DOCSLIB.ORG

Asteroids Sun’S Planets

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Asteroids Sun’s Planets • Earth • Historical planets: (ρλανετ, or wanderer) – Mercury – Venus – Mars – Jupiter – Saturn • Later discoveries – Uranus (1781) – Neptune (1846) Titius-Bode Law A mathematical relation published by J.E. Bode in 1772 a = (2n x 3 + 4) / 10 • a is the semimajor axis of the orbit in au • n is an index: – Mercury: -1 (define 2-1 = 0) – Venus: 0 – Earth: 1 – Mars: 2 – Jupiter: 4 – Saturn: 5 a matches observation to within a few %. The Titius-Bode law is empirical: there is no physical reason why it should hold, but it has proven of some use as a predictor. Titius-Bode Law. II a = (2n x 3 + 4) / 10 “Missing” values of n: • 3: corresponds to the distance of Ceres, discovered in 1801 by Piazzi. • 6: corresponds to Uranus • 7: a=40 au. Neptune is at 30 au Why does the Titius-Bode Law appear to work? Simulations show planets cannot be too close together. Simulated stable planetary separations can often be approximated as a geometric series Asteroids means star-like • 1 Ceres discovered 1801 • 10 known by 1850 – Brightest: Ceres, Pallas, Juno, Vesta • Today: – Over 1 million known – Over 600,000 with orbits Asteroid ProperFes • Largest: Ceres, radius= 473 km (1/3 lunar) • Over 1 million with radius >1 km • Total mass < lunar mass • Most are aspherical – Too liRle mass to overcome the strength of the rock • 3 types from spectra: – C: resemble carbonaceous chondrite meteorites – S: resemble stony meteorites – M: resemble metallic meteorites Minor Planets 1 Ceres 4 Vesta R = 457 km 573 x 557 x 446 km Minor Planets 21 Lutetia (M) 951 Gaspra (S) 121 x 101 x 75 km 19 x 12 x 11 km Minor Planets 253 Mathilde (C) 66 x 48 x 46 km Minor Planets 25143 Itokawa (S) 535 x 294 x 209 m Minor Planet 443 Eros 40 x 14 x 14 km NEAR flyby 12/23/98 Bennu Minor Planets up close: the Dawn Mission • Launched 9/27/2007 – Encountered 4 Vesta 2012 – Arrived at 1 Ceres March 2015 • Uses ion drive for conFnuous acceleraon 4 Vesta 4 Vesta 4 Vesta 4 Vesta South Pole 4 Vesta Surface: Snowman Craters 4 Vesta Interior History of Vesta 4 Vesta • Brightest asteroid. – Distance = 2.4au • Second most massive asteroid (aer Ceres) – 9% of mass of asteroid belt • Second largest asteroid (aer Ceres) – Oblate spheroid (<r>=260 km) • Rocky: ρ = 3.4 g/cm3 • DifferenFated with metallic core – Surface composiFon matches 1200 “Vestan achondrite” meteorites – Evidence for chondric material, hydrated minerals • Last remaining rocky protoplanet? 1 Ceres 1 Ceres • First asteroid discovered – Distance = 2.8 au • Most massive asteroid – 30% of mass of asteroid belt • Largest asteroid – <r>=473 km • Icy: ρ = 2.6 g/cm3 • DifferenFated: rocky core with icy mantle – Evidence for chondric material, hydrated minerals – Outgassing H2O • Probably formed outside frost line 1 Ceres Rotang Ceres viewed by Dawn Bright Spots – Ice? Occator Crater (91 km diameter) Kerwan Crater 280 km diameter Ceres: 6 km mountain Ahuna Mons 5000 meter high cryo-volcano AnFpodal from 280km Kerwan crater Landslides on Ceres Type I: similar to rock glaciers Type II: resembles avalanches. Type III: related to craters. and icy landslides on Earth Most common type on Ceres Impact melFng? Dawn