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ASTRA Workshop 2002 © ROGER Study Team, 2002
M. Kassebom, D. Koebel, C. Tobehn
OHB-System AG, Universitätsallee 27-29, 28359 Bremen,Germanymailto: [email protected]
H. Petersen
Dutch Space, Newtonweg 1, 2333CP Leiden, The Netherlands
H. Stokes, D. Smith, C. Martin
Space Department, QinetiQ, Farnborough, Hampshire GU14 0LX, UK
A. Shaw
ESYS plc, Surrey Research Park, Guildford, Surrey GU2 7HJ, UK
ASTRA - Advanced Space Technologies for Robotics and Automation
ESA/ESTEC, Noordwijk, November 19 - 21, 2002
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ASTRA Workshop 2002 © ROGER Study Team, 2002
■ Introduction
■ Simulation of the GEO Environment & Collision Risk Analysis
■ Intervention & Mission Concepts
■ Concept Analysis Trade-Offs
■ Generic Mission Constraints
■ Technical Solutions for Capture & Docking
■ Mission Profile & Target Number Analysis
■ Economic Analysis
■ Conclusions & Outlook
Table of ContentTable of Content
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ASTRA Workshop 2002 © ROGER Study Team, 2002
IntroductionIntroduction
■ The ROGER Study is an on-going ESA Study with the aim to assessthe economical and technical feasibility of a GEO service mission.
■ It has the following main objectives:
■ analysis of the GEO environment, including the establishment of a GEO orbitsimulator,
■ definition of scenario types and service levels for the ROGER mission,
■ analysis of the economical viability of the scenario types,
■ definition of the most promising baseline mission scenario,
■ investigation of the design and development of the related ROGER spacecraftand Robotic subsystem,
■ definition of a demonstration mission.
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Simulation of the GEO EnvironmentSimulation of the GEO Environment
GEO SpacecraftFailures Data
Current GEO Status
Collision Risks
GEOSIMGEOSIM
A model to determine collision risksdue to the future evolution of controlled
and uncontrolled objects in GEO
Market Trends
Orbit Propagation
■ The GEO Simulation combinesdetailed GEO status data andtraffic projections with realisticorbit dynamic and collisionprediction algorithms.
■ The results of GEO simulationand collision analysis providesthe basis for possible ROGERmission scenarios and thejustification for the final missionbaseline selection.
[Source: QinetiQ]
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Current and Future GEO Status (1)Current and Future GEO Status (1)
Currently (2002) Estimation for 2030
Evolution of Number of Uncontrolled Objects in GEO
[Source:QinetiQ, ESYS]
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Current and Future GEO Status (2)Current and Future GEO Status (2)
0
10
20
30
40
50
60
0 20 40 60 80 100
120
140
160
180
200
220
240
260
280
300
320
340
Longitude East (5 degree bins)
No.
Obj
ects
20302002
Evolution of the Longitude Distribution of GEO Objects
[Source:QinetiQ, ESYS]
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Collision Risk Analysis - ResultsCollision Risk Analysis - Results
0.0E+00
2.0E-04
4.0E-04
6.0E-04
8.0E-04
1.0E-03
1.2E-03
1.4E-03
1.6E-03
1.8E-03
2.0E-03
2000 2005 2010 2015 2020 2025 2030Year
Pro
babi
lity
Nominal
Low launch rate
High launch rate
0.0E+00
4.0E-04
8.0E-04
1.2E-03
1.6E-03
2.0E-03
2.4E-03
2.8E-03
2000 2005 2010 2015 2020 2025 2030Year
Pro
babi
lity
Nominal
Best re-orbit rate
Worst re-orbit rate
■ The number of objects on GEO andtherefore the future evolution of collisionrisk is governed by the balance betweenthe number of satellites launched and thenumber re-orbited at end-of-life.
■ The collision risk probability varies three-fold between the most optimistic, thenominal and the pessimistic re-orbit case(first picture).
■ Variations in the predicted launch trafficrate do not play a significant role in theevolution of the collision risk (secondpicture).
