BIRDY T. Daniel Hestroffer - IMCCE/Paris obs., PSL Research univ., France

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1 BIRDY T Daniel Hestroffer - IMCCE/Paris obs., PSL Research univ., France M. Agnan ESEP - Odysseus Space Ltd., Taiwan J.J. Miau - NCKU, Taiwan G. Quinsac - LESIA/Paris observatory, France P. Rosenblatt - ROB, Belgium B. Segret LESIA-ESEP/Paris observatory, France J. Vannitsen - NCKU - Odysseus Space Ltd., Taiwan

2 Small bodies NEO, MBAs, Trojans,... Asteroid-Comet continuum Small and irregular satellites Planetary resources exploitation PHA threat to Earth Science: origins, formation and evolution physics and dynamics Mass, internal structure, mechanical behaviour 2

3 Space missions asteroids, comets +Phobos/Deimos Small bodies diversity size-surface-structure no Trojan ; no binary ( * )... yet 3 (P&G 2017)

4 Internal structure Rotation spin-rate Gravitational aggregates spin-rate barrier binary and multiple systems small asteroids rubble piles (Pravec, Harris) 4

5 Internal structure mass for 50 asteroids average densities with taxonomic class variation with porosity variation with size (Carry 2012) 5

$NEAs P-type & comets rubble-piles coherent fractured (Baer et al.2011) (Britt et al.$

6 Internal structure Porosity Gravitational aggregates or rubble-piles post-collision, YORP? NEAs P-type & comets rubble-piles coherent fractured (Baer et al.2011) (Britt et al. 2010) S-type Itokawa porosity 40% (Fujiwara et al.2016) 6

7 Planetary geodesy Mission to small body Didymos (AIDA/AIM) Phobos (MMX, Dephine)... MBAs, Trojans interplanetary mission hosting CubeSats Derive mass, density, and moments of inertia +higher moments of gravity field (spherical/elliptical harmonics) test internal structure and density distribution Advantages of CubeSat CubeSat spacecraft dedicated to instrument (or target) autonomy in operations/orbits closer to surface (higher risks) proximity operations Constraints no direct link to Earth (à priori), => relying on mothercraft no example of radio-science cubesat, nor interplanetary 7

8 Planetary geodesy Radio-science and Imaging Radio-science echo(/ranging) + Doppler stellar astrometry Imaging shape and size rotation, landmarks attitude additional Delta-DOR (PRIDE,...), Lidar or radio link to surface (MASCOT2,...) 8

9 BIRDY concept BIRDY: CubeSat to small body concept piggyback, cruise or proximity operations mothercraft relay need of autonomy complementary observations by 1 or 2 CubeSats end of life: land on surface, radio operations Main features developed propulsion autonomous orbit navigation and control radio science (POD) 9

BIRDY heritage Operations - Flying legs Autonomous navigation - astrometry and position - orbit correction and attitude control Ground segment - models in the loop,

10 BIRDY heritage Operations - Flying legs Autonomous navigation - astrometry and position - orbit correction and attitude control Ground segment - models in the loop, prepares ref. orbit Flight segment - autonomous ΔV impulse, navigation, science, link mothercraft flying legs Propulsion - PPT see Quinsac et al. session B2 (Segret IFOD) 10

11 Autonomous navigation star tracker - object tracker in-flight attitude and orbit on-board AOCS in cruise, or in proximity see Segret et al. IFSSD 2017 see Agnan et al. COSPAR 2017 Symp. SmallSat 11

Radio-science Basic concept of radioscience experiment X

Earth CubeSat and the spacecraft xxx orbiting the system

Determination (POD) Dedicated orbitography software (like

fitting of a dynamical model of motion to tracking data

(Mass and gravity field of primary, mass of secondary) (1)

by the French space agency (CNES) and further adapted to

12 Radio-science Basic concept of radioscience experiment X band Ka-band Tracking data: 2-way radio-link between the Earth CubeSat and the spacecraft xxx orbiting the system Doppler and range measurements mothercraft x Precise Orbit Determination (POD) Dedicated orbitography software (like GINS (1) ): Calculation of orbit from least squares fitting of a dynamical model of motion to tracking data Determination of the parameter of geophysical interest (Mass and gravity field of primary, mass of secondary) (1) Géodésie par Intégration Numériques simultanées, developed by the French space agency (CNES) and further adapted to planetary geodesy applications by the Royal Observatory of Belgium (ROB). 12

13 Radio-science RDV flyby experiment object (Didymos) density 2000 kg/m 3 diameter 800 m measure Doppler X-band 0.02 mm/s over 60s relative vel. 20 to 30 cm/s GM 0.03% single 13

14 Radio-science Orbit (planar) stabilities around binary asteroid Didymos over 1month on resonances polar orbits, close to secondary hovering and rdvs, no perturbations (F. Damme DLR 2012) (Escorial GMV 2016) POD and Ji coeff. determination 14

15 Radio-science Optimising: polar orbits, close to surface Phobos QSO 50km, hovering km Didymos QSO 2-10 km, hovering km multiple rdv (Phobos case, or QSOs) RS assessment radio-link analysis (bands, one-or-two way, USO) one or two CubeSats external forces, accelerations orbit correction constraints POD 15

16 Development plan BIRDY T 16

BIRDY-T : Focus on propulsive aspects of an icubsat to small bodies of the solar system

BIRDY-T : Focus on propulsive aspects of an icubsat to small bodies of the solar system Gary Quinsac, PhD student at PSL Supervisor: Benoît Mosser Co-supervisors: Boris Segret, Christophe Koppel icubesat,