Mission • Nominal mission end July 2015 • Actual mission end Nov 1 2018 – Hydrazine fuel for poinFng ran out • Legacy: – Explored 2 very different worlds, Ceres and Vesta – Demonstrated ion engine technology Water in Asteroid Spectra 2/12/01: NEAR Lands on Eros Surface of Eros Asteroid ProperFes • Composion – M: metals. ρ ~ 3-5 g/cm3 – S: rocks. ρ ~ 2-3 g/cm3 – C: rocks/carbonaceous materials. ρ ~ 1-2 g/cm3 – General trend with distance from Sun • Structure: differenFated • Families: – Outer edge of belt: evidence for water & ices Binary Asteroids é 243 Ida 45 Eugenia çDactyl 90 AnFope Period 16.5 hours; diameters about 80 km Historical Evidence Lac à l'Eau Claire, Quebec 26, 36 km diameters Asteroid Orbits Asteroid Orbits Green: Main belt Red: Earth Crossers Blue: Trojans Near-Earth Asteroids Asteroid Orbits Resonances in the Asteroid Belt What is Wrong with this Picture? Do asteroids collide? • Assume there are: – 1 million asteroids, with – orbits between 2.2 and 3.3 AU, – the belt is 1 million km thick (h/r = 0.2%). • The volume of the asteroid belt is 2 2 23 3 – V ~ π(R out – R in)h = 4.3 x 10 km • The volume per asteroid is – v = V/N = 4.4 x 1017 km3 • So the distance between the asteroids is – D ~ v⅓ = 750,000 km They are so far apart, there is not much to dodge! Do asteroids collide? Somemes 4 HST images over 5 months appear to show collision. Dust tail emanates from object 400 km across. Dust volume ~ 10m radius hp://solarsystem.nasa.gov/mulFmedia/ display.cfm?IM_ID=11223 Asteroid Families • Based on – Spectral similariFes – Orbital similariFes • Most asteroids can be classified as a member of a small number of families • Most probably are fragments of larger asteroids • A 100 km radius asteroid can produce 106 1 km fragments Meteors, Meteorites, and Meteoroids • Meteor: the streak of light seen in the sky • Meteorite: the rock found on the ground • Meteoroid: the rock before it hits Earth Meteorites are easily-studied remnants of the formaon of the solar system Meteors “It is easier to believe that Yankee professors would lie than that stones would fall from heaven.” -- aributed to Thomas Jefferson From below … Meteors … and above Meteors • Most are the size of a grain of sand • They vaporize about 75-100 km up when they hit the atmosphere • Impact velociFes >20 km/s • The trails are ionized gas • Best viewed aer midnight Meteor Showers Occur when Earth passes through the orbit of a comet. Examples: • Orionids: comet 1P/Halley Oct 21-22 • Leonids: comet 109P/Tempel-Tule Nov 17-18 • Geminids: asteroid 3200 Phaeton Dec 13-14 • Perseids: comet 55P/Swi]-TuRle Aug 12-13 • Lyrids: comet Thatcher Apr 22-23 Orbits of Meteor Showers Fireballs and Bolides • Very bright meteors • May leave a persistent trail • Due to impacFng object bigger than about 1m Geminid Fireball 12/9/2010. source: S. Korotkiy, Russian Academy of Sciences Grand Tetons Meteor 8/10/72. 