Experimental satellite to have extended mission

The Earth Observing-1 (EO-1) satellite, launched by NASA in late 2000, carries two remote-sensing instruments that may become operational devices in the future, given a proven track record on EO-1 and, of course, sufficient funding.  One, the Advanced Land Imager (ALI) is a test bed for sensors earmarked for the follow-on to the current Landsat-7 Enhanced Thematic Mapper+ (ETM+).  As well as the existing ETM+ six bands, ALI covers three others close to existing bands.  Whether by design or good fortune, two of these help define the important VNIR broad absorption by ferric iron minerals, neglected in remote sensing since the early days of the Landsat Multispectral Scanner.  Like the ETM+, ALI also carries a panchromatic band that spans the visible range, and which is aimed at providing a means of sharpening detail in images.  On ALI, however, this band has an improved resolution of 10 metres as opposed to the current 15.

More innovatory is the Hyperion instrument, a hyperspectral device that spans the visible to short-wave infrared range with 242 bands that are 10 nanometre wide.  Hyperion is comparable with airborne hyperspectral devices, such as AVIRIS.  In the experiment it captures data swathes that 7.7 km wide, made up from 256 pixels with a resolution of 30 m.  After initial difficulties with allowing for atmospheric effects  on the data, newly calibrated Hyperion data closely mimic mineral spectra.

Early work on EO-1 data in many fields, including geology, has proved sufficiently promising that NASA has given the mission a year-long extension.  Although data are restricted to only a few target areas suggested by the investigators, the extension is good news.  It is a reassurance about continuity of the Landsat programme, and a tantalising indication that the ill-fated hyperspectral Lewis satellite may be resurrected.

Information from: http://eo1.gsfc.nasa.gov/


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