The SSA-NEO Segment, Feb 2013, D. Koschny - Page 4 Asteroid Hazards Gerhard Drolshagen, Detlef Koschny Presented in ESOC, Darmstadt, 05 Sep 2013 Image credit: ESA

Near-Earth Object (NEO): Any asteroid coming closer than 0.3 AU to the Earth 1 AU = Astronomical Unit = distance Sun-Earth = Mio km Threatening object: Any asteroid that may hit the Earth Risk list: A list containing all threatening objects Definitions/terminology 500 m NEO Itokawa (credit: JAXA) SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 4

What is the threat? Sample case: Chelyabinsk What is ESA doing? What is everybody else doing? “War Game” – a simulated real threat Conclusions/questions Outline Meteorite (10 cm) SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 4

The Tunguska Event Juni years ago 2000 km 2 of Taiga were destroyed in Sibiria SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 4

Small impacts are relatively frequent Crater with 14- m diameter formed by impact from space in 2007 in Carancas, Peru. SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 5

Known number of Near Earth Asteroids SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 6

Near Earth Objects population (From JPL – NEO site) SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 7

Estimated Number of Asteroids and NEOs (Data from NEODyS or JPL NEO site, Aug 2013) > known Asteroids > known NEOs > 400 NEOs in risk list (NEOs with small but non-zero impact probability within next 100 years) Estimated number of known NEOs: 90% of NEOs with diameter larger than 1 km (≥ 860 NEAs + 94 near- Earth Comets of a total of ≈ 1050) 15-25% of NEOs larger than 140 m (total ≈ 20, ,000) < 2.0% of NEOs larger than 30 m (total ≈ 500, ,000,000) Most NEOs are still unknown!

Chelyabinsk impact event Video from dashboard camera (from N. Artemieva) SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 9

Chelyabinsk impact event Ground effects SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 10

Chelyabinsk impact event Ground effects SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 11

Chelyabinsk impact event SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 12 Location: 55.2 o N, 61.4 o E (near Chelyabinsk, Russia) Date/time: 15 Feb 2013, 03:20 UT (09:20 LT) Diameter of object: 19 m, mass ≈ t Entry velocity: 18.6 km/s, entry angle: 20 o from surface Total energy: equiv. to 480 kt TNT Altitude of main explosion: 30 – 25 km Max brightness of fireball: m ≈ -30 (about 30 x sun brightness) 7300 buildings damaged > 1500 people injured > 100 kg of meteorites found (usually small pieces, asteroid was ordinary chondrite) Asteroid could not be seen approaching (too close to sun direct.) and was too faint for prior detection during the last 10 years

NEO impacts: frequency and effects NEO diameterImpact energy [Megatons TNT] (1g TNT ≡ 4184 J) Typical interval [Years] Effect 2 mm1 per hour (visible for each location) Nice meteor 3 m Fireball, Sudan Event, Meteorites reach ground 10 m Big fireball, fear, shock wave, 5- fold energy of Hiroshima bomb 40 m5500 Tunguska explosion or Crater 140 m22010,000 Regional destruction, Tsunami 500 m10,000200,000 Europe-wide destruction 1 km80,000700,000 Millions dead, global effects 10 km80 million100 million End of human civilisation Asteroids (and Comets) hit Earth with very high velocities. typical: km/s, 20 times faster than a gun bullet!

ESA’s SSA-NEO System

System overview National Cooperating telescopes SSA tasking centre SSA sensors Space missions Minor Planet Center (US) NEOs Political entities General users NEO image credit: JAXA National research expertise - Risk assessment - Obs. Planning - Phys. Properties SSA-NEO Coord. Centre - Databases - Light curves - Shape models Space mission studies

NEO Coordination Centre – ESRIN, Italy SSA-NEO Coordination Centre - inaugurated 22 May 2013 SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 16

The SSA-NEO web portal Federates some key European assets: NEODyS = orbit computation, prediction, risk list Physical properties database Priority list = showing objects in need of observations SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 17

Risk list SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 18

Observations The SSA-NEO Segment, Feb 2013, D. Koschny - Page A2, an asteroid collision observed in February 2002 Flyby of asteroid 2012 DA14. Courtesy F. Kugel and J. Caron, Dauban observatory, IAU A77 SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 19

Discussions within UN COPUOS Action Team 14 of the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS) has developed a response strategy Adopted in Jun 2013 by COPUOS Two groups are to be installed: International Asteroid Warning Network (includes interface to emergency response) Space Missions Planning Advisory Group SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 20

Case study – detection of a threatening object – 05 Sep 2015… ESA SSA-NEO survey telescope discovers moving object close to the celestial equator Position measurements are sent to Minor Planet Center (MPC) in US as part of regular observation process MPC checks orbit; object is potential NEO. Posted on ‘NEO Confirmation Page’

Other observers perform ‘follow-up’ observations Object is confirmed after 24 hours – receives a ‘designation’ NEODyS computes detailed orbit – finds an impact solution. Impact risk: 1/10 => SSA-NEO managers are informed Based on visual brightness: size estimate 20 m +/- 10 m => could generate ground effects JPL Sentry impact monitoring system confirms SSA Programme Manager is informed news release is sent to an distribution list (triggered at impact probability of >1/100). Notification to special distribution list (including civil protection specialists) SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 22 Case study – detection of a threatening object – 06 Sep 2015…

06 Sep: 14 days before impact Velocity: 18.7 km/s Size: 20 m +/- 10 m Density: 1 g/cm g/cm 3 Impact probability: 1/10 Time of impact: 20 Sep 2015, 20:10 +/- 3 min Kinetic energy: min: 21.9 Kt max: 4.87 Mt

Starting 06 Sep 2015 Observations continue (professional and amateur telescopes) Special observations with infrared telescopes, radar systems (mostly US-based) => allows to constrain physical properties Arecibo radar Puerto Rico High-end amateur telescope SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 24

07 Sep: 13 days before impact Background: Comet PanSTAARS C/2011 I4, 12 Mar 2013, D. Koschny Velocity: 18.7 km/s Size: 20 m +/- 10 m Density: 1 g/cm g/cm 3 Impact probability: 1 Time of impact: 20 Sep 2015, 20:10 +/- 1 min Kinetic energy: min: 21.9 Kt max: 4.87 Mt SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 25

Possible press response Reports on Alien invasions Claim that Space Agencies are hiding information Killer-asteroid on the way! Deadly asteroid will destroy Berlin/New York /Tokyo /Moscow/Sidney/Bejing… The SSA-NEO Segment, Feb 2013, D. Koschny - Page 4

13 Sep: 7 days before impact Velocity: 18.7 km/s Size: 20 m +/- 3 m Density: 1 g/cm g/cm 3 Impact probability: 1 Time of impact: 20 Sep 2015, 20:10 +/- 10 sec Kinetic energy: min: Kt max: 1.04 Mt SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 27

20 Sep 2015 The SSA-NEO Segment, Feb 2013, D. Koschny - Page 4

Questions to the audience… Who should be informed? At which point in time would you expect to be informed? And at which impact probability? Only when 1? Which information would you need? Recommended measures? … SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 29