3-14m Apollo asteroid. V=15 km/s; 15km alFtude Peekskill Meteorite 10/9/92 12 kg Stony-Iron Classificaon PrimiFve meteorites (chondrites) Unchanged since solar system formaon • Stony: rocky minerals + small fracFon of metal flakes • Carbonaceous (Carbon-rich): like stony, with large amounts of carbon compounds PrimiFve meteorites (chondrites) Majority of meteors • Accreted from solar nebula – Chondrules: droplets formed during accreFon • Stony/Carbon-rich – > 3 AU, carbon compounds condense – Carbon-rich formed at outer edge • More stony hit Earth than carbon-rich Processed meteorites (achondrites) Fragment of larger, differenFated object • Metal rich: mostly iron/nickel • Stony-Iron: composiFon resembles terrestrial planet crust/mantle; some with basalts Processed meteorites (achondrites) Fragment of large asteroid that differenFated • Rocky – Made from lava flows – Surface material • Metal-rich – Proof of differenFaon EsFmate: ~10 geologically acFve asteroids iniFally • Last remaining: the asteroid Vesta Biases • Irons most likely to survive impact • Stony most likely to be overlooked C type Marília Meteorite: chondrite H4. Marília, Brazil, 10/5/1971 M type WillameRe - AMNH Pallasite Chelyabinsk 2/15/2013 Chelyabinsk • Incoming speed ~ 19 km/s • Shallow entry angle • Mass ~ 10,000 tons • Radius ~ 20 m • Stony (S) type meteorite – LL Chondrite (low Fe and total metal abundance) • Orbit derived from observaons • Originated in the Apollo group of asteroids Chelyabinsk KineCc Energy • 200-990 kT of TNT – kT = 4x1012 Joules = 4x1019 ergs – Hiroshima atom bomb: 15 kT • EsFmate from – a.) airburst shock waves (38-23 km alFtude) – b.) radiated energy • Damage as far as 120 km from impact • Largest fragment: 1.5m diameter Chelyabinsk Fragment 112 gm; cube is 1 cm Origin of Chelyabinsk Meteorite Dates to 4.6 Gya • Parent body affected by impacts at 30 Myr and 100 Myr • Argon isotopes suggest impact 29 Mya • Surface exposed to solar radiaon 1.2 Mya Dates from radioisotopic analysis Meteors and Asteroids • Most meteors originate in the asteroid belt • Meteors and asteroids – Have similar spectra – Have similar orbits – Differ primarily in size Orbits of Meteors Tunguska Event • June 30 1908 • 2150 km2 of forest flaened • No crater • Probably air burst at 5-10 km • EsFmated diameter 60-190 km • Equivalent of 3-5 MT explosion • Pressure wave equivalent of mag 5 earthquake • Comet or stony asteroid? Tunguska aermath Tunguska Event • Expect one about every 300 years • Since 2/3 of Earth is ocean, expect one on land every millenium. Yesterday’s Fireballs Nov 12 2018 UT 19 fireballs : 17 sporadics, Northern Taurids Yellow: 30 km/s Green: 45 km/s Blue: 60 km/s Source: spaceweather.com/ Near Earth Asteroids Near Earth Asteroids • PotenFally Hazardous Asteroids – Earth Minimum Orbit IntersecFon Distance (MOID) of 0.05 AU or less – diameter larger than 150 m • 1936 known • Not all will hit Earth Halloween Asteroid 2015 TB 145 Passed at 0.003AU on 10/31/15 Near Earth Asteroids Near Earth Asteroids Near Earth Asteroids Near Earth Asteroids NEAs this month Asteroid Date(UT) Miss Distance km/s D(m) • 2018 VY4 2018-Nov-11 5.5 LD 12.6 14 • 2018 VH5 2018-Nov-11 6 LD 6 13 • 2018 VA4 2018-Nov-11 3.1 LD 7.4 8 • 2018 VZ6 2018-Nov-12 9.5 LD 10.3 27 • 2018 VN6 2018-Nov-12 1.9 LD 14.2 8 • 2018 VC7 2018-Nov-13 0.9 LD 4.5 12 • 2018 VR6 2018-Nov-13 8 LD 9.5 12 • 2018 VF5 2018-Nov-13 9.7 LD 6.8 11 • 2018 UQ1 2018-Nov-13 9.4 LD 12.3 146 • 2018 VO3 2018-Nov-14 4.1 LD 7.7 14 • 2018 VX5 2018-Nov-14 3.6 LD 8.3
Recommended publications
  • The Cratering History of Asteroid (21) Lutetia

