Testing New Technology: Faster, Better, Cheaper
EO-1 was commissioned as part of NASA’s New Millennium Program, set up to develop and fly technology that would reduce the risk and cost of future science missions. In short, NASA told its engineers: find a way to fly faster, better, and cheaper.
“EO-1’s primary purpose was to demonstrate that the Advanced Land Imager (ALI) was a suitable follow-on instrument for Landsat,” says Bryant Cramer, the program manager at GSFC during EO-1’s development and launch. Like Landsat-7, ALI records seven wavelengths of light reflected from Earth’s surface. ALI also records an additional two wavelengths to improve measurements of forests and crops, coastal waters, and aerosols.
Later, an innovative new instrument, the Hyperion imaging spectrometer, was added to the mission. Hyperion records more than 200 adjacent wavelengths of light to even better understand the makeup of Earth’s surface.
“EO-1 succeeded beyond anyone’s expectations,” says former project scientist Steve Ungar (GSFC). He credits the mission’s success to EO-1’s “crackerjack team” of engineers and scientists, who were drawn to the mission because they recognized that they could have a stake in the future of satellite technology.
In addition to the two primary sensors, the team proposed 32 new technologies for EO-1, including:
- An improved antenna design that enhances the signal to the ground (a phased array antenna),
- A fast data recorder and processor connected by fiber optic cables to improve the speed and capability of onboard computing systems,
- “Formation flying” software to keep the satellite exactly one minute behind the Landsat satellite,
- A pulsed plasma thruster with a teflon fuel rod; the team wanted to know if teflon fuel would maintain the satellite’s position without contaminating the science data,
- A lightweight, flexible solar panel,
- Carbon-coated plates (radiators) to cool the instruments,
- The Linear Etalon Imaging Spectrometer Array (LEISA) Atmospheric Corrector (LAC), a hyperspectral instrument designed to improve the way the atmosphere is filtered out of images taken by sensors like Landsat.
Though each new technology had the potential to advance spacecraft design, they also posed risks. The carbon-carbon radiators used for passive cooling, for example, were much lighter and simpler than traditional cryocoolers. “But when you touched the first carbon plates, your hand would come away black,” recalls Ungar.” Since this posed a risk to the imagers, the engineers had to come up with a coating to prevent contamination.”