■ Note: These analyses exclude theconsideration of the untracked debrispopulation. [Source:
QinetiQ]
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Collision Risk Analysis - RecommendationsCollision Risk Analysis - Recommendations
■ As a result of the GEO environment simulation and collision risk analysisthe following re-orbit policies & strategies can be recommended:
■ Mass removal is required for general GEO resident objects, although massremoval for GTO objects is less significant.
■ A mass removal effectively needs to keep the number of objects static. Theearlier such a programme is started the less the future risk will be.
■ A removal programme could be based on removing objects as they becomeuncontrolled or removing objects in high-risk longitudes.
■ There is no immediate need to consider older objects, with higherinclinations.
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Intervention Concepts and Failure Event TypesIntervention Concepts and Failure Event Types
■ The ROGER study developed a list of potential mission scenarios, includingdifferent intervention concepts and failure event types to be served:
■ For each scenario various trade-offs were performed in order to derive theirtechnical and economical feasibility and to select a mission baseline for ROGER.
InterventionConcept
Description
Concept i) A re-orbiting only mission, focussed on removing potentiallyhazardous objects from the GEO region.
Concept ii) An intervention mission aimed at some mature aspects of servicing,based on basic robotic and docking technology, and advanced S/Cplatform design.
Failure Event Type 6 Temporary attitude failure by uncontrolled spin-up
Failure Event Type 8 Catastrophic premature fuel exhaustion or attitude control failure
Failure Event Type 9 Deployment failure, e.g. stuck in GTO
Concept iii) An intervention mission aimed at a more sophisticated level ofservicing, making use of advanced robotic capabilities.
Failure Event Type 3 Antenna or solar array release (major events)
Failure Event Type 4 Mechanical / thermal alignment problems (minor)
Failure Event Type 5 Other in-service mechanism problems (typically solar array drives)
Failure Event Type 7 Accessible electrical problems (e.g. solar array shorts)
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Mission Scenario Trade-OffsMission Scenario Trade-Offs
Trade-offs were performed with respect to the following main aspects:
■ Technical Aspects:■ Identification of technical constraints,
■ Robotic solution vs. non-robotic solution,
■ Consideration of different propulsion systems for orbit manoeuvres,
■ Mission Aspects:■ Single target vs. multiple target mission,
■ Consideration of mission profile and resulting schedule,
■ Economic Aspects:■ ROM cost assessment for different scenarios and technical solutions,
■ Consideration of mission benefits and funding sources.
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Basic Mission ConstraintsBasic Mission Constraints
■ Previous studies have investigated the rendezvous and docking with anuncontrolled target and concluded a basic technical plausibility.
■ Some basic constraints were identified wrt. the following aspects:
■ Kinematics of uncontrolled target object:■ Uncontrolled S/C will acquire a Flat Spin around the main inertia axis.
■ Assumption of the residual flat spin of GEO target objects:
■ This is considered to be manageable for available capture & docking technology.
■ Servicing of “quasi”-operational target objects (intervention concepts ii & iii):■ such target objects shall not be damaged or hindered during the capture and docking,
■ No further space debris shall be produced during the capture.
■ Advanced GNC requirements compared to other missions, incl. advancedrequirements for the attitude and orbit control.
RPMf SpinFlat 5.0≤⇒
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Apogee Nozzle coupling
Robotic SolutionRobotic Solution
Lathe Clamp couplingmechanism
[Source: ESS/T Study]
■ Robotics:■ Identification of technical
solution based on the ERARobotic arm,
■ Baseline specification:~ 11m span, 6 DoF, 2 cameras.
■ Capture & Docking:■ Focus on the utilisation of the
Apogee Motor Nozzle and theLauncher Adapter Ring asgrappling points.
ERA Robotic Arm,provided by Dutch Space
➪ A Robotic Solution provides a greater flexibility for the chosen missionscenario (intervention concept), but has higher mass and powerrequirements at higher cost.
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Non-Robotic SolutionNon-Robotic Solution
■ Non-Robotic Technologies:■ Several technologies and designs
have been investigated, such as:■ inflatable structures, e.g. wings,
■ throw-nets,
■ tethers.