    The Cratering History of Asteroid (21) Lutetia

    Planetary and Space Science 66 (2012) 87–95 Contents lists available at SciVerse ScienceDirect Planetary and Space Science journal homepage: www.elsevier.com/locate/pss The cratering history of asteroid (21) Lutetia S. Marchi a,n, M. Massironi b, J.-B. Vincent c, A. Morbidelli a, S. Mottola d, F. Marzari e,M.Kuppers¨ f, S. Besse g, N. Thomas h, C. Barbieri i, G. Naletto j, H. Sierks c a Departement Cassiope´e, Universite de Nice – Sophia Antipolis, Observatoire de la Coteˆ d’Azur, CNRS, Nice, France b Department of Geosciences, Padova University, Italy c Max Planck Institute for Solar System Research, Lindau, Germany d Institut fur¨ Planetenforschung, DLR-Berlin, Germany e Department of Physics, Padova University, Italy f ESA-ESAC, Villanueva de la Can˜ada, Madrid, Spain g Laboratoire d’Astrophysique de Marseille, France h Physikalisches Institut, University of Bern, Switzerland i Department of Astronomy, Padova University, Italy j Department of Information Engineering, Padova University, Italy article info abstract Article history: The European Space Agency’s Rosetta spacecraft passed by the main belt asteroid (21) Lutetia on 10th Received 1 July 2011 July 2010. With its 100 km size, Lutetia is one of the largest asteroids ever imaged by a spacecraft. Received in revised form During the flyby, the on-board OSIRIS imaging system acquired spectacular images of Lutetia’s northern 23 October 2011 hemisphere revealing a complex surface scarred by numerous impact craters, reaching the maximum Accepted 26 October 2011 dimension of about 55 km. Available online 7 November 2011 In this paper, we assess the cratering history of the asteroid.
  • Asteroids 2867 Steins and 21 Lutetia: Surface Composition from Far Infrared Observations with the Spitzer Space Telescope

    Asteroids 2867 Steins and 21 Lutetia: Surface Composition from Far Infrared Observations with the Spitzer Space Telescope

    A&A 477, 665–670 (2008) Astronomy DOI: 10.1051/0004-6361:20078085 & c ESO 2007 Astrophysics Asteroids 2867 Steins and 21 Lutetia: surface composition from far infrared observations with the Spitzer space telescope M. A. Barucci1, S. Fornasier1,2,E.Dotto3,P.L.Lamy4, L. Jorda4, O. Groussin4,J.R.Brucato5, J. Carvano6, A. Alvarez-Candal1, D. Cruikshank7, and M. Fulchignoni1,2 1 LESIA, Observatoire de Paris, 92195 Meudon Principal Cedex, France e-mail: [email protected] 2 Université Paris Diderot, Paris VII, France 3 INAF, Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Roma, Italy 4 Laboratoire d’Astrophysique de Marseille, BP 8, 13376 Marseille Cedex 12, France 5 INAF, Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy 6 Observatorio National (COAA), rua Gal. José Cristino 77, CEP20921–400 Rio de Janeiro, Brazil 7 NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA Received 14 June 2007 / Accepted 3 October 2007 ABSTRACT Aims. The aim of this paper is to investigate the surface composition of the two asteroids 21 Lutetia and 2867 Steins, targets of the Rosetta space mission. Methods. We observed the two asteroids through their full rotational periods with the Infrared Spectrograph of the Spitzer Space Telescope to investigate the surface properties. The analysis of their thermal emission spectra was carried out to detect emissivity features that diagnose the surface composition. Results. For both asteroids, the Christiansen peak, the Reststrahlen, and the Transparency features were detected. The thermal emissiv- ity shows a clear analogy to carbonaceous chondrite meteorites, in particular to the CO–CV types for 21 Lutetia, while for 2867 Steins, already suggested as belonging to the E-type asteroids, the similarity to the enstatite achondrite meteorite is confirmed.
  • (21) Lutetia: Shape and Flyby Geometry Benoit Carry, Mikko Kaasalainen, Cedric Leyrat, William J

    (21) Lutetia: Shape and Flyby Geometry Benoit Carry, Mikko Kaasalainen, Cedric Leyrat, William J

    Physical properties of ESA Rosetta target asteroid (21) Lutetia: Shape and flyby geometry Benoit Carry, Mikko Kaasalainen, Cedric Leyrat, William J. Merline, Jack D. Drummond, Al Conrad, Hal A. Weaver, Peter M. Tamblyn, Clark R. Chapman, Christophe Dumas, et al. To cite this version: Benoit Carry, Mikko Kaasalainen, Cedric Leyrat, William J. Merline, Jack D. Drummond, et al.. Physical properties of ESA Rosetta target asteroid (21) Lutetia: Shape and flyby geometry. Astronomy and Astrophysics - A&A, EDP Sciences, 2010, 523 (A94), 19 p. 10.1051/0004-6361/201015074. hal- 00618654 HAL Id: hal-00618654 https://hal.archives-ouvertes.fr/hal-00618654 Submitted on 14 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. A&A 523, A94 (2010) Astronomy DOI: 10.1051/0004-6361/201015074 & c ESO 2010 Astrophysics Physical properties of the ESA Rosetta target asteroid (21) Lutetia II. Shape and flyby geometry, B. Carry1,2, M. Kaasalainen3,C.Leyrat1, W. J. Merline4,J.D.Drummond5,A.Conrad6,H.A.Weaver7, P. M. Tamblyn 4,C.R.Chapman4,C.Dumas8,F.Colas9, J. C. Christou10, E. Dotto11,D.Perna1,11,12, S. Fornasier1,2, L.
  • The Rosetta Fly-By at (21) Lutetia – Ten Weeks After Closest Approach

