29 Apr 2013
Highly compact imager will launch on board a satellite and be used to monitor volcanic gases.
by Ford Burkhart in Baltimore
As the curtain went up at SPIE’s Defense, Security and Sensing (DSS) symposium, the focus was on a tiny satellite, with a sensor just over 16 inches long, set to launch in Hawaii this fall. It may enhance the field of geological study from space.
Called the SUCHI, for Space Ultra Compact Hyperspectral Imager, it is a slimmed-down version of an earlier long-wave infrared (LWIR) hyperspectral vehicle.
It will help geological scientists assess volcanic hazards, in particular gas emissions and lava flow cooling rates. Its images will be useful in the mapping of major rock mineralogy, said Sarah Crites, a team member from the University of Hawaii, which developed and built SUCHI.
“This demonstrates a new, very compact spectrometer that can characterize the geology of major rock-forming minerals on the Earth,” Crites said.
The SUCHI sensor, described during the first session of the Sensors and Systems for Space Applications VI conference at DSS, will be the primary payload on HiakaSat, the first satellite built by the Hawaii Space Flight Lab. It will launch from the island of Kauai.
An application that hits close to home for Hawaii residents involves sulfur dioxide, a volcanic gas constantly erupted by the active volcano Kilauea. That forms aerosols they call "vog" that float across the islands and cause respiratory complaints.
Emissions can be tracked and quantified using a diagnostic feature in the 9 µm spectral region. Additionally, that portion of the infrared is an ideal range for geologic mapping of important minerals.
This latest version of the spacecraft was designed to meet tightened mass and power constraints, with a development team of scientists and engineers from the University of Hawaii led by the principal investigator Robert Wright, a professor in the Hawaii Institute for Geophysics and Planetology.
SUCHI will be sealed at launch so that its interior pressure remains at around one atmosphere. In orbit, it is designed to maintain approximately that level of pressure inside for the full mission lifetime, a six-month primary mission extendable to two years.
The imager will make use of a Fabry-Perot Fourier transform spectrometer, while the camera is a commercial off the shelf (or COTS) FLIR A35 product featuring four shutters. The team added heaters for temperature calibration of the infrared data, all of which are, along with the temperature and pressure sensors employed, COTS components. The camera offers a 320x256 array of 38 µm pixels.
“We made minor modifications to it once it was purchased to incorporate it into the sensor,” Crites said.
SUCHI’s hyperspectral “sensor” – combining camera, several lenses, shutters, and the interferometer – allows researchers to collect data across a very broad range of frequencies.
This approach has myriad applications across scientific, commercial and military fields, thanks to the way in which chemical species can be identified by their spectral “fingerprints”, for example helping mineralogists to locate new oil fields.
About the Author
Ford Burkhart is a freelance journalist based in Tucson, Arizona.