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ASTER User
Notification - October 2011
The Ministry of Economy, Trade, and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA) announced the release of the Version 2 ASTER Global Digital Elevation Model (GDEM) on October 17, 2011.
The Version 2 release features improved spatial resolution, increased horizontal and vertical accuracy, and superior water body coverage and detection. Version 2 ASTER GDEM data is available to users free of charge from
NASA Reverb, Land Processes Distributed Active Archive Center (LP DAAC) Global Data Explorer,
or Earth Remote Sensing Data Analysis Center (ERSDAC) Ground Data System (GDS) GDEM Page.
ASTER User
Notification - May 2011
All 11 years of ASTER Level-1B data over the U.S. and Territories have been made available by the LP DAAC. Users may browse, search, and download their product(s) of interest from several sites.
The USGS Earth Explorer (EE) client at http://earthexplorer.usgs.gov is the newest.
The first step is to register for a free account. Then click on the "Data Sets" tab, expand "NASA LP DAAC Collections," and select ASTER. Next use the search criteria to choose location and time periods.
The data are also available from NASA Reverb, the Warehouse Inventory Search Tool (WIST), USGS Global Visualization Viewer (GLOVIS),
and the LP DAAC Data Pool.
ASTER User
Notification - February 2011
As of February 2011, the LP DAAC Data Pool has eliminated the two-year rolling archive and expanded holdings to include data covering the U.S. and territories for the lifetime of the Terra mission. Data Pool holdings are available to the user at no cost.
Data Pool
ASTER Website Update - February 2011
Added the Full ASTER Bibliography (pdf 887 KB) to the Presentations and Documents page.
ASTER User
Notification - August 2009
As of August 2009, ASTER billable orders from non NASA affiliated users are no longer being accepted from the
Land Processes Distributed Active Archive Center (LP DAAC). Metadata search and browse imagery
continue to be available through Glovis
(or WIST).
The Earth Remote Sensing
Data Analysis Center (ERSDAC) is available to provide billable ASTER products to non NASA
affiliated users. Please contact LP DAAC
User Services for additional information.
ASTER User Notification - June 29, 2009
Japan’s Ministry of Economy, Trade and industry (METI) and NASA announced the release of the ASTER Global Digital Elevation Model (GDEM) on June 29, 2009. The GDEM was created by stereo-correlating the 1.3 million scene ASTER VNIR archive, covering the Earth’s land surface between 83N and 83S latitudes. The GDEM is produced with 30 meter postings, and is formatted in 1 x 1 degree tiles as GeoTIFF files. Each GDEM file is accompanied by a Quality Assessment file, either giving the number of ASTER scenes used to calculate a pixel’s value, or indicating the source of external DEM data used to fill the ASTER voids.
The GDEM is available for download from NASA’s EOS data archive and Japan’s Ground Data System. ASTER Global DEM and archived data are only available through the links above.
This ASTER product is available at no charge for any user pursuant to an agreement between METI and NASA. For more information about the GDEM, see the Validation Report: ASTER GDEM Validation Summary Report.
ASTER User
Advisory -
Change in Status Alert - January 12, 2009
ASTER SWIR detectors are no longer functioning due to anomalously high SWIR detector temperatures. ASTER SWIR data acquired since April 2008 are not useable, and show saturation of values and severe striping. All attempts to bring the SWIR bands back to life have failed, and no further action is envisioned. VNIR and TIR data continue to show excellent quality, meeting all mission requirements and specifications.
ASTER User
Advisory - Change in Status Alert - September 1, 2008
ASTER SWIR bands continue to be adversely impacted by an anomalously high
SWIR detector temperature. Although the ASTER team continues to focus on
this situation, no improvement is anticipated in the next few weeks. Users
are advised that ASTER SWIR data acquired from late April 2008 to the
present exhibit anomalous saturation of values and anomalous striping.
Cloud cover assessment and TIR location accuracy have also been affected.
Earlier archived data conform to mission specifications.
Additional advisories will continue to be provided.
ASTER User
Advisory - Change in Status Alert - May 7, 2008
Users are advised that ASTER SWIR data acquired in late April
and early May 2008 exhibit anomalous saturation of values and anomalous
striping. Cloud cover assessment and TIR location accuracy have also been
affected by the present situation.
Since January 2008, SWIR performance has been stable and data
quality has been nominal. On April 23, 2008, the SWIR detector temperature rose
precipitously, and SWIR Bands 5-9 saturated.
In an attempt to lower the SWIR detector temperature and improve
data quality, the ASTER Team plans to commence another SWIR recycling procedure
on May 7, 2008. If successful, stable SWIR performance and nominal data quality
will be restored.
The data quality impacts referenced in the April 9, 2008 alert
still apply for the periods specified.
Additional advisories will continue to be provided.
ASTER User
Advisory - February 5, 2008
This advisory is written to users of ASTER SWIR data to alert them to the
fact that some anomalous saturation of values has been observed in ASTER Bands 5
through 9 since May 2007. This problem is attributed to an increase in ASTER SWIR detector temperature believed to be caused by increased thermal resistance
in the SWIR cryocooler. VNIR and TIR bands are unaffected by this problem.
The slow increase in SWIR detector temperature did not become a problem until
early in 2007, and it did not really affect data quality until the detector
temperature exceeded 83ºK. Figure 1 shows the trend in SWIR detector temperature
for the past year. Note that the detector temperature first exceeded 83ºK on about May 1, 2007.
Following that date, four attempts have been made to lower the detector
temperature by recycling the cryocooler, including increasing the stroke length
of the cryocooler piston. The first attempt in May succeeded in reducing the
temperature to 82ºK, but the temperature soon began to increase again, exceeding
83ºK in late July. Second and third attempts to reduce the SWIR detector
temperature essentially failed in October. However, a fourth attempt in
mid-January, 2008 succeeded in reducing the SWIR detector temperature to 83ºK.
Since that date the SWIR detector temperature has remained stable at 83ºK.
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Figure 1. ASTER SWIR detector narrow temperature trend. Maximum (red),
average (black), and minimum (green) lines are plotted. |
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As long as the detector temperature remains at 83ºK, little or no degradation of
ASTER SWIR data is expected. However, users are advised that for ASTER SWIR data
collected between late May 2007 and late January 2008, the SWIR detector
temperature exceeded 83ºK, except for about six weeks in June and July. SWIR
data acquired during these periods may exhibit anomalous saturation of values,
particularly at high sun angles and for materials that are highly reflective in
the SWIR bands.
Figure 2 shows an example of SWIR saturation in an extremely bright desert
scene acquired over northern Africa in August 2007, when the detector
temperature was at about 83.5ºK. Saturation is especially prevalent in Bands 5,
6, and 7. Saturated pixels with DN = 255 are displayed in black. All other
colors are unsaturated pixels.
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Figure 2. SWIR saturation example. August 24, 2007 Africa observation. Pixels
with DN = 255 are colored black. |
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