Origin of the Spacewatch Small Earth-Approaching Asteroids
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1986 DA and 1986 EB: IRON OBJECTS in NEAR-Eakm ORBITS; J.C
LPSC XVIII 349 1986 DA AND 1986 EB: IRON OBJECTS IN NEAR-EAKm ORBITS; J.C. Gra- die, Planetary Geosciences Division, Hawaii Institute of Geophysics, University of Hawaii, Bonolalu, HI 96822 and E.F. Tede sco, Jet Propulsion Laboratory, Pasadena, CA 91109. The estimated 1,500 asteroids, with diameters larger than a few hun- dred meters, which cross or closely approach the Earth' s orbit are divided into three orbital classes: the Aten asteroids with semi-maj or axes less than 1 AU and which cross the Earth's orbit near aphelia, the Apollo asteroids with semi-major axes greater than or equal to 1 AU and with per- ihelia greater than 1.17 AU, and the Amor asteroids with perihelia between 1.17 and 1.3 AU (1). These asteroids which have orbits stable against col- 8 lision with or ejection by a planet on the order of lo7 to 10 years must be derived from either extinct cometary naclei (2) or the asteroid belt (C f. 1). These near-Earth asteroids are important for several diverse reasons: they represent a group of obj ect s from which at least some of the meteor- ites arc derived, they may harbor extinct cometary nuclei thought to con- tain some of the most primitive and, perhaps, pristine material in the solar system, occasionally collide with the Earth, and are among the most accessible objects in the solar system. Study of the physical properties of the Earth-approaching asteroids is constrained by the generally long time between close approaches and poorly known orbits. -
Cross-References ASTEROID IMPACT Definition and Introduction History of Impact Cratering Studies
18 ASTEROID IMPACT Tedesco, E. F., Noah, P. V., Noah, M., and Price, S. D., 2002. The identification and confirmation of impact structures on supplemental IRAS minor planet survey. The Astronomical Earth were developed: (a) crater morphology, (b) geo- 123 – Journal, , 1056 1085. physical anomalies, (c) evidence for shock metamor- Tholen, D. J., and Barucci, M. A., 1989. Asteroid taxonomy. In Binzel, R. P., Gehrels, T., and Matthews, M. S. (eds.), phism, and (d) the presence of meteorites or geochemical Asteroids II. Tucson: University of Arizona Press, pp. 298–315. evidence for traces of the meteoritic projectile – of which Yeomans, D., and Baalke, R., 2009. Near Earth Object Program. only (c) and (d) can provide confirming evidence. Remote Available from World Wide Web: http://neo.jpl.nasa.gov/ sensing, including morphological observations, as well programs. as geophysical studies, cannot provide confirming evi- dence – which requires the study of actual rock samples. Cross-references Impacts influenced the geological and biological evolu- tion of our own planet; the best known example is the link Albedo between the 200-km-diameter Chicxulub impact structure Asteroid Impact Asteroid Impact Mitigation in Mexico and the Cretaceous-Tertiary boundary. Under- Asteroid Impact Prediction standing impact structures, their formation processes, Torino Scale and their consequences should be of interest not only to Earth and planetary scientists, but also to society in general. ASTEROID IMPACT History of impact cratering studies In the geological sciences, it has only recently been recog- Christian Koeberl nized how important the process of impact cratering is on Natural History Museum, Vienna, Austria a planetary scale. -
Spacewalch Discovery of Near-Earth Asteroids Tom Gehrele Lunar End
N9 Spacewalch Discovery of Near-Earth Asteroids Tom Gehrele Lunar end Planetary Laboratory The University of Arizona Our overall scientific goal is to survey the solar system to completion -- that is, to find the various populations and to study their statistics, interrelations, and origins. The practical benefit to SERC is that we are finding Earth-approaching asteroids that are accessible for mining. Our system can detect Earth-approachers In the 1-km size range even when they are far away, and can detect smaller objects when they are moving rapidly past Earth. Until Spacewatch, the size range of 6 - 300 meters in diameter for the near-Earth asteroids was unexplored. This important region represents the transition between the meteorites and the larger observed near-Earth asteroids (Rabinowitz 1992). One of our Spacewatch discoveries, 1991 VG, may be representative of a new orbital class of object. If it is really a natural object, and not man-made, its orbital parameters are closer to those of the Earth than we have seen before; its delta V is the lowest of all objects known thus far (J. S. Lewis, personal communication 1992). We may expect new discoveries as we continue our surveying, with fine-tuning of the techniques. III-12 Introduction The data accumulated in the following tables are the result of continuing observation conducted as a part of the Spacewatch program. T. Gehrels is the Principal Investigator and also one of the three observers, with J.V. Scotti and D.L Rabinowitz, each observing six nights per month. R.S. McMillan has been Co-Principal Investigator of our CCD-scanning since its inception; he coordinates optical, mechanical, and electronic upgrades. -
