6 th Internatinal Cnference n Astrdynamics Tls and Techniques (ICATT) Darmstadt 14 17 March 2016 Cupling High Fidelity Bdy Mdeling with Nn- Keplerian Dynamics t Design AIM-MASCOT-2 Landing Trajectries n Didyms Binary Asterid Fabi Ferrari*, Michèle Lavagna*, Ian Carnelli * Plitecnic di Milan, Department f Aerspace Science and Technlgy Eurpean Space Agency, General Study Prgram Office, ESA HQ
Cntent 2 Intrductin: AIM and MASCOT-2 landing Dynamical envirnment arund Didyms system Gravity mdel Estimate f dynamical perturbatins Design f MASCOT-2 ballistic descent Requirements Assumptins Escape velcities in the three-bdy system Sensitivity analyses Successful landing prbability Landing dispersin at rest Fabi Ferrari
Asterid Impact Missin (AIM) 3 65803 Didyms will transit near Earth (less than 0.1 AU) in late 2022 [ Didyms = Didymain + Didymn ] Credits: ESA AIDA - Asterid Impact & Deflectin Assessment AIM - Asterid Impact Missin (ESA) Gals: Study f binary system Deplyment f a lander (MASCOT-2) Deplyment f cubesats (COPINS) DART - Duble Asterid Redirectin Test (NASA) Gals: High velcity kinetic impact Fabi Ferrari
MASCOT-2 landing highlights 4 MASCOT-2 shall land n the smaller asterid (Didymn) MASCOT-2 is a passive prbe N actuatrs fr trajectry cntrl N actuatrs r devices fr anchring t the surface Extremely lw gravity field n Didymn s surface MASCOT-2 can bunce but it shall stay n the surface MASCOT-2 release pint shall be safe frm AIM spacecraft pint f view Fabi Ferrari
Didyms system 5 1.18 km Credits: ESA Diameter [m] Mass [kg] Didymain 775 5.2 e11 Didymn 163 4.8 e9 Tw rders f magnitude lwer than 67/P C-G (Rsetta/Philae) Fabi Ferrari
Didyms system 6 1.18 km Credits: ESA Diameter [m] Mass [kg] Didymain 775 5.2 e11 Didymn 163 4.8 e9 Fur rders f magnitude lwer than 67/P C-G (Rsetta/Philae) + Didymain s perturbatin Fabi Ferrari
Didyms system Gravity mdel 7 1.18 km MASCOT-2 dynamics Three-bdy system L* 1.18 km µ 9.2 e-3 Credits: ESA T 11.92 h Diameter [m] Mass [kg] Didymain 775 5.2 e11 Didymn 163 4.8 e9 CR3BP t mdel the mtin f the asterids center f mass Fabi Ferrari
Didyms system Gravity mdel 8 CR3BP t mdel the mtin f the asterids center f mass Gravity surce Didymain (sphere) + Didymn (sphere) Didymain (sphere) + Didymn (ellipsid) Didymain (plyhedrn) + Didymn (ellipsid) Dynamical mdel S1+S2 (CR3BP) S1+E2 P1+E2 S1+E2 P1+E2 Fabi Ferrari
Didyms system Dynamical perturbatins 9 Relevant effects at 1 km [m/s 2 ] Acceleratin due t Didyms system s gravity e-5 Acceleratin due t SRP n MASCOT-2 lander e-8 Perturbatin due t Sun s gravity (third bdy) e-11 Perturbatin due t Earth s gravity (third bdy) e-13 Nt relevant fr MASCOT-2 scenari Irregularities in Didyms gravity field are the mst relevant perturbatins N relevant differences fund between S1+E2 and P1+E2 mdeling Fabi Ferrari
MASCOT-2 landing design Requirements 10 MASCOT-2 shall land n the smaller asterid (Didymn) MASCOT-2 is a passive prbe N actuatrs fr trajectry cntrl N actuatrs r devices fr anchring t the surface Extremely lw gravity field n Didymn s surface MASCOT-2 can bunce but it shall stay n the surface MASCOT-2 release pint shall be safe frm AIM spacecraft pint f view Ballistic descent with n escape after buncing v aftertd < v esc Fabi Ferrari
Escape velcity frm Didymn s surface Theretical limits 11 Dynamical mdel v esc [cm/s] S2 7.70 S1+S2 4.95 S1+E2 4.58 P1+E2 4.57 Values t escape Didymn s SOI (r neighbrhd) It depends n latitude they depend n latitude and lngitude The escape velcity is the tuch dwn velcity fr a pure ballistic landing frm the SOI v TD v esc Minimum energy t land / escape: thrugh L1 pint Fabi Ferrari
Tuch-dwn velcity Mnte Carl backwards integratin 12 Energy v TD < v L1 v L1 < v TD < v L2 v TD > v L2 Minimum v td [cm/s] Thrugh L1 neck (v L1 ) Thrugh L2 neck (v L2 ) S1+S2 4.95 5.23 S1+E2 4.58 5.11 P1+E2 4.57 5.11 Fabi Ferrari
