Results of 1996 Data Analysis Survey

Note: This information has been updated from the article published in the June 1996 issue of the Laser Ranging Newsletter of the SLR/LLR Subcommission of the CSTG.

A regular question that arises at each CSTG SLR Subcommission meeting is: Are we doing the best we can to satisfy the needs of the science community? Do we understand their needs? In this connection: Are we making most effective use of our SLR station resources? Are we setting priorities correctly and are we allocating tracking time in the most effective manner? Should different stations be tracking with different sets of priorities? Should stations use priorities that are set dynamically?

To begin to address these issues as a community, we have started at a fundamental level to find out

Who is using the SLR data?
What data are they using?
What data is not being used?
What applications are being studied?
Does the data satisfy the analysts' needs? and
What is missing?

In a recent survey of the analysis groups, we asked the following questions:

Which satellites are you currently using in your analyses?
What are the applications for each satellite (station position, motion, gravity field, Earth rotation, altimetry, etc.) ?
Are you receiving sufficient data for your analyses?
Are you receiving sufficient geographic coverage?
Are the data of sufficient accuracy for your applications?
Are there other satellites that you plan to use in the future? For what applications?
What else do you need that you are not getting?

Some general comments received from the respondents regarding areas that need attention were:

Data quality:
- Large disparity in data quality among stations
- Often, data of poor quality are worse than no data at all
- Too many systems with poor data quality
Data Volume:
- Tracking coverage from some stations is very sporadic and sparse
- Some stations do not provide a minimum level of contribution
- Tracking gaps of more than ten days are a problem
- Weeks with less than 100 LAGEOS passes are sparse
- Much more data required on ETALON-1 and -2, GPS-35/36, and GLONASS
- GFZ-1 data is insufficient
Geographic Coverage:
- Better geographic coverage needed in the Southern hemisphere, Russia, and China
Temporal Coverage:
- Tracking gaps over weekends are a problem
- LAGEOS-1 and -2 data is adequate for three-day resolution, but inadequate for one-day resolution
- More data on STELLA, STARLETTE, and AJISAI required for one-day resolution of higher order perturbations
Local Surveys:
- More reliable local surveys and more information about the surveys and local eccentricities required
Operational Follow-up:
- Lack of communications with some stations regarding problems
Satellites:
- More satellite targets of high quality needed

Table SLR Analysis Survey Results
Organization	Respondent	Satellites by Priority	Areas of Investigation
University of Southampton	Graham Swinerd	STARLETTE STELLA AJISAI LAGEOS-1/2 ERS-1/2	Ocean Tides Gravity Field Long Period Aerodynamics Gas Surface Interactions
Delft University	Ron Noomen	LAGEOS-1/2 ERS-1/2 TOPEX GPS-35/36 STELLA STARLETTE	Orbit Analysis Earth Rotation Position/Motion Altimetry
National Aerospace Lab, Tokyo	Masaaki Murata	LAGEOS-1/2 ETALON-1/2 TOPEX GPS-35/36 (GFZ-1)	Position/Motion Gravity Field Earth Rotation Altimetry Orbital Analysis
RGO	Graham Appleby	ETALON-1/2 LAGEOS-1/2	Non-Gravitational Acceleration Earth Rotation Position/Motion
Astronomical Institute of Berne	Werner Gurtner	GPS-35/36 Add'l GPS sat.	Position/Motion Earth Rotation Technique Comparison
Russian Academy of Sciences	Suriya Tatevian	LAGEOS-1/2 ETALON-1/2 (STARLETTE) (STELLA)	Position/Motion Earth Rotation (Gravity Field)
NASA/GSFC	Erricos Pavlis	LAGEOS-1/2 GPS-35/36 STARLETTE STELLA AJISAI ETALON-1/2 GFZ-1 TOPEX ERS-1/2 GLONASS	Position/Motion Earth Rotation Gravity Field Altimetry
Shanghai Observatory	Tan Detong	LAGEOS-1/2 ETALON-1/2 GLONASS-63/67 TOPEX ERS 2	Earth Rotation Position/Motion Altimetry
Auston University, Birmingham, UK	Philip Moore	ERS-1/2 TOPEX STELLA (GFZ-1)	Gravity Field Aerodynamics Altimetry
GFZ/DLR	Heiner Massmann	ERS-1/2 GFZ-1 LAGEOS-1/2 (STELLA) (AJISAI) (TOPEX) (High Alt. Sat.)	Precise Orbits for Altimetry and SAR Gravity Field Position/Motion Atmospheric Density
CSR/University of Texas	Richard Eanes	LAGEOS-1/2 STARLETTE STELLA AJISAI GFZ-1 ETALON-1/2 TOPEX ERS-1/2 GPS-35/36	Position/Motion Earth Rotation Gravity Field Altimetry Performance Assessment
IfAG/Branch Potsdam	Bernt Richter	LAGEOS-1/2 ETALON-1/2 GPS-35/36 STARLETTE STELLA	Orbit Analysis Earth Rotation Position Velocity Combined Solution with Other Techniques
GRGS/CNES and OCA	Richard Biancale	STARLETTE STELLA LAGEOS-1/2 AJISAI TOPEX ERS-1/2	Gravitiy Field and Long Period Variations Ocean Tides Position/Motion Atmospheric Density Altimetry and Calibration
ASI	Pippo Bianco	LAGEOS-1/2 AJISAI STARLETTE STELLA ERS-1/2	Position/Velocity Earth Rotation/Polar Motion Non-Gravitational Perturbations on Satellites' Orbits Precise Orbits for Altimetry Fundamental Physics Gravity Field and Long Period Variations Atmospheric Density
University of Padova	Alessandro Caporali	LAGEOS-1/2 (GPS 35/36)	Position/Motion Earth Rotation/Polar Motion (Earth and Ocean Tides) (Gravity Field)
MIT/Lincoln Labs	Mike Gaposhkin	LAGEOS-1/2 ETALON-1/2 AJISAI STARLETTE STELLA ERS-1/2 TOPEX GLONASS	Precise Orbit for Calibration of Satellite Surveillance Radars

Updated: October 12, 1996

Responsible Government Official: Carey Noll
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