EPIC Workshop 2017 SES Perspective on Electric Propulsion - - PowerPoint PPT Presentation

SES Proprietary | SES Proprietary

PRESENTED BY Eric Kruch PRESENTED ON 24 October 2017

EPIC Workshop 2017 SES Perspective on Electric Propulsion

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SES Perspective on Electric Propulsion

Agenda

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1 Electric propulsion at SES today

• A. SES Fleet Overview
• B. Growth of Electric Propulsion in the SES fleet
• C. Drivers for Electric Propulsion

2 Trade Off Considerations

• A. Performance Trade-Offs
• B. System Implications considered by Operators
• C. Change in the Launcher Industry Landscape

3 How Electric Propulsion fits within SES Procurement 4 Conclusion

• A. Needed electric propulsion improvements

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

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Electric Propulsion at SES today

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EPIC Workshop 2017 – SES Perspective on Electric Propulsion

 5 GEO satellites under procurement (4 full electric propulsion)  15 MEO satellites under procurement (8 hydrazine, 7 full electric propulsion)

Electric Propulsion at SES today

SES Fleet Overview

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EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Electric Propulsion at SES today

Growth of Electric Propulsion at SES

 SES has been flying Electric Propulsion for over 20 years

2 4 6 8 10 12 14 16 18 20 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

Propulsion types repartition for launched satellites

Electric Mixed Hydrazine + Arcjet Chemical

SES4,5 (SPT100 + Biprop) SES9 (XIP + Biprop) SES15 (XIPS) SES17 (SPT140) SES12,14 (SPT140) SES10 (SPT100 + Biprop) Electra (PPS5000)

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EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Electric Propulsion at SES today

Drivers for Electric Propulsion

 30 years of commercial satellites evolution from Astra 1A to SES-12  Significant evolution in payload mass and power over this period

Body size: 1.5 x 1.7 x 2.1 m Dry mass: 900 Kg Launch mass: 1800 Kg Solar panel span: 19 m Payload Power: 1.6 kW 16 active transponders Body size: 2.1 x 2.35 x 5.3 m Dry mass: 4250 Kg Launch mass: 5470 Kg Solar panel span: 42 m Payload Power: 15.1 kW 76 active transponders

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 Cost of launching a satellite has always been a barrier to entry for new satellite businesses and a huge penalty compared to terrestrial solutions  In recent years, the launch industry started to address this issue through more economical but less powerful launchers, e.g. SpaceX Falcon 9, Soyuz from Kourou  Due to the increasing mass of commercial satellites, some could not be launched by these launchers, despite clear economic advantage  This triggered the need to reduce drastically the satellite launch mass

• Liquid propellants typically represent 50 to 60% of a GEO chemical propulsion satellite dry mass

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Electric Propulsion at SES today

Drivers for Electric Propulsion

SES12, with a dry mass above 4200 Kg, was only made possible through an electric propulsion subsystem

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Trade Off Considerations

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 Electric propulsion offers an Operator a higher specific impulse, resulting in a lower launch mass to achieve the same on-station lifetime

• High thrust (typ 1-500N) and low Isp (typ 200-350 sec) for chemical propulsion
• Low thrust (typ < 0.3 N) and high Isp (typ>1500 sec) for electric propulsion

 The following table (based on a 2000Kg dry mass) illustrates the huge launch mass gain granted by electric propulsion

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Trade-off Considerations

Performance Trade-offs – Launch Mass

The mass represented by an electrical solution is increasing the choice among the potential launchers which can considerably improve the launch cost

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 BUT at the expense of the satellite time to orbit  Time spent between contract signature and in-orbit delays the revenues and the satellite profitability, it is thus crucial to minimize it

• The following table (based on a 2000Kg dry mass) illustrates the significant duration imposed by

electric propulsion

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Trade-off Considerations Performance Trade-offs – Time to Orbit

2000 2500 3000 3500 4000 4500 5000 100 150 200 250 300 350 400 450 Mass [Kg] EOR Duration [days]

Falcon9 case - mass vs EOR duration

HET - Dry Mass HET - Launch Mass GIT - Dry Mass GIT - Launch Mass

The higher thrust of a chemical propulsion reduces the time between launch and

• n-orbit, allowing the customer to have the satellite in operation quicker

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 Spacecraft system design

• Need for increased electrical power capability, and for heavy power processing units which are

highly dissipative. In combination with higher dissipative payloads, this may trigger the need for more efficient thermal control, lighter solar arrays, more efficient solar cells

• Plume effects, solar arrays interconnector and OSRs erosion leading to performance

degradations

• Potential need for auxiliary propulsion system and larger reaction wheels for initial de-tumbling,

safe mode, faster anomaly recoveries

 Space environment

• Low thrust => long (in the order of 200 days) orbit raising duration => increased time spent

inside the Van Allen belt => extensive exposure to radiations leading to higher solar array power degradation and other potential environment effects

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Trade-off Considerations System implications considered by Operators (examples) (1/2)

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 Technological risk, maturity

• New electric thrusters with no or limited on-orbit heritage have an unknown inherent

technological risk that can be evaluated only with time

• Most propulsion system components (valves, regulators…) are not tested with Xenon because its
• expensive. This could lead to potential undisclosed long term issues

 Schedule risk, qualification duration

• The timeframe for new technologies to go from concept to validation and qualification can be

rather long

• Low thrust of electric propulsion means very long life tests

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Trade-off Considerations System implications considered by Operators (examples) (2/2)

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 Future Launcher capabilities

• More powerful launchers coming (e.g. Falcon heavy, Ariane6) may allow to send much heavier

chemical propulsion satellites to geostationary orbit

• On the other hand, the removal of the big constraint represented by launcher capabilities may

reduce the impact related to transfer orbit duration

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Trade-off Considerations Change in the Launcher Industry Landscape

Both chemical and electrical thrusters should thus still play a role in future satellite designs

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How Electric Propulsion fits within SES Procurement

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 Commercial geostationary spacecrafts are strongly dependent on financial aspects. Satellite, but also launcher, insurance and operational costs have an important weight  SES is thus looking at the overall S/C in orbit price per sellable unit (where a sellable unit, e.g. classical transponder, MHz or Mbit, is depending on the target market)

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

How Electric Propulsion fits within SES Procurement

In the end, SES does not specify the propulsion technology, but specifies the capability, need date and price target. The satellite vendor presents the most optimal propulsion subsystem(s) to SES for each specific mission

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Conclusion

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 For SES, electric propulsion has allowed embarking more payload and less fuel on recent satellites while staying within launcher capability. This has come at the cost of extended time to orbit, extended time to revenue, and increased time spent in higher radiative environment  Potential avenues of investigation at this workshop

• increasing the thrust per power ratio while keeping sufficient high specific impulse
• combining satellites with faster electric orbit raising capability and light chemical last stage added

to launchers

• modular S/C design approach (chemical propulsion module dedicated to orbit raising only)

EPIC Workshop 2017 – SES Perspective on Electric Propulsion

Conclusion Electric Propulsion Improvements

The launch mass benefits of electric propulsion combined with a much reduced time to orbit is highly desirable

SES Proprietary Q2 '16 – Executive Committee – SES PPT Template – KSM – md

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