Operational Collision Avoidance by ESA's Space … UNCLASSIFIED - For Official Use Klaus Merz |...

ESA UNCLASSIFIED - For Official Use

Operational Collision Avoidance by ESA's Space Debris Office

Klaus Merz

03/11/2016

ESA UNCLASSIFIED - For Official Use Klaus Merz | 03/11/2016 | Slide 2

Outline

• Introduction • Space Debris Office • Collision avoidance at ESA

• Reaction threshold with CDMs • ESA’s DRAMA/ARES tool

• Current process • Drivers • Back-end database and tools • Front-end • Process control

• Statistics • Summary


ESA’s Space Debris Office

OPS-GR Space Debris System SCARAB

DISCOS Database 50 users

Space Debris Tools 400 users

Collision Avoidance System Debris Evolution Model


Covered missions Since 2002: Operational collision avoidance activities at SDO for ESA missions in LEO • Conjunction event detection • Collision risk assessment • Chaser orbit determination and orbit and

covariance propagation Current focus on ESA’s/Copernicus EO (LEO) Third party customer • Planet (RapidEye: constellation of 5

satellites) • EUMETSAT (Sentinel 3) Upcoming missions (selection) Sentinels, Earth Explorers, LEOPs, CHEOPS

Satellite Comment

ERS-2 Manoeuvre/TLE screening, CDM processing including de-orbiting phase in 2011

Envisat Manoeuvre/TLE screening, CDM processing until failure in 2012

Cryosat-2 Manoeuvre/MC screening, CDM processing since launch

Swarm-A, B, C Manoeuvre/MC screening, CDM processing since launch

Sentinel-1A/B, 2A, 3A Manoeuvre/MC screening, CDM processing since launch

Proba 1, V Only review of JSpOC alerts, automated CDM processing

Proba 2 MC screening, CDM processing, support of thruster experiments

RapidEye 1-5 Manoeuvre/MC screening, CDM processing, since 2012

Cluster-II 1-4 Manoeuvre/TLE/MC screening, during GEO passages

XMM Manoeuvre/TLE screening, during GEO passages and LEO passages

Galileo/Giove/MetOp-A/B/MSG-3/4 JSpOC alerts received for a limited period of time (LEOP)

Artemis CSM/JSpOC alert received until operations handed over, now case-by-case support


ESA’s MASTER-2009: Spatial Density > 10cm

Swarm A,C

Swarm B

Sentinel-1A/B Cryosat-2

Sentinel-2A

RapidEye 1-5

Sentinel-3A


Outline






Recommended reaction threshold

What is a good reaction threshold? • Requires a management decision • Trade ignored/accepted risk vs. risk reduction • Estimate cost i.e. manoeuvre frequency for the selected reaction threshold

• Depends on orbit uncertainties of the secondary (chasing) objects • TLE vs CDM: collision avoidance manoeuvres reduced by roughly one

order of magnitude for same threshold • Uncertainties of TLEs for collision risk assessment? See detailed studies • CDM/CSM: improvement of uncertainties by one order of magnitude

• Typical managerial target function: • avoid 90% of the accumulated collision probability (CDM era) • avoid 50% of the accumulated collision probability (TLE era)


ESA’s DRAMA SW Tool Suite “The aim of DRAMA is to support the objectives of the ESA Space Debris Mitigation Requirements by enabling satellite programs in Europe to assess their compliance with the recommendations contained in that document.”

ARES Assessment of Risk Event Statistics: Analyze requirements for collision avoidance manoeuvres expected for a mission.

MIDAS MASTER (-based) Impact Flux and Damage Assessment Software: Modeling of the collision flux and damage statistics for a mission.

OSCAR Orbital Spacecraft Active Removal: Analyze disposal manoeuvres of spacecraft and compliance with ESA’s mitigation requirements.

CROC Compute projected cross-sectional areas of complex bodies

SARA Spacecraft Entry Survival Analysis Module (SESAM): Modeling the re-entry of a spacecraft. Spacecraft Entry Risk Analysis Module (SERAM): Assessing the on-ground risks of objects surviving re-entry.


DRAMA/ARES

• Providing statistics related to the collision risks for a mission.

