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| Posted By : nathan - 5/24/2006 12:42 PM | | Does anyone know if a sat camera in low earth orbit can see through cloud cover if on an IR setting?
"Writing the wet dreams of teenage boys" - Lindsey Llyod, Tangent Reviews |
| Posted By : erazmus - 5/24/2006 1:44 PM | Nathan,
Yes, I know if it can. I was an imagery interpeter for the US airforce and used IR imagery daily for some years.
And the answer is, (drum roll)
that depends. On what you mean by "see" . See what? A road? A beach? A girl on a beach? Don't even say Lisence plate! Also, with infrared imagery there is more to consider.
First, the clouds. How much clouds? At what level? Thick clouds on multiple levels of atmosphere will obscure more than a single layer. Even more important is temprature.
You can be looking at a black-top highway in winter, it shows nicely, very bright, hard to miss, suddenly it comes to a river and stops, continueing on the other side. You can't see the bridge, because it and the frozen river beneath it are the same temp. In a peace-time setting, you assume the bridge is there though you might be wrong, there might be a ferry. In a war zone it is much harder to say, is the bridge still there or has it been destroyed? You can not say.
In a less extreme temperture setting, say hawaii, clouds (and rain) over a beach, you might see the people on the beach, still surfing or clustered under shelters. With no clouds you will see the people with photo imagery but IR may not show them, if the temp is between 98 and 99 degrees, they might be the same temp as the sand.
IR cameras can be set to see through clouds, assuming they are not set to read air-temps of different levels, such as a weather sat's cameras. If they are ground survellance cameras, and in the right area, and in use (IR is not infinite in these things, you generally turn them on when you want to look at something) You might see something. What you see depends on a lot of factors, including the weather conditions, the age and condition of the equipment of the available satallite, and the skill and experience of the person looking at the imagery. Roads yes, cars maybe, details, generally not.
Mike
Michael D. Turner
"Psyched Up" in _Turn the other Chick_-ed. E. Friesner-Baen books
www.baen.com
"Two Ravens" in Amazing Journeys Magazine #9 Sept. 05
"An Incident at Black Tongue Tavern" in _Bash Down the Door and Slice Open the Badguy_ from Fantasist Enterprises |
| Posted By : nathan - 5/24/2006 1:58 PM | God bless you, Mike. I mean wow, when I suggested "ask the expert" this is exactly what I was praying for. 
The National Reconissance Office is following three troop movments. They are converging on a single village. Two moving overland, the thrid on a national highway in convoy. The first overland one numbers about a company sized element being followed by a battalion sized element. Head towards them is another battalion sized element in a mechanized convoy with mobile field artillery.
The terrian/topography is sub-saharran (sp, as always) grassland in Western Africa well inland from coastal 'jungle swamp'. The problem is it is monsoon season. In this instantce the cloud cover is thick and low [under 1k in ft].
If the NRO sats had been tracking a] the column mobilizing on the highway and b] the exchange of fire between the first two elements would the monsoon clouds make their positions 'invisible' to low earth sats [or possibly spy aircraft if I'm forced to go that route]?
Thanks much, Mike!
VIEW IMAGE
"Writing the wet dreams of teenage boys" - Lindsey Llyod, Tangent Reviews |
| Posted By : erazmus - 5/24/2006 2:26 PM | Okay,
Vehicles on the highway, you can see them and ID them by type.
Mechanized units overland, for sure, you can see the vehicles, you may be able to see the men, usually some probably not all, you'd ID the unit size and composition from what you do see (and maybe be wrong). If you have fireing going on while your sat is looking, you will see the heat of the rifle barrles and flash/ heat signiture from buring propellant, even if you can't see anything else.
Generally, the less fun the troops on the ground are having-ie Mud, cold, no hot food, no smoking, good terrain use etc, the harder they are to see, IR or Visual. Remember Arnold in Preditor? Cold mud and near hyperthermia can hide you from infra-red. It can also kill you . . .
Details are harder. You couldn't find one guy with any system, out in the bush with all the usual activity. You may see your guy, but you won't know he's your guy. Ten guys you may see and might ID but probably not. A hundred guys stand out okay, even in a rain storm, especially in a rainstorm if they are all moving together. Vehicles are easier to see and easier to tell what they are. Meat and Potatoes for Imagery Interpeters train all day long for that and have ton's of specialized reference, starting with unclassified Jane's manuals and working up to various DoD, NRO and USAF publications, the titles of which I cannot say under penalties of law. None of the titles shows the slightst creativity anyway.
Anyway, any piece of military equipment in use larger than a genade launcher could be seen and identified, if you have enough skilled people looking at it and if you wanted to task that many. A single good PI (photo interpeter, the old designation still used in the trade) could tell you what was going on overall with the imagery feed, pretty much in real time or NRT (near Real Time), but cataloging every thing that shows up on the imagery takes a whole shop, 12-16 guys, and hours, or one guy and weeks. The important information is NRT and a good PI can count how many (soldiers, tanks, APCs, artillary tubes or what ever) pretty much at a glance and transmit that information as fast as he could type, if the shop doing the looking is set up for that. Communicating the information is much easier now than my day, though I was cutting edge back in the day so not as much as you think. Unless you are using the images as a narrative device, you have to allow for information exchange rates for anyone to benifit from it.
Mike
Michael D. Turner
"Psyched Up" in _Turn the other Chick_-ed. E. Friesner-Baen books
www.baen.com
"Two Ravens" in Amazing Journeys Magazine #9 Sept. 05
"An Incident at Black Tongue Tavern" in _Bash Down the Door and Slice Open the Badguy_ from Fantasist Enterprises |
| Posted By : nathan - 5/24/2006 2:34 PM | Nicely done, Mike. Thanks much.
It works the plot just fine and I haven't over streched actual field tech by any means. This is great to know.
"Writing the wet dreams of teenage boys" - Lindsey Llyod, Tangent Reviews |
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