Earth is sandwiched between Mars and Venus, and the same could be said of the Earth scientists at NASA's Goddard Space Flight Center. Between the adventures of the Mars Pathfinder, the comings and goings aboard Mir, and the commotion surrounding the upcoming Cassini launch, all eyes are focused skyward. Meanwhile, a band of researchers with their feet on the ground is quietly using space to get the big picture when it comes to our mother planet.
It's no coincidence these scientists came to the 1,200-acre plot of land only miles from the Beltway; Goddard is the hub of NASA's Earth science research and houses the current Mission to Planet Earth project.
Goddard research scientist Dorothy Hall recalls there being only 50 or 60 Earth scientists at the time she was hired in 1975. Now there are several hundred who have gravitated to the suburban Maryland campus to examine Earth from the high altitudes of glaciers and snowfall down to the depths of the oceans where miniscule vegetation resides.
This on-foot exploration combined with studies of satellite data has helped researchers like Hall examine how changes in the sizes of glaciers influence the earth's climate and, likewise, how the climate affects the size of glaciers.
Hall, who has spent parts of many winters hiking glaciers and snowy mountains, understands the language of frozen water. "If, in one area, you see a glacier moving forward over 20 years, then you know it's getting wetter and colder," said Hall, who looks upon her studies of glaciers as a hobby - and as a way to get to interesting places.
A strong interest in ice formations led Claire Parkinson down the path that brought her to Goddard 19 years ago. Parkinson started out her academic career studying math, enthralled by symbols and numbers. But the end of her undergraduate career happened in the late 1960s, and thoughts of war and destructive weapons were on Parkinson's mind. "I was uncertain of what math would be used for, so I switched to science and working on climate issues," she said.
Enchanted by articles about Anarctica, Parkinson decided to go on an expedition to the region to work on models of sea ice. These models became the foundation of Parkinson's PhD thesis and postdoctoral work. This work caught the attention of some Goddard scientists, who offered her a research job.
Now, Parkinson is the project scientist for the Earth Observing System PM mission, a satellite set for launch in 2000 that will use a battery of instruments to take Earth's atmospheric vital signs in the afternoons. The data will help Parkinson and her colleagues form a better picture of Earth's climate - and get over some of the obstacles that come from studying lands ruled by ice and snow.
"It's dark for months at a time, and it's difficult to pull up data," Parkinson said. "We'll have microwave instruments that will measure the radiation from clouds and the earth that will give us the images we want."
Early on in her life, Hall learned the value of getting a bigger picture of the environment - a pilot's license gave Hall the keys to her high school hobby, aerial photography. This led to her interest in remote sensing, which in turn brought her to her current project, the Moderate Resolution Imaging Spectro-Radiometer (MODIS) sensor that will be launched next June.
MODIS will capture images of Earth's snow cover and generate maps that will give Hall and her colleagues more accurate data from which to see how changes in temperature are affecting snow fall. This information can help in determining, for example, areas where floods may occur or places where snow melt may be lower than normal.
Such data will augment Hall's trips to Earth's cooler regions - but cause her to forfeit some frequent flier mileage. "You can see 20 glaciers [with the sensor] instead of one, but it's not as fun as going to the places," said Hall.
"You could never get this information any other way," said Goddard physical scientist Compton Tucker, who uses data from a NASA satellite to supplement his current field research in the rainforests of Bolivia, Peru, Columbia, and Venezuela.
Tucker has used a variety of satellites to look at color data images of Earth to get a bead on land issues such as the conversion of tropical and temperate forest regions. Data which Tucker has employed has helped him determine, for example, how the growing seasons are getting longer in the northern latitudes of Europe and North America. Information like this is not something that can be gathered by going to one site for a few days, he explains.
To understand trends like this, a researcher needs to observe a spot everyday and through different seasons to get a better picture of what is happening to the earth. This is the sort of data Tucker looks forward to getting from the recently launched Sea-Viewing Wide Field-of-View Sensor system that will begin sending back color imaging data of Earth in mid- to late September.
Nonetheless, field and satellite work go hand-in-hand for Goddard scientists. In his current project, a study of the rainforests, Tucker flys in a small plane, armed with satellite data and other maps to pick out an areas to study before landing at the next campsite, most often near a former drug lab airstrip. From base camp, Tucker's expedition, which includes scientists from Bolivia and Europe, ventures out into the rainforest to gather vegetation and study animal life to get a first-hand account of what the satellite data may mean for local areas.
It is trips like Tucker's that allows Earth science researchers to check on the observations made by their spaceborne instruments - a luxury not afforded to space scientists. This multilevel examination helps keep the NASA Earth scientists honest, notes Goddard oceanographer Gene Carl Feldman.
"For people who look outwards, the only truth they have is what remote sensing instruments tell them," explained Feldman. "It doesn't work that way on Earth. There are people down here who can tell you when you're off."
