Asteroid Impact Mission (AIM)

Andrés Gálvez, ESA HQ, Paris, France Ian Carnelli, ESA HQ, Paris, France Carlos Corral, ESTEC, Noordwijk, The Netherlands

& the AIDA team (JHU/APL, NASA, OCA. DLR) NEO mission studies in ESA

 Near- Objects (NEOs); impact probability is very low but effects can be extremely severe ;   ESA addresses risk assessment and works with data users, but these users also need missions

 There is still very limited practical knowledge on the best technology approach to tackle NEO impact threats.

NASA/JHU ESA study

. After ESA’s Mission Advisory Panel recommendation, ESA studied Don Quijote mission . Two launches . Interceptor . Rendezvous . Not affordable techno demonstration for ESA 5/29/2012 3 AIDA Background

. The Double Asteroid Redirection Test (DART) study undertaken by APL in 2011-2012 with participation of NASA  NASA HQ, GSFC, JSC, LaRC, JPL  Asteroid impact and deflection,

. The Asteroid Impact Mission (AIM) study undertaken by ESA in 2012 with OCA, DLR  Impact test and characterization

5/29/2012 4 The AIDA concept

. AIDA will send two spacecraft to the  Asteroid impactor  Asteroid rendezvous . Each AIDA component is independent and has unique value

AIDA = AIM + DART

5/29/2012 5 Target: Didymos

Didymos Spectral type Xk Primary rotation 2.26 hr Binary orbit period 11.91 hr Binary orbit semi-major axis 1.05 km Primary diameter 800 m Secondary diameter 150 m Magnitude H 18 Pole Solutions (λ,β) = (157°,19°); (329°,-70°)

Heliocentric Orbit . Spacecraft impact (in Eccentricity 0.384 2022) will change Inclination 3.41° mutual orbit of binary Semi-major axis 1.645 AU . Period change is Heliocentric period 2.11 yr measurable from Aphelion 2.28 AU Earth by shift in Perihelion 1.01 AU mutual event timing

5/29/2012 6 Key Objectives AIM as a monitoring mission . target characterization through a rendezvous and observation from a distance . characterization also from ground (radar, optical) – simpler, more robust mission . autonavigation demonstration . cost target under 150M€

Distance: 5-17 km (100 km for DART impact)

Characterization point

NAC, thermal IR, NIR spectrom.

to Sun

5/29/2012 7 AIM Payload Objectives

P# Parameter Relevance to goal Possible measurement / is it a must have?

1 • Orbital state • Key to determine momentum • Ground (photometry, radar), in-space (CAM) – a must

2 • Rotation • Key to determine momentum • Ground (photometry, radar), in-space (CAM) – a must state

3 • Size, Mass, • Mass key to momentum, size to shape, • Mass from binary orbit, shape model from CAM (or Gravity volume, gravity to internal structure, ), a must, gravity field RSE (not a must?) operations

4 • Geology, • Bulk composition, material mechanical • VIS photometry to derive spectral type (must), IR surface properties, surface thermal inertia spectrometer mineralogy (not a must) properties • TIR for Yarkowski / YORP (not a must if not large source of error)

5 • Density, • Affects absorption of impact energy, • Bulk values derived from mass, shape model internal • “data point” for study of asteroid • Radar Tomography, seismic probing. l largely increases structure mitigation. complexity and not a must (conclusion Don Quijote/NEO1). = outside scope AIM

5/29/2012 8 AIM Strawman payload

Instrument Mass Power FOV Aperture Dimensions Notes (kg) (W) (deg) (mm) (mm)

NAC 2.0 0.75 5.3 x 14.2 200x150x50 Combines navigation and science 5.3 purposes. Measure orbital, rotational state, shape. Heritage: AMIE (SMART-1). Micro Laser 2.5 4 0.003 30 200x150x50 Precise shape model Altimeter Low TRL in Europe (BELA, ALADIN). Operational range should be higher than 10 km. Thermal IR 1.5 1 4 40 60x40x40 Study of surface temperature and Imager thermal inertia. Heritage: MERTIS (BepiColombo). Mass assumes further miniaturization. NIR 1.5 7 4 38 100x50x50 Global mapping of the surface spectrometer mineralogy. Heritage from SIR (SMART-1) and SIR-2 (Chandrayaan-1). Mass estimate assumes further miniaturization

5/29/2012 9 Payload Options

AIM p/l

Dust Camera TIR Detector

Laser Altimeter

Surface system

Radio Science Experiment

5/29/2012 10 Interplanetary transfer (EP option)

Launch 19/08/2019 Escape velocity [km/s] 1.0 Declination [deg] -14.46 Escape mass [kg] 400 Earth swing-by 07/11/2020 Infinite velocity at SB [km/s] 5.44 Vel. at pericentre [km/s] 10.8 Pericentre altitude [km] 2854 Arrival 01/08/2022 Final mass [kg] 324 SEP delta-v [km/s] 2.9 Xenon consumption [kg]: 73 Hydrazine consumption [kg]: 5 Thruster on time [d]: 213 Total Impulse[10^6kg m/s]: 1.05

