Extending the Envisat Mission - Impacts on Ground and Space Segment Operations

Diekmann, Frank; Mesples, Daniel; Nilsson, Magnus; Ventimiglia, L.; Canela, Miguel Ángel; Vazzana, S.; Fehr, T.

doi:10.2514/6.2010-2257

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…The crux of the Metop-A lifetime extension is therefore continuing operations without significant fuel consumption. A typical strategy to cope with this situation would be to gradually lower the orbit in order to maintain the same precession of the orbit plane as the inclination drifts, as was done with Envisat [4] . For example, lowering the orbit by 48km to 772km means a Sun-Synchronous orbit is still maintained after the inclination has drifted from the current 98.7 degrees to 98.5 degrees, which would take around 2.5 years.…”

Section: Introductionmentioning

confidence: 99%

Metop-A Mission Extension: Surviving on a Drifting LTAN

Dyer

Righetti

Vera

et al. 2018

2018 SpaceOps Conference

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In order to maximize the utilization of existing assets and help guarantee the transition to next generation systems, there is a desire to extend the lifetime of the Metop-A spacecraft, which along with Metop-B and the soon to be launched Metop-C comprises the space segment of the current EUMETSAT Polar System (EPS). Despite being specifically designed for a Sun-Synchronous orbit with an LTAN of 21:30 and having the fuel to maintain that LTAN for at least more 10 years, a combination of system level constraints and a desire to adhere to ISO 24113 debris mitigation guidelines [5] means that the only feasible strategy for a lifetime extension is to allow Metop-A's LTAN to drift outside its design envelope. This paper identifies the main impacts of operating on a drifting LTAN, with detailed analysis concentrated on the critical Power and Thermal aspects in order to determine the permissible lifetime extension. A Key finding presented in this paper is that while the LTAN is drifting from 21:30 to earlier LTANs, the integrated solar flux falling on the spacecraft body and solar arrays remains almost constant, and there is very little overall impact: Shortening eclipses almost exactly compensate for the less favorable angle of incidence of sunlight. This indicates that there are generally regions of LTAN where the Power and Thermal situation can be inherently stable for any polar orbiting spacecraft. Once eclipses disappear however, both energy margins and temperatures will drop very rapidly with small changes in LTAN, and seasonal variations can dramatically exacerbate this effectthere are situations for example where the Metop-A orbital energy margins would make the transition from having been continuously at near nominal values to critical within just 6 weeks. Due to the uncertainty outside the inherently stable LTAN region which has been identified, the Metop-A Lifetime is extension is currently targeted for the end of 2021, which will mean a total of 15 years in orbit. Options to extend to 2022 and beyond are pending more detailed analysis.

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Section: Introductionmentioning

confidence: 99%

Metop-A Mission Extension: Surviving on a Drifting LTAN

Dyer

Righetti

Vera

et al. 2018

2018 SpaceOps Conference

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A Satellite Retires - The ERS-2 Deorbiting in Summer 2011

Diekmann¹,

Marc²,

Canela³

et al. 2012

SpaceOps 2012 Conference

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The ERS-2 deorbiting started on 6 th July 2011 after 16 years of successful operations of this ESA Earth Observation satellite. Many orbit lowering maneuvers were necessary to reach the target altitude of 570 km. Apart from the late failure of a backup gyro, which had no impact on the overall activity, all subsystems onboard performed perfectly. Although not originally foreseen in the early mission days, the later decision to deorbit ERS-2 was mostly compliant with international guidelines and ESA requirements on space debris mitigation and ensured a re-entry of the satellite in less than 25 years. The ERS-2 deorbiting was the first such activity of an ESA polar orbiting satellite. It was started with an initial re-orbiting in Feb 2011 in order to achieve a 3-days repeat cycle for scientific reasons for a period of 3 months. This orbit change served as a dress rehearsal for the later orbit lowering maneuvers and platform operations. The deorbiting related operations were implemented at ESA's Operations Centre ESOC in Darmstadt, Germany, in close collaboration with the Mission Management, the ESTEC based Post Launch Support Office and industrial support by ASTRIUM Toulouse. This included the definition of the overall operations concept, the maneuver strategy, on-board configuration trade-offs, contingency plans, new and modified procedures, extensive simulation and training sessions and an extended ground station network. This paper summarizes these activities together with the deorbiting background and objectives, timeline and results.

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Extending the Envisat Mission - Impacts on Ground and Space Segment Operations

Cited by 2 publications

References 3 publications

Metop-A Mission Extension: Surviving on a Drifting LTAN

Metop-A Mission Extension: Surviving on a Drifting LTAN

A Satellite Retires - The ERS-2 Deorbiting in Summer 2011

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