A Low-Cost Modular Platform for GEOSTATIONARY and NAVIGATION

satellite missions

Stuart Eves, Phil Davies, Doug Liddle,John Paffett, Martin Sweeting, Alex Da Silva Curiel

Email: s.eves@sstl.co.uk, p.davies@sstl.co.ukTel: +44 1483 683347

Responsive Space – LA - April 2004

Why GMP?

• A new, much smaller, platform family– Geostationary minisatellite platform (GMP)

• Designed to fill the market requirement for cost-effective, fast-response small geostationary spacecraft.

• The GMP family will target the missions with payload requirements of 90-260kg and 800-1500W

The SSTL geostationaryminisatellite (GMP)has been designedspecifically to addressthe market requirementfor a small,low-cost,rapid-schedule,geostationary platform.

Benefits of Modularity

• Reduced Cost - <$20m

• Rapid Response – Target time of 1 year to launch

• Reduced Risk – Flight proven hardware

• System Growth – Allows for demand change during system life

• Geographic Diversity – More options for slot coordination

• Robustness – Graceful system degradation in case of failure

• Technology Insertion – Opportunities to demonstrate new satellite technologies and services

GMP - Complementary not competitive

• SSTL GMP has been designed specifically to address lower end of the market:

• Intended to complement existing traditional GEO platforms and not compete with them

• The future could see small satellites used for proof of market, with larger spacecraft used to provide bulk capacity

• The GMP design allows clusters of satellites to be used as a coordinated asset

The GMP Family

• Platform variants– Two platform variants are planned

• Direct injection variant (GMP-D)• Transfer variant (GMP-T)

– GMP-D• Designed to utilise low-cost secondary direct

injection launch opportunities e.g. Proton, Atlas 5, Soyuz, Zenit, Angara, Dnepr

• Constraints – 400kg maximum launch mass– Results in limited payload accommodation capacity

– GMP-T (under development)• Designed for conventional delivery into GTO• Includes propellant for transfer• Allows increased payload capacity• Constraints – Complement not competition

– 1500 W / 260kg payload limit

$17m (GMP-D)$24m (GMP-T)

Target Recurrent Platform Costs

Semi-autonomous ground station employing COTS hardwareGround Segment & Operations

Flexible baseline architecture capable of supporting plug-and-play replacement and upgrade.3-axis stabilised platform with fully autonomous station keeping.GPS and PRN rangingGMP-D: Hydrazine Mono-propGMP-T: MMH/N2O4 Bi-propGaAs/Ge Triple JunctionLi-Ion, sized for payload eclipse operationsPrimary through payloadRedundant through S-band

Platform Avionics

AOCS Orbit Determination Propulsion

Arrays Battery TT&C

None - full eclipse operation requiredup to 110kg (GMP-D) or 260kg (GMP-T)up to 1 KW (baseline), with upgrade can go to > 1.5kW

Payload Operational limitations  Mass carrying capability Power available

Up to 7 year mission lifetimeLEO, GTO, MEO, GEO, HEO

LifetimeOperating Orbit

Target - 12 months - Contract signature to launch readiness

Production schedule

GMP Specification

GMP – Payload Accommodation

Example GMP-D Payload

• Description: 6x Ku-band transponders

• Coverage: Regional • Uplink: Single receiver

• cold redundant backup receiver• G/T: 10dB/K

• Downlink: Six transmit chains• Two cold redundant backup HPA’s• Transponder bandwidth : 72 MHz• Typical EIRP : 50 dBW

• TT&C: Continuous telemetry and telecommand feed

• Satellite Antennas: 0.5 – 0.7m • Applications: Television, Direct-To-

Home broadcast, Internet connectivity, VSAT, telephony, Etc.

GMP – AIT

• Modular design – Allows short duration programmes

• By permitting parallel manufacture and test

Propulsion BayAvionics Plate Payload Frame

GMP – Operations

• As with SSTL’s LEO spacecraft, GMP has sufficient on-board autonomy to provide the necessary payload availability without needing to resort to a traditional “24/7” man-in-the loop operations strategy:

– Autonomy is distributed between on-board and on-ground systems

– On-board systems protected by rad-hard safety monitor– Anomalies generate operator alerts via SMS/Internet

GMP 1st Flight 2005

• ESA GSTB-V2– Precursor to European Galileo programme

– Objective• Secure frequency filing• Measure MEO environment• Demonstrate key payload technologies• Provide Signal-in-Space for Experimentation

– Requirements • Two year mission lifetime• Low cost, rapid schedule

Ideally suited to a SSTL solution

GSTB Platform

GSTB-V2/ A Platform Specification Mission Launch Date: October 2005

Launch: Direct Injection into MEO from a Soyuz/Fregat Lifetime: 27 months

Platform Dimensions: 1.3m x 1.3m x 1.4m (stowed) Wet Mass: 525kg Solar Panels: Deployable Sun Tracking Dutch Space Arrays Sensors: Galileo Avionica IRES-NE, Sun Sensors BAE Systems Gyros Actuators: SSTL SmallSat Wheels, SSTL Magnetorquers, SSTL Prop System Pointing: Pitch/Roll: 0.55 Solar Array Pointing Error: 2.1 Orbit Detn: NORAD, GPS, Reverse GNSS, Laser Retroreflector Propulsion: Resistojet Butane System, 58 ms-1 (including 500km graveyard) TTC: S band

GSTB Schedule

• Schedule driven by Autumn ’05 launch

QSR PDR CDR

IRR

FRR

TRR

MRDesign

Manufacture

Integration

Environmental Test

Launch

QSR : 31/07/03

PDR : 27/11/03

CDR : 30/06/04

IRR : 23/08/04

TRR : 04/05/05

FRR : 10/08/05

LW : October 05

KO +5 +12 +14 +22 +25 +27

Other Payloads Studied

• In addition to FSS and Galileo, SSTL has assessed the suitability of GMP for:– Mobile (S-UMTS) coverage over a region the size of Europe– Bent-pipe and regenerative SBAS augmentation systems– Slot clouds using ISL

Conclusions

• In GMP, SSTL now has a responsive,low-cost ‘beyond LEO’ platform

• GMP extends SSTL’s low-cost engineering approach into new application areas:– Telecommunications– Navigation– Science

• Platform can also be used in MEO, GTO & LEO• SSTL’s future developments will extend the

capability and clusters of GMP could compete with the capabilities of traditional “big” satellites

• First flight of GMP will be ESA’s GSTB-V2/A in ’05– Demonstrating GMP’s ability to carry complex payloads– Demonstrating the ‘rapid response’ capability…– …on a high profile mission

End

Thank You!

GMP Avionics Architecture

GSTB Avionics Architecture