MAIA (Multi-Angle Imager Aerosols)
The Multi-Angle Imager Aerosols (MAIA) mission is led by NASA, in partnership with the Jet Propulsion Laboratory (JPL) and Agenzia Spaziale Italiana (ASI), and is designed to study the impact of different sizes and compositional mixtures of particulate matter on adverse health outcomes. The MAIA instrument will be hosted onboard the PLATiNO-2 satellite, with launch planned for 2025 on board a Vega-C rocket.
The PLATiNO-2 satellite will carry the MAIA instrument built by JPL to measure the radiance and polarization of sunlight scattered by atmospheric aerosols, from which the abundance and characteristics of ground level particulate matter (PM) are derived. The instrument contains two pushbroom VIS/NIR/SWIR 14-channel spectropolarimetric cameras on a two-axis gimbal for multi angle viewing, frequent revisits and inflight calibration.
MAIA uses a pushbroom scanning technique with frames of 300 km x 150 km within ±60° along-track and ±45°, with about 10 different viewing angles. MAIA will be launched into an altitude of approximately 740 km with a global revisit time of 3 days.
Space and Hardware Components
MAIA weighs in at approximately 80 kg with a power output of 85 W and a data rate of 10 Mbps. The instrument will be hosted onboard the PLATiNO-2 satellite, an experimental thermal infrared earth observation satellite. PLATiNO-2 is also equipped with the magnetically shielded HT 100, an improved version of the SITAEL electric thruster.
In partnership with JPL (Jet Propulsion Laboratory) and Agenzia Spaziale Italiana (ASI), NASA has designed the Multi-Angle Imager Aerosols (MAIA) mission to study the impact of different sizes and compositional mixtures of particulate matter on adverse health outcomes. Observations of small atmospheric aerosols from MAIA, will be combined with health information to determine the toxicity of different particulate matter types in airborne pollutants over the world's major cities. Those results will then be compared to human birth, death, and hospitalization records to answer pressing questions about the health impacts of solid and liquid particles that contaminate the air we breathe. These particles, called aerosols, have been linked to respiratory diseases such as asthma and lung cancer, cardiovascular diseases such as heart attack and stroke, and adverse reproductive and birth outcomes, including premature birth and low infant birth weight.
MAIA marks the first NASA mission whose primary goal is to benefit societal health, as well as the first time epidemiologists and public health researchers have been directly involved in development of a satellite mission. 1) 2) 3)
The MAIA instrument will be hosted onboard PLATiNO 2, an experimental Thermal Infrared (TIR) Earth observation satellite project by the Italian Space Agency (ASI). This mission envisages the development of the second satellite based on the PLATiNO platform and carries a Thermal Infrared (TIR) payload, validating the multi-applicability feature of the PLATiNO platform. Developed by Leonardo and SITAEL, the TIR imager will be used to provide valuable services for territory control and protection such as monitoring waters, glaciers, pollutants, state of crops and vegetation, energy consumption in urban areas. PLATiNO-2 is also equipped with the magnetically shielded HT 100, an improved version of the SITAEL electric thruster.
Alongside the TIR imager, PLATiNO 2 will host NASA's MAIA payload. The imager is a state-of-the-art satellite instrument producing data that will be used in health studies to examine the health effects of various types of air pollution, and contains a specialized digital camera that peers at how the Sun’s light reflects off of the Earth and its atmosphere. This is no ordinary camera, however. It uses a combination of observing techniques to capture information about a layer of air pollution. MAIA will be able to distinguish types of particulate matter (PM) based on how the particles reflect or absorb sunlight. 4)
PLATiNO 2, carrying MAIA, is planned to launch in 2025 on-board the Vega-C rocket into a sun synchronous orbit with a planned lifetime of 3 years at an approximate altitude of 740 km and inclination of 98°. The period will be 98 minutes, and the local solar noon will occur at 10:30.
- March 8, 2023: NASA and the Italian Space Agency (ASI) are partnering to build and launch the Multi-Angle Imager for Aerosols (MAIA) mission, an effort to investigate the health impacts of tiny airborne particles polluting some of the world’s most populous cities. MAIA marks the first NASA mission whose primary goal is to benefit societal health, as well as the first time epidemiologists and public health researchers have been directly involved in development of a satellite mission.
