Novel Tracking Techniques for ESA's Future Deep Space Missions
 
Future Deep Space Scientific Missions will require novel tracking techniques.
These new techniques have been proposed recently for ESA Deep Space missions and forecast improvements with respect to current Deep Space tracking methods of around one order of magnitude.

Accurate tracking is mainly driven by two factors, the intrinsic performance of a particular method, and Ground Station frequency stability.
ESA is at present devoting a big effort to the latter, whose major outcome has been the procurement of Hydrogen Masers for the Agency's first Deep Space facility (DSA1) in New Norcia, Western Australia.
A similar system will be procured for the coming DSA2 in Cebreros, Spain.

Tracking accuracy requirements for Deep Space missions are continuously getting more and more demanding.
Apart from Ground Station Stability figures, there is a need to understand how new tracking methods could be performed from the Agency's current and upcoming Deep Space Ground Station facilities, and moreover, what modifications would be needed.

During this study, at least three major novel tracking techniques would be considered, namely:

• Delta Differential One-Way Range (DOR): Simultaneous use of two or more Deep Space Stations for spacecraft's angular determination.
• Wideband Ranging System (WBRS): Use of high frequency Ranging tones for more accurate Ranging measurements.
• Regenerative Pseudo-Noise Ranging: Increased efficiency of the downlink's link budget based on the removal of uplink noise at the spacecraft's transponder.

The study will address the feasibility of implementing the above methods in ESA's Deep Space Facilities.

Using DSA1 as starting point, this study would present the capabilities Ground Station equipment needs to fulfil, in order to support future tracking methods for Deep Space missions.
The study should propose a general station solution that permits tracking support based on novel tracking methods.
The study should at least address:

• Frequency and Time issues (e.g. time tagging required accuracies and Ground Station synchronization aspects, in particular for DOR techniques).
• Expected Signal to Noise Ratios (SNR) in future Deep Space Missions.
• Operational frequency bands
• Ground Station operational bandwidths
• Most suitable IF frequencies
• Data collection related issues (e.g. sampling frequencies, observation times)
• Data correlation aspects for the DOR method
• Calibration activities, in order to remove tracking uncertainties
• Interoperability with other organisations interested in Deep Space missions, such as JPL, NASDA, etc.

The output of the study will be an assessment on what needs to be done in Ground Stations to support novel tracking techniques, in terms of:

• Architecture of the whole station
• Station's RF performance
• Implications on Frequency and Timing system
• Implications on receivers and baseband processing equipment
• Implications on communications to control centres
• Recommendations and for subsequent ad-hoc technological developments on the above areas (to be financed by subsequent, more focalised study activities)
• Feasibility assessments on required developments

The study will conclude with an evaluation of achievable performance in future Ground Stations.