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DEEP IMPACT and ROSETTA – Cometary Science Today and in 7 Years from Now Hermann Boehnhardt Max-Planck Institute for Solar System Research Max-Planck Institute for Solar System Research (until 2005 MPI for Aeronomy) • Solar Physics • Planetary Sciences • Spacecraft & balloon instrumentation • Earth-based observations Content of the Talk • Why Cometary Research? • DEEP IMPACT: Comet Crash 2005 • ROSETTA: Comet Exploration 2014/15 Comets & Solar System Formation • Comets are dirty iceballs or icy dirtballs (gas/dust ratio varies) evolution result?! • Ices of supervolatiles (CO, CO2, CH4) comets were deeply frozen over their whole lifetime formation region = outer planetary disk (Jupiter and beyond) supervolatiles (& ortho-para ratio of H2O and others) are T tracers of evolution history of comets back to formation era • Small in size (m – km) Irregular shape (potato) primordial planetesimals (how primordial are they?) Komet Borrelly von DEEPSPACE 1 IR spectrum Mumma Weidenschilling C/1999 S4 (Mumma etal. 2000) Comets of 1-50km size have “typical” planetesimal masses Weidenschilling 2000 Run-away growth of planet embryos produces planets at random distances Cometary Orbits & Comet Reservoirs • Members of the solar system in very eccentric orbits - Oort Cloud comet - long-periodic comet - short-periodic comet no interstellar comet • Comet reservoirs - Oort Cloud - Kuiper Belt (+Centaurs) with “graveyards” for - Jupiter family comets - dormant comets - main belt comets ? Oort Cloud Dormant comets Tisserand constant of orbit as invariance parameter aj/a + 2 (a/aj (1-e-2))1/2 cos i = C Kuiper Belt The Main Belt Comet Asteroids Making the Oort Cloud from the Planetary Disk Comets & Earth Ocean Water • Earth after formation: hot, hence no water on Earth • Clean-up of formation disk produced bombardment (most likely in 2 phases) import of water on terrestrial surface Problem: D/H ratio of ocean water differs from (barely known) D/H ratio of comets way-around: mixing of 2 or more sources with different D/H ratio, cometary source would have contributed about 30% early bombardment late bombardment (comets?) Organics in Comets • Comets contain organic compounds both in volatile ices (simple organics) and solid dust (CHON, most likely more complex organics) long-term storage facility • CI chondrite meteorites are most likely related to comets 2 CI chondrites had amino acids with preference for left-handed enantiomer contribution to life formation on Earth (if cometary material can reach Earth surface reasonably intact) GIOTTO CHON dust in Halley POM in comet Halley?? Import channels of cometary material to Earth surface • impacts (large pieces, discontinuous) • gentle “rain” (micron size, continuous) cometary material has reached and still reaches terrestrial surface SL9 impact at Jupiter in 1994 IDP from U2 in-flight collection Comets and the Formation of the Planetary System – Series of (Hypo)Theses • Comets are building blocks of planets in the outer solar system • Most primordial & widely unaltered material (deeply frozen) • Reflect the conditions in the formation environment of the planets (exo-planets) • Important for early history of the Earth (ocean water) • Bringer of life (pre-biotic material)? Comet Halley by GIOTTO Cometary Science – In Praxi • Telescopes: Ground & Orbit - remote sensing through light • Space missions - fly-bys (10x) remote sensing through light & insitu lab experiments short duration (~h) rendez-vous: much better & longer landing: “touching a comet” The Latest Coup: Deep Impact Live Impact & Cratering Experiment • NASA mission to 9P/Tempel 1 - impact: 4 July 2005, 05:52UT - impactor: 360kg – speed: 10 km/s – vis. camera – fly-by S/C: vis. cameras & IR spectrometer – impact site visibility: 14min Deep Impact: Learning by Doing • impact: shot in the blind • shape of ejecta cloud indicates low strength dominated impact regime • DI impact crater not found cratering science suffers (now to be imaged by STARDUST in 2011) • surface: many natural craters occurence frequency consistent with expected cratering rate of inactive body but impact craters should not survive cometary activity for very long (erosion rate ~ 1 m/rev) DI: The Expected & the Unexpected • low bulk density 0.6 g/cm3 Kuiper Belt objects are heavier (Pluto: 2 g/cm3) • low thermal conductivity (100 W/K/m2/s1/2) very porous material • comet: very weak (~300 Pa) (weaker than powder snow) loosely bound, signature of soft aggregation process during formation, unclear whether planetesimal or impact formation 1km DI: The Expected & the Unexpected • water ice exists on surface at < 1% surface coverage most of water production is subsurface surface must be rejuvenated quickly (no deep layering zones in cometary nuclei) • dust ejecta: micron size & partially crystalline silicates (heated > 1000K) (already known from HB) hot & cold phase are intimately mixed in nucleus (and even on grain level from STARDUST) radial mixing of crystalline and amorphous dust in formation disk to large distances • phyllosilicates are interesting! ESA’s ROSETTA Mission Goal: rendez-vous with a comet (orbiting) surface samples (landing) Start: 1993 Launch: 2 March 2004 (1 year delay) Target: 67P/CG Arrival: May 2014 67P/Churyumov-Gerasimenko ARIANE 5 & ROSETTA The ROSETTA S/C • ROSETTA Orbiter (ESA) Dimensions: Weight: 2.8 x 2.1 x 2.0 m 3000 kg 1600 kg fuel 165 kg experiments Instrumente: 11 - close sensing (~ telescopes) - in-situ experiments (~ lab) • PHILAE Lander (DLR/CNES/ASI) Dimensions: Weight: 0.7 x 0.7 x 0.9 m 100kg 15kg experiments Instruments: 10 (telescope & lab & samples) The Flight Schedule Duration: ~ 10 years 4x planet swing-bys (Earth, Mars) Cruise science: 2 x asteroids Earth/Mars fly-bys Science at comet: > 1 ½ years in orbit lander delivery 1 Launch Earth 02.03.2004 2 Swing-by 1/Earth 04.03.2005 3 Swing-by 2/Mars 25.02.2007 4 Swing-by 3/Earth 13.11.2007 5 Fly-by Steins 05.09.2008 6 Swing-by 4/Earth 13.11.2009 7 Fly-by Lutetia 10.07.2010 8 Rendez-vous comet 22.05.2014 9 Landing on comet 10.11.2014 OSIRIS - The ROSETTA Eyes © OSIRIS team (close sensing) 2 cameras (wide & narrow angle + stereo) for vis. + UV wavelength region Science: nucleus mapping geology, activity (backbone inst.) Orion nebula © DLR © NASA Resolution: 1 cm/pixel 100 x better than any existing comet image Komet Wild2 mit STARDUST Farbe 100x 1x ROSINA – COSIMA The Comet Chemistry Labs ROSETTA (in-situ) Science goal: original gas and dust chemistry cometary organics Isotope ratio in comets (ocean water from comets?) Instrument type: mass spectrometers (lab exp.) GIOTTO CONSERT- The Nucleus Tomograph (close sensing) Science goals: inner constitution of the nucleus building blocks Instrument type: radio sounder with sender/receiver onboard orbiter and repeater onboard lander Life Science: COSAC @ PHILAE (sampling & lab exp.) Science goals: chemistry of cometary soil organics in particular amino acids Instrument type:drill and sample device (SD2) mass spectrometer gas chromatograph clou: determination of chirality of material life on Earth: left handed chirality each result will have important consequences on scenarios of life formation on Earth bitings are still accepted ... more in 2014/2015