The Catalina Sky Survey
The Catalina Sky Survey Current Operaons and Future CapabiliKes Eric J. Christensen A. Boani, A. R. Gibbs, A. D. Grauer, R. E. Hill, J. A. Johnson, R. A. Kowalski, S. M. Larson, F. C. Shelly IAWN Steering CommiJee MeeKng. MPC, Boston, MA. Jan. 13-14 2014 Catalina Sky Survey • Supported by NASA NEOO Program • Based at the University of Arizona’s Lunar and Planetary Laboratory in Tucson, Arizona • Leader of the NEO discovery effort since 2004, responsible for ~65% of new discoveries (~46% of all NEO discoveries). Currently discovering NEOs at a rate of ~600/year. • 2 survey telescopes run by a staff of 8 (observers, socware developers, engineering support, PI) Current FaciliKes Mt. Bigelow, AZ Mt. Lemmon, AZ 0.7-m Schmidt 1.5-m reflector 8.2 sq. deg. FOV 1.2 sq. deg. FOV Vlim ~ 19.5 Vlim ~ 21.3 ~250 NEOs/year ~350 NEOs/year ReKred FaciliKes Siding Spring Observatory, Australia 0.5-m Uppsala Schmidt 4.2 sq. deg. FOV Vlim ~ 19.0 2004 – 2013 ~50 NEOs/year Was the only full-Kme NEO survey located in the Southern Hemisphere Notable discoveries include Great Comet McNaught (C/2006 P1), rediscovery of Apophis Upcoming FaciliKes Mt. Lemmon, AZ 1.0-m reflector 0.3 sq. deg. FOV 1.0 arcsec/pixel Operaonal 2014 – currently in commissioning Will be primarily used for confirmaon and follow-up of newly- discovered NEOs Will remove follow-up burden from CSS survey telescopes, increasing available survey Kme by 10-20% Increased FOV for both CSS survey telescopes 5.0 deg2 1.2 ~1,100/ G96 deg2 night 19.4 deg2 2 703 8.2 deg 2 ~4,300 deg per night New 10k x 10k cameras will increase the FOV of both survey telescopes by factors of 4x and 2.4x. -
NASA Chat: Asteroid 1998 QE2 to Sail Past Earth Expert Dr. Bill Cooke May 30, 2013 ______
NASA Chat: Asteroid 1998 QE2 to Sail Past Earth Expert Dr. Bill Cooke May 30, 2013 _____________________________________________________________________________________ Moderator_Brooke: Welcome everyone! We're just about to start the chat, so please go ahead and send in your questions. Thanks for being here -- now let's talk asteroids! RSEW: Hello Bill_Cooke: We're here! Do you have a question? Moderator_Brooke: All right, here we go...Bill, over to you. tyler_hussey : I was wondering if people in New Hampshire will be able to view this asteroid pass by, and if so, what is the length it will be visible, what direction, and how close to the horizon? Bill_Cooke; Hi Tyler. You need a telescope to see the QE2 asteroid, and of course, it needs to be dark. It's visible there in N.H. with a small telescope about 10:30 p.m. local time. It will be in the constellation Hydra and be about eleventh magnitude. tyler_hussey: I was wondering if people in New Hampshire will be able to view this asteroid pass by, and if so, what is the length it will be visible, what direction, and how close to the horizon? Bill_Cooke: Unless you are Asia or Europe, you will not be able to see the asteroid at close approach. However, you can see it tonight around 10:30 pm local time with a small telescope. It will be in the constellation of Hydra. Moderator_Brooke: You can also find more information about QE2 at this link: http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130530.html guest100: where did this asteroid come from Bill_Cooke: The asteroid 1998 QE2 is an amor asteroid which means it approaches Earth from the outside. -
Martian Crater Morphology
ANALYSIS OF THE DEPTH-DIAMETER RELATIONSHIP OF MARTIAN CRATERS A Capstone Experience Thesis Presented by Jared Howenstine Completion Date: May 2006 Approved By: Professor M. Darby Dyar, Astronomy Professor Christopher Condit, Geology Professor Judith Young, Astronomy Abstract Title: Analysis of the Depth-Diameter Relationship of Martian Craters Author: Jared Howenstine, Astronomy Approved By: Judith Young, Astronomy Approved By: M. Darby Dyar, Astronomy Approved By: Christopher Condit, Geology CE Type: Departmental Honors Project Using a gridded version of maritan topography with the computer program Gridview, this project studied the depth-diameter relationship of martian impact craters. The work encompasses 361 profiles of impacts with diameters larger than 15 kilometers and is a continuation of work that was started at the Lunar and Planetary Institute in Houston, Texas under the guidance of Dr. Walter S. Keifer. Using the most ‘pristine,’ or deepest craters in the data a depth-diameter relationship was determined: d = 0.610D 0.327 , where d is the depth of the crater and D is the diameter of the crater, both in kilometers. This relationship can then be used to estimate the theoretical depth of any impact radius, and therefore can be used to estimate the pristine shape of the crater. With a depth-diameter ratio for a particular crater, the measured depth can then be compared to this theoretical value and an estimate of the amount of material within the crater, or fill, can then be calculated. The data includes 140 named impact craters, 3 basins, and 218 other impacts. The named data encompasses all named impact structures of greater than 100 kilometers in diameter. -