MASCOT-2 landing design Trajectry selectin 13 Requirements Ballistic descent with n escape after buncing v aftertd < v esc Safety: release far frm Didymn cnstraints the dynamics t v TD v esc Design strategy Keep v TD as lw as pssible Trajectries with lw v TD are thse passing thrugh the L1 r L2 neck with lw energy (L2 neck is cnsidered fr safer release) Maniflds assciated t L2 pint Fabi Ferrari
MASCOT-2 landing design Example f landing slutin 14 Release frm 200 m altitude Manifld High time f flight Nt rbust after release dispersin Fabi Ferrari
MASCOT-2 landing design Example f landing slutin 15 Release frm 200 m altitude Near the manifld Lw time f flight Rbust after release dispersin Fabi Ferrari
MASCOT-2 landing design Assumptins 16 BALLISTIC DESCENT: MASCOT-2 dispersin at release Navigatin errr Release mechanism errr 5 deg (1σ) half cne angle arund nminal release directin 0.5 cm/s (1σ) uncertainty in release velcity BOUNCING DYNAMICS: velcity after tuch dwn Directin accrding t sil inclinatin Unifrm distributin in azimuth Gaussian distributin in elevatin: 90 ± 70 deg (µ ± 3σ) Nrm f velcity dumped accrding t the restitutin cefficient η = v aftertd v befretd = 0.9 0.6 = 0.54 asterid s sil lander s structure Fabi Ferrari
MASCOT-2 landing design Escape prbability 17 Frm release up t escape r stay n Didymn s surface Mnte Carl simulatin (200000 cases fr each release pint) S1+E2 mdel used (equivalent t P1+E2) Release frm 200 m altitude Release frm 250 m altitude Fabi Ferrari
MASCOT-2 landing design Escape prbability 18 Frm release up t escape r stay n Didymn s surface Mnte Carl simulatin (200000 cases fr each release pint) S1+E2 mdel used (equivalent t P1+E2) Release altitude [m] Escaped trajectries [%] After release After tuch dwn TOT 100 1.14 0.00 1.14 150 1.26 0.00 1.27 200 3.18 0.01 3.19 250 5.79 0.04 5.83 300 6.03 0.32 6.35 Fabi Ferrari
MASCOT-2 landing design Landing dispersin at rest 19 Frm release up t rest n Didymn s surface: utging vertical velcity lwer than 0.5 cm/s Mnte Carl simulatin (200000 cases fr each release pint) S1+E2 mdel used (equivalent t P1+E2) Release altitude [m] Dispersin at rest (µ ± 3σ) Latitude [deg] Lngitude [deg] Tf [h] 100 0.2 ± 32.5 23.3 ± 87.9 1.81 ± 0.95 150 0.0 ± 31.5 20.1 ± 66.7 2.19 ± 1.06 200 0.1 ± 32.9 19.7 ± 60.5 2.50 ± 1.21 250-0.1 ± 36.6 20.5 ± 64.8 2.77 ± 1.41 300 0.1 ± 44.3 19.5 ± 86.0 2.95 ± 1.35 Fabi Ferrari
MASCOT-2 landing design Landing dispersin at rest: release frm 200 m 20 Release altitude [m] Dispersin at rest (µ ± 3σ) Latitude [deg] Lngitude [deg] Tf [h] 200 0.1 ± 32.9 19.7 ± 60.5 2.50 ± 1.21 Fabi Ferrari
MASCOT-2 landing design Landing dispersin at rest: release frm 200 m 21 Release altitude [m] Dispersin at rest (µ ± 3σ) Latitude [deg] Lngitude [deg] Tf [h] 200 0.1 ± 32.9 19.7 ± 60.5 2.50 ± 1.21 Fabi Ferrari
MASCOT-2 landing design Cnclusin 22 Summary The main perturbing actin is due t the uncertainty n Didyms/Didymn gravity field Higher successful landing prbability fr lwer release pints Landing dispersin at rest is cnfined within a certain latitude-lngitude band Gd results with current assumptins n release dispersin, sil uncertainty and restitutin cefficient Release altitude [m] Successful prbability [%] 100 98.86 150 98.73 200 96.81 250 94.17 300 93.65 Fabi Ferrari
6 th Internatinal Cnference n Astrdynamics Tls and Techniques (ICATT) Darmstadt 14 17 March 2016 Cupling High Fidelity Bdy Mdeling with Nn- Keplerian Dynamics t Design AIM-MASCOT-2 Landing Trajectries n Didyms Binary Asterid Fabi Ferrari*, Michèle Lavagna*, Ian Carnelli * Plitecnic di Milan, Department f Aerspace Science and Technlgy Eurpean Space Agency, General Study Prgram Office, ESA HQ