NOAA Logo National Centers for Environmental Information

formerly the National Oceanographic Data Center (NODC)...  more on NCEI

NOAA Satellite and Information Service
Logo Image of NODC Satellite Oceanography Team

Geodetic Satellite Exact Repeat Mission 9-Track Tape Altimetry SDR Data Recovery

 


The US Navy Geodetic Satellite (Geosat) radar altimeter mission lasted for nearly 5 years (March 1985 to January 1990) and collected approximately 750 million measurements of sea level, wave height, and wind speed over the global oceans. During the Geodetic Mission (March 1985 to September 1986), the satellite did not repeat its ground track for the duration of the mission. The orbit of the satellite was changed in October 1986 to begin the Exact Repeat Mission (ERM) which lasted from October 1986 until the satellite stopped functioning in January 1990. During the ERM, the satellite repeated its ground track every 17 days.

The Exact Repeat Mission Sensor Data Records (SDR) were originally preserved at NODC in 9-track tapes, and each tape contained the data collected in one day. From March 2008 to April 2009, these tapes were sent to Data Recovery International, Inc., Hurst, TX for processing and the recovered data were sent back to NODC via DVD. In total, 1098 tapes were recovered. Among those recovered tapes, only EIGHT 19-second tape blocks were unrecoverable, which equates to a loss of only 0.000172%!


Geosat Introduction

An brief introduction on the US Navy Geodetic Satellite mission.

Processing Procedures for 9-Track Tape Recovery

The basic procedures and responsibilties in the data recovery process.

Recovery Progress and Information for Tape Damage

The progess of the recovery and some pictures for the tapes with some physical damage.

Frame Count Check on SDR Record Data

Access to results of the frame count check on the recovered tapes.

Data Range Check on SDR Header Data

Access to results of the data quality check on the header data in the recovered tapes.

Data Range Check on SDR Record Data

Access to results of the data quality check on the record data in the recovered tapes.


Download Cumulative Recovery Log for all tapes


Red number : represents a tape with one block (19 records) loss caused by tape damage; Green shading: data in a tape has been fully recovered; White background: tape is missing because of satellite observation loss; Gray shading: tape is marked as "missing" or not shown in the tape inventory at NODC.


Geosat Exact Repeat Mission SDR 9-Track Data Tapes

Bill King (Data Recovery International) and 1098 9-Track SDR data Tapes

9-Track Tape Reader and DVD-ROMs

Contact: Dr. Yongsheng Zhang, National Oceanographic Data Center, NOAA/NESDIS E/OC1 SSMC3, 4th Floor; 1315 East-West Highway Silver Spring, MD 20910-3282. E-mail: Yongsheng.Zhang@noaa.gov

Acknowledgment: We gratefully acknowledge the efforts of Bill King at Data Recovery International, Inc., Hurst, TX in implementing data recovery from the 9-track tapes, and we also appreciate his kindness in providing us the valuable photos used on this web page.

SOG NetCDF NOAA CLASS AVHRR SST GODAE MPMC GAC RSMAS GHRSST MCSST NLSST SeaWiFS
GOSTA NPOESS VIIRS OPeNDAP DODS LAS HRPT LAC GAC HDF-SDS DMAC PO.DAAC LTSRF CoRTAD

  Last modified:    Thu, 5-Sep-2013 22:37 UTC NCEI.info@noaa.gov
 
Dept. of Commerce - NOAA - NESDIS - NCEI
* Offsite Link Notification
USA.gov - The U.S. Government's Web Portal