Ocean Surface Topography Science Team Meeting

1. Ocean Surface Topography Science Team Meeting Jason-1 JPL Project StatusGlenn M. ShirtliffeNASA/JPL Jason-1 Project Manager

2. Jason-1 Mission Overview • The 14+ year combined data record from T/P and Jason-1 is the only climate data record that is able to address the problem of global change of sea level and ocean circulation and its relation to climate change. • Continuation of this data record is critical to meeting NASA’s Earth Science goals. • A key objective of extending Jason is to have overlap with OSTM and perform cross-calibration to ensure consistency in the data record initiated by TOPEX/Poseidon in 1992. • The consistent data record built by T/P, Jason-1 and OSTM will then become the first multi-decadal global record for addressing the issue of sea level rise, which has been identified by the 2007 IPCC assessment as one of the most important consequences and indicators of global climate change. • The OSTM Mission will extend the global sea level data record into the decade of 2010s.

3. Jason-1 JPL Mission Operations: Current Status • Joint CNES-JPL operations continuing to proceed extremely well • Weekly joint telecon for normal satellite uploads, and as required • Regular proficiency and training tests ongoing • Instruments and ground operations systems at JPL are meeting, and routinely exceeding all mission objectives • Jason entered extended operations phase in December 2006 • The Jason Mission is currently funded by NASA through October 2009 • A second NASA “Senior Review” is currently in progress

4. Earth terminal operations are nominal and meeting mission requirements. S/C Telemetry, command and health/safety monitoring is nominal. Staff is fully trained for routine operations and contingency procedures. Sequencing Hardware/software and team are operating well All products and services are meeting requirements Earth terminal scheduling Generation of routine flight time-tagged sequence Generation of all routine flight operations support data products Many tasks at JPL control center are performed automatically Jason-1 Ground Status

5. In the period since the last OSTST Meeting in Venice, no science or engineering data has been lost due to NASA ground system anomalies or command errors. The current NASA ground system configuration and station performance is adequate to meet mission requirements. In the past year, 95.3% of all possible over-ocean science data was received. Excluding the two-week safe hold event in Oct.-Nov. 2006, the total data recovery rate exceeds 99.97% of all available science data. JPL Mission Operations Assessment

6. TOPEX/Poseidon—Jason-1 collision avoidance monitoring TOPEX/Poseidon can no longer be maneuvered. Jason-1 and OSTM must monitor the drift of TOPEX/Poseidon and possibly maneuver to avoid a collision. Occasional AUS ET pass loss issues remain open: DCN saturation on the primary 256-kbps line often results in the loss of AUS telemetry and command connections. Recovery requires a base-band hardware (SEBB) reboot after the lost pass. JPL and CNES are investigating router prioritization of JTCCS-JCCC traffic. The 128-kbps backup DCN line will be discontinued by NASA Jason must identify and pay for a replacement solution (ISDN) JPL Mission Operations Concerns

7. Jason-1 JPL Mission Operations Summary • Mission operations will continue through (at least) launch of OSTM to satisfy the goal of long-term contiguous ocean surface topography data • Data reprocessing will continue to be a high priority in the near-term • A comprehensive 102-Cycle reprocessing effort is nearing completion (Began in Dec. 2006; nearing completion in Mar. 2007) • Tentative plans call for one additional comprehensive reprocessing campaign • OSTST should continue its on-going advocacy of the necessity and requirements for future missions to support and maintain robust research programs on ocean circulation, climate variability, and sea-level monitoring

8. Jason-1 JPL Instrument Status • NASA/JPL provided three payload instruments for the Jason-1 Mission: • Microwave Radiometer (JMR) • Laser Retroreflector Array (LRA) • Turbo Rogue Space Receiver (TRSR)

9. Jason-1 Microwave Radiometer (JMR) • Presentation contributors: • Shannon Brown, JPL • Shailen Desai, JPL • Summary: • Continues to operate nominally • No Alarms • No Commanding (Except for SHM recoveries) • No engineering anomalies since launch • Three confirmed science anomalies since launch: • Cycle 31 and 68 anomalies corrected in Version B GDRs • Cycle 136 anomaly will be corrected in Version C GDRs • One possible science anomaly after Cycle 177 safehold is under investigation • Will be corrected in Version C GDRs, if necessary

