# Remote sensing

Remote sensing (wiktionary | wikipedia | wikibooks)
The topic of Remote Sensing includes all earth-pointing satellites both past and presently operational. It can include aircraft remote sensing but in general that is generally not included because one cannot achieve global coverage as is possible with ease using satellites.

## Overview

Remote Sensing refers to the ability to make observations remotely. Since the very first satellites were launched, their capability became obvious. Today remote sensing is a major enterprise and has become a vital part of weather forecasting, studying the climate and oceans and fields as diverse as oil exploration, geology, volcanology, sea-ice measurements, glaciers, agriculture, forestry and numerous other fields.
It holds an important role in helping track, study and understand global warming, and has been crucial in the detection of the ultimate extent of the ozone hole over the Antarctica and it's subsequent monitoring ever since.
Remote Sensing is an exciting multi-disciplinary subject that cuts across broads fields in science and technology and its applications and uses. It is now a vital element in humanity's ability to monitor the health and state of the Earth and will ultimately become an element when the collective decision is made to look after it properly.
The material presented here and still to be completed, should prove to be a good starting point to learn more, appreciate and understand this subject.

## Learning Task

* Explore different areas of peaceful application of remote sensing
** Landslide detection by before and after comparison of the Digital Elevation Model (DEM)
** Electricity Detection before and after comparison of light emission after Disasters,
* How can remote sensing be used as Sustainable Development Goals indicators
** Deforestation
** Bush Fire

## Required Knowledge

It would be useful to have a basic knowledge of orbits and space, some basic physics, the solar spectrum.

### Desirable

Knowledge of Blackbody radiation and it's characteristics. See Black_body (wiktionary | wikipedia | wikibooks)

## Learning Material
### Historical Overview

* General historical overview
* Technological development
* Application development
* Scientific progress
* Timeline of key events

### Basic Concepts

* Satellites Orbits -This should cover basic celestial mechanics and the different types of orbits.
* Weather Satellites

### General Material

* Current weather satellites
* Land remote sensing satellites, covering early pioneering satellites and then the Landsat and SPOT series.
* Ocean remote sensing satellites covering radar satellites for ocean waves, ice measurement and ocean color remote sensing

### Operational Aspects

* Ground stations -Discuss what they are, why they are needed, how many of them there are, and where they are sited.
* Launches and orbital corrections
* Onboard power and electronics -This is a topic in itself.
* Data storage -this should give a brief history and then discuss volumes of data and locations and access
* Communications and data transfer -give an overview of the way data is transferred and discuss the different transmission formats.

### Data Processing

* Techniques
* Software programs
* Calibration and Ground Truth Data
* Satellite Data Archive Datasets -This should give a summary of the major sets data from current and previous satellites that is available for research, analysis and general study

### Uses of Remote Sensing

Remote sensing is put to a wide range of uses and can be divided up into these broad categories below.

#### Agriculture

* Precision agriculture and calculation of NDVI

#### Weather Forecasting

* Clouds, weather fronts, cyclones, hurricanes, wind speeds over the oceans, sea surface temperature, atmospheric moisture levels.

#### Aviation

* Weather reports (e.g., forecasts of headwinds and storms)

#### Ecosystems

* Mapping of ecosystems.

#### Mapping

* The date from Landsat and SPOT are of main interest here.

#### Climatology

* This section should discuss remote sensing of sea-ice, global cloudiness, Earth Radiation Budget, Ocean temperatures, biomass.

## Satellite Classification

Satellites can be divided up into different types by orbit and also by type:

### Satellites Classed by Orbit

* geostationary satellites (wiktionary | wikipedia | wikibooks)
* polar orbiting (wiktionary | wikipedia | wikibooks)
* ...others...

### Satellites Classed by Type

* weather satellites (wiktionary | wikipedia | wikibooks)
* land satellites (wiktionary | wikipedia | wikibooks) -This would cover Landsat and SPOT especially.
* oceanic satellites (wiktionary | wikipedia | wikibooks)
* environmental satellites (wiktionary | wikipedia | wikibooks)
* research satellites (wiktionary | wikipedia | wikibooks)

## Remote Sensing Instrument Classifications

This covers the different types of instruments

### Passive Instruments

* Visible wavelengths
* Infrared scanners
* Microwave scanners
* Gravational Effect -This actually has a different name.

### Active Instruments

* Radar
* Lidar

## Data Archives

This will list some of the archives available
US Satellites
* Landsat data
* NOAA
* GOES
* TOPEX and Jason (follow-on)
* ERBS
* TRMM Tropical Rainfall Measuring Mission
* Nimbus
* ERBS
* SeaStart -(carries the SeaWIFS instrument)
* Terra (formerly EOS AM-1) Atmospheric Science
* CloudSat
* Aqua
* Others....
European (ESA) Satellites
* Meteosat
* SPOT
* ERS-1, ERS-2
* Envisat (Environmental Satellite)
* Others....

### Free Software and Data

See the NASA World_Wind software which is like Google Earth but has access to a large quantity of NASA satellite imagery including Landsat.
See World wind