Gibbings, Alison

Martinez, Cesar

Novak, Daniel

Rizzi, Francesco

Vasile, Massimiliano

Zuiani, Federico

English

Name not available

European Student Moon Orbiter (ESMO) - Mission Overview : Presentation

University of Strathclyde Institutional Repository

Strathprints Institutional RepositoryGibbings, Alison and Vasile, Massimiliano and Zuiani, Federico and Novak, Daniel and Rizzi,Francesco and Martinez, Cesar (2010) European Student Moon Orbiter (ESMO) - Mission Overview: Presentation. In: ESA/ESTEC Systems Requirement Review Workshop, 2010-03-22 - 2010-03-26, Noordwijk.Strathprints is designed to allow users to access the research output of the University of Strathclyde.Copyright c© and Moral Rights for the papers on this site are retained by the individual authorsand/or other copyright owners. You may not engage in further distribution of the material for anyprofitmaking activities or any commercial gain. You may freely distribute both the url (http://strathprints.strath.ac.uk/) and the content of this paper for research or study, educational, ornot-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to Strathprints administrator:mailto:strathprints@strath.ac.ukhttp://strathprints.strath.ac.uk/Changing the economics of spaceESMO – Mission AnalysisSRR WorkshopAlison Gibbings22nd – 26th March 2010Commercial in Confidence 2Contents• Review of the existing baseline• Sensitivity analysis– At lunar Injection– Along the WSB-Moon transfer, two weeks before injection• Trade-off to reduce the mission delta-V– Varying the apolune– Frozen orbit (case 1, case 2, case 3)• Proposed transfer and orbit insertion – WSB transfer– Frozen orbit around the Moon– Ground access time & eclipse • Summary – Conclusion of results and influence on requirements• Acknowledgments • QuestionsCommercial in Confidence 3Existing Baseline • Utilises a WSB transfer in the Earth-Moon-System – Obtain an inclination change and rise at perigee at zero-cost– Saving delta-V • Transfer is divided into two legs– Periapsis of GTO to WSB region– Departure from the lunar target orbit and propagate backwards to the WSB region• Two legs are linked through delta-V manoeuvres • Mid-course correction in the WSB region to increase flexibility when targeted the required orbit at the moon Commercial in Confidence 4Existing Baseline • WSB transfer trajectory with phasing leg at the Earth (blue = Moon orbit, yellow = Earth spacecraft trajectory)Commercial in Confidence 5Orbital Elements Values a 3586 kme 0.4874i 89.9 ºΩ 63.8 ºω 292.9 ºv 0 ºExisting Baseline Commercial in Confidence 6Existing Baseline WSB Transfer∆V at Earth [m/s] (nominal escape) 747.7∆V at WSB [m/s] (matching manoeuvre) 71.02∆V at Moon [m/s] 297.57Total ∆V ( [m/s] 1116.29Departure Date [UTCG] 25/02/2012 14:34Time of flight Earth-WSB [days] 40.82Time of flight WSB-Moon [days] 60.31Total time of flight [days] 101.13Arrival Date [UTCG] 05/06/2012 17:39Arrival Orbit: semi-major axis [km] 3586Arrival Orbit: eccentricity 0.4875Arrival Orbit: inclination [deg] 89.9Commercial in Confidence 7Sensitivity at Lunar Injection• Introduction of error into the orbital elements of the lunar orbit (existing baseline) • Error of 1,2,3,4 and 5 % – Deviation of ten samples • Used Matlab to generated ten cases from random points between upper and lower limits  – Assessed the altitude of perilune against T+ (Days)– Larger the