10. Recalibration of the JMR performed to correct anomalies in Version A GDRs. Cycle 31 and 68 anomalies corrected. Cycle 136 anomaly < 2 mm in wet path delay. Cycle 177 anomaly likely to be < 2 mm in wet path delay. Small yaw state dependence possibly introduced - under investigation. Calibration of JMR continues in preparation for Version C GDRs. JMR Measurements on Version B GDRs

11. Presentation contributor: Glenn Shirtliffe, JPL Summary: The LRA continues to provide returns adequate for tracking. Laser Retroreflector Array (LRA)

12. Presentation contributors: Tim Munson, Cognizant Engineer, JPL Glenn Shirtliffe, JPL Science contributors: Bruce Haines, JPL Shailen Desai, JPL Willy Bertiger, JPL Summary: TRSR2 (primary receiver) operates in a degraded mode, but still supports orbit determination (with significantly reduced accuracies). TRSR1 (redundant receiver) was powered up to support a software upload but experienced a critical failure and will remain powered off. Turbo Rogue Space Receiver (TRSR)

13. TRSR1 failed prior to a software upload on 13 September 2006. TRSR2 was powered down and the redundant TRSR1 was powered up to perform a software code upload. Real-time monitoring indicated that the turn on was normal in all respects. While Jason was out of ground station contact, the primary current degraded and after approximately one hour the receiver went offline. Recorded housekeeping data showed that the 1553 current and voltage monitors showed sudden erroneous operations during the preceding hour. Due to the severity of the problem and the interface to the spacecraft, the TRSR Instrument Team does not anticipate powering up the TRSR1 for any further testing or diagnostics. TRSR1 Redundant Receiver Status

14. TRSR2 reset behavior changed during a fixed-yaw period in mid-July 2006. TRSR2 nominally resets 4-9 times a day from different sources, but is now becoming increasingly less tolerant of these resets. The preponderance of these resets occur in the South Atlantic Anomaly and at high orbital latitudes indicating a radiation component. The TRSR receivers have a significant number of commercial parts susceptible to radiation. There is a clear correlation between these problems and the temperature of the TRSR unit, indicating a total-dose radiation effect. The problem became progressively worse to the point that it not only occurred during fixed-yaw periods, but now occurs during the cooler yaw-steering modes. This is also indicative of a total-dose radiation effect. TRSR2 Performance Degradation

15. TRSR Long-Term Performance Metrics

16. 1-cm Orbit Accuracy Achieved and Maintained

17. Life expectancy of the TRSR receivers has been surpassed TRSR2 Continues to provide tracking data of high accuracy. 4-5 mm for carrier phase (biased range) 20 cm for 5-min compressed pseudorange (vs. 50–70 cm for GPSDR on T/P) Temporal coverage and geometric diversity of tracking data has been severely compromised since mid-2006 Nominal (2002–2006): 8–12 GPS tracked spacecraft simultaneously Current: 4 satellites tracked with 12-hr on/off cycle 2002–2006 data set new POD standards for both accuracy and latency <1-cm RMS radial accuracy for definitive solutions 0.8 cm RMS agreement with new GDR-B orbits (SLR+DORIS+GPS) 1.1 cm RMS agreement with independent high-elevation SLR data. 2-cm RMS radial accuracy within 5–7 hrs of real time Capitalizes on NASA global differential GPS system Real-time orbit solutions are a cornerstone of JPL’s near-real-time sea surface height product POD performance in current, degraded tracking mode is highly variable Typical RMS radial accuracies of 1–5+ cm. TRSR POD Performance Summary

18. TOPEX/Poseidon and Jason-1 Science/Outreach Success • T/P and Jason-1 science open literature database available on-line • Over 2,000 articles citing data utilization from TOPEX/Poseidon and Jason-1 have appeared in over 335 Journals or Publications • Searchable by author, title, keyword, abstract, & category for T/P and Jason-related science, engineering, applications, and education research from 1990-present

19. TOPEX/Poseidon, Jason-1 and OSTMOnward and Upward! • T/P data reprocessing effort ongoing, funded primarily through science team and PO.DAAC • OSTST input will be critical to ensure that a continuous validated data record is available • Scientists, NASA and CNES must continue joint efforts to demonstrate the applications and value of ocean science to the public • Societal benefits will define NASA/CNES strategy for long-term ocean observing systems OSTM Tandem Science Mission