Terra: NASA'S New Breed of Satellite
Rensselaer alumni take part in a major international program to monitor climate and environmental change on Earth
By Jodi Ackerman
With an estimated six billion people living on Earth, is today’s level of human impact on our planet sustainable?
In an effort to find out, several Rensselaer alumni helped build Terra, the first of a new breed of Earth-observing satellites that will create a comprehensive, integrated science file for studying global environmental change.
Terra is part of a NASA search mission program called the Earth Observing System (EOS). It’s a major international program to monitor climate and environmental change on Earth over the next 15 years.
The satellite was launched Dec. 18 at the Vandenberg Air Force Base in Lompoc, Calif. Lockheed Martin Missiles & Space at Valley Forge, Pa., received the contract for the construction of the 11,000-pound spacecraft that measures 22 feet tall and 10 feet wide.
Scott Carey ’81, the project’s systems engineering and integration manager, has been working on Terra since NASA proposed the $1 billion project in the late 1980s. At the height of construction, more than 300 engineers were working on the satellite.
Through Terra, scientists hope to learn more about changes our planet may be undergoing, such as global warming.
“What Terra will provide is long-term data that will be used to create more accurate computer models to determine to what degree global warming is here and to perhaps find out what causes it,” says Carey, who earned his bachelor’s and master’s degrees at Rensselaer in computer science in 1981 and 1982 respectively.
“There is evidence of global warming. What we don’t know is whether this is something that man is significantly contributing to, or whether there are natural cycles that wipe out anything we could be doing.”
Carey monitored Terra’s development from beginning to end, defining and allocating requirements for the spacecraft. His final responsibility in the mission is to operate Terra from Goddard Space Flight Center in Maryland for the first 90 days it’s in orbit. The job then will be handed over to NASA officials.
Terra’s five instruments will allow scientists to conduct new research into the ways that Earth’s oceans, lands, air, ice, and life function as a collective environmental system. The instruments will provide measurements of ocean life, land vegetation, cloud cover, and fires. They will also measure two important pollutants—carbon monoxide and methane—in the lower atmosphere.
The instruments will
conduct many of Terra’s observations simultaneously—
“The instruments have the ability to cross-register with one another at the same spot at the same time,” says Carey. “By collecting data in this way, scientists hope to conclude things that they wouldn’t be able to do if the instruments collected data at different times or individually.”
Out of the five instruments, the Multi-Angle Imaging Spectro-Radiometer (MISR) is the most unique in that no instrument like it has ever flown in space before, says Carey. MISR is composed of nine cameras that observe the Earth’s surface from different angles simultaneously, providing images and information about the properties of surface features, clouds, and particulates.
Terra’s sensors collected its first images about 30 days after launch. As the data is received, it will be distributed via the Internet to scientists all over the world, and archived at various analysis centers.
“The fact that the project is a multinational effort is a very rewarding element as we see the world shrinking,” says Dorothy Braun ’82. “The Earth is something we all share, and it’s rewarding to work with people all over the world to better understand it.”
Braun, Carey’s wife, graduated with her bachelor’s degree in mechanical engineering from Rensselaer. She served as manager of equipment engineering for the Terra project, and later headed a team working on electrical ground support equipment.
“The level of excellence in my colleagues leads me to believe that Terra will not only succeed in its mission, but exceed it for years,” says Marion Riley ’85, who earned her bachelor’s degree in mechanical engineering at Rensselaer.
As the product integrity engineer for the attitude control system, Riley was responsible for writing, monitoring, and testing the product specifications for the sensors and actuators of the attitude control equipment. The equipment keeps the spacecraft pointed at Earth so the five instruments can collect their data.
Just as the Terra project was beginning to take off in 1991, Carey hired Gene Keeling ’85, who eventually became manager of integration and testing. Keeling earned his master’s in computer engineering at Rensselaer.
One of Keeling’s biggest responsibilities was to create testing mechanisms for several pieces of high-tech equipment never before used. For instance, Keeling had to figure out how to test Terra’s cooling system that was made to work in zero gravity. Testing it on Earth, therefore, was a difficult task, he says. He was also responsible for making sure the parts of the spacecraft could be assembled properly.
“Since the beginning, I had the opportunity to influence the satellite design and the kind of testing equipment to be used, and carry the project to its final stages,” Keeling says. “To be able to spend eight years on something like this and demonstrate you can take it from beginning to end is exciting."
Alumni and Terra
Luke Axiotakis ’84