New satellite sensor will help gauge the influence of atmospheric aerosols on cloud formation
August 21, 2019
By André Julião | Agência FAPESP – A satellite no bigger than a loaf of bread will spend a year collecting data on atmospheric aerosols and their interactions with Earth’s clouds.
The nanosatellite was developed by a group led by Vanderlei Martins, a professor at the University of Maryland, Baltimore County (UMBC) in the United States, with funding from NASA’s Earth Science Technology Office.
Aerosols are tiny particles suspended in Earth’s atmosphere. They include dust, sea salt and pollen, as well as anthropogenic (human-made) particles from urban pollution and soot from forest fires.
The device is called HARP (Hyper Angular Rainbow Polarimeter) and will ride on the CubeSat spacecraft to be flown in October 2019 on an uncrewed mission to deliver supplies to the International Space Station (ISS). Shortly thereafter, it will be released from a mini launch station on the ISS together with other small satellites developed by different research groups and will become a fully autonomous data-collecting satellite.
Martins delivered a presentation on the HARP CubeSat project at the São Paulo School of Advanced Science on Atmospheric Aerosols, held on July 22-August 2, 2019, at IF-USP in São Paulo. Attended by 156 students from Brazil and 33 other countries, the School was supported by FAPESP via its São Paulo School of Advanced Science (SPSAS) program.
“We measure atmospheric aerosols with several types of sensor. Some are on the ground, others airborne on planes or satellites. Each kind has a different scope,” Martins told Agência FAPESP.
“HARP CubeSat generates images similar to those of a smartphone camera, as well as other information for use in producing scientific measurements. The images it sends will be used to reproduce geophysical parameters such types and amounts of atmospheric pollution,” said Martins, one of the founders of AirPhoton, a company that makes equipment to measure air pollution.
Henrique de Melo Jorge Barbosa, a professor at IF-USP, chaired the organizing committee of the SPSAS on Atmospheric Aerosols and is also collaborating on the HARP CubeSat project.
Barbosa is working on the development of the algorithm that will analyze the measurements made by HARP to obtain the properties of the aerosols and clouds. He performed part of the work in 2017-18 while he was at UMBC with a Research Scholarship Abroad from FAPESP.
“The HARP sensor on board the CubeSat records two images per second in three simultaneous polarization states and four wavelengths, with high spatial resolution,” Barbosa said. “This means that the same point on Earth’s surface can be observed from 60 viewing angles. When launched and operated continuously at high resolution, it will generate more data from space than any other environmental sensor.”
After a year in orbit, however, HARP CubeSat will start to fall, eventually disintegrating in the atmosphere. Another limitation is that small satellites lack the capacity to store huge amounts of data and transmit them to Earth. Only a few low-resolution images can be sent every day.
Martins and his group are already preparing HARP2, the next-generation HARP, to join other instruments on board a satellite called PACE (Plankton, Aerosol, Cloud, ocean Ecosystem), a new NASA mission that will observe global ocean color, biogeochemistry and ecology, as well as the carbon cycle, aerosols and clouds. Launch is scheduled for 2023.
On board the PACE satellite, HARP2 will collect and transmit a far larger amount of data than can be handled by any CubeSat and will be capable of monitoring the entire globe every two days.
Sensors like HARP are vitally important to enable scientists to deepen their understanding of atmospheric aerosols.
“These liquid or solid particles suspended in air greatly influence the global climate balance. They are one of the key ingredients of global climate change, alongside greenhouse gases. Aerosols have a huge impact on climate, cloud formation, rainfall, and the functioning of ecosystems. In general, they’re poorly understood. The São Paulo School of Advanced Science on Atmospheric Aerosols was designed to disseminate the knowledge we have about the role of atmospheric aerosols,” said Paulo Artaxo, Full Professor at IF-USP, a member of the steering committee for the FAPESP Research Program on Global Climate Change (RPGCC), Martins’ postdoc supervisor, and a member of the School’s teaching staff.
In his opening presentation to the School, Artaxo explained that aerosols directly influence the balance of radiation in the atmosphere and exert a cooling effect on Earth’s surface. During the last century, he said, they played a decisive role in determining whether the planet’s global temperatures rose or fell. Nevertheless, they are powerful atmospheric pollutants.
“In São Paulo City, the black smoke that belches from bus exhausts, for example, is very harmful to human health. The municipal government and those of other major cities worldwide are taking steps to reduce emissions of aerosols, which kill some 30 million people per year, according to the World Health Organization,” Artaxo stressed.
Other lecturers included Alfred Wiedensohler (Leibniz Institute for Tropospheric Research, Germany), Hans-Christen Hansson (Stockholm University, Sweden), Lorraine Remer (Joint Center for Earth Systems Technology, NASA/UMBC, USA), Ilan Koren (Weizmann Institute of Science, Israel), Luiz Machado (National Space Research Institute – INPE, Brazil), Eduardo Landulfo (Nuclear and Energy Research Institute – IPEN, Brazil), Maria Kanakidou (University of Crete, Greece), and Helmuth Horvath (University of Vienna, Austria).
More information about the School can be found at spsas-aerosols.if.usp.br. Read more about research on atmospheric aerosols at agencia.fapesp.br/29665, agencia.fapesp.br/27125, agencia.fapesp.br/25512, agencia.fapesp.br/24184, agencia.fapesp.br/22465 and agencia.fapesp.br/18803.
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