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SES Proprietary |SES Proprietary

PRESENTED BYEric Kruch

PRESENTED ON24 October 2017

EPIC Workshop 2017

SES Perspective on Electric

Propulsion

SES Proprietary |

SES Perspective on Electric Propulsion Agenda

2

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

SES Proprietary 3

Electric Propulsion at SES today

SES Proprietary | 4EPIC 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 todaySES Fleet Overview


Electric Propulsion at SES todayGrowth of Electric Propulsion at SES

SES has been flying Electric Propulsion for over 20 years

02468

101214161820

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)


Electric Propulsion at SES todayDrivers 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 mDry mass: 900 Kg

Launch mass: 1800 Kg Solar panel span: 19 mPayload Power: 1.6 kW16 active transponders

Body size: 2.1 x 2.35 x 5.3 mDry mass: 4250 Kg

Launch mass: 5470 Kg Solar panel span: 42 mPayload Power: 15.1 kW76 active transponders

SES Proprietary | 7

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


Electric Propulsion at SES todayDrivers for Electric Propulsion

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

SES Proprietary 8

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


Trade-off ConsiderationsPerformance 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

SES Proprietary | 10

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


Trade-off ConsiderationsPerformance Trade-offs – Time to Orbit

2000

2500

3000

3500

4000

4500

5000

100 150 200 250 300 350 400 450

Mas

s [K

g]

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


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


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


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


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


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


Trade-off ConsiderationsChange in the Launcher Industry Landscape

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

SES Proprietary 14

How Electric Propulsion fits within SES Procurement


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)


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


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)


ConclusionElectric 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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