5/29/2012 11 AIM Spacecraft Concept

5/29/2012 12 AIM Mass Budget

Propulsion Stage Mass (kg) Rendezvous S/C Mass (kg)

Structure 23.21 Dry Mass w.o. margin 269.60 Clampbands S/C I/F 6.60 Dry Mass + 20% margin 323.52 S/C adaptor 16.61 Propellant Hydrazine 9.00

Mechanisms 35.20 Propellant Xenon 73.00 Clamp Band spin table 14.30 Wet Mass 405.52 Spring set spin table 3.30 Clamp Band prop module 14.30 Spring set prop module 3.30 Propulsion 137.55 SRM Star 48 137.55 Dry Mass Propulsion 195.96 Stage Propellant STAR 48 1222.00

5/29/2012 13 A Simpler Mission than Don Quijote

DQ AIM/DART Comment 2 s/c launched 2 s/c developed and AIM and DART C/D phase separately launched separately independence Impactor launched AIM launched to rdv AIM and DART still fully after Orbiter rdv (in principle) before meaningful in absence of the DART hits other spacecraft NEA CoG Δa ≥ 100 m Binary ΔP/P>0.1, no Measure in-space (CAM) and requirement on Δa ground (photometry),

Orbiter and RSE Co-flying, orbiting or Simple telecom subsystem required RSE not strictly and operations possible required

In-situ experiment In-situ as an option, Secondary p/l depends of only at end of mission likely after impact mass, operations cost, PI contribution

Autonomous optical Autonomous optical Technology experiment for navigation Autonav as an option rendezvous spacecraft 2 days before impact only. Not mandatory

5/29/2012 14 Impact Test and Characterisation

P# Parameter Relevance to goal AIDA measurement

1 Orbital state Key to determine momentum Ground (photometry, radar), in-space (CAM/ LIDAR)

2 Rotation state Key to determine momentum Ground (photometry, radar), in-space (CAM)

3 Size, Mass, Mass key to momentum, size to shape, Mass from binary orbit, shape model from CAM Gravity volume, gravity to internal structure, (+LIDAR), gravity field RSE (option) operations 4 Geology, surface Bulk composition, material mechanical • AIM+DART images properties properties, surface thermal inertia • VIS photometry to derive spectral type, IR spectrometer mineralogy • TIR for Yarkovski / YORP, • surface payload (option) 5 Density, internal Affects absorption of impact energy, Bulk value derived from mass, shape model structure “data point” for study of asteroid mitigation. 6 Sub-surface Bulk composition, if significant changes Crater interior (CAM, IR) properties w.r.t surface, post-impact change to thermal inertia

5/29/2012 15 AIDA Firsts

Themes Comments First demonstration of Both capabilities, to deflect and to measure the capability to deflect an deflection, are required to assure that mitigation asteroid and measure the reduces (and does not increase) an impact hazard trajectory change Binary systems are an important component of Solar First rendezvous with a binary System small body populations and planetary and asteroid stellar systems First visit to an X-type NEO Spectral type X is of unknown composition Most , and NEAs in close binaries, are believed to be rubble piles, but we don’t know how First characterization of they would respond to large scale impacts (needed hypervelocity impacts on an information to understand asteroid collisional asteroid evolution and size distributions, as well as asteroid deflection for hazard mitigation) First active probes of internal Although Didymos is not necessarily a human structure and measurements exploration target, these measurements expand our of surface geotechnical knowledge base of asteroid surfaces and help prepare properties for human exploration

5/29/2012 16 Summary

 ESA, OCA, DLR studied AIM, a simple binary asteroid rendezvous inspired on “Don Quijote”  Ongoing work on JHU/APL’s DART to complement AIM for a joint mission to Didymos, eclipsing binary  AIM+ DART = AIDA (Asteroid Impact Deflection Assessment), an affordable, risk free cooperation  AIDA is a good opportunity to study hypervelocity impacts, ejecta and crater formation and to deepen our knowledge on how impact affects dynamics of objects in space  Call for payload ideas coming soon

5/29/2012 17 AIDA mission rationale report

. Naomi Murdoch (OCA, Coor.) . Andrés Gálvez (ESA) . Paul Abell (NASA) . Detlef Koschny (ESA) . Ian Carnelli (ESA) . Michael Kueppers (ESA) . Benoit Carry (ESA) . Patrick Michel (OCA) . Andy Cheng (JHU/APL) . Cheryl Reed (JHU/APL) . Gerhard Drolshagen (ESA) . Stephan Ulamec (DLR) . Moritz Fontaine (ESA) . ...

http://www.esa.int/neo Contributions on tests or payload ideas compatible with the mission are very welcome