Reference impact scenarios – an example 18 Feb 2013 Reference impact scenarios – an example Gerhard Drolshagen, Detlef Koschny Presented in ESOC, Darmstadt, 06 Feb 2014 Image credit: ESA The SSA-NEO Segment, Feb 2013, D. Koschny - Page 4

Definitions/terminology Near-Earth Object (NEO): Any asteroid coming closer than 0.3 AU to the Earth 1 AU = Astronomical Unit = distance Sun-Earth = 149.6 Mio km Threatening object: Any asteroid that may hit the Earth Risk list: A list containing all threatening objects NEO Itokawa (credit: JAXA) 500 m SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 4

The Tunguska Event Juni 1908 - 105 years ago 2000 km2 of Taiga were destroyed in Sibiria SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 4

NEO impacts: frequency and effects Asteroids (and Comets) hit Earth with very high velocities. typical: 10 - 20 km/s, 20 times faster than a gun bullet! NEO diameter Impact energy [Megatons TNT] (1g TNT ≡ 4184 J) Typical interval [Years] Effect 2 mm 1 per hour (visible for each location) Nice meteor 3 m 0.002 1 Fireball, Sudan Event, Meteorites reach ground 10 m 0.08 10 Big fireball, fear, shock wave, 5-fold energy of Hiroshima bomb 40 m 5 500 Tunguska explosion or Crater 140 m 220 10,000 Regional destruction, Tsunami 500 m 200,000 Europe-wide destruction 1 km 80,000 700,000 Millions dead, global effects 10 km 80 million 100 million End of human civilisation

ESA-centric view of a 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’

Case study – detection of a threatening object – 06 Sep 2015… 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 email 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 6

06 Sep: 14 days before impact Velocity: 18.7 km/s Size: 20 m +/- 10 m Density: 1 g/cm3 .. 8 g/cm3 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 High-end amateur telescope 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 SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 8

07 Sep: 13 days before impact 18 Feb 2013 07 Sep: 13 days before impact Velocity: 18.7 km/s Size: 20 m +/- 10 m Density: 1 g/cm3 .. 8 g/cm3 Impact probability: 1 Time of impact: 20 Sep 2015, 20:10 +/- 1 min Kinetic energy: min: 21.9 Kt max: 4.87 Mt Background: Comet PanSTAARS C/2011 I4, 12 Mar 2013, D. Koschny SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 9

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/cm3 .. 3.8 g/cm3 Impact probability: 1 Time of impact: 20 Sep 2015, 20:10 +/- 10 sec Kinetic energy: min: 110.6 Kt max: 1.04 Mt SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 11

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

For SMPAG Develop similar sample reference cases – e.g. 2011 AG5 Detected 2011 Impact probabilty up to 1/500 in 2040 But: ‘Keyhole’ passage in 2023 Difficult to get more observations to improve orbit Solved by obserations with large telescope SSA-NEO-ESA-HO-0150/1.0 – interface to emergency response, Sep 2013, - Page 13