ESA ground antennas and their compatibility with the MORE experiment

1. ESA ground antennas and their compatibility with the MORE experiment R. Maddè, M. Mercolino ESA/ESOC

2. ESA deep space network • ESA deep space network consists of two stations • New Norcia (NNO) DSA-1, operational since 2001, western Australia • S- and X- band uplink and downlink capabilities • Ka-band downlink optional (not yet taken) • Currently supporting Mars Express (MEX) and Rosetta • Cebreros (CEB) DSA-2, operational since 2005, Spain. • X- band uplink and downlink, Ka- band downlink capabilities • Ka-band uplink optional (not yet taken) • Currently supporting Venus Express (VEX) • Cebreros will be the station supporting BepiColombo • Future deep space station • DSA-3 mat be located in the southern hemisphere at American longitudes (Chile or Argentina) • X- band uplink and downlink (baseline), Ka- band downlink (optional)

3. Cebreros block diagram

4. Ka-band D/C output BW: 220 MHz X-band D/C output BW: 100 MHz L-band D/C output BW: 30 MHz 3L-band D/Cs per station 3 IFMS per station (2 for TT&C and 1 for RSI) Each input BW: 28 MHz 70 MHz 8400 – 8500 MHz 31800 – 32300 MHz 540-640 MHz Switch Switching Matrix X-band D/C L-band D/C 1 RHC RHC IFMS1 LHC LHC C F E GDSP 420-640 MHz L-band D/C 2 Ka-band D/C GDSP UCPU Test Test Estrack LAN Detail of the back-end (Rx side only)

5. IFMS characteristics Input BW: 28 MHz (High-speed mode) IF at 70MHz CFE (common front end) samples at 280 Ms/s Open loop capabilities Sampling rate from 1kHz to 4MHz Quantisation levels: 1,2,4,8,16 bits Up to 4 channels per each DSP card Ranging capabilities Maximum ranging tone frequency at 1.5 MHz (as per ECSS and CCSDS standards) Back end – Receiver (IFMS)

6. MORE requirements (generals) • Unlike most scientific experiments mounted on ESA missions, MORE heavily involves both space and ground segment • Different requirement “levels” can be defined • PI “level 1” performance requirements are the “end-to-end” requirements • A set of “level 2” performance requirements has been prepared by the PI, with the intention to apportion them to the space and ground segments • Some “level 2” requirements are related to media calibration

7. MORE requirements (level 2) • MORE requirements can be split into four main areas: • Requirements on the needed multi-frequency link • Requirements on Doppler performance (all links) • Ka/Ka link: adev (1000 s) < 6*10-15 • Other links: σX/X/ σKa/Ka=4; σX/Ka/ σKa/Ka=10 • Requirements on media effects • Uncalibrated contribution adev (1000 s) < 1*10-14 (or 3*10-15 ??) (all media) for antenna elevation > 15 deg • Requirements on Ranging performance (all links) • Ka/Ka ranging calibration error shall be less then than 0.3 ns (1 σ, 1-w) over half a day (X/Ka and X/X: 1.5 ns) • Ka/Ka, X/X and X/Ka ranging signals shall be as defined in the SGICD (WBRS – either with tone or PN codes) • Question for PI: are “ageing” requirements intended for the Ground Segment as well?

8. Current compatibility of MORE requirements with DSA • Need for a multi-frequency link • Imply a station Ka-band uplink upgrade (A in the next chart) • Requirements on Doppler performance (all links) • Imply the adev characterisation of the station on all links (B) • Imply the evaluation of the mechanical noise contribution (B) • Requirements on media calibration • Imply the use of an ad-hoc calibration system (which does not exist in ESA stations) (C) • Requirements on ranging performance • Imply the development, deployment and validation of a wide-band ranging processor (D) • Imply the development of a proper calibration strategy & the conduction of related test campaign (E)

9. Implementation approach List of needed activities: • Ka-band transmission implementation • Assessment of ADEV performance of the station • Media calibration • WBRS (Wide band ranging) processor • Ranging calibration Ancillary activities F. Check station location accuracy G. Extension of station baseband capabilities

10. Ka-band transmission • What has been done • High stability Ka-band up- and down-conv. are available • Ka-band feed, mirrors and dichroic are in production • Development of a movable mirror, to squint Ka-Tx beam respect Ka-Rx beam, on going • What needs to be done • Development of the transmitter HPA • Production and procurement of 2 operational units • Installation of all Ka-band uplink elements in CEB • Test and validation campaign • Verification of the Ka-band uplink stability

