Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/calibration/documentation/epic_cal_meetings/201203/kirsch-cal-2012.pdf Дата изменения: Tue May 13 17:37:29 2014 Дата индексирования: Wed Apr 13 13:31:30 2016 Кодировка: Поисковые слова: m 8

CAL/OPS meetings
M. Kirsch ESA/ESOC
with input from the XMM FCT

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menu

spacecraft status & mission performance

special events

outlook

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solar arrays

power generation capabilities are normal

no sign of unexpected degradation visible

Actual

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fuel

Remaining fuel

6 5 . [k g ]

Consumption last 12 month

6 .2 [k g ]

0 .4 8
[kg/month]

average fuel consumption (since 2003-03-01)

residual lifetime in month extrapolated milage

97 [-] Feb. 2020

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LCL statistics

2012: ·02-01-2012: HLCL 4.2A trip off (powers 2 heaters of the main branch of the EPIC and RGS electronics.) ·2012-01-25: HLCL STA PAN B trip off (powers redundant IMU/RW heaters)

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spacecraft/mission status
Funded until next extension request remaining Use per year Mileage left 2020 1350 W 545 W 350 W 15+ y < 20 % < 44 %
Stuck at one position Back up not used instead transponders are switched

Money 65 kg 6 kg

End 2012/14 in 2012 2016

Fuel

Solar array power Maximum required Current margin Margin end of 2018 According to UHB Usage Usage Usage

Battery

Gyros/(IMUs)

Reaction wheels

RF switches

Transponder switches

TX A LCL switches 584 TX B LCL switches 595(Qualified to 25000)

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mission performance

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eclipse winter/spring 2011/2

15/12-10/01

max. discharge duration: 0h55m55s Max. Depth of Discharge: 17.2 % (100%=35Ah)

Automated TT generation now fully operational

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special events

Collision avoidance in place (November 2011 ­ March 2012)

Reaction wheel cage instability:

· ·

XMM_SC-72, 2011-08-16, Reaction Wheel 1 unexpected increase in torque and current during stable pointing Switch of reaction wheel configuration from 1-2-3 to 2-3-4 in December 2011

4WD project

·

Wheel4 tested up to 3750 rpm in July

MCS migration

Fuel migration

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collision avoidance

XMM orbit crossing GEO for a period of ~ 5 month

Conjunction monitoring in place and procedure for collision avoidance maneuver

Detected conjunctions (Screening Volume: 300km x 300km x 300km): 9

No need for maneuver so far (below 20 km)

Objects: Rocket bodies (3), Rocket body deb. (3), Spacecraft (3)

Miss distance [km]

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cage instability: symptoms
wheel 2 wheel 3
RW1 commanded torque and RWDE1 current sometimes during stable pointing suffers a jump The reason for these jumps is most probably a sudden increment of the bearing friction level. Well known phenomena with bearings running in marginally lubricated regimes Chaotic vibration of cage Caused by too much or too little oil (late in the mission can only be due to reduction in oil quantity)

wheel 1

Torque [Nm]

310

331

Time [DOY 2010]

Vibration causes increased friction, causes bearing to run hotter, oil gets thinner and gets ejected from bearing as micro droplets, oil runs hotter, oil starts to degrade, lighter fats boil off, oil runs hotter, oil degrades further, oil runs hotter, more complex fats boil off, bearing runs hotter, bearing fails

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cage instability: analysis

Screen data for non slew and non RWB times

Produce monthly histograms of commanded torque

First peak shows nominal torque distribution

If there is second peak, this shows cage instability

Height/integral of second peak gives indication of amount of caging

Difference of peak position between 1st and 2nd peak gives strength of caging

no cage instability 2006/09

cage instability RW1 2010/11

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cage instability analysis evolution
analysis of histogram plots for each month from 2005 until now clear on-set of cage instability in 2008 evolution over the last 2 years shows no significant further degradation

peakmax

no caging peak caging peak

peak position

caging peak no caging peak

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wheel1 wheel2 wheel3


cage instability analysis ­ butterfly plots

Plotting wheel speed versus torque indicates if the cage instability is present for all wheel speeds

For higher the factor increase d caging sta flatten off

speeds in torque uring the te does

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cage instability: actions taken

ASU recommended to go ASAP from wheel 1-2-3 to 2-3-4 control

After testing on the simulator wheel 1 has been switched of and wheel 4 has been put into control

·

F/D configuration control issue in combination with F/D design issue and TOO request caused an ESAM entry some days later

Wheel 1 is now waiting for "re-lubrication": each reaction wheel has an oil reservoir, that allows injecting oil in the bearing. This should cure the cage instability

Currently Astrium/Bradford in combination with ESOC are working on a procedure to perform this re-lubrication

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cage instability monitoring

Comparing the as a function of with the actual indicates when caging stage

predicted torque wheel speed speed over time a wheel is in

This method can be used near real time

Weighting cage states with 1 and one cage stages with 0 gives as well the cage fraction in a certain time interval

This method is been implemented to monitor

Derived parameter implemented on MCSs

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fuel saving options

4WD: potential for 50 % of fuel saving according to F/D estimates

·

Feasibility phase 1 has been kicked off September 2011 with Astrium

·

Algorithms:

- 2 new modes (TCM4W, IPS4W)

- Slight modification on AMD

- TBD: check ESAM and FDIR

·

S/W

- The average processor load is estimated to increase by < 1%

- From a RAM memory point of view, about ~ 2300 words will be required by the new (8000 words still available)

·

Cost and schedule for Phase 2 (implementation) will be available by mid April

·

Decision at MEOR 28/06

Reduction of wheel speed limits around 0 from 200 rpm to 65 rpm

Flexible Perigee attitude: delayed until end of collision monitoring, since fixed attitude is required

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MCS migration

Mission Control System H/W has reached its end of life support

Migration process has been started

· Migration to Solaris 10 using H/P T4 server

· Virtualization of Clients and Servers

· Migration in parallel with INTEGRAL

· End of process in 2013

· Will migrate as well the Back Up system at Redu while moving it to ESAC/Cebreros (TBD)

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fuel migration
Tank3 Tank4

Tank1

Tank2

Design of Tank system of XMM requires fuel migration from auxiliary tanks to main tank at near depletion status (38 kg left) Fuel migration will be performed by temperature delta between main tank and aux tanks (Delta T = 8-11 K) First migration process planned for 2015 (3WD) Migration process needs to be repeated after usage of 8 kg (1 per year 4WD, Ѕ year with 3WD)

2+2+2+2

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outlook

Astrium final presentation for XMM 4WD 17/04 UG meeting 19/04 Mission Extension Operations Review 28/06

MCS migration with finalization early 2013 Wheel-1 re-lubrication in Summer Fuel Migration "dry-run" in autumn

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