1. RADARSAT-1/RADARSAT-2/ENVISAT Mission Status Adrian Bohane IICWG St. Petersburg April 2003

2. RADARSAT-1 Mission n RADARSAT Mission Life was specified for 5.25 years from launch in November 1995. n The 5.25 year goal was a program requirement from the Canadian government; the satellite and ground infrastructure were built in response to this and to meet or exceed the program goal. Significant redundancy was built into all aspects of the program. n The satellite is working well and is producing reliable and good quality data going into the 8th year of operation

3. Momentum Wheels: December outage n RADARSAT has 2 sets of 3 orthogonal wheels that measure changes in the spacecraft inertia and provide input to the attitude correction system n During fall of 1999, speed variations were observed in 1 wheel of the primary set possibly due to breakdown or loss of lubricant. n In October 1999 all wheels were switched from primary to redundant; the ‘all wheel switch’ was the only one configured at CSA; redundant wheels continue to perform well. Procedures have been developed subsequently to switch individual wheels

4. Momentum Wheels (cont’d) n In the fall of 2002, the primary pitch wheel was restarted to test its performance; no improvement was observed n Shortly after, the redundant pitch wheel displayed similar indications of high temperature and speed variation; it was shut down in December 2002 n Over a 4 week period in December 2002 procedures were developed and simulated to operate the spacecraft without input from the pitch momentum wheel; this procedure uses the torque rods to provide input in place of the wheel and one of the pitch wheels is kept stationary and used as a reaction wheel n Operations resumed on 24 December 2002; subsequent analysis has shown that the satellite pointing and stability are as good as they were prior to shutdown of the pitch wheel

5. Horizon Scanner n HS2 failed in first year of operations; cause is not yet clear n HS1 has been used successfully, but since April 2000 warnings regarding motor speed control have been received in telemetry perhaps indicating impending bearing failure n If both fail risk: management has focused upon improving spacecraft performance using Attitude Determination Method 3 (ADM3) and on reduction of risks during critical attitude control regimes (Eclipse entry/exit transitions) n Tests conducted to date show that spacecraft can be controlled in ADM3 mode sufficiently well to permit successful imaging ; ground processors have been validated for handling the data n Failure of both HS1 and HS2 would therefore not end the mission because of redundant sources of attitude information

6. Consumables n Main consumable is propellant required to maintain orbit n Currently, burns are more frequent than at first due to solar pressure effects during solar maximum; Solar maximum peaked in summer 2000 and has been declining since n Change to orbit maintenance strategy (+/- 2 km) has no impact on total fuel consumption n It has been estimated that sufficient fuel remains to maintain orbit beyond 2070

7. Spacecraft Power n Ability of the solar array (SA) to generate power degrades with time; Original estimate was that SA power would last for 2-3 years beyond nominal life; On-going monitoring of degradation indicates 2012 to be a more realistic date n Therefore no threat to mission expected for several years

8. On Board Tape Recorders (OBR) n RADARSAT-1 has 2 mechanical on board recorders, both performed well until April 2002. n In late April 2002, OBR 1 showed sudden signs of high error, preliminary analysis indicated a failure and it was shut down; Recently OBR 1 was restarted and successfully used to record data. n OBR 2 continues to work well but in order to conserve the tape recorder life the number of playbacks per day was reduced from 3 or 4 to 1. n Bit Error Rate analysis of both recorders is constantly monitored.

9. Leonids n In 1999 predictions prompted shutdown of the payload high-voltage units for 12 hours on 18 November to prevent arcing n 2000 event was insignificant n 2001 event was predicted to be 5x greater than 1999; similar high-voltage shutdown strategy employed as in 1999 n Predictions are monitored each year and risk mitigation strategy employed as necessary

10. Summary of Satellite Health n Sudden catastrophic failure is always a risk n There is no key component currently indicating that is likely to fail or expire prior to the scheduled launch of RADARSAT-2 n Strategies and ‘work-arounds’ exist and are development is on-going to extend the mission n RSI is optimistic that RADARSAT-1 will remain operational until the launch of RADARSAT-2

11. RADARSAT-2 Status n RADARSAT-2 is currently in the manufacturing phase and is scheduled for launch in 2005. A Boeing Delta launch is the chosen vehicle. –Launch is dependent on the end of the manufacturing phase. The main complex component is the active antenna and the 512 tx/rx modules on the antenna. The end of the production run of the modules (known in 6 months) is the key determinant in the launch date. –The current manufacturing schedule points to a launch in early to late 2005. n First pre-launch commitment signed recently between Norwegian and Canadian governments and respective commercial partners (RSI and KSAT).

12. ENVISAT Update Adrian Bohane IICWG St. Petersburg April 2003

13. ENVISAT Instruments n MERIS - Medium Resolution Imaging Spectrometer n MIPAS - Michelson Interferometric Passive Atmospheric Sounder n GOMOS - Global Ozone Monitoring by Occultation of Stars n RA2 - Radar Altimeter 2 n MWR - Microwave Radiometer n LRR - Laser Retro Reflector n ASAR - Advanced Synthetic Aperture Radar

14. ENVISAT Image Acquisition Modes n ESA Multi-instrument with C- band ASAR on board n Launched March 2002 n Operational 2003? (Officially 1st May 2003) n Image mode (100km x 100km, 30m resolution) n Wide Mode (400km x 400km, 150m resolution)

15. ENVISAT Imaging and Viewing Angles Image Wide Swath Alternating/Cross Polarisation Wave Global Monitoring 100 400 100 5 400 30 150 30 10 1000 Nominal Swath Width (km) Nominal Resolution (m) Polarisation VV or HH VV/HH, VV/VH or HH/HV VV or HH

16. ENVISAT Mission Scenarii n Primary downlink to ESA X-Band stations at Kiruna (Sweden) and Matera (Italy). Production at processing and archive centres (PAC) in UK, Germany and Italy (ESRIN). n Other direct X-Band downlink planned when requested by authorised National or Foreign Ground Stations e.g. Canada (Gatineau and Prince Albert), Norway (Tromsø and Svalbard). n SSR data downlinked to Kiruna and Svalbard. Data can also be relayed via Artemis relay satellite (first successful test 2 weeks ago)

17. Data Distribution n Category 1 - Academic/Research and Application Development (Announcement of Opportunity - AO) n Category 2 - Operational/Commercial Use n Category 2 requests have priority over Category 1 in ASAR tasking n Category 2 users must purchase data through a Distributing Entity (DE): SARCOM, EMMA

18. Data Distribution SARCOM Consortium n Distributing Data from ERS and Envisat Worldwide n Aimed at supporting a sales strategy for providing multi- source satellite imagery n SARCOM Members include –RADARSAT International –Kongsberg (KSAT)

19. Data Availability n Official date: May 1st, 2003 n Order tracking? n Priority Programming? n NRT Processing? n Guarantee of Image Acquisition? The above still needs to be clarified with ESA and will become clearer over the coming weeks n KSAT currently ready for NRT services n RSI/CDPF ready for NRT June 2003