    The Rosetta Fly-By at (21) Lutetia – Ten Weeks After Closest Approach

    EPSC Abstracts Vol. 5, EPSC2010-18, 2010 European Planetary Science Congress 2010 c Author(s) 2010 The Rosetta fly-by at (21) Lutetia – ten weeks after closest approach R. Schulz (1), A. Accomazzo (2), M. Küppers (3), G. Schwehm (3), K. Wirth (3) (1) Research and Scientific Support Department, ESA/ESTEC, Noordwijk, The Netherlands (2) European Space Operations Centre, ESA/ESOC, Darmstadt, Germany (3) Science Operations Department, ESA/ESAC, Madrid, Spain ([email protected] / Fax: +31 565 4697) Abstract characteristics of carbonaceous chondrites, but also to metallic surface features. This contradiction makes The International Rosetta Mission is one of ESA’s it a very interesting object for close inspection. Cornerstone Missions on its way to rendezvous with Jupiter-family comet 67P/Churyumov-Gerasimenko Table 1: Orbital parameters of (21) Lutetia in 2014, to accompany the comet into the inner solar Perihelion distance 2.036 AU system, and land on the comet nucleus. On cruise to Aphelion distance 2.834 AU the main target the spacecraft had been scheduled for Semi-major axis 2.435 AU close fly-bys at two main-belt asteroids. After the Eccentricity 0.164 successful fly-by at E-type asteroid (2867) Steins in Inclination 3.0648 September 2008, Rosetta had its second close Orbital period 3.80 yrs encounter with an asteroid, (21) Lutetia, on 10 July 2010. A first summary of the fly-by is presented. 3. (21) Lutetia Fly-by Payload Operations 1. Overview of Asteroid Fly-by Geometry Most of the scientific instruments on board Rosetta were switched on obtaining imaging and spectral Rosetta had a close fly-by at asteroid (21) Lutetia on observations covering wavelengths from the UV to 10 July 2010, with closest approach at 15:44:53 UTC sub-mm, as well as in-situ measurements of the at a targeted minimum distance of 3160 km.
  • A Visit to Gaspra

    A Visit to Gaspra

    A Visit to Gaspra This is a ground-based photo of the first minor planet ever to be visited by a spacecraft. On October 29, 1991, the NASA spacecraft Galileo flew past minor planet No. 951 Gaspra on its way to Jupiter where it will arrive in De- cember 1995. The distance to Gaspra from the Earth was 410 million km at the time of the fly-by. Although Galilw's high-galn antenna has not yet been un- folded and could therefore not be used, JPL engineers succeeded In getting a 300-line Image via the low-gain antenna; the others will be sent when Gallleo is again near the Earth. The first image showed the irregular form of Gaspra and Several craters on its surface with a res- otution of ht130 metres. The diarne- ter was measured as 16 kilornetms. Gaspra was discovered on July 30, 191 6 at the Simeis Observatq in the mountains of Cximea, the Russia. The sofi on the southern coast of Crimea, in On this date, Its distance from the Earth discoverer was the welt-known Russian which the famous Russian writer Lev was 262 million km and the magnitude astronomer Grigorij Nikolaevich Neuj- Nikolaevfch Tolstoy (1828- 1910) spent was about 15. min (born 1886 in Tbilisi, Georgia; died many years of his life." The village of The background of the photo is a I946 in Leningrad), who later became Gaspra is located about 10 krn south- region in the southern constellation Director of that observatory (1925- 1931 west of Yalta. Ophlochus (the Serpent-holder) which is and 1936-1941) and Director of the The present photo was obtained with characterld by relatively few stars, but Pulkovo Obsewatoty near St.
  • Asteroid Touring Nanosatellite Fleet

