OSTST Meeting Hobart, Australia GMS - 1 March 12, 2007 Ocean Surface Topography Science Team Meeting...

OSTST MeetingOSTST MeetingHobart, Australia

GMS - 1March 12, 2007

Ocean Surface TopographyScience Team Meeting

Jason-1 JPL Project

Status

Glenn M. Shirtliffe

NASA/JPL Jason-1 Project Manager


GMS - 2March 12, 2007

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.


GMS - 3March 12, 2007

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


GMS - 4March 12, 2007

Jason-1 Ground Status

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


GMS - 5March 12, 2007

JPL Mission Operations Assessment

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.


GMS - 6March 12, 2007

JPL Mission Operations Concerns

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)


GMS - 7March 12, 2007

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


GMS - 8March 12, 2007

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)


GMS - 9March 12, 2007

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


GMS - 10March 12, 2007

JMR Measurements on Version B GDRs

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.

-15

-12

-9

-6

-3

0

3

6

9

12

15

0 20 40 60 80 100 120 140 160 180 200

JMR (GDRB) - GPSJMR (GDRB) - SSMIJMR (GDRB) - TMIJMR (GDRB) - ECMWF

Cyc

le A

vera

ge

of

Wet

Pat

h

Del

ay D

iffe

ren

ces

(mm

)

Jason Repeat Cycle

JMR from GDRB


GMS - 11March 12, 2007

Laser Retroreflector Array (LRA)

Presentation contributor: Glenn Shirtliffe, JPL

Summary: The LRA continues to provide

returns adequate for tracking.


GMS - 12March 12, 2007

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)


GMS - 13March 12, 2007

TRSR1 Redundant Receiver Status

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.


GMS - 14March 12, 2007

TRSR2 Performance Degradation

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.


GMS - 15March 12, 2007

TRSR Long-Term Performance Metrics

4

6

8

DAILY POSTFIT RESIDUAL OF IONOSPHERE-FREE CARRIER PHASE (LC)

RM

S (

mm

)

0

1000

2000

DAILY NUMBER OF TRACKING OBSERVATIONS (LC, FROM POD)

No.

0

50

100 PERCENTAGE TIME (DAILY) WITH NO TRACKING DATA

2002 2003 2004 2005 2006 2007

RM

S (

mm

)


GMS - 16March 12, 2007

1-cm Orbit Accuracy Achieved and Maintained


GMS - 17March 12, 2007

TRSR POD Performance Summary

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.


GMS - 18March 12, 2007

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

TOPEX/Poseidon and Jason-1 Science/Outreach Success


GMS - 19March 12, 2007

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

Tandem Science Mission

OSTM

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OSTST Meeting Hobart, Australia GMS - 1 March 12, 2007 Ocean Surface Topography Science Team Meeting...

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