error, the greater the range of data plots • Has an implication on the requirement for the accuracy of the orbit insertionCommercial in Confidence 8Sensitivity at Lunar Injection at 1 %Commercial in Confidence 9Sensitivity at Lunar Injection at 2 %At 2 % Error-500501001502002503003500 20 40 60 80 100 120 140 160 180 200T+0 (days)Altitude of Perilune (km)Sample 1Sample 2Sample 3Sample 4Sample 5Sample 6Sample 7Sample 8Sample 9Sample 10Commercial in Confidence 10Sensitivity at Lunar Injection at 3 %Commercial in Confidence 11Sensitivity at Lunar Injection at 4 %At 4 % Variance-500501001502002503003504000 20 40 60 80 100 120 140 160 180 200T+0 (days)Altitude of Perilune (km)Sample 1Sample 2Sample 3Sample 4Sample 5Sample 6Sample 7Sample 8Sample 9Sample 10Commercial in Confidence 12Sensitivity at Lunar Injection at 5 %Commercial in Confidence 13Sensitivity along the Transfer• Using an 1 % error, the trajectory corridor for obtaining lunar orbit injection was assessed. – From lunar orbit the trajectory was propagated backwards for two weeks towards the WSB. – Propagated 1000 perturbed solutions with the maximum values of error for position and velocity – Requirement to know ESMO’s position and velocity • ODTK verified that the estimated position and velocity after orbit determination was inside the corridor. Therefore confirming that orbit insertion was possible. Commercial in Confidence 14Sensitivity at two Week from Insertion-5 -4 -3 -2 -1 0 1 2 3 4x 104-6-4-20246x 104 Perturbed, estimated and reference solutions 2 weeks before LOOr [Km]t [Km] -200 -100 0 100 200-5000500r [Km]t [Km]• Error in radial and transversal position of ESMO– Requirement on the accuracy of orbit determination Commercial in Confidence 15Sensitivity at two Week from Insertion-5 -4 -3 -2 -1 0 1 2 3 4x 104-3-2-10123x 104 Perturbed, estimated and reference solution in r-h plane after 2 weeksr [Km]h [Km]Commercial in Confidence 16Navigation Strategy • Using the existing baseline transfer • From Earth (GTO) to WSB – Modelled the orbit determination • First obit determination (OD) one week after trans-lunar injection from GTO• If required, target correction manoeuvres (TCMs) – Correct for the error in the trans-lunar injection burn & typical dispersion error of the launcher (A5) » Error: 1*10-3 km/s in every direction – Assumed that an error was created in every TCM (km/s)» Error: 1*10-4 km/s in every direction, caused by the thrusters– Outcome is the error in position and velocity, and is measured at the next OD point • Typical one OD every three days • Leads to a final delta-V/fuel budget for the navigation budgetCommercial in Confidence 17Navigation Strategy1 st Orbit Determination Start: 19/3/2011 05:54:30End: 22/3/2011 05:54:30TCM 1 Date :22/03/2011 16:42:4 ΔV = 2.09 * 10^-2 km/s2 nd Orbit Determination Start: 2/04/2011 12:00:6End: 5/04/2011 12:00.6TCM 2 Date: 15/04/2011 20:18:23ΔV = 5.8369*10^-4 km/s3 rd Orbit Determination Start: 19/4/2011 06:24:57End: 22/4/2011 06:24:57TCM 3 Date: 24/04/2011 5:29:35ΔV = 1.1*10^-4 km/sTCM 4 Date :26/04/2011 15:23:47 ΔV = 5.15* 10^-2 km/s• Etc…..where ESMO OD & TCM’s actions are focused on maintaining its position and velocity within the trajectory corridor to enable lunar injection.  