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By: 14th January 2016 at 11:05 Permalink - Edited 1st January 1970 at 01:00
-Also in the future can sattelites get super sensitive they can track entire oceans and strips of land and even perhaps stealth aircraft?
I am not too deep in this stuff but I have read that due to satellite tracking the interest for large nuclear-powered submarines has been in steady decline as there is simply no way how to hid that monster in shallo waters.
By: 14th January 2016 at 12:36 Permalink - Edited 1st January 1970 at 01:00
-There are very few if any satellite use radar , from the top of my head I can only recall the Legenda system use such method to track target ,radar transmitter diminishes as the inverse of the fourth power of the distance so for the surveillance radar to work effectively satellites had to be placed in low Earth orbit and powered by a nuclear reactors
GPS satellite on the other hand operate base on triangulation , they used to determine the coordinate of a known place but satellite don't know exactly what is there
Another kind of satellite is spy satellite , they mostly use camera and take photo of the specific location that they fly pass by , these photo are then processing at the command center to see what happens at a certain place , because the photo are often huge the process are very time consuming so it is not possible to find and track noncooperate aircraft in real time . ( I won't give much faith in them trying to find a ship or submarine hiding somewhere in the ocean either ,given the fact that they are still unable to find MH370 even now )
Spy satellite are place on very low earth orbit of around 300 km .By contrast GPS satellite are at medium earth orbit or 20,200 km aways make them effectively invulnerable to any air defense system
By: 14th January 2016 at 23:51 Permalink - Edited 1st January 1970 at 01:00
-I have question on satellites in combat. Satellites mainly radar, infrared, and visual are the ones used for military tracking. GPS guided weapons like the JDAM and Tomahawk are used by what type? Also, can satellites lock on to a target like a aircraft carrier and guide a ballistic missile with midcourse updates to home in on a target even at terminal phase? If its a visual satellite it cannot be jammed other than its datalink correct?
Yes satellites use radar, IR and visual spectrums for monitoring earth including for military forces.
For navigation and positional info there are now four different constellations, Navstar (GPS), Beidou (china), Glonass (Russia) and Galileo (EU). Navstar and Glonass are pretty complete while Beidou and Galileo are not yet global but are planned to be. These systems provide accurate positional info to platforms and weapons. The signals are very low power though so are susceptible to jamming in various forms and effectiveness.
You could also jam a visual or IR satellite by firing lasers onto the sensors which may have already occurred. http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html
As far as I'm aware no satellite provides direct mid course guidance imagery to weapons except for positional info. Any imagery info is typically fed back to a command centre, analysed and fused to a wider picture and then disseminated to forward units.
Satellites already have very large field of views but are often limited by the sensors and the payload power requirements. The more focused you want the sensor then the more focussed the antenna needs to be, often reducing the field of view. Correspondingly the more focused the sensor typically the higher the data being gathered is and therefore a correspondingly higher downlink is required to transfer the info. For the low earth orbit sats you need multiple ground stations in different parts of the globe to control them if you want 24 hour global coverage and download.
The power issues come from power primarily being generated by the solar panels and onboard manoeuvre fuel. The satellite requires fuel to continue to orientate the satellite as its orbit will slowly degrade over time. The sat panels lose efficiency as they are impacted, accumulate particles, age etc. Either way, a satellite has the power systems and sensors that you launch it with and it will die with these same systems. Sat life times used to be 5 years or so but these have extended now to 10 and sometimes 15 years plus.
Also in the future can sattelites get super sensitive they can track entire oceans and strips of land and even perhaps stealth aircraft?
Probably can do some of this now. The US has the SBIRS which is an Infra-red payload used to monitor for BM launches but looks to provide better capability than just BM. http://www.lockheedmartin.com.au/us/products/sbirs.html
The issue remains getting to a ground station in a timely manner or to an operational platform in a format it could use and understand.
By: 15th January 2016 at 00:07 Permalink - Edited 1st January 1970 at 01:00
-There are very few if any satellite use radar , from the top of my head I can only recall the Legenda system use such method to track target ,radar transmitter diminishes as the inverse of the fourth power of the distance so for the surveillance radar to work effectively satellites had to be placed in low Earth orbit and powered by a nuclear reactors
More radar sats than you think. A quick google search shows that Israel, India, the US, China, Russia, Japan etc. A few links
China - http://spaceflightnow.com/2015/11/27/radar-spy-satellite-launched-by-china/
Japan - http://www.space.com/13900-japan-reconnaissance-satellite-launch.html
India - https://en.wikipedia.org/wiki/RISAT
Israel - https://en.wikipedia.org/wiki/TecSAR
Spy satellite are place on very low earth orbit of around 300 km .By contrast GPS satellite are at medium earth orbit or 20,200 km aways make them effectively invulnerable to any air defense system
They can be higher than that. The Israel sat from above is between 450 and 580 kms above the earth and that is just one example. It really depends on the coverage area you want, what sensors you are using, your orbit of choice and the capability of your booster.
I also doubt that medium earth orbit will stay safe for long. The US and China have both demonstrated an ability to hit LEO sats. In fact the China test was against a weather sat at 865km. https://en.wikipedia.org/wiki/2007_Chinese_anti-satellite_missile_test
While a MEO sat is a lot further away most of the work has been done getting to LEO so MEO, from a fuel use perspective, is not that much further. The issues then become guiding, types of kinetic or explosive payloads and finally the ethics of destroying a sat in orbit and filling the void with junk, potentially knocking out your own sats as well as the enemies...
By: 15th January 2016 at 02:52 Permalink - Edited 1st January 1970 at 01:00
-I think the guide phase again MEO satellite would be very hard
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By: Armed Update - 14th January 2016 at 08:35
I have question on satellites in combat. Satellites mainly radar, infrared, and visual are the ones used for military tracking. GPS guided weapons like the JDAM and Tomahawk are used by what type? Also, can satellites lock on to a target like a aircraft carrier and guide a ballistic missile with midcourse updates to home in on a target even at terminal phase? If its a visual satellite it cannot be jammed other than its datalink correct?
Also in the future can sattelites get super sensitive they can track entire oceans and strips of land and even perhaps stealth aircraft?