Auburn Mountainview

Karl Steffin, 2014

4/26/2015

Asteroids

• On January 1, 1801, discovered an object (Ceres) which he first thought was a new planet.

• After its orbit was better determined it was clear that it was not a comet but more like a small planet.

• By the end of the 19th century there were several hundred small ‘planets’ discovered.

• Sir William Herschel proposed the name asteroids after the joining of Greek words ‘star’ and ‘like’.

Billions and Billions

• There are twenty-six known asteroids larger than 200 km in diameter.

• 99% of the asteroids larger than 100 km in diameter have been documented.

• There are probably considerably more than a million asteroids in the one km range.

• If all asteroids were smashed together, it would create a ball smaller than the moon.

Composition

• Most of the Asteroids reside between Mars and Jupiter (2-4 AU).

• Asteroids are classified into a number of types according to their chemical composition:

• C(arbon)-Type, 75%+ of known asteroids: extremely dark (Albedo~0.03); similar chemical composition as the Sun minus hydrogen, helium and other volatiles;

• S(tony)-Type, ~17% of known asteroids: relatively bright: (Albedo~.10-.22); Iron mixed with Magnesium-silicates;

• X-Type, Includes M(etallic) ~8% of known asteroids: bright (Albedo~.10-.18); pure nickel-iron.

Where are they?

• Asteroid belt: An esimated 1.1-1.9 lager and millions of smaller asteroids reside between Mars and Jupiter. Distributed among the Kirkwood gaps.

• Trojans: Asteroids that share an orbit with a planet due to Lagrangianstability (60° in front or behind). Found by Jupiter and Mars.

• NEA’s: Near Earth Asteroids, 11,600 known.

Distribution of Asteroids Mass

Top TenName Sym Disc Named

Ceres 1801Roman goddess of

agriculture. (Demeter)

Vesta 1807Goddess of hearth and

home. (Hestia)

Pallas 1801Goddess of wisdom.

(Athena)

Hygiea 1849Goddess of Health.

(Sirona)

Euphrosyne 1854One of the Greek

Charities. Joy/Mirth.

Name Sym Disc Named

Interamnia 1910 Latin for Teramo, Italy

Davida 1903Prof David Peck Todd

(Amherst College).

Herculina 1904 Name origin unknown.

Eunomia 1851Goddess of Law and

Legislation

Psyche 1852Mortal woman. Married

to Cupid.

What is What?

• Asteroid: A space rock (smaller than a planet) orbiting the sun.

• Meteoroid: A space rock that has entered Earth’s atmosphere.

• Meteorite: A space rock that has fallen to earth.

• Bolide: (Greek Missile), extremely bright impact with the atmosphere.

Where are they not?

Comets (Gr: Wearing Long Hair)

• On January 1, 1801, discovered an object (Ceres) which he first thought was a new planet.

• After its orbit was better determined it was clear that it was not a comet but more like a small planet.

• By the end of the 19th century there were several hundred small ‘planets’ discovered.

• Sir William Herschel proposed the name asteroids after the joining of Greek words ‘star’ and ‘like’.

Composition

• Nucleus: Rock, H2O, CO2,CO, CH4, NH3. Organic compounds present.

• Coma: Released matter forms dense atmosphere.

• Radiation and Solar wind cause coma to form away from sun.

• Tail: Melting and Sublimating debris.

• Dust: Curves away from comets motion.

• Gas: Points away from the sun.

• Jets: Geysers that come out from uneven heating.

Where are they?

• Kupier Belt (1992): Region beyond Pluto hypothesized since 1930.

• Oort Comet Cloud (1932): Birth place of long period comets.

We’re All Gonna Die!!!

• Near-Earth Asteroids (NEAs): Asteroids that closely approach the Earth.

• Atens: Semi-major axes less than 1.0 AU and aphelion distances greater than 0.983 AU.

• Apollos: Semi-major axes greater than 1.0 AU and perihelion distances less than 1.017 AU.

• Amors: Perihelion distances between 1.017 and 1.3 AU.

Near Earth Objects (NEO’s)• Objects hitting Earth are an a inevitability.

• Two things determine the potential damage.

• Size of the Object. (Mass)

• Speed of the Object. (Velocity)

• These variables relate to Kinetic Energy.

• EnergyKinetic= ½ mass x velocity2.

• To put this into understandable terms a scaled system was developed.

7 grams (center) shot at 7 km/s (the orbital velocity of the ISS) made this 15 cm crater in a solid block of aluminum.