1. Some of the Definitions of the Different Types of Objects in the Solar
1. Some of the definitions of the different types of objects in has the greatest orbital inclination (orbit at the the solar system overlap. Which one of the greatest angle to that of Earth)? following pairs does not overlap? That is, if an A) Mercury object can be described by one of the labels, it B) Mars cannot be described by the other. C) Jupiter A) dwarf planet and asteroid D) Pluto B) dwarf planet and Kuiper belt object C) satellite and Kuiper belt object D) meteoroid and planet 10. Of the following objects in the solar system, which one has the greatest orbital eccentricity and therefore the most elliptical orbit? 2. Which one of the following is a small solar system body? A) Mercury A) Rhea, a moon of Saturn B) Mars B) Pluto C) Earth C) Ceres (an asteroid) D) Pluto D) Mathilde (an asteroid) 11. What is the largest moon of the dwarf planet Pluto 3. Which of the following objects was discovered in the called? twentieth century? A) Chiron A) Pluto B) Callisto B) Uranus C) Charon C) Neptune D) Triton D) Ceres 12. If you were standing on Pluto, how often would you see 4. Pluto was discovered in the satellite Charon rise above the horizon each A) 1930. day? B) 1846. A) once each 6-hour day as Pluto rotates on its axis C) 1609. B) twice each 6-hour day because Charon is in a retrograde D) 1781. orbit C) once every 2 days because Charon orbits in the same direction Pluto rotates but more slowly 5. -
A Ballistics Analysis of the Deep Impact Ejecta Plume: Determining Comet Tempel 1’S Gravity, Mass, and Density
Icarus 190 (2007) 357–390 www.elsevier.com/locate/icarus A ballistics analysis of the Deep Impact ejecta plume: Determining Comet Tempel 1’s gravity, mass, and density James E. Richardson a,∗,H.JayMeloshb, Carey M. Lisse c, Brian Carcich d a Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA b Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USA c Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA d Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA Received 31 March 2006; revised 8 August 2007 Available online 15 August 2007 Abstract − In July of 2005, the Deep Impact mission collided a 366 kg impactor with the nucleus of Comet 9P/Tempel 1, at a closing speed of 10.2 km s 1. In this work, we develop a first-order, three-dimensional, forward model of the ejecta plume behavior resulting from this cratering event, and then adjust the model parameters to match the flyby-spacecraft observations of the actual ejecta plume, image by image. This modeling exercise indicates Deep Impact to have been a reasonably “well-behaved” oblique impact, in which the impactor–spacecraft apparently struck a small, westward-facing slope of roughly 1/3–1/2 the size of the final crater produced (determined from initial ejecta plume geometry), and possessing an effective strength of not more than Y¯ = 1–10 kPa. The resulting ejecta plume followed well-established scaling relationships for cratering in a medium-to-high porosity target, consistent with a transient crater of not more than 85–140 m diameter, formed in not more than 250–550 s, for the case of Y¯ = 0 Pa (gravity-dominated cratering); and not less than 22–26 m diameter, formed in not less than 1–3 s, for the case of Y¯ = 10 kPa (strength-dominated cratering). -
Using Resources from Near-Earth Space
USING RESOURCES FROM NEAR-EARTH SPACE JOHN S. LEWIS University of Arizona DAVIDS. McKAY NASA Johnson Space Center and BENTON C. CLARK Martin Marietta Civil Space & Communications The parts of the solar system that are most accessible from Earth (the Moon, the near Earth asteroids, and Mars and its moons) are rich in materials of great potential value to humanity. Immediate uses of these resources to manufacture propellants, structural metals, refractories, life-support fluids and glass can support future large-scale space acitivites. In the longterm, non-terrestrial sources of rare materials and energy may be of great importance here on Earth. I. INTRODUCTION Space activities have become so much a part of modem life that they are almost invisible. We are aware how important communications satellite relays are for inexpensive long-distance telephone calls and television news broadcast, and we see the color images of Earth's cloud cover in the weather reports on TV. But we are usually not aware that the commercial airplane in which we fly or the ferry we ride locates itself by using navigation satellites 12,000 miles above our heads. We may never hear that the Soviet Union launched several satellites each year dedicated to assessing the American, Canadian, and Argentine wheat crops to help plan their grain purchases. We may be even more astonished to know that the truck we just passed on the highway is being tracked by a satellite, or that the strategic balance between the great powers has long been monitored based on photographic, electronic imaging, radar, infrared, and signal monitoring from space. -
Impact Cratering