• Determines required CAM fuel mass

• Flux based on MASTER-2009

• Results statistical, based on “average encounters”

• Four functionalities:

• Annual collision probability

• Manoeuvre rate, false alarm rates, risks as a function of accepted collision probability level (ACPL)

• Estimate DV to perform CAMs

• Estimate propellant mass for CAMs

Risk reduction: risk actually removed by manoeuvres Residual risk: risk not intended to be reduced (although it would be possible) Remaining risk: risk which cannot be reduced (caused by undetectable objects) + Residual risk


ARES example

Envisat-like: 780 km altitude polar, 26 m diameter, chaser limit size 10 cm

Catalogue covariance as per CDM Catalogue covariance as per TLE

Higher risk reduction for same ACPL, in particular for 10-4 almost all risk reduced with CDM accuracy, only half the risk with TLE accuracy


ARES example - manoeuvres

With TLE accuracies: Much higher number of manoeuvres for same ACPL. Risk reduction 50 % at ACPL of 10-4 at cost of approx. 30 manoeuvres!

Catalogue covariance as per CDM Catalogue covariance as per TLE


Outline






Operational process - drivers

• CDM information for enlarged screening volumes used as baseline • CDM superior to TLE in accuracy and its knowledge

• Automation of CDM processing due large number of CDMs • Including combined/mixed processing using OO information on target and

JSpOC CDM information on chaser (“MiniCatalog”) • Interface to mission control teams streamlined

• Simplifying data provision and interpretation • Providing concise status display to missions

• Internal coordination within collision avoidance support team simplified with help of a conjunction management tool and manoeuvre monitoring system

• Overall driver: support of task automation thereby reducing process risk


Database of conjunction events

• Central DB for all automatic and manual processing • Grouping by conjunction event ID: unambiguous description by 2 conjunction partners and

TCA • DB content

• CDM data obtained from JSpOC • Augmented by collision risk and other analyses results/sources • Automated insertion and standard analysis

• “Mini-catalogue” screening results against operational ephemeris/cov. • Same data model as CDM (but different originator) • Automated insertion and standard analysis after each update

• Scenario results for collision avoidance • Same data model as CDM (but different originator, multiple eph.)

• Fed manually by analyst


automated Target

properties

Flight Dynamics

Debris Analyst

Flight Dynamics SC Operators

CRASS/ CORAM

Solar & geomag. activity data

Chaser orbits and covariance data

ODIN

Orbit tracks

JSpOC Automated retrieval CDMs

Target orbits Covariance

Event characteristics

„Minicat“ pool of chaser ephemeris and covariances

Propagation

Target properties

DISCOS

SCARF/PREEMPT Visualisation

Extended operational collision avoidance process at ESA/ESOC with CDMs


Risk assessment and avoidance manoeuvres

Collection of Algorithms for collision risk assessment among two objects (CORCOS): • Alfriend Akella • Maximum Probability • Covariance scaling • Algorithms for low delta-v approaches • Non-spherical objects • Monte-Carlo

Support of manoeuvre planning (CAMOS) • Minimising risk or maximising (radial)

separation at TCA • Varying size, direction, epoch • Constraints (bounds, fixed, free) • Parametric or evaluation mode • Trajectory parameters (latitude/longitude,

eclipses, SAA crossing)


SCARF - Spacecraft Conjunction Assessment and Risk Frontend Web-frontend to CDM/Event database • Mission

“dashboard” view • Event view • Analyst view • Link to 3D

visualisation


Manoeuvre Monitoring System

• Process control and tasks allocation system • “ticket” per manoeuvre • Assignee management • Status transitions

• Views: • Status filter • Gantt • Calendar • Wiki (procedures)

• Redmine-based


Outline






Event Statistics from ESA/ESOC (end 2015)

0

10

20

30

40

50

60

70

80

90

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

CRASS warnings JSPOC warnings Tracking campaigns Avoidance Manoeuvres

ESA Space Debris Office


O/O vs. TLE orbits (in 10 km x 25 km x 10 km ellipsoid) CDM events as per screening volume

0%

20%

40%

60%

80%

100%

S/C R/B MRO

Fragments FengYun 1C Cosmos/Iridium

0

2000

4000

6000

8000

10000

12000

cosmos2251 iridium33 fengyun1c other

Classes of close approach objects – sampling of the LEO environment


Fly-by Statistics

0

5

10

15

20

25

30

35

40

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8Miss distance [km]

Frequency of conjunction events by miss distance CRY-2 (2010-013A)

SW-A (2013-067B)

SW-B (2013-067A)

SW-C (2013-067C)

S-1A (2014-016A)

S-2A (2015-028A)


Frequency of events per risk level

• Highest risk of all CDMs for a given conjunction

• CDMs received from JSpOC (SP vs SP)


Latency of CDMs

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7

[%]

of a

ll ev

ents

Time between first notification and TCA [d]


Summary • For more than a decade, ESA has a well-established collision avoidance process

• supporting several own and third party missions • ESA’s system and processes look back on a history of highly dynamic adaptation and innovation.

