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ASTER


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ASTER Website Update - June 2013

As of June 20th, Japan Space Systems offers combined search and order capabilities for ASTER and PALSAR data: ASTER/PALSAR Unified Search. New users and GDS-IMS account holders will need to create a new account to access the combined search and order tool. GDS-IMS was deactivated on June 17th.


ASTER Website Update - April 2013

A report on the 42nd ASTER Science Team Meeting was published in the March/April issue of The Earth Observer.


ASTER Website Update - February 2013

Updated the Full ASTER Bibliography (pdf 2.9 MB) on the Presentations and Documents page.


ASTER User Notification - November 2012

In order to serve the Land Processes Distributed Active Archive Center (LP DAAC) user community more effectively, the LP DAAC will transition from FTP to HTTP for ASTER and MODIS downloads on December 12, 2012. The HTTP updates are designed to increase performance and improve security during data retrieval. Both FTP and HTTP capabilities will be available through January 16, 2013. After January 16, only the HTTP option will be available. Users of LP DAAC data should plan to update any automated scripts for LP DAAC data retrieval before the January 16, 2013 deadline.

ASTER Website Update - July 2012

Added the Full ASTER Bibliography (pdf 2.5 MB) to the Presentations and Documents page.


ASTER User Notification - May 2012

The LP DAAC updated their ASTER Level 1 processing software with geometric correction database Version 3.02. This correction, generated by the Earth Remote Sensing Division of Japan Space Systems, improves the geolocation error in ASTER TIR nighttime observations. ASTER data processed through GDS IMS and the LP DAAC uses the improved geometric correction DB Ver. 3.02. Further details are available in the LP DAAC Software Update notice.

ASTER User Notification - April 2012

The Terra website has a new look. Learn about the EOS flagship satellite Terra and how its five onboard instruments provide insight into the total Earth system.

ASTER User Notification - April 2012

As of March 30, 2012, the Earth Remote Sensing and Data Analysis Center (ERSDAC) merged with the Institute for Unmanned Space Experiment Free Flyer (USEF) and the Japan Resources Observation System and Space Utilization Organization (JAROS) to form a new organization called Japan Space Systems (J-spacesystems). ERSDAC is now referred to as the Earth Remote Sensing Division. Activities and services previously carried out by ERSDAC, including the distribution of ASTER data, will continued to be provided by the new organization.

ASTER User Notification - March 2012

WIST has been retired and replaced by Reverb. Should you have further questions about Reverb, please visit the Reverb Tutorial.

ASTER User Notification - February 2012

Version 3 of the North American ASTER Land Surface Emissivity Database (NAALSED), developed at the Jet Propulsion Laboratory (JPL), is now available for download through Reverb, LP DAAC Data Pool, and USGS EarthExplorer (EE). NAALSED provides seamless emissivity data for use in climate research.

NAALSED is a collection of 3,327 1 degree by 1 degree tiles compiled from all clear ASTER "leaf on" season (July, August, September) data collected over North America from 2000 to 2010. Each tile contains several layers of science data sets, including surface emissivity, temperature, and a top of atmosphere Normalized Difference Vegetation Index (NDVI). Each tile also contains supplemental layers, such as a regional version of the ASTER GDEM resampled to 100 meters, geographic coordinates, a land-water map, and the number of observations used as input. More information on NAALSED may be obtained from the Joint Emissivity Database Initiative (JEDI) website and the LP DAAC NAALSED Data Product Page.

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 Japan Space System's ASTER 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 EarthExplorer (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 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.

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 Reverb. Japan Space System's Ground Data System (GDS) IMS 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 Reverb and Japan Space System's ASTER GDEM Page. Please refer to the Reverb GDEM ordering tutorial for guidance in placing an order through Reverb.

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 83 K. Figure 1 shows the trend in SWIR detector temperature for the past year. Note that the detector temperature first exceeded 83 K 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 82 K, but the temperature soon began to increase again, exceeding 83 K 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 83 K. Since that date the SWIR detector temperature has remained stable at 83 K.

Figure 1. ASTER SWIR detector narrow temperature trend. Maximum (red), average (black), and minimum (green) lines are plotted.

As long as the detector temperature remains at 83 K, 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 83 K, 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 83.5 K. 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.

Figure 2. SWIR saturation example. August 24, 2007 Africa observation. Pixels with DN = 255 are colored black.

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