Commercial in Confidence 18Navigation StrategyCommercial in Confidence 19Navigation StrategyError into GTO-burn manouver 1* 10^-3 km/sError Introduced in Every TCM 1*10^-4 Km/sFinal Error in Position  @ W.S.B. region Δr = 93.53 Km• Total delta-V to perform the four TCMs. – Trajectory corridor allowing lunar insertionFuel Budget for TCMs ΔV = 0.0840 km/sFINAL MISSON DELTA-V BUDGET ΔV = 1.1257 km/sCommercial in Confidence 20Sensitivity Analysis at the Moon• At 1 % accuracy of lunar injection– Error in positionCommercial in Confidence 21Sensitivity Analysis at the Moon• At 1 % accuracy of lunar injection– Error in velocityCommercial in Confidence 22Recommendations on Orbit Determination• From the previous plots considering the required accuracy of position and velocity, SpaceART offers the following recommendations:• New proposed requirement• Position25 km radial (range)10 km along track10 km out of plan• Velocity0.008 km/s radial (range rate)0.01 km/s along track0.013 km/s out of plane• This is considered to be the worst case condition and should therefore be applied to all aspects of the WSB transfer legs and lunar orbit insertion. Commercial in Confidence 23Trade-Off of Delta-V Reduction• Investigated the possibility of changing the baseline orbital transfer to reduce the total mission delta-V– Still providing a stable orbit for 6 months– Having multi-passage at 200 km or below at peripasis at the South Pole• Resolution requirement of the Narrow angle camera• Investigated:– Varying the apolune of the lunar orbit• Orbital lifetime, associated perilune altitude – Use of frozen orbits…..…influence on the mission requirementsCommercial in Confidence 24Orbital Analysis – Varying the Apolune • Varying the apolune– Entering a higher lunar orbit • Altitude of apolune varied • Altitude of perilune at 100 km: comply with the 200 km camera resolution requirement  • Apolune 10,000 km • Apolune 20,000 km • Apolune 56,000 km Orbital Elements Values Altitude of perilune 100 kmi 89.9 ºΩ 63.8 ºω 292.9 ºv 0 ºCommercial in Confidence 25Varying the Apolune - AnalysisVarying the Apolune-1000-50005001000150020002500-10 10 30 50 70 90 110T+0 (days)Altitude of Periapsis (km)Apolune 10,000 km Apolune 20,000 km Apolune 56,000 km Commercial in Confidence 26Frozen Orbits • Explored the benefits of families of frozen orbits with stable liberation • Longer orbital life• Minimises station keeping  delta-V• Reduces s/c mass Ely T, Lieb E (2006) Constellations of Elliptical Inclined Lunar Orbits Providing Polar and Global Coverage The Journal of the Astronautical Sciences, Vol 54, Vol 1, pg 53-67Ely T (2005) Stable Constellations of Frozen Elliptical Inclined Lunar OrbitsJournal of the Astronautical Sciences, Vol 53, No 3, pg 301-311Kumar K, Noomen R(2008) Stability of Highly Elliptical Orbits at the Moon. AIAA/AAS Astrodynamics Specialist Conference and Exhibit, 18th-21st August, Honolulu, Hawaiii >= 39.2 ºω 90 or 270 ºCommercial in Confidence 27• Tested the stability of three families of frozen orbits• At higher eccentrity and semimajor axisFrozen Orbit – Analysis a 6542 kme 0.6i 56.2 ºΩ 104.99 ºω 270 ºM 349.36 ºT 56082.5799 MJDa 13084 kme 0.8i 56.2 ºΩ 103.63 ºω 270 ºM 345.51 ºT 56082.5799 MJDa 6808.1 kme 0.73i 56.2 ºΩ 98.27 ºω 270 ºM 332.92 ºT 56082.55082 MJDCASE 1 CASE 2 CASE 3Commercial in Confidence 28• Conditions of analysis – For each new orbit, the WSB transfer was re-iterated – Resulted in updated values for:• Moon insertion date  4th June 2012• RAAN • Mean motion• Used the Moon’s  