Impacts with Space Objects
description
Transcript of Impacts with Space Objects
![Page 1: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/1.jpg)
Impacts with Space Objects
![Page 2: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/2.jpg)
Moon shows many impact scars though most are prior to 3.8 billion years ago
![Page 3: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/3.jpg)
Earth destroys most evidence over time. Why?
![Page 4: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/4.jpg)
ASTEROIDSOriginate in the asteroid belt between Mars and Jupiter
![Page 5: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/5.jpg)
Mostly pieces of rock and metals that never coalesced to form a planet
![Page 6: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/6.jpg)
• 200 asteroids with diameters >100km
• ~1000 asteroids >30km diameter
• ~1,000,000 >1km diameter
![Page 7: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/7.jpg)
COMETSShort-period comets
They are part of the Kuiper belt, a flattened disk of comets made up of icy debris left over from the formation of the outer planets.
![Page 8: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/8.jpg)
Make a complete orbit in <200 years.
Haley’s Comet every ~75 years
![Page 9: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/9.jpg)
Comet Orbits
• http://www.st-andrews.ac.uk/~bds2/ltsn/ljm/JAVA/COMETORB/COMET.HTM
![Page 10: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/10.jpg)
Long-period cometsThey are part of the Oort cloud, a vast diffuse envelope
of encircling comets. Period may thousands of years of more.
![Page 11: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/11.jpg)
Comet Hale Bopp – visible for 18 months in 1996 - 1997
![Page 12: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/12.jpg)
• All comets are mainly made of ice and rocky debris.
![Page 13: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/13.jpg)
IMPACTSEnergy release depends on speed and size.
Asteroids may impact at >30,000mph.Long-period comets >150,000mph.M-16 rifle ~2250 mph.
![Page 14: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/14.jpg)
Given equal size, the mass of an asteroid is greater than that of a comet.
![Page 15: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/15.jpg)
Atmosphere may heat the asteroid to 3,000oC.
Impact instantly released enormous heat and energy, melting and vaporizing not only rock but also much of the asteroid itself.
Crater may end up filled with crushed and shattered rock.
![Page 16: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/16.jpg)
![Page 17: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/17.jpg)
Comet Shoemaker Levy 9 impact with Jupiter July 16-22, 1994
![Page 18: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/18.jpg)
Fragment Q impacts on Jupiter. There were 21 discernable fragments up to 2km diameter.
![Page 19: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/19.jpg)
Meteor Crater Arizona>1km wide (4,000 ft.) impact crater created ~50,000
years ago.
![Page 20: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/20.jpg)
METEOR CRATER, ARIZONA
Impact from nickel-iron metallic meteorite (asteroid).
Diameter ~40m (120ft.).
Speed at impact ~27,000mph.
Crater floor holds 365m (870ft.) of shattered rock.
![Page 21: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/21.jpg)
Tektites – glassy spherules formed by in-air-cooling of impact melted rock.
Happens with large asteroid impacts.
![Page 22: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/22.jpg)
Wolfe Creek Australia – age ~300,000 years
![Page 23: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/23.jpg)
Manicouagan Impact Site ~215.5 million years B.P.
~5km (3mi) diameter asteroid~70km (40mi) diameter crater
![Page 24: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/24.jpg)
Extinction of Dinosaurs ~65 Million Years B.P.
![Page 25: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/25.jpg)
KT boundary clay layer and iridium
![Page 26: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/26.jpg)
KT boundary layer Raton Basin
![Page 27: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/27.jpg)
![Page 28: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/28.jpg)
![Page 29: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/29.jpg)
![Page 30: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/30.jpg)
![Page 31: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/31.jpg)
![Page 32: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/32.jpg)
Figure 17.25
![Page 33: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/33.jpg)
Tunguska, June 30, 1908
![Page 34: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/34.jpg)
TUNGUSKA
Probably a stony meteorite or comet possibly smaller than 40m in diameter.
Exploded 5 – 10km (3 – 6mi.) above the earth’s surface.
![Page 35: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/35.jpg)
Flattened trees over 2,150km2 (830mi2)
![Page 36: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/36.jpg)
Figure 17.26
![Page 37: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/37.jpg)
• Tunguska originally thought to be ~60m in diameter. If so, similar impacts every ~2,000 years.
• But, with new estimate of 40m or less, once every ~300 years.
• Total potential hazard from impacts has increased.
![Page 38: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/38.jpg)
NEAR-EARTH OBJECTS (NEOs) PROJECT
Monitors and identifies near earth-objects for potential impact of objects >1km (.62mi.) diameter.
Average time interval between impacts of this size >100,000 years.
![Page 39: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/39.jpg)
However, objects 40m(or less) – 100m in diameter can cause devastating local effects (like Tunguska).
Smaller potentially damaging events occur perhaps every couple of centuries.
![Page 40: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/40.jpg)
Would we have warning before an impact?
Maybe, maybe not.
![Page 41: Impacts with Space Objects](https://reader031.fdocuments.in/reader031/viewer/2022020320/56815e2d550346895dcc8663/html5/thumbnails/41.jpg)
November 2011 Asteroid
http://neo.jpl.nasa.gov/news/news171.html
Near Earth Objects Tracking
http://neo.jpl.nasa.gov/risk/#legend