NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Remote and Ground Truth Spectral Measurement ComparisonsFORMOSAT III are a set of six research satellites from Taiwan that were launched in April 2006. The satellites are in 800 km, 71 degree inclination orbits and separated by 24 degrees in ascending node. Ground truth spectral measurements were taken of outer surface materials on FORMOSAT III. From those measurements, a computer model was built to predict the spectral reflectance, which included phase angle and orientation of the spacecraft relative to the observer. However, materials exposed to the space environment have exhibited spectral changes including a darkening and a reddening of the spectra. This reddening was seen as an increase in slope of the reflectance as the wavelength increases. Therefore, the model of pristine materials was augmented to include the space weathering effects. Remote data were collected on two of the six FORMOSAT satellites using the 1.6 meter telescope at AMOS (Air Force Maui Optical and Supercomputing) site with the Spica spectrometer. Due to the separation in ascending node, observations were made on whichever one of the six satellites was visible on that specific night. Three nights of data were collected using the red (6000 9500 angstroms) filter and two nights of data were collected using the blue (3200 -6600 angstroms) filter. A comparison of the data showed a good match to the pristine model for the blue filter region. The absorption feature near 5500 angstroms due to the copper colored Kapton multi-layer insulation (MLI) was very apparent in the remote samples and a good fit to the data was seen in both satellites observed. The features in the red filter regime agreed with the pristine model up through 7000 angstroms where the reddening begins and the slope of the remote sample increases. A comparison of the two satellites showed similar features in the red and blue filter regions, i.e. the satellites were aging at the same rate. A comparison of the pristine model to the first month of remote measurements showed the amount by which the satellite had reddened. This information was used in the space weathered model to predict the second month s reflectance measurement. The results showed that the reddening did not increase from the first month of observations to the second. A third month of data will be necessary to determine if the reddening occurs instantly and then stabilizes with time or if the effect continues to increase with time.
Document ID
20070017979
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Abercromby, Kira Jorgensen
(Jacobs Sverdrup Technology, Inc. Houston, TX, United States)
Hamada, Kris
(Boeing LTS, Inc. Maui, Hawaii, United States)
Guyote, Michael
(Boeing LTS, Inc. Colorado Springs, CO, United States)
Okada, Jennifer
(Boeing LTS, Inc. Colorado Springs, CO, United States)
Barker, Edwin
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2007
Subject Category
Spacecraft Design, Testing And Performance
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available