➪ Non-robotic solutions can provide reduced mass and power requirementsat reduced cost,
➪ Non-robotic solutions are assumed to be only valid for the re-orbitmission; the multiple-target capability depends on the used technology.
■ Docking & Re-orbiting Scenario:■ Can also utilise simple robotic arms or extendable booms to provide coupling.
■ Throw-net like solutions provide the docking and re-orbiting by means of a tether (thedynamics of the coupled system have to be analysed in more detail here).
[Source: Dutch Space]
Outline sketch of non-roboticinflatable structures
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Mission Profile & Duration of PhasesMission Profile & Duration of Phases
D: Inspection & Final Approach C: Homing B: Ground Guided
Phase(incl. Drifting to Target)
IAP
10 km
S1
1km
S2
100 m
S3
(Delta H = 300 km)
OTPITP
E: Capture&
Docking
Inspectionfly-by(optional)
Sensor Range
Injection Orbit(GTO)
PhasingOrbit
TargetTracking
ROGERTracking
ROGER drifts towards Target
TM/TC
ISA
A: LEOP & C/O
HorizontalRange fromTarget
Radial Distancefrom Target
Target on GEO
TransferInjection
ProgressiveTransfer
S/C-based Navigation
Ground-basedNavigation
ISA -IAP -S1 -S2 -S3 -
OTP -ITP -
Inter S/C AcquisitionInitial Aim Point (~10 km)Hold Point 1 (~1 km)Hold Point 2 (~100 m)Hold Point 3 (~50 m)Outer Target Point (~20 m)Inner Target Point (up to 2m)
Delta Hcirc ~ 475 km(for 180° phasing
in 30 days)
G: Re-orbit to GYO H: Retreat & Parking Orbit Acquisition ( GYO as parking orbit (TBC))
Back to B: Phasing Orbit
Acquisition
➩ Very detailed analysis of the duration of the different mission phases, as afunction of the used propulsion technology and the number of targets.
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ASTRA Workshop 2002 © ROGER Study Team, 2002
ROM Cost vs. Technology and No. of TargetsROM Cost vs. Technology and No. of Targets
■ Furthermore, a ROM Cost Analysis has been performed for the ROGER system,depending again on the implemented technology and the number of targets:
100
200
300
20 30 40
Number of Targets
Rec
urr
ing
Mis
sio
n C
ost
[M
io. E
uro
s]
Robotic Solution
Non-Robotic SolutionBi-Propellant
Ion Thrusters
Ion Thrusters
Bi-Propellant
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Economic AnalysisEconomic Analysis
■ Principal driver for a ROGER business case are mission cost versus thepotential benefit for each target and servicing type.
■ The economic analysis included therefore a detailed investigation of thepotential benefit for each identified intervention concept and event type.
■ This includes: ⇒ insurance claims for in-orbit failure events,
⇒ cost-effectiveness of ROGER re-orbit service compared to the propellant effort of a operator’s voluntary graveyard transfer at EOL.
■ For the re-orbit service scenario it can be concluded:
■ there is potentially a sufficient number of GEO Sats being voluntarily re-orbited at EOL,
■ propellant saving can result in an operator’s additional revenue at EOL of 5 M - 15M ,
■ if the ROGER cost per target are in that range of benefit, it can be assumed that a re-orbitmission scenario is a viable business case for ROGER.
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ASTRA Workshop 2002 © ROGER Study Team, 2002
Conclusions & OutlookConclusions & Outlook
■ Detailed analyses have been performed to define a mission baselinescenario for ROGER which is:
■ politically desirable,
■ technically feasible,
■ economically viable.
■ The final mission scenario and the related detailed system design areactually under iteration.
■ Especially the following study tasks are being performed currently:
■ investigation of the design and development of the related ROGER spacecraftand the Capture & Docking subsystem,
■ definition of a demonstration mission.
■ A final economic evaluation of the ROGER mission will be performed atthe end of the study.