11. Assessment of ADEV performances of the station • An end-to-end assessment on all the three links is required • What has been done • At station level, a tool has been developed to compute the ADEV of the station, given the measurements of each of the equipment (X/X link only) • ADEV characterisation has been performed in both NNO and CEB (not taking into account the antenna mechanical noise) • Development of system able to assess antenna mechanical noise (to be deployed and validated in a test antenna in Villafranca) • What needs to be done • Evaluate CEB mechanical noise • Evaluate overall adev of X/X link, once mechanical noise is known • Evaluate overall adev of X/Ka link, once mechanical noise is known • Evaluate overall adev of the Ka/Ka link, once the antenna is upgraded

12. Measured ADEV performances Measured Ka-band UC ADEV < 1*10-16

13. Measured ADEV performances Measured Ka-band DC ADEV of 1*10-16

14. Measured ADEV performances (CEB X/X) The MORE X/X adev requirement is 2.4*10-14 @ 1000 s

15. Media calibration • The effect of dispersive media will be almost totally cancelled by means of the multifrequency link • Requirements on the level at which troposphere effects have to be calibrated have to be frozen • The current requirements are not enough to define the needed system • There is the need to define the system in terms of • Technical performance • Station interfaces • Interfaces to the final user • What has been done • Nothing • What needs to be done • Study and assessment of technical specification of the needed media calibration system • Development and procurement of the operational system • Installation, testing and long term calibration of the operational system

16. WBRS processor • Both the proposed MORE ranging systems (with tone at 20MHz or using PN codes) require the development of a new TT&C platform • This platform shall anyhow be developed due to obsolescence of the current IFMS (in operation since 2001) • What has been done • Nothing • What needs to be done • Study on new wide-band TT&C processor • New wide-band TT&C processor development • New wide-band TT&C processor procurement • Procurement of operational units • Installation and test of new TT&C processor in CEB

17. Ranging calibrations • Requirements on ranging calibration need some further clarifications • ESA has never faced requirements on ranging calibration so stringent. Therefore, ranging calibration achievable accuracies have to be further characterised • What has been done • Some preliminary test campaigns on the existing links (X/X, X/Ka) • What needs to be done • Requirement analysis and test with the current available equipment • Based on the outputs of the characterisation of the current ranging calibration system, one may consider further activities (if needed – i.e. On-line ranging calibration)

18. Check station location • The ADEV contribution due to the uncertainty of the station location is required to be less than 1.2*10-15 @ 1000 s. This means a sub-centimetre accuracy (0.9 cm) in the station location. • The declared accuracy of ESA deep space antennas is in the order of 1-2 cm over short time periods. • Over long time periods, the effect of the tectonics movement must be taken into account. • Too little data available to characterise the tectonics movement in CEB. • A survey using DDOR/VLBI techniques for evaluating the station coordinates may be considered. This possibility is at the moment TBD.

19. Extension of station baseband capabilities • The advent of a new ranging processor has high impact on baseband station integration • The number of receiving/transmitting chains (and related connectivity to the RF equipment) shall be reviewed, depending upon the final mission operational requirements • Once this is clear, and the new processor produced, an upgrade of the baseband configuration shall take place

20. Tentative schedule

21. Schedule assumptions • The main assumption is to have the station ready 6 months before launch • Launch is currently scheduled for August 2013 • It has to be noted that the station is operational, and would require major upgrade (i.e. a considerable down-time) •  In order to minimise operational impacts, all integration activities shall be grouped in the same time period

22. Costs • This presentation does not talk about costs • It just shows how MORE needs can be mapped in the existing ESA infrastructure • However, it has to be noted that: • All that has been mentioned under “what has been done” has been covered by ESA • Most of what has been mentioned under “needs to be done” is currently not financed • The PI is invited to acknowledge the above-presented current status

23. Final remarks • ESA CEB station would welcome to host the ground segment of the MORE experiments • CEB is an operational station, used to support several missions. Therefore: • Station configuration is ruled by ESA • Station operation is restricted to ESA • Interfacing to experiment data has to be done through ESA • CEB station will provide in any case routine operations to the BC mission