gravitational force as a central body– Data gained from the Lunar Prospector Orbiter – With the Earth and Sun as a 3rd body point mass effect• Each STK simulation was run for six monthsFrozen Orbit – Analysis  Commercial in Confidence 29Frozen Orbits – Analysis, Case 1• CASE 1a 6542 kme 0.6i 56.2 ºΩ 104.99 ºω 270 ºM 349.36 ºT 56082.5799 MJDCommercial in Confidence 30Frozen Orbit – Analysis, Case 1T + (days)Altitude of Perilune (km)Argument ofPerilune (deg)Inclination(deg)Eccentricity7 820.7632 267.292 55.747 0.60892934 821.278195 264.418 55.19 0.60881634 814.794859 264.5 55.209 0.60986361 751.881313 262.033 54.367 0.61944562 747.960826 262.202 54.378 0.62009689 640.36707 260.605 53.303 0.636406116 513.20599 260.271 52.064 0.655838143 382.622987 261.086 50.742 0.675958170 237.199371 263.18 49.488 0.69798183 123.993065 264.031 48.895 0.715461Commercial in Confidence 31• CASE 2Frozen Orbit – Analysis, Case 2a 13084 kme 0.8i 56.2 ºΩ 103.63 ºω 270 ºM 345.51 ºT 56082.5799 MJDCommercial in Confidence 32Frozen Orbit – Analysis, Case 2 T + (days)Altitude Of Perilune (km)Argument of Perilune (deg)Inclination (deg) Eccentricity6 513.214605 267.018 55.081 0.82729734 1204.384562 279.113 57.69 0.77394761 2167.882635 274.749 60.941 0.70104588 1648.570095 266.014 61.262 0.73822589 1718.745606 265.247 61.237 0.73563116 538.973873 267.789 59.798 0.824661143 498.81615 279.162 63.654 0.828001170 1578.427517 276.41 68.846 0.743906183 1767.462828 271.237 68.337 0.729623Commercial in Confidence 33Frozen Orbit – Analysis, Case 3• CASE 3a 6808.1 kme 0.73i 56.2 ºΩ 98.27 ºω 270 ºM 332.92 ºT 56082.55082 MJDCommercial in Confidence 34Frozen Orbit – Analysis, Case 3T + (days)Altitude Of Perilune (km)Argument of Perilune (deg)Inclination (deg)Eccentricity7 15.251774 268.343 55.704 0.74237634 58.809417 269.194 55.408 0.73592861 96.259455 269.878 55.232 0.73037289 134.343993 270.378 55.182 0.724739116 166.80333 270.487 55.215 0.720014143 170.530942 270.285 55.247 0.719597170 116.923328 270.366 55.251 0.727148171 131.937598 270.265 55.286 0.725333183 38.92874 271.159 55.063 0.73892Commercial in Confidence 35Frozen Orbits - ComparisonFrozen Orbits - Decay Analysis050010001500200025000 20 40 60 80 100 120 140 160 180 200T+ (Days)Altitude of Periapsis (km)Case 1 Case 2Case 3Commercial in Confidence 36Frozen Orbits – Delta-V • Case 1  delta V 946.91 m/s • Case 2  delta V 854.85 m/s (a= 13084 km, e = 0.8 )• Case 3  delta V 947.87 m/s – Investigated changing the perilune of Case 2, assessing the orbit lifetime and associated altitudes. – Found that there was sensitivity to the RAAN (below 100º), resulting in the fast decay of the orbit with an reduction in the semimajor axis Commercial in Confidence 37Frozen Orbits – Continued Analysisa 10084 kme 0.8i 56.2 ºΩ 103.63 ºω 270 ºM 345.51 ºCommercial in Confidence 38Continued Analysis - Orbital Profile T + (days)Altitude Of Perilune (km)Argument of Perilune (deg)Inclination (deg) Eccentricity6 106.412074 267.768 55.468 0.81684134 366.039082 275.196 56.174 0.79074361 796.395115 276.896 58.313 0.74758788 1105.725242 273.287 59.853 0.71691389 1162.787506 273.073 60.015 0.712189116 1002.679975 267.703 60.201 0.728253143 477.762938 266.284 59.506 0.780311170 37.913977 271.264 59.561 0.823777183 167.756208 274.111 60.752 0.810885Commercial in Confidence 39Proposed Transfer and Orbit Insertion• The updated baseline – Earth to WSB– WSB to Moon – Moon insertion at:– Separate burn to lower the perilune • Reduce the semimajor axis by 3000 km, additional 47.2 m/sa 13084 kme 0.8i 56.2 ºΩ 103.63 ºω 270 ºM 345.51 ºT 4th July 2012 13.55.03 UTCGCommercial in Confidence 40Proposed WSB TransferCommercial in Confidence 41Access - Proposed Baseline Transfer• Good ground access, despite the single eclipse at Earth departure of ~670 sec (approx. 