    Asteroid Touring Nanosatellite Fleet

    Asteroid Touring Nanosatellite Fleet S Mihkel Pajusalu Postdoctoral fellow Massachusetts Institute of Technology (and Tartu Observatory) [email protected] + Pekka Janhunen, Andris Slavinskis, and the MAT collaboration Bio • 2010 MSc in Physics, University of Tartu, Estonia • 2010-2015 ESTCube-1 team, leader of Electrical Power Subsystem • 2014 PhD in Physics University of Tartu, Estonia • 2015 - 2019 Postdoc at MIT, Seager Group (astrobiology and instrumentation development for the MAT mission) Only 12 asteroids have been visited this far 1 Ceres Image Credit: NASA / 4 253 Mathilde 433 Eros JPL-Caltech / UCLA / Vesta NEAR /NASA NEAR Shoemaker MPS / DLR / IDA / Justin NASA/JPL/JHUAPL Cowart 951 Gaspra 243 Ida and 2867 Šteins 21 Lutetia Dactyl Galileo/NASA Rosetta ESA MPS ESA 2010 MPS for Galileo/NASA / JPL/USGS for OSIRIS Team OSIRIS Team MPS/UPD/LAM/IAA MPS/UPD/LAM/IAA/RSS D/INTA/UPM/DASP/IDA 9969 Braille 5535 Annefrank Deep Space 25143 Itokawa 4179 Toutatis Stardust/JPL/NASA 1/NASA/JPL/USGS Hayabusa/JAXA Chang’e/CNSA Multiple Asteroid Touring (MAT) mission See Slavinskis et al, “Nanospacecraft Fleet for Multi-asteroid Touring with Electric Solar Wind Sails”, IEEE Aerospace conference, 2018 Mission details • The reference mission contains 50 identical CubeSats • Estimated total cost <100 million USD • Each to visit 6 targets on average • 100 km – 1000 km flybys • Total of 300 visits during 3.2 years • Even if 50% are successful, number of visited asteroids would increase by a factor of 10 • First published concept from Finnish Meteorological
  • Phase Integral of Asteroids Vasilij G

    Phase Integral of Asteroids Vasilij G

    A&A 626, A87 (2019) Astronomy https://doi.org/10.1051/0004-6361/201935588 & © ESO 2019 Astrophysics Phase integral of asteroids Vasilij G. Shevchenko1,2, Irina N. Belskaya2, Olga I. Mikhalchenko1,2, Karri Muinonen3,4, Antti Penttilä3, Maria Gritsevich3,5, Yuriy G. Shkuratov2, Ivan G. Slyusarev1,2, and Gorden Videen6 1 Department of Astronomy and Space Informatics, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine e-mail: [email protected] 2 Institute of Astronomy, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine 3 Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2, 00560 Helsinki, Finland 4 Finnish Geospatial Research Institute FGI, Geodeetinrinne 2, 02430 Masala, Finland 5 Institute of Physics and Technology, Ural Federal University, Mira str. 19, 620002 Ekaterinburg, Russia 6 Space Science Institute, 4750 Walnut St. Suite 205, Boulder CO 80301, USA Received 31 March 2019 / Accepted 20 May 2019 ABSTRACT The values of the phase integral q were determined for asteroids using a numerical integration of the brightness phase functions over a wide phase-angle range and the relations between q and the G parameter of the HG function and q and the G1, G2 parameters of the HG1G2 function. The phase-integral values for asteroids of different geometric albedo range from 0.34 to 0.54 with an average value of 0.44. These values can be used for the determination of the Bond albedo of asteroids. Estimates for the phase-integral values using the G1 and G2 parameters are in very good agreement with the available observational data.
  • Iso and Asteroids