6 Impact cratering The dominant surface features of the Moon are approximately circular depressions, which may be designated by the general term craters … Solution of the origin of the lunar craters is fundamental to the unravel- ing of the history of the Moon and may shed much light on the history of the terrestrial planets as well. E. M. Shoemaker (1962) Impact craters are the dominant landform on the surface of the Moon, Mercury, and many satellites of the giant planets in the outer Solar System. The southern hemisphere of Mars is heavily affected by impact cratering. From a planetary perspective, the rarity or absence of impact craters on a planet’s surface is the exceptional state, one that needs further explanation, such as on the Earth, Io, or Europa. The process of impact cratering has touched every aspect of planetary evolution, from planetary accretion out of dust or planetesimals, to the course of biological evolution. The importance of impact cratering has been recognized only recently. E. M. Shoemaker (1928–1997), a geologist, was one of the irst to recognize the importance of this process and a major contributor to its elucidation. A few older geologists still resist the notion that important changes in the Earth’s structure and history are the consequences of extraterres- trial impact events. The decades of lunar and planetary exploration since 1970 have, how- ever, brought a new perspective into view, one in which it is clear that high-velocity impacts have, at one time or another, affected nearly every atom that is part of our planetary system. -
Dust Coatings on Basaltic Rocks and Implications for Thermal Infrared Spectroscopy of Mars Jeffrey R
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. E6, 10.1029/2000JE001405, 2002 Dust coatings on basaltic rocks and implications for thermal infrared spectroscopy of Mars Jeffrey R. Johnson Branch of Astrogeology, U.S. Geological Survey, Flagstaff, Arizona, USA Philip R. Christensen Department of Geology, Arizona State University, Tempe, Arizona, USA Paul G. Lucey Hawaii Institute for Geology and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii, USA Received 2 October 2000; revised 6 July 2001; accepted 12 October 2001; published 5 June 2002. [1] Thin coatings of atmospherically deposited dust can mask the spectral characteristics of underlying surfaces on Mars from the visible to thermal infrared wavelengths, making identification of substrate and coating mineralogy difficult from lander and orbiter spectrometer data. To study the spectral effects of dust coatings, we acquired thermal emission and hemispherical reflectance spectra (5–25 mm; 2000–400 cmÀ1) of basaltic andesite coated with different thicknesses of air fall-deposited palagonitic soils, fine-grained ceramic clay powders, and terrestrial loess. The results show that thin coatings (10–20 mm) reduce the spectral contrast of the rock substrate substantially, consistent with previous work. This contrast reduction continues linearly with increasing coating thickness until a ‘‘saturation thickness’’ is reached, after which little further change is observed. The saturation thickness of the spectrally flat palagonite coatings is 100–120 mm, whereas that for coatings with higher spectral contrast is only 50–75 mm. Spectral differences among coated and uncoated samples correlate with measured coating thicknesses in a quadratic manner, whereas correlations with estimated surface area coverage are better fit by linear functions. -
An Early Warning System for Asteroid Impact
An Early Warning System for Asteroid Impact John L. Tonry(1) ABSTRACT Earth is bombarded by meteors, occasionally by one large enough to cause a significant explosion and possible loss of life. It is not possible to detect all hazardous asteroids, and the efforts to detect them years before they strike are only advancing slowly. Similarly, ideas for mitigation of the danger from an impact by moving the asteroid are in their infancy. Although the odds of a deadly asteroid strike in the next century are low, the most likely impact is by a relatively small asteroid, and we suggest that the best mitigation strategy in the near term is simply to move people out of the way. With enough warning, a small asteroid impact should not cause loss of life, and even portable property might be preserved. We describe an \early warning" system that could provide a week's notice of most sizeable asteroids or comets on track to hit the Earth. This may be all the mitigation needed or desired for small asteroids, and it can be implemented immediately for relatively low cost. This system, dubbed \Asteroid Terrestrial-impact Last Alert System" (AT- LAS), comprises two observatories separated by about 100 km that simulta- neously scan the visible sky twice a night. Software automatically registers a comparison with the unchanging sky and identifies everything which has moved or changed. Communications between the observatories lock down the orbits of anything approaching the Earth, within one night if its arrival is less than a week. The sensitivity of the system permits detection of 140 m asteroids (100 Mton impact energy) three weeks before impact, and 50 m asteroids a week be- fore arrival.