NASA and the Italian Space Agency (ASI) are collaborating to build and launch the Multi-Angle Imager for Aerosols (Maia) mission, which aims to study the impact on human health of aerosols that pollute some of the world's most populous cities, including Rome. The data collected will be correlated with birth, death, and hospitalization records to evaluate the impact on human health of solid and liquid particles that contaminate the air we breathe.
Maia represents NASA's first mission whose primary goal is to promote society's health, as well as the first time that epidemiologists and public health researchers have been directly involved in the development of a satellite mission.
The Maia observatory, scheduled to launch by the end of 2024, will consist of the ASI's Platino-2 satellite and a scientific instrument built at the Jet Propulsion Laboratory, containing a spectro-polarimetric camera to capture digital images from multiple angles in the ultraviolet, visible, near-infrared, and infrared electromagnetic spectrum bands. These data will help explore the size, geographic distribution, composition, and abundance of suspended particles in the air and investigate how they relate to patterns and prevalence of health problems resulting from poor air quality.
The mission will collect and analyze data from the observatory, ground sensors, and atmospheric models. These will then be correlated with birth, death, and hospitalization records of residents in the areas studied to evaluate the impact on human health of solid and liquid particles that contaminate the air we breathe.
Maia's measurements of sunlight reflected by suspended particles in the air will help researchers determine the abundance, size, and optical properties of some pollutants in the atmosphere. The use of such data will help researchers decipher the chemical composition of the particles. Particles with a diameter of 10 micrometers or less (PM10) are small enough to be inhaled, potentially causing tissue damage and inflammation in the nose, throat, and lungs. Particles smaller than 2.5 micrometers (PM2.5) can penetrate deeper into the lungs and be absorbed into the bloodstream, where they can cause more serious health problems.
The composition of such particles depends on how they formed. For example, black carbon comes from the combustion of fossil fuels and trees, while mineral dust comes from soil and sand. Other particles – organic carbon, sulfates, and nitrates – can form through chemical reactions between gases in the atmosphere. Maia's main goal is to study whether exposure to these different types of particle pollution has different impacts on health.During its three-year mission, Maia will focus on 11 primary target areas covering some of the world's major urban centers: Los Angeles, Atlanta, Boston, Addis Ababa, Barcelona, Beijing, Johannesburg, New Delhi, Taipei, Tel Aviv, and Rome. From 740 kilometers above the Earth's surface, the mission will also collect some data on 30 secondary target areas around the world.
The scientific team's epidemiologists intend to study the effects of short-term exposure to particulate pollution on a timescale of days, as well as chronic exposure, which can last many years. Subchronic exposure, such as inhaling pollutants for months, is also of interest.
A normal digital camera captures images using a rectangular array of sensors (pixels) for each snapshot. Maia's camera uses a similar device, but its sensors are arranged in single rows. This type of sensor is called a pushbroom imager. When Maia passes over Earth, the satellite's motion causes the row of sensors to sweep across the observed area like a broom across a floor. This technique requires each exposure to be very brief, as the satellite will be traveling at around 25,000 kilometers per hour. Credits: NASA.
"Breathing in air pollution particles has been associated with many health problems, but the toxicity of different mixes of particles has been less well understood," says David Diner, principal investigator at NASA. "Working together with colleagues in Italy and around the world, we expect Maia to help us understand how airborne particulate pollution poses a risk to our health and provide useful insights for public health officials and other policymakers."
"Maia marks an important moment in the long history of cooperation between NASA and ASI and symbolizes the best that our two agencies can bring in terms of expertise, knowledge, and Earth observation technologies," concludes Francesco Longo, head of the Earth Observation and Operations unit at ASI. "The science produced by this joint mission will bring benefits to humanity for years to come."