    Iso and Asteroids

    r bulletin 108 Figure 1. Asteroid Ida and its moon Dactyl in enhanced colour. This colour picture is made from images taken by the Galileo spacecraft just before its closest approach to asteroid 243 Ida on 28 August 1993. The moon Dactyl is visible to the right of the asteroid. The colour is ‘enhanced’ in the sense that the CCD camera is sensitive to near-infrared wavelengths of light beyond human vision; a ‘natural’ colour picture of this asteroid would appear mostly grey. Shadings in the image indicate changes in illumination angle on the many steep slopes of this irregular body, as well as subtle colour variations due to differences in the physical state and composition of the soil (regolith). There are brighter areas, appearing bluish in the picture, around craters on the upper left end of Ida, around the small bright crater near the centre of the asteroid, and near the upper right-hand edge (the limb). This is a combination of more reflected blue light and greater absorption of near-infrared light, suggesting a difference Figure 2. This image mosaic of asteroid 253 Mathilde is in the abundance or constructed from four images acquired by the NEAR spacecraft composition of iron-bearing on 27 June 1997. The part of the asteroid shown is about 59 km minerals in these areas. Ida’s by 47 km. Details as small as 380 m can be discerned. The moon also has a deeper near- surface exhibits many large craters, including the deeply infrared absorption and a shadowed one at the centre, which is estimated to be more than different colour in the violet than any 10 km deep.
  • (2000) Forging Asteroid-Meteorite Relationships Through Reflectance

    (2000) Forging Asteroid-Meteorite Relationships Through Reflectance

    Forging Asteroid-Meteorite Relationships through Reflectance Spectroscopy by Thomas H. Burbine Jr. B.S. Physics Rensselaer Polytechnic Institute, 1988 M.S. Geology and Planetary Science University of Pittsburgh, 1991 SUBMITTED TO THE DEPARTMENT OF EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN PLANETARY SCIENCES AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY FEBRUARY 2000 © 2000 Massachusetts Institute of Technology. All rights reserved. Signature of Author: Department of Earth, Atmospheric, and Planetary Sciences December 30, 1999 Certified by: Richard P. Binzel Professor of Earth, Atmospheric, and Planetary Sciences Thesis Supervisor Accepted by: Ronald G. Prinn MASSACHUSES INSTMUTE Professor of Earth, Atmospheric, and Planetary Sciences Department Head JA N 0 1 2000 ARCHIVES LIBRARIES I 3 Forging Asteroid-Meteorite Relationships through Reflectance Spectroscopy by Thomas H. Burbine Jr. Submitted to the Department of Earth, Atmospheric, and Planetary Sciences on December 30, 1999 in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Planetary Sciences ABSTRACT Near-infrared spectra (-0.90 to ~1.65 microns) were obtained for 196 main-belt and near-Earth asteroids to determine plausible meteorite parent bodies. These spectra, when coupled with previously obtained visible data, allow for a better determination of asteroid mineralogies. Over half of the observed objects have estimated diameters less than 20 k-m. Many important results were obtained concerning the compositional structure of the asteroid belt. A number of small objects near asteroid 4 Vesta were found to have near-infrared spectra similar to the eucrite and howardite meteorites, which are believed to be derived from Vesta.
  • Impact-Produced Seismic Shaking and Regolith Growth on Asteroids 433 Eros, 2867 Šteins, and 25143 Itokawa James E

    Impact-Produced Seismic Shaking and Regolith Growth on Asteroids 433 Eros, 2867 Šteins, and 25143 Itokawa James E

    Icarus 347 (2020) 113811 Contents lists available at ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Impact-produced seismic shaking and regolith growth on asteroids 433 Eros, 2867 Šteins, and 25143 Itokawa James E. Richardson a,<, Jordan K. Steckloff b, David A. Minton c a Planetary Science Institute, 536 River Avenue, South Bend, IN, 46601, USA b Planetary Science Institute, 2234 E. North Territorial Road, Whitmore Lake, MI, 48189, USA c Purdue University, Department of Earth, Atmospheric, and Planetary Sciences, 550 Stadium Mall Drive, West Lafayette, IN, 47907, USA ARTICLEINFO ABSTRACT Keywords: Of the several near-Earth and Main Belt asteroids visited by spacecraft to date, three display a paucity of Asteroids small craters and an enhanced number of smoothed and degraded craters: 433 Eros, which has a deficit of Surfaces craters ¿ 100 m in diameter; 2867 Šteins, which has a deficit of craters ¿ 500 m in diameter; and 25143 Asteroid eros Itokawa, which has a deficit of craters ¿ 100 m in diameter. The purpose of this work was to investigate Asteroid Itokawa and model topographic modification and crater erasure due to impact-induced seismic shaking, as well as Impact processes Regoliths impact-driven regolith production and loss, on these asteroid surfaces. To perform this study, we utilized the numerical, three-dimensional, Cratered Terrain Evolution Model (CTEM) initially presented in J. E. Richardson, Icarus 204 (2009), which received a small-body (SB) specific update for this work. SBCTEM simulations of the surface of 433 Eros correctly reproduce its observed cratering record (for craters up to ∼ 3 km in diameter) at a minimum Main Belt exposure age of 225 , 75 Myr using a `very weak rock' target strength of 0.5–5.0 MPa, and producing a mean regolith depth of 80 , 20 m, which agrees with published estimates of an actual regolith layer ``tens of meters'' in depth.
  • Observations of 21 Lutetia in the 2–4 Μm Region with the NASA IRTF

