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HRDI Key Operational Events

Operational Notes

            The following table lists the key operational events during the UARS/HRDI mission.  Operational changes have the potential to introduce offsets in the data.  Considerable effort has been expended to minimize this, but users should check this table if a shift in the data is observed. Users should also check the bad day list if anomalies are seen in the data.

 

Date

(UARS day)

Date

(day-month-year)

Date

(year-day of year)

Event

1

12 September 1991

1991-255

UARS launch

18

29 September 1991

1991-272

HRDI activated

18-51

29 September 1991 - 1 November 1991

1991-272 thru 1991-305

Do not process HRDI winds or temperatures before version 'J' coefficients are used

52

2 November 1991

1991-306

HRDI useful scientific measurements began – version 'J' coefficients are loaded

52-77

2 November 1991 - 27 November 1991

1991-306 thru 1991-331

Do not process HRDI stratospheric winds or aerosols due to problems with the scene selector

78

28 November 1991

1991-332

Modified HRDI modes to use the same side of the scene selector.  Modification remains in effect for rest of mission

154

12 February 1992

1992-043

Standardize mesosphere lines used by HRDI to 13138, 13076, 13043, 13041 cm-1

181

10 March 1992

1992-070

Change HRDI stratospheric mode to use one line (b or gamma band) in a limb scan

201

30 March 1992

1992-090

Replaced HRDI use of 13043 cm-1 weak line, which was contaminated by potassium emission, with 13052 cm-1 weak line. HRDI MRE post 2 partial failure – addressed by changing instrument programming.

265

2 June 1992

1992-154

UARS solar array drive initial failure. HRDI was not turned on again until day 310.

282-283

19/20 June 1992

1992-171/172

HRDI temperature reached -18.5oC

458

12 December 1992

1992-346

Extend HRDI mesospheric altitude range to 50 – 115 km

510

2 February 1993

1992-033

HRDI MRE post 1 partial failure – instrument programming was updated to work around this problem – slew data are not scientifically useful after this date, since the slew time was used for re-tuning the instrument

583

16 April 1993

1993-106

UARS horizon sensor failed

590

23 April 1993

1993-113

Modify HRDI thermal control to set the radiator to -10oC at night and -7.5o at day.  Before this the radiator was held at -10oC

620

23 May 1993

1993-143

Replace use of 13041 cm-1 weak line with 13052 cm-1 weak line for HRDI

642

14 June 1993

1993-165

Implement revised temperature control for HRDI.  If MRE bulk temperature is greater than -8.5oC, then set the radiator temperature to -12.5oC; otherwise set it to -7.5oC

691

2 August 1993

1993-214

Start improved temperature control for HRDI.  If bench temperature 2 is greater than -8.5oC, then set the radiator temperature to -12.5oC; otherwise set it to -7.5oC

693

4 August 1993

1993-216

UARS solar array drive second failure – HRDI re-started on day 698.

737

17 September 1993

1993-260

UARS solar array drive third failure. Array (and HRDI) was re-started after a week.

752

02 October 1993

1993-275

UARS solar array drive anomaly. HRDI re-started day 775.

996

03 June 1994

1994-154

Begin using mesosphere combined wind/photometric mode at night for HRDI.

1087

2 September 1994

1994-245

Update UARS Fixed Head Star Tracker (FHST) scale factors/offsets at 15:42 UT

1220/1221

13/14 January 1995

1995-013/014

UARS solar array drive anomaly – HRDI off about 8 hours

1289

23 March 1995

1995-082

UARS Earth sensor problem – HRDI off until day 1304

1314

17 April 1995

1995-107

UARS solar array drive ceased rotation – HRDI off until day 1392

1372/1373

14/15 June 1995

1995-165/166

HRDI temperature reached -21oC

1392

4 July 1995

1995-185

Began reduced frequency of operation for HRDI due to lack of power available on spacecraft

1475

25 September 1995

1995-268

Update UARS FHST 1 offsets and/or scale factors

1477

27 September 1995

1995-270

UARS Narrow Band Tape Recorder (NBTR) A increased noise starts – NBTR B is used for much of the data hereafter

1775

21 July 1996

1996-203

UARS battery 1 failed

1821

5 September 1996

1996-249

Update UARS FHST 1 scale factors

2004

7 March 1997

1997-066

Turn off UARS FHST 1, use FHST 2.

2192

11 September 1997

1997-254

UARS epoch change

2287

15 December 1997

1997-349

UARS gyro anomaly

2577

1 October 1999

1998-274

Began continuous daytime operations for HRDI. By operating only in the daylight parts of orbits, HRDI can be operated more often (ie without relying on batteries).

2948

7 October 1999

1999-280

Partial failure of HRDI  telemetry.  Caused some engineering values to be intermittently unreliable – software was updated to compensate for this problem, but some data were unrecoverable thru day 3019

2967

26 October 1999

1999-299

Initial indication of failure of  UARS NBTR B (tape recorder). After this, nearly all days have data gaps – some days are only 1/3 as large as a full day. Much of the data is acquired directly thru TDRSS satellites.

3009

7 December 1999

1999-341

Modified HRDI modes to compare the actual filter position to that desired to be sure filter wheels are in position.  Before this, filter wheel were operated open loop.

3019

17 December 1999

1999-351

Modified HRDI coefficients to remove effects of  bad temperatures – assumes a fixed temperature

3096

03 March 2000

2000-063

Upload revised HTC feedback for HRDI – ignores bad temperatures

3122

29 March 2000

2000-089

Change HRDI instrument programming to correct for HRDI instrument temperature at each terminator crossing

3123

30 March 2000

2000-090

Modified HRDI slew mode to compare the actual telescope position with the desired to be sure telescope is in the desired position.  Before this, the telescope was operated open loop.  This was implemented to account for the slowing and variable slew rate.

3190

5 June 2000

200-157

Update HRDI thermal control scheme – reported instrument temperatures between -6 and -12 are assumed ok

3221

6 July 2000

2000-188

UARS star tracker 2 failed – use Fine Sun Sensor and FHST 1. Attitude is less precise and stable, FHST 1 coefficients were updated several times in the weeks that followed.

3306

29 September 2000

2000-273

UARS star tracker 1 turned off. After this the three axis magnetometer (TAM) and solar sensors are used for attitude, attitude is less precise and stable. Over the next few months, the TAM is adjusted several times to try to upgrade it's results, with varying results.

3341-3359

03 November 2000 thru 21 November 2000

2000-308 thru 2000-320

UARS yawed to keep sun in solar sensor view (since TAM isn't working well and star sensors are off).

3727

24 November 2001

2001-328

Last good stratospheric winds/aerosols measurement

4060

23 October 2002

2002-296

HRDI temperature reached -29.8oC

4089

21 November 2002

2002-325

Begin using 'overscan' mode for HRDI mesospheric measurements, to make sure altitude range of interest is covered, since UARS attitude is not precise

4950

31 March 2005

2005-090

Last HRDI science measurement

5208

14 December 2005

2005-348

UARS decommissioned

 

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