Thermal Evolved Gas Analyzer (TEGA) data sets

Data Set Overview

The Telltale wind indicator is a mechanical anemometer designed to operate on the Martian surface as part of the meteorological package on the NASA Phoenix lander. It consists of a lightweight cylinder suspended by Kevlar fibers and is deflected under the action of wind. Imaging of the Telltale deflection allows the wind speed and direction to be quantified and image blur caused by its oscillations provides information about wind turbulence.

The Telltale data set consists of a single comma-delimited ASCII table, TELLTALE.CSV, and its PDS label TELLTALE.LBL.

The table contains the following columns:

Sol	Phoenix Sol
LTST	Local True Time given im image header
v (m/s)	Wind speed in meters/second
dv+ (m/s)	Error in wind speed (positive)
dv- (m/s)	Error in wind speed (negative)
Dir (deg)	Wind direction in degrees given in meteorological convention (0 = from N, 90 = from E, 180 = from S, 270 = from W)
dDir (deg)	Error in direction (given in degrees)
Exposure time	Exposure time by SSI in milliseconds
File name	SSI image filename used for the analysis

Processing

This data set has been generated by analysis of SSI images of the Telltale. The images have been analyzed to determine the position of the Kapton tube in the Telltale reference frame. The shift from rest position is calculated, and the wind velocity and errors determined from the methods described in [HOLSTEIN-RATHLOU2008, GUNNLAUGSSON2008]. The directions are finally converted to areographic directions using the orientation of the lander. The result is an ASCII table of time, wind velocity and direction, errors in wind velocity and directory, and names of SSI images used to derive the values.

Confidence Level Overview

Estimated errors are included in the table.

Data Coverage and Quality

Data coverage during the course of the Phoenix mission is dependent on when the Surface Stereo Imager could be used to obtain movies of the telltale. This typically occurs one to several times per sol. Quality indicators are included in the table in the form of wind velocity errors.