The Telltale project

Participants: Haraldur Páll Gunnlaugsson, Jonathan Merrison, Christina von Holstein-Rathlou

The Telltale is a passive wind indicator mounted on the NASA Phoenix lander, which landed on Mars in May 2008 and operated for 5 months. It was developed and constructed at the Mars Simulation Laboratory at the Aarhus University.



The Phoenix Lander
Phoenix landed close to the North Pole of Mars on May 25, 2008. In this region, ice has been detected in the soil by means of a gamma ray spectrometer (GRS) on the Mars Oddyssey. The lander dug for samples and delivered them to various chemistry experiments on the lander deck. Having crude information on the wind cycle at the landing site, it was possible to select times for delivery of samples where the dust is not blown away in the wind.

Drawing of the Phoenix lander showing the Telltale on top of the Meteorology mast (NASA/JPL). Picture of the Telltale delivered to NASA.

The Telltale
The Telltale consists of a gallow that is mounted on top of the meteorological mast of the Lander. The active element of the instrument is an extremely lightweight Kapton tube hanging in Kevlar fibers. Images taken of the instrument show the deflection of the Telltale due to the wind. A mirror is mounted below the active part to enable better direction information.

Picture of the Telltale delivered to NASA.

Film strip showing the performance of one of the tested units at iABG, Germany under the vibration levels that can be expected during launch and landing.

 

Telltale history
The Telltale was developed, constructed and delivered at extremely short time compared to what is usually the case with scientific equipment for Mars missions. In April 2005, only a concept of the experiment existed, and in February 2007 Telltale was delivered fully tested and calibrated. In the meantime, the team experienced failed tests and redesigning of the experiment.

After the landing on Mars in May 2008, data collection operations started in Tucson , Arizona. During the summer the Telltale team worked on analyzing the incoming data from Mars to determine wind speeds and directions. It  was a help in classifying the diurnal wind cycle and supporting sample delivery to other instruments on the Phoenix lander.  

An example of wind speed data collected by the Telltale during the mission is seen here

 

 



Animated gif showing a series of 5 pictures taken within an 8 minute time period on Mars. The pictures were taken on Sol 8, the eighth day of the mission, just after 1 pm, local lander time.