On May 2, the National Research Council issued a report detailing the rapid and imminent decline of orbiting weather satellites. According to the report, the number of satellites from NASA and the National Oceanic and Atmospheric Administration is expected to drop from 23 to six by the year 2020. Larry Di Girolamo, a professor of atmospheric sciences at the University of Illinois, is an expert in remote sensing using satellites. He discussed the forecasting and monitoring implications of the satellite decline with News Bureau physical sciences editor Liz Ahlberg.
What are Earth-observing satellites used for?
The data from Earth-observing satellites continues to increase our scientific understanding of planet Earth and how the various Earth systems are interconnected. These satellites also drive technological advancements, and challenge and inspire young scientists and engineers.
Data from Earth-observing satellites are used to improve weather forecasting greatly, particularly for coastal regions and in regions of the world where there is a lack of ground observations (which is most of the world). They are used in detecting volcanic eruptions and tracking volcanic plumes - recall the recent eruption of Eyjafjallajokull and its impact on aviation. Satellites are routinely used in detecting other hazards as well, such as fires and oil spills. These applications save lives. They also have a huge impact on commerce: for example, in defining the optimum air and shipping routes on any given day over the entire world.
What can orbiting satellites tell us that radar or other technology on the ground cannot?
Our current Earth-observing satellites measure a wide range variables, including the vertical profiles of temperature, humidity and ozone; the concentration of various air pollutants; precipitation amounts; the amount of liquid and ice in clouds; wind velocities, land and ocean surface temperatures; the amount of phytoplankton near the ocean surface; fresh water storage and fluxes; sea ice coverage; and the amount, type and health of vegetation cover. This is done over the entire planet, all the time.
In principle, many of these variables can be measured by instruments on the ground. But ground-based instruments are limited to very few locations. For example, radars that measure precipitation are largely confined to land. Because of their limited range, radars cannot monitor the development and track of oceanic storms, such as hurricanes, that can have a profound impact on people.
What are the reasons for such a steep drop in satellite numbers?
In 2005, the National Research Council provided a report warning of the decline of our Earth-observing satellites. The council called for immediate and long-term financial investments. Congress never made those investments at the levels required for sustainability.
What could be the impact of such a decline in satellite capabilities?
The impact will be profound. There will be a reduction in the accuracy of weather forecasts and in our ability to detect both manmade and natural hazards. This will cost lives and negatively impact businesses and decision-makers who rely on the accurate forecasts and information that real-time satellite data offers. We will lose our ability to monitor from space things that matter to all of us, such as air quality, fresh water storage and a changing climate. The fantastic rate of scientific advancements toward understanding the Earth system that we have made since the launch of the first satellite will decline.
In addition, the lack of investment will impact the industries, agencies and universities that develop satellite technologies and infrastructures. Our nation will experience a larger loss of young talent, as our graduating scientists and engineers seek employment in other nations that are experiencing a growth in the space sector.
Are there any ways to extend the lives of currently orbiting satellites? Are there any alternatives?
NASA has done a tremendous job at keeping our current Earth-observing satellites operational, but there is only so much they can do. Most of the satellites were meant to have a three- to six-year life span. Most are already past their life expectancy. The satellite that I have been working on for much of my career is now 12 years old. NASA and NOAA have the vision, plans and capacity to do their job. What they need is greater support from Congress. None of the alternatives are attractive for our nation.