- March 10, 2016: NASA has selected two proposals for new Earth science investigations, including one from the Jet Propulsion Laboratory (JPL) that will put new instruments in low-Earth orbit to track harmful particulate air pollutants.
Data collected by the MAIA instrument, orbiting the Earth at 740 km overhead, needs to be able to tell a group of tiny sulfate particles apart from a group of equally tiny dust particles. This is certainly a challenge, but MAIA will be able to distinguish types of particulate matter (PM) based on how the particles reflect or absorb sunlight.
MAIA contains a specialized digital camera that peers at how the Sun’s light reflects off of the Earth and its atmosphere, which uses a combination of observing techniques to capture information about a layer of air pollution.
Camera: MAIA’s camera uses a set of mirrors made of polished aluminum. It is designed this way so that the camera can record light at many more wavelengths than are seen by a conventional camera.
Filters: The MAIA instrument has 14 filters to capture not just visible light, but also ultraviolet, near-infrared, and shortwave-infrared. Tiny particulate matter (PM) particles tend to scatter light most efficiently at wavelengths similar to their own size, so shorter-wavelength visible spectral bands will provide information about the smallest aerosol particles (PM2.5 - particles with a diameter of 2.5 micrometres or less) while the shortwave infrared bands provide information about the larger types of aerosols in the atmosphere, like dust and volcanic ash. Ultraviolet wavelengths are sensitive to absorption of sunlight by particles containing certain types of minerals and organic matter.
Detector: The MAIA camera has its detectors arranged in individual rows - called a pushbroom imager. As MAIA passes over the Earth, the motion of the satellite pushes the line array over the area like a broom being pushed across the floor. (A flatbed scanner is another example of a pushbroom imager.) The pushbroom technique requires each exposure to be very rapid, since MAIA’s host satellite will be travelling at about 25,000 kilometres per hour.
Gimbal: The MAIA camera is mounted on a motorised gimbal that can rotate 60 degrees forward and backward. As MAIA passes over a target on the Earth, the gimbal will rotate to point the camera at the target several times, capturing images from different angles. This technique is called “step and stare.” The gimbal can also point to the left or right, which allows the camera to see cities that aren’t directly underneath the satellite.
Photoelastic Modulators (PEMs): The MAIA camera uses devices called photoelastic modulators (PEMs) and quarter-wave plates (QWPs). When used in combination with polarising filters placed above the camera’s detectors, MAIA is able to make accurate measurements of the degree to which the incoming light is polarised by particles in the atmosphere.
Onboard calibrator: MAIA also contains an onboard calibrator to maintain the accuracy of its measurements. The calibrator has a series of wire grid polarizers lit by sunlight that has passed through a diffusing screen. Observing the calibrator routinely will allow the MAIA team to correct for any changes in the camera’s sensitivity to polarisation. The calibrator also contains a dark target, so that the signals generated by the detectors when it’s dark can be measured and subtracted out. 5)
1) Nastan, A., et al. “NASA's Multi-Angle Imager for Aerosols (MAIA): Applications of NASA Satellite Data to Airborne Particulate Matter Exposure and Human Health | ISEE | 2020.” Environmental Health Perspectives, https://ehp.niehs.nih.gov/doi/abs/10.1289/isee.2020.virtual.P-1017
2) “New NASA Instruments to Study Air Pollution, Cyclones.” Jet Propulsion Laboratory, 10 March 2016, https://www.jpl.nasa.gov/news/new-nasa-instruments-to-study-air-pollution-cyclones
3) “NASA and Italian Space Agency Join Forces on Air Pollution Mission.” Jet Propulsion Laboratory, 8 March 2023, https://www.jpl.nasa.gov/news/nasa-and-italian-space-agency-join-forces-on-air-pollution-mission
4) “PLATiNO 2.” Gunter's Space Page, 8 March 2023, https://space.skyrocket.de/doc_sdat/platino-2.htm
5) “MAIA | Investigation.” NASA MAIA, https://maia.jpl.nasa.gov/investigation/
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (firstname.lastname@example.org).