11 mins).Commercial in Confidence 42Access - Proposed Baseline TransferCommercial in Confidence 43Ground Station Access TimeCommercial in Confidence 44Total Transfer – Summary of Nominal  WSB Transfer Comparison Baseline New Transfer to HE OrbitTotal ∆V (plus additional orbit transfer at Moon) [m/s] 1116.29 854.85+47.2 = 902.05∆V at Earth [m/s] (nominal escape) 747.7 748.25∆V at WSB [m/s] (matching manoeuvre) 71.02 34.16∆V at Moon [m/s] (plus additional orbit transfer) 297.57 72.45+47.2Departure Date [UTCG] 25/02/2012 14:34 25/02/2012 19:03Time of flight Earth-WSB [days] 40.82 40.76Time of flight WSB-Moon [days] 60.31 59.08Total time of flight [days] 101.13 99.84Arrival Date [UTCG] 05/06/2012 17:39 04/06/2012 15:11Arrival Orbit: semi-major axis [km] 3586 10084Arrival Orbit: eccentricity 0.4875 0.8Arrival Orbit: inclination [deg] 89.9 56.2Commercial in Confidence 45In Summary • Proposed a new baseline lunar orbit– Highly eccentric, frozen orbit   – Higher altitude of perilune – Achieves a stable orbit for 6 months, with possible extension – Delta –V saving of 214.24 m/s– Completed mission occurs under 1 km/s (902.05 m/s)• Not including margins • Influence on the Requirements – Higher periline  payload resolution– 11 mins eclipse time  power budget – Updated reduction in delta-V  propulsion, s/c mass Commercial in Confidence 46Acknowledgements • Team Composition– Supervisor• Dr Vasile – Mission Analysis• Federico Zuiani (PhD)• Daniel Novak (PhD)• Alison Gibbings (PhD)– Flight Dynamics (incl orbit determination and control)• Francesco Rizzi (Erasmus) • Cesar Martinez (Erasmus)Commercial in Confidence 47Capabilities of SpaceART• The design process is based on the following Matlab modules:– Orbit simulator (complemented now by a spacecraft simulator)– Ground station and measurement simulator – Filtering module– Optimisation module• DITAN (direct transcription of optimal control problems with finite elements in time) is used for thrust manoeuvre modeling and optimisation• STK with Astrogator is used for ground station visibility analysis , eclipse analysis, orbit propagation • ODTK is used for verification of the OD processCommercial in Confidence 48Capabilities of SpaceART• The orbit simulator contains:– Analytical ephemeris – 3rd body perturbations– Gravity perturbations– Light pressure– Simplified drag model• The spacecraft simulator currently contains the following modules:– Thermal analysis module– Attitude dynamics module– Orbit simulation moduleChanging the economics of spaceThank YouAny Questions?agibbing@eng.gla.ac.uk© Surrey Satellite Technology Ltd.Tycho House, 20 Stephenson Road, Surrey Research Park, Guildford, Surrey, GU27YE, United KingdomTel: +44(0)1483803803 | Fax:+44(0)1483803804 | Email: info@sstl.co.uk | Web:www.sstl.co.uk

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European Student Moon Orbiter (ESMO) - Mission Overview : Presentation

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