Marc Imhoff celebrates 10 years of Terra satellite

Marc Imhoff: Terra’s 10th anniversary is just a good time to essentially extol the virtues of looking at the Earth from orbital space. It’s a tremendous vantage point.

Marc Imhoff is the project scientist for NASA’s Terra mission. Terra is a research satellite. And in December of 2009, Terra celebrated its 10th year in orbit. Being able to look at Earth’s climate system more completely, on a global scale, said Imhoff, has been the biggest accomplishment of Terra.

Marc Imhoff: Having data collected over a ten-year period over the entire Earth has enabled scientists to look at the balance of energy going into the system and going out of the system.

Imhoff is referring to the balance between energy coming to Earth as sunlight, and energy radiating out from Earth as heat and reflected sunlight. Imhoff said that there are lots of questions about where that energy goes.

Marc Imhoff: For example, how much is being sequestered in the deep oceans, how much of the incoming or build-up of energy is being dissipated by melting arctic sea ice or glaciers in Greenland and Antarctica, how much is a result of clouds and aerosol changing, so that more radiant energy goes out into space. Being able to have these data over a very long period of time allows scientists to tie those various processes together and then look at them as a system to try to figure out what’s happening.

Dr. Imhoff said that the Terra satellite measures changes in the atmosphere, oceans, and land surface on a global scale all at once, or what he called the ‘synoptic point of view.’

Marc Imhoff: That synoptic point of view, of being able to look down at the globe, during the day, during the night, during the winter, during the summer, spring, fall, what have you, being able to observe so many different aspects of the Earth’s surface, and our interaction with it has been extremely useful in furthering climate science, looking at biological sciences and ecology, and even trying to link ecology and natural resources and climate and weather.

What’s more, Imhoff said, research satellites like Terra have recorded evidence that humans have altered our environment on a planetary scale.

Marc Imhoff: One of the primary goals of the Terra mission was to look at land surface. And one of the big, potential drivers of not just climate change, but also in terms of our ability to survive on the planet is what happens with land use and land cover. One of the questions is, how are the changes on the land surface, when we cut down forests and convert the areas to agriculture, or then convert agricultural areas to urban areas, how is that going to impact a number of different things, from carbon sequestration, the amount of carbon taken out of the atmosphere, to the heating of the surface, to the absorption of water for fresh water recharge of the ground table.

The combination of five instruments on board Terra, said Imhoff, allowed it to take vital information on wildfire activity and impact to the air.

Marc Imhoff: Since we are talking about a complex system, Terra has five instruments on board: the ASTER instrument, an instrument that was built by Japan’s Ministry of Economy, Trade, and Industry, and has run on the science side by Jet Propulsion’s Laboratory. And we have the CERES instrument. We have another instrument called MODIS, the Moderate Resolution Imaging Spectrometer, we have MISR, which is the Multi-Angle Imaging Spectral Radiometer, and then we have a fifth one called MOPPET, which is measurements of pollution in the troposphere, which is provided by the Canadian Space Agency. And if you look at all of those instruments in combination, what they allow us to do is look at all the various coupled systems that are going on.

Dr. Imhoff said there’s a long list of people to thank for the success of the Terra mission, and he wanted to at least include a few people.

Marc Imhoff: Without getting into a really long list, but certainly the instrument PIs should be mentioned. CERES has Norman Loeb from Langley Research Center. Dave Diner out at JPL for MISR. Mike Abrahms out at JPL for ASTER. James Drummand of Dalhousie, John Gilley at NCAR for MOPETT. Then for MODIS, Michael King, and Vince Solomon for many years. Being project scientist with such giants is a little bit daunting sometime, because these guys have all been there from the very beginning, many years before I got involved.

Our thanks today to NASA’s Terra Mission, helping us better understand and protect our home planet.

December 7, 2009

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