Landsat7 is the latest satellite launched in 1999 in the long running Landsat program. Landsat7 encircles the earth at an altitude of 705km, imaging a swath of the earth 185km wide. Landsat7 collects digital images of the globe on a 16-day cycle with 30 meter resolution, which means each pixel in an image covers an area of the earth's surface about half the size of a football field. For over three decades the Landsat's Global Survey Mission has been to acquire repetitive observations over the Earth's land mass, coastal boundaries, and coral reefs. The specialized images allow scientists to observe changes on our planets surface that result from both natural processes and human practices. Landsat7 images are used to make maps of the earth's surface, study the urban sprawl of cities, and the changes in landscape due to erosion. The Landsat program is run by a joint effort of NASA and US Geological Survey.

MODIS, which stands for Moderate Resolution Imaging Spectroradiometer, is one of the key components of the Terra satellite mission launched by NASA in 1999. The MODIS instrument collects images of every point of our world every 1-2 days. The images are collected from a 2,330km wide swath with resolutions of 250km and 100km. As compared to the Landsat7 satellite, the images collected by MODIS are much less detailed, yet are used to study a greater range of components of our planet. For instance, MODIS can observe the changing cloud cover of the earth and detect how pollution moves within our atmosphere. MODIS is used to monitor large-scale changes in the biosphere such as the photosynthetic rate of the world's forests and the ocean's phytoplankton, measuring these values helps scientists understand the global carbon cycle and how greenhouses gases in the atmosphere are being distributed with the earth's terrestrial and oceanic carbon reservoirs.

AVHRR stands for Advanced Very High Resolution Radiometer, it is part of the National Oceanic and Atmospheric Administration's (NOAA) polar operational environmental satellite (POES). The AVHRR can be used to determine the surface temperature of the earth, cloud tops, and bodies of water, all of which are important for meteorological forecasting. The POES satellite offers the advantage of daily global coverage, by making nearly polar orbits roughly 14 times every day. The AVHRR is used by scientists for many environmental monitoring applications such as including global sea surface temperature measurements, volcanic eruption monitoring, forest fire detection, global vegetation analysis, and many other applications.