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Importance of Asteroids Science Origin of the Solar System Resources Metals, ice Impact mitigation Deflection https://solarsystem.nasa.gov/planets/ceres Asteroid structure From Walker et al 2006 Seismic Geophysics

SLIDE 1

SLIDE 2

Importance of Asteroids

Science

Origin of the Solar System

Resources

Metals, ice

Impact mitigation

Deflection

https://solarsystem.nasa.gov/planets/ceres

SLIDE 3

Asteroid structure

From Walker et al 2006

SLIDE 4

Seismic Geophysics

http://geologylearn.blogspot.com.au/2015/06/marine‐and‐land‐seismic‐aquisition.html

SLIDE 5

Seismic Geophysics

Active vs passive source What can we determine through seismic?

1. Seismic velocity (P‐ and S‐wave)
From this and other data, we can infer strength and other

properties

Fracture presence and orientation
2. Imaging (requires a lot of source and receiver locations)

SLIDE 6

Seismic Geophysics

http://epic.awi.de/35606/

SLIDE 7

Seismic Sources & Receivers

http://www.kgs.ku.edu/Publications/PIC/pic37.html http://www.hohoilfieldservices.co.uk/industry‐seismic.php http://www.kgs.ku.edu/Publications/PIC/pic37.html

SLIDE 8

Seismic sources and receivers

From Bagaini et al 2010

SLIDE 9

Planetary Seismic Missions

Moon

Apollo 17’s Lunar Seismic Profiling Experiment (LSPE) http://www.dlr.de/pf/en/desktopdefault.aspx/tabid‐8635/

SLIDE 10

Planetary Seismic Missions

Seismic wave travel times vs distance between source and receiver. From Kovach et al 1973.

SLIDE 11

Planetary Seismic Missions

Moon
Mars
Venus

Apollo 17’s Lunar Seismic Profiling Experiment (LSPE) http://www.dlr.de/pf/en/desktopdefault.aspx/tabid‐8635/

SLIDE 12

Planetary Seismic Missions

Moon
Mars
Venus
Future: InSIGHT – will place a

seismic receiver station on Mars

https://www.nasa.gov/press‐release/nasa‐suspends‐2016‐launch‐of‐insight‐mission‐to‐mars

SLIDE 13

Asteroid Missions

Deep Space 1
Hayabusa 1 & 2
Rosetta
AIM DART
ARM

http://sci.esa.int/rosetta/14615‐comet‐67p/

SLIDE 14

Asteroid Seismic Geophysics

From Walker and Huebner 2004

SLIDE 15

Value of Asteroid Seismic Geophysics

What can we determine through seismic on an asteroid that is useful?
Structure
Strength/rippability
Layering and internal features
Composition… not so much

SLIDE 16

Challenges

Limited mass (sources and receivers, input energy, bandwidth of

returned data)

Low gravity (potentially difficult anchoring)
No atmosphere
Unknown environment
Accurate digital elevation model required for quality imaging
Perturbation of environment during measurement
Attenuation and scattering of seismic signal

SLIDE 17

Emplacement of Seismic Tools

Traditional anchoring, e.g. harpoons (67P)
Releasing a hardening fluid
Penetrators

SLIDE 18

Emplacement of Seismic Tools

The Lunar Net penetrator design. From Smith et al (2012).

SLIDE 19

Emplacement of Seismic Tools

DS2 penetrator schematic in ground. From Lorenz et al 2000.

SLIDE 20

Emplacement of Seismic Tools

Traditional anchoring, e.g. harpoons (67P)
Releasing a hardening fluid
Penetrators
Covering an asteroid with single use receivers and using an impact

source

Laser receiver
More exotic designs – solar sail, ion thrusters

SLIDE 21

Open Questions

What are the effects of an asteroid environment (gravity,

atmosphere, temperature etc) and how do they impact seismic measurement, if at all?

Is there a correlation between surface and

subsurface/geomechanical properties of asteroids?

Can we develop relationships between relevant

parameters and seismic data so we can predict the

utcome of seismic exploration on asteroids?

SLIDE 22

Acknowledgements

Serkan Saydam Robert Anderson Simit Raval Andrew Dempster

SLIDE 23

References

First image credit: https://www.space.com/11093‐photos‐asteroids‐deep‐space‐ rocks.html Walker et al 2006, A preliminary analysis of seismological techniques to study Eros and other asteroids, Adv. in Space Res., 37, 142‐152. Bagaini et al 2010, Land seismic techniques for high‐quality data, Oilfield Review, 22, 28‐39. Kovach et al 1973, The structure of the lunar crust at the Apollo 17 site, Proc. of the Fourth Lunar Sci. Conf., 3, 2549‐2560. Walker and Huebner 2004, Seismological investigation of asteroid and comet interiors, in: Mitigation of Hazardous Asteroids and Comets, Cambridge University Press, Cambridge. Smith et al 2012, Lunar Net – a proposal in response to an ESA M3 call in 2010 for a medium sized mission, Exp. Astron., 33, 587‐644. Lorenz et al 2000, Penetration tests on the DS‐2 Mars microprobes: penetration depth and impact accelerometry, Plan. & Space Sci., 48, 419‐436.