• Excellent collaboration with USSTRATCOM/JSpOC for years! • DRAMA/ARES ready to support mission / operations concept design phase

(https://sdup.esoc.esa.int) • to estimate collision avoidance needs • Use of CDMs as baseline, allowing lower manoeuvre thresholds, but reducing more overall risk than TLE-based

• Operational toolchain evolved significantly to meet growing needs • Approach centred around database of processed CDMs • “minicat”: flexibility, manoeuvre support with short turn-around times for small delta-v (changes) • Automation of CDM mixed CDM/OO processing (needed due to large number of CDMs) • Web-based interfaces for visualisation and coordination (Space Debris experts and FCT/FDT) • Support tools for specific analysis in back-end

• Improved/expanded risk assessment and avoidance manoeuvre planning • Maintain capability to acquire dedicated tracking

• The presented statistics show that the challenges differ over time and for each orbit type

https://sdup.esoc.esa.int/


Questions?

Thank you for your attention!

Abstracts due 22 Nov 2016

https://conference.sdo.esoc.esa.int/


Extra slides


Method Threshold to trigger…

Threshold to trigger manoeuvre

Manoeuvre screening Manoeuvre target Time

TLE screening Meeting: Pc > 10-4

D < 300m

Pc > 1-5*10-3

D < 300m TLE screening None 2003-2011

TLE screening + Tracking

Tracking: Pc > 10-4

D < 300m

Distance based (no mano for low risks)

Screen against precise chaser orbit only

None 2006-2011

JSpOC alerts Meeting: alert

Dradial < 3σchaser+3σtarget+cross-section radii

Request to JSpOC for a new alert message

Dradial > 3σchaser+3σtarget+cross-section radii

2010

CSM/CDM Meeting: Pc > 10-4

Pc > 10-4 Request to JSpOC (Pc < 10-6)

2010-2013

CSM/CDM full volume

Meeting: Pc > 10-4

Pc > 10-4 MINICAT and JSpOC (Pc < 10-6)

2013-

Typical thresholds used to trigger avoidance manoeuvres


SCARF - Dashboard Dashboard view - presentation of most relevant information for a mission: • Highest probability, smallest miss

distance, smallest radial miss distance; also “top 10” list for these criteria

• Highlighting escalated events, i.e. those for which control teams have been informed

• Some charts: Evolution of maximum collision probability, cumulative risk, number of events (total and above threshold), scatter plots showing collision probability and miss distance of upcoming events over time


SCARF - Event view Event view - presentation of all information related to a single event: • Reached via clicking on event in

dashboard view or event ID search • Interface to manage the status

(ownership, escalation level) • Lists core event data (objects,

TCA, CDMs) • Trend plots for relevant data • or all related CDM data in tabular

view


SCARF - Event view Event view - presentation of all information related to a single event: • Objects Info • Single CDMs can be displayed,

commented, get status changed • Log sub-view • E-mails can be triggered via templates • Single CDMs can be displayed,

commented, get status changed


SCARF – Analyst view

Analyst view - presentation of CDM information as one-liners • Selection of CDMs via filtering, options include

• Event, target, chaser, TCA interval, owner, assignee, collision risk, miss distance (components), uncertainties, originator, relative spread, approach azimuth/elevation, etc.

• Sorting data by any column • Optional grouping of CDMs by event


Conjunction visualisation

• 3D dynamic visualisation of close approaches: Earth, trajectories, covariance ellipsoids, CDM data, …

• Interactive control of camera position, view angle, time, zoom, …



• Zooming in showing conjunction details and object positions (boxes)



• Zooming in showing conjunction details and object positions and covariance ellipsoids (here 3 sigma)

Operational Collision Avoidance by ESA's Space … UNCLASSIFIED - For Official Use Klaus Merz |...

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