Torino Scale

• Originally called the NEO hazard index was created by Richard P. Binzel, Professor of Massachusetts Institute of Technology, in 1995.

• In 1999 at a conference in Turin, Italy it was ratified for use (hence the name).

• In 2005 the system was reworded to be more user friendly.

Torino: No Hazard Normal

0: The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage.

1: A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern.

Torino: Meriting Attention

2. Object making a somewhat close pass near the Earth. There is no cause for public attention/ concern as an actual collision is very unlikely.

3. A close encounter, 1% or greater chance of collision capable of localized destruction. Public awareness merited if less than a decade away.

4. A close encounter. 1% or greater chance of collision capable of regional devastation. Public awareness merited if less than a decade away.

5. A close encounter posing a serious, but still uncertain threat of regional devastation. Critical attention by is needed to determine whether a collision will occur. Governmental contingency planning may be warranted.

6. A close encounter by a large object posing a serious but still uncertain threat of a global catastrophe. Critical attention by is needed to determine whether a collision will occur. Governmental contingency planning may be warranted.

7. A very close encounter by a large object, which if occurring this century, poses an unprecedented but still uncertain threat of a global catastrophe.

Torino: Threatening

8. A collision is certain, capable of causing localized destruction for an impact over land or possibly a tsunami if close offshore. (Chance of 1 per 50-1000’s years).

9. A collision is certain, capable of causing unprecedented regional devastation for a land impact or the threat of a major tsunami for an ocean impact. (Chance of 1 per 10,000-100,000 years)

10. A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it, whether impacting land or ocean . (Chance of 1 100,000 years or more)

Torino: Certain Collisions

How Bad is Bad?

• The current record is 99942 Apophis (400-m asteroid) which was a level 2 in 2004

• Later was upgraded to a level 4.

• Now thought to pass closely by in 4/13/2029.

• Due to the potential gravity disturbances it will be a level 1 (reclassified to 0) in the 2036 pass.

• In 2/06 2004 VD was given a 2. impct: 2102

• In 11/06 1950 DA was given a 1.

• Vredefort Crater in South Africa.

• Largest verified crater (over 300-km).

• Mostly eroded away

Prior Impact: 2023 million

• Chicxulub Crater in Yucatán.

• Half as large as (180-km).

• Triggered mass extinction of K-Pg boundary (non-avian dinosaurs).

Prior Impact: 65 million

• Barringer Meteorite Crater in Arizona caused by 50-meter wide iron rich impact.

Prior Impact: 50 thousand

From the slopes 2-million people can watch twenty football games being played.

Prior ‘Impact’

• On June 30, 1908 an object exploded in the upper atmosphere (~4 miles) near the Tunguska River in Russia.

• The explosion leveled the area even though it never hit the ground.

• The shockwave was estimated at a 5.0 on the Richter scale.

1927 2008

Prior ‘Impact’

• On February 15, 2013 the superbolide Chelyabinsk meteor reached speeds of 19-km/s, exploded 29.7-km above Russia.

• The explosion created a shockwave over 20-km across.

• The shockwave caused $33-million in damage and injuries.

99942 Apophis Impact (0: 2036)

• On slight chance of impact it will release 510-megatons.

• The Tunguska ‘Impact’ was estimated at 10-15 megatons.

• The eruption of Krakatoa (1883) was 200 megatons.

Stopping Disaster

• Orbit@home (2008): Designed to optimize detection strategies. Lack of funding halted the project in 2013, set to resume 2015???

• Sentinel Mission (2017-2018): Telescope to catalog NEO’s and also looking into gravity as a means of redirecting.

• Other ideas include: Nuclear Detonation on/near, Kinetic Impact, Ion Beam Shepherd, Solar Energy, Mass Driver and Rocket Engines.

In Culture

• Books-The Valley of Fear (1914): Sir Arthur Conan Doyle made a short story with Professor Moriarty matching wits with Sherlock Holmes.

• Games-Asteroids (1979): Arcade game developed by Atari with over 70,000 units. Now ported onto many systems. Upcoming movie to follow.

• Movies-Starship Troopers (1959/1997),Armageddon (1998): Asteroids used as a weapon or as a catalyst to destroy humanity.

Rosetta

• Built by ESA to study Churyumov–Gerasimenko.

• Contains a disc with documents in 1200 different languages.

• Launch: 3/2004, Contact: Aug/2014, Lander: Nov/2014, Com Lost: Jul/2015

• Philae: Probe Made a soft landing in comet

• Landed of axis and did not collect solar power needed to function.