Sensors are instruments that collect data about Earth processes or atmospheric components. Along with being carried aboard satellites or aircraft, sensors also can be installed on the ground (in situ). There are two types of sensors: active and passive. Active sensors provide their own source of energy to illuminate the objects they observe; passive sensors detect energy emitted or reflected from the environment. The following list describes sensors aboard NASA and joint NASA missions.

MOPITT is an instrument designed to enhance our knowledge of the lower atmosphere and to observe how it interacts with the land and ocean biospheres.
MLS is a passive microwave radiometer/spectrometer that measures microwave thermal emission from the limb of Earth’s atmosphere to sense vertical profiles of atmospheric gases, temperature, pressure, and cloud ice.
MWR supports the SAR Radar ALtimeter (SRAL) in achieving overall altimeter mission performance by providing wet atmosphere correction.
MODIS collects data in 36 spectral channels with global coverage every 1 to 2 days. Its exceptionally broad spectral range enables MODIS data to be used in studies across numerous disciplines.
MAS supports MODIS remote sensing algorithm development.
MISR views Earth with cameras pointed at nine different angles and acquires data in four wavelengths.
MCoRDS is a multichannel radar used to measure ice sheet thickness and terrain beneath the ice.
MABEL was developed by NASA at the same time as ATLAS to serve as a testbed for ATLAS.
NPOL measures radar reflectivity, Doppler velocity, differential reflectivity, correlation, differential phase, rainfall rate, particle size distribution, water contents and precipitation type.
The NISAR L-band SAR will be a side-looking, fully polarimetric, interferometric SAR operating at a wavelength of 24 cm.
The NISAR S-band SAR will operate at a wavelength of 12 cm for use sensing light vegetation.
NISTAR measures the absolute irradiance integrated over the entire sunlit face of Earth to measure Earth’s energy balance.
OLCI is a visible imaging push-broom radiometer with five camera modules that acquire data in 21 spectral bands ranging from 400 to 1200 nm.
OLI measures in the visible, near infrared, and short wave infrared portions of the spectrum.
OMPS uses three spectrometers to track the health of Earth’s ozone layer and measure the concentration of atmospheric ozone.
OMI uses an imaging spectrometer to distinguish between aerosol types, such as smoke, dust, and sulfates. It measures cloud pressure and coverage, which provides data to derive tropospheric ozone.
PALSAR is an active SAR system that is extremely flexible and provides information for a broad range of science disciplines.
Designed to measure polarized and directional solar radiation that is reflected by land and ocean surfaces as well as the atmosphere in the visible and near-infrared spectrum.
Mapped sea level, wind speed and wave height for more than 95% of Earth's ice-free ocean, provided new insights into ocean circulation, tracked our rising seas and enabled more accurate weather, ocean and climate forecasts.
A dual frequency radar altimeter which measures significant wave height, altimeter range, sigma naught, and ionospheric correction in the Ku (13.575 GHz) and C (5.3 GHz) bands.
Poseidon-4 dual-frequency radar altimeter measures include sea surface height (SSH), significant wave height (Hs), and wind speed.
Was an electronically scanning radar that measured the 3-D rainfall distribution over both land and ocean, and define the layer depth of the precipitation.