370. What has happened to those satelites that can focus on the words in the book we are reading? or is this a load of bull?
I think possibly the best satelite images I've seen are on google earth. I would have expected spy satelites to be much better. Is it even worth launching cameras into orbit, if they haven't the resolution to distinguish aeroplane wings from floating pallets and 40 foot containers.

Google earth only uses satellite images to a certain degree. The really close up images on Google earth where you can make out cars and houses aren't from satellites they are aerial photography taken with cameras on low flying planes.

2 stroke

Thanks AC, but I do know satelite images from arial photography.

xper

Well all other things being equal, it's a choice between the level of detail and area of coverage. And they've a huge area to cover.


The media coverage of and public reaction to the MH370 search illustrates very clearly the vast gulf between what technology can achieve in adverse and unanticipated circumstances and what many people believe we can "just do".

Mickeroo

There is no satellite in existence that can focus on the words in a book. The best resolution I've heard of is 0.5m spatial resolution on Geoeye - 1 which means each pixel represents 0.5m squared on the ground, and it no longer produces those images since digital globe raised it's orbit after the contract with the US government finished. I think the standard Geo-Eye product is 1m resolution now.

Also the ones with the best resolution tend to be commercial satellites and their images cost a lot of money.

I suppose it's possible there's secret government satellites with better capabilities but I don't think it's likely tbh and I don't think it would be drastically better.

GeoEye - 1 would be more than capable of spotting a plane wreckage but things like cloud cover and orbit path also play a part.

Zubeneschamali

Mickeroo wrote: »

The best resolution I've heard of is 0.5m spatial resolution on Geoeye

I think the lads are thinking of spy satellites like KeyHole - the ones the size of Hubble, with a 2.4 meter mirror, and theoretical resolution of 15cm or so.

Or maybe the Hollywood versions which can look down girl's cleavage from orbit.

Justin1982

Spy satellites probably only able to resolve as good as the pictures of Osama Bin Laden standing in the yard that were released when he was shot. Anything else is probably overkill. Atmospheric distortion probably becomes a problem if you try to magnify up to the size of letters on a page even if they could resolve to that degree even in perfect conditions.

Popoutman

The limitation isn't atmospheric distortion - it's the diffraction limitation of the size of the mirror used in the satellite in orbit. The bigger the mirror, the smaller the item that can be discerned. If you wanted to read words in a book, you'd need a mirror in the '00s of metres across.

Zubeneschamali

Popoutman wrote: »

The limitation isn't atmospheric distortion - it's the diffraction limitation of the size of the mirror used in the satellite in orbit.

They are both limits - for those KeyHole spy satellites with a Hubble sized mirror, the mirror size gives a theoretical limitation of 15cm, but atmospheric effects give a practical limitation nearer 50 cm.

Son Of A Vidic

Stuxnet wrote: »

Nations don't want to show their capabilities I assume.

I agree with you there, especially when it comes to the capabilities of their military/spy satellites.

ps200306

xper wrote: »

Well all other things being equal, it's a choice between the level of detail and area of coverage. And they've a huge area to cover.

+1. Quite apart from any optical limitations, the southern Indian ocean -- south of the line from Perth to Madagascar is more than 20 million square kilometres, or 2x10^13 square metres. At only half a square metre width for an aeroplane seat, you'd need ten terabytes of data just to photograph the ocean in pure black and white at a resolution of one pixel to an aeroplane seat. At a more realistic requirement of many pixels per seat in greyscale, you are up into petabytes of data.

To even cover this area of the globe would need a satellite in a highly inclined orbit, which would take weeks just to pass over the entire area, let alone photograph it (assuming perfect weather conditions) and send back petabytes of data which it probably doesn't have the bandwidth for. It's not like a bus that you can just drive to the desired location and leave it there.

irishgeo

Corvus Maximus wrote: »

I agree with you there, especially when it comes to the capabilities of their military/spy satellites.

nothing of interest in the Southern Ocean for spy satellites, so i guess they are not focused on that area.

Thargor

Mickeroo wrote: »

There is no satellite in existence that can focus on the words in a book. The best resolution I've heard of is 0.5m spatial resolution on Geoeye - 1 which means each pixel represents 0.5m squared on the ground, and it no longer produces those images since digital globe raised it's orbit after the contract with the US government finished. I think the standard Geo-Eye product is 1m resolution now.

Also the ones with the best resolution tend to be commercial satellites and their images cost a lot of money.

I suppose it's possible there's secret government satellites with better capabilities but I don't think it's likely tbh and I don't think it would be drastically better.

GeoEye - 1 would be more than capable of spotting a plane wreckage but things like cloud cover and orbit path also play a part.

I dont know about that tbh, Im not a conspiracy nut but Id say the CIA/NSA and others would stay pumping money into it from the 60s onwards until they had perfect orbital surveilance. It would be too tempting a prize for them. This kind of thing is pocket change to them:

http://www.space.com/16000-spy-satellites-space-telescopes-nasa.html

They probably supress the capabilities of companies like GeoEye aswell.

Mickeroo

Thargor wrote: »

I dont know about that tbh, Im not a conspiracy nut but Id say the CIA/NSA and others would stay pumping money into it from the 60s onwards until they had perfect orbital surveilance. It would be too tempting a prize for them. This kind of thing is pocket change to them:

http://www.space.com/16000-spy-satellites-space-telescopes-nasa.html

They probably supress the capabilities of companies like GeoEye aswell.

That's interesting about the spy satellite agency donating telescopes for sure.

I don't think they would be suppressing stuff like Geo-Eye though to be honest since Digital Globe are a private company. They also made no secret of the US government having exclusive rights to their highest resolution imagery when the satellite was first launched and since that contract ran out that product is no longer available to anyone.