XMM-Newton’s operations preparation for the 4 wheel drive project

Pantaleoni, Mauro; Chapman, P.; Harris, R. S.; Kirsch, Marcus; Kresken, Rainer; Martin, Jim; McDonald, Alastair; Strandberg, Tommy; Filippantonio, Denis Di; Tuttlebee, M.

doi:10.2514/6.2014-1908

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…Since then, RW1 has been reactivated in September 2013 when the 4WD operations started, with the wheels operated at lower speed than for 3WD. In this way the RW1 can be safely used even if the wheel still presents some cage instability (see (12) (14) ).…”

Section: Discussionmentioning

confidence: 98%

“…We have started to force a similar situation in operations, commanding the wheel to perform a zero crossing and changing its speed sign, if the caging lasts more than a defined time. For more information about the active de-caging strategy refer to (12) . As already mentioned before, the problem of cage instability is well known by reaction wheels manufacturers.…”

Section: Curing and Preventing The Cage Instabilitymentioning

confidence: 99%

“…The recommendation from industry regarding the prevention of the bearing cage instability is to run the wheels at lower speed, as far as possible and as an attempt to cure it, to perform a re-lubrication of the wheel"s ball bearings. The option of running the wheels at low speed has been made possible by the recent on-board patch, to run the AOCS with 4 active reaction wheels, which was uploaded in September 2013 (see (12) for more details). Using four wheels for active control also allows the wheels to be run at lower speeds, which reduces the risk of bearing cage instability.…”

Section: A Spacecraft Statusmentioning

confidence: 99%

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Curing XMM-Newton’s reaction wheel cage instability: the in-flight re-lubrication experience

Pantaleoni

Chapman²,

Harris³

et al. 2014

SpaceOps 2014 Conference

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ESA's XMM-Newton space observatory, the flagship of European X-ray astronomy, is after its launch in 1999 the most powerful X-ray telescope ever placed in orbit. The mission originally had a design goal of a 10 years lifetime is planned to be operated long into its third decade since spacecraft and instruments are operating admirably without major problems. The most significant degradation was noticed since summer 2008 when one of the reaction wheels started to show an intermittent anomalous behaviour; sometimes during stable pointing RW1 had a jump, with increased value of drawn current. After some investigation it was recognized to be the well-known problem of cage instability in the bearings. Later on RW2 showed the same symptoms. A cure -or mitigation -for this problem consists in a re-lubrication of the ball bearings of the reaction wheel. Re-lubricating the bearing in flight is possible thanks to the design of an oil reservoir placed in the proximity of the ball bearing. In December 2011 it was decided to switch RW1 off to avoid further degradation of the bearing, reconfiguring the AOCS with RW 2-3-4, and on 12 November 2012 the bearing was re-lubricated for the first time with a special procedure. Since the cage instability appeared again after few days a longer relubrication was attempted on 27 November 2012. This second re-lubrication was not conclusive, since another event of cage instability occurred during the following month. On 18 December 2012 it was decided to switch off again the RW1, to be on the safe side. At the same time a re-lubrication of RW2 was performed. This paper describes the challenges to re-lubricate two RWs and the outcome of such operations.

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Section: Discussionmentioning

confidence: 98%

Section: Curing and Preventing The Cage Instabilitymentioning

confidence: 99%

Section: A Spacecraft Statusmentioning

confidence: 99%

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Curing XMM-Newton’s reaction wheel cage instability: the in-flight re-lubrication experience

Pantaleoni

Chapman²,

Harris³

et al. 2014

SpaceOps 2014 Conference

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“…In 2013 a new AOCS operations scenario has been put in place called 4 wheel drive (4WD). 3,4,5 With this control strategy, all four wheels can be operated. The degree of freedom that is introduced by this change, allows to reduce the fuel consumption and to provide mitigation measures against cage instabilities.…”

Section: B a New Aocs Mode: 4 Wheel Drivementioning

confidence: 99%

Extending the lifetime of ESA's X-ray observatory XMM-Newton

Kirsch¹,

Elfving²,

Kresken³

et al. 2014

SpaceOps 2014 Conference

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ESA's XMM-Newton space observatory launched in 1999, is the flagship of European Xray astronomy and the most powerful X-ray telescope ever placed in orbit. The mission, originally designed for a 10 years lifetime, is planned to be operated long into this decade since spacecraft and instruments are performing admirably without major degradation. The ultimate mission end of life was defined as 2019, limited by the hydrazine reserves on board. Since scientific demand on XMM-Newton is very high and the mission has been ranked top level by the ESA advisory structure, various options to reduce the fuel consumption have been investigated. Some of these have been put in place in the course of the last years, especially we have updated the on-board software of the Attitude Control Computer to allow operating all four reaction wheels in parallel instead of only running three of them as done previously. Simulations and experience from ESA's HERSCHEL mission have shown that this should reduce the fuel consumption by up to a factor of two. In addition, operating with four reaction wheels offers the possibility to apply some measures against increased bearing noise due to aging, which has been detected on two of the XMM-Newton reaction wheels. The usage of all fuel saving methods may extend the potential lifetime to 2030. We present the implementation and results of the applied fuel saving methods and describe the increased bearing noise and its mitigation measures. In addition will report on the outcome of relubrication exercises performed on two of the wheels to cure the increased bearing noise. Furthermore we describe plans that are currently developed to operate the Hydrazine Propulsion System in the so-called near fuel depletion regime at the end of the technical life limit. In addition, ground segment evolution related to hardware, software and automation possibilities facing the new very long term perspective are discribed.

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XMM-Newton Fuel Saving Strategy

Kresken¹

2014

SpaceOps 2014 Conference

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XMM-Newton’s operations preparation for the 4 wheel drive project

Cited by 3 publications

References 2 publications

Curing XMM-Newton’s reaction wheel cage instability: the in-flight re-lubrication experience

Curing XMM-Newton’s reaction wheel cage instability: the in-flight re-lubrication experience

Extending the lifetime of ESA's X-ray observatory XMM-Newton

XMM-Newton Fuel Saving Strategy

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