Asteroid Hazards Gerhard Drolshagen, Detlef Koschny Presented in ESOC, Darmstadt, 05 Sep 2013

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

Asteroid Hazards

Gerhard Drolshagen, Detlef Koschny

Presented in ESOC, Darmstadt, 05 Sep 2013

Imag

e c

red

it:

ES

A

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

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)


The Tunguska Event

Juni 1908 - 105 years ago

2000 km2 of Taiga were destroyed in Sibiria


Small impacts are relatively frequent

Crater with 14-m diameter formed by impact from space in 2007 in Carancas, Peru.


Known number of Near Earth Asteroids


Near Earth Objects population(From JPL – NEO site)


Estimated Number of Asteroids and NEOs(Data from NEODyS or JPL NEO site, Aug 2013)

> 600 000 known Asteroids

> 10 000 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 - 30,000)

• < 2.0% of NEOs larger than 30 m (total ≈ 500,000 - 1,000,000)

Most NEOs are still unknown!

Chelyabinsk impact eventVideo from dashboard camera

(from N. Artemieva)


Chelyabinsk impact eventGround effects


Chelyabinsk impact eventGround effects


Chelyabinsk impact event


Location: 55.2o N, 61.4o E (near Chelyabinsk, Russia)

Date/time: 15 Feb 2013, 03:20 UT (09:20 LT)

Diameter of object: 19 m, mass ≈ 12000 t

Entry velocity: 18.6 km/s, entry angle: 20o 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 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 10,000 200,000 Europe-wide destruction

1 km 80,000 700,000 Millions dead, global effects

10 km 80 million 100 million End of human civilisation

Asteroids (and Comets) hit Earth with very high velocities.

typical: 10 - 20 km/s, 20 times faster than a gun bullet!

ESA’s SSA-NEO System

System overview

Nat

iona

lC

oope

ratin

gte

lesc

opes

SSA tasking centre

SS

A s

enso

rsS

pace

m

issi

ons

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

Spacemissionstudies

NEO Coordination Centre – ESRIN, Italy

SSA-NEO Coordination Centre - inaugurated 22 May 2013


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

http://neo.ssa.esa.int


Risk list


Observations


2010A2, an asteroid collision observed in February 2002Flyby of asteroid 2012 DA14. Courtesy F. Kugel and J. Caron, Dauban observatory, IAU A77


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


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 email distribution list (triggered at impact probability of >1/100).

Notification to special distribution list (including civil protection specialists)


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/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

Observations continue (professional and amateur telescopes)

Special observations with infrared telescopes, radar systems (mostly US-based) => allows to constrain physical properties

Arecibo radarPuerto Rico

High-endamateurtelescope


07 Sep: 13 days before impact

Backg

rou

nd

: C

om

et

Pan

STA

AR

S

C/2

01

1 I

4,

12

Mar

20

13

, D

. K

osch

ny

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


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…


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


20 Sep 2015


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?

…


Documents

Asteroid Hazards Gerhard Drolshagen, Detlef Koschny Presented in ESOC, Darmstadt, 05 Sep 2013