    Observations of 21 Lutetia in the 2–4 Μm Region with the NASA IRTF

    42nd Lunar and Planetary Science Conference (2011) 1439.pdf OBSERVATIONS OF 21 LUTETIA IN THE 2-4 µM REGION WITH THE NASA IRTF . A. S. Rivkin1, B. E. Clark2, M. E. Ockert-Bell2, M. K. Shepard3, E. L. Volquardsen4, E. S. Howell5, and S. J. Bus4, 1JHU/APL, Laurel MD ([email protected]), 2Ithaca College, Ithaca NY, 3Bloomberg College, Bloomberg PA, 4Institute for As- tronomy, Hilo HI, 5Arecibo Observatory/NAIC, Arecibo PR. Background: It has been difficult to reach a con- Lutetia was warm enough to exhibit measurable sensus on the composition of the asteroid 21 Lutetia. It thermal flux in the longer-wavelength portions of our was one of the original members of the M asteroid spectra. This thermal flux was removed using a ver- class, and thought likely to be either akin to iron mete- sion of the standard thermal model (STM), modified so orites or enstatite chondrites [1]. However, decades of as to allow the “beaming parameter” (η) to vary. We more in-depth observations have interpretations that found the best values for η to be 0.75-0.82 for the are difficult to reconcile with those analogs (particu- SpeX data, near the low end of the observed range for larly iron meteorites). asteroids but not unprecedentedly so. Recorrecting the For instance, Lutetia’s radar albedo is similar to NSFCam data indicates higher values of η for those that of the C and S asteroids rather than what is ex- spectra, in the range of 0.9-1.0, will result in good pected of a metal-rich surface [2].
  • Magnetic Field Measurements During the ROSETTA Flyby at Asteroid

    Magnetic Field Measurements During the ROSETTA Flyby at Asteroid

    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Institute of Transport Research:Publications Planetary and Space Science ] (]]]]) ]]]–]]] Contents lists available at SciVerse ScienceDirect Planetary and Space Science journal homepage: www.elsevier.com/locate/pss Magnetic field measurements during the ROSETTA flyby at asteroid (21)Lutetia I. Richter a,n, H.U. Auster a, K.H. Glassmeier a,b, C. Koenders a,b, C.M. Carr c, U. Motschmann d,e, J. Muller¨ d, S. McKenna-Lawlor f a Institut fur¨ Geophysik und extraterrestrische Physik, Technische Universitat¨ Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany b Max Planck Institute for Solar System Research, Lindau, Germany c Imperial College London, London, UK d Institut fur¨ theoretische Physik, Technische Universitat¨ Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany e DLR-Institut fur¨ Planetenforschung, Rutherfordstr. 2, 12489 Berlin, Germany f Space Technology Ireland, National University of Ireland Maynooth, Co. Kildare, Ireland article info abstract Article history: On July 10, 2010, the ROSETTA spacecraft performed a flyby at asteroid (21)Lutetia at a solar distance of Received 13 May 2011 2.72 AU. The spacecraft–asteroid distance at closest approach was 3120 km. The magnetometers Received in revised form onboard ROSETTA were operating but did not detect any conclusive signature of the asteroid. 18 August 2011 Any magnetic field signature which could possibly be attributed to the asteroid was below 1 nT. Accepted 19 August 2011 Consequently an upper limit for the global magnetic properties of asteroid (21)Lutetia could be derived: À maximum dipole moment r1:0 Â 1012 Am2, global maximum magnetization r2:1 Â 10 3 A=m, À Keywords: specific moment r5:9 Â 10 7 Am2=kg.