M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
M.A.D.A.N.A.C
Measurement And Discovery of Asteroids and NEOs in
AntarctiCa
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Physical characterization is losing the race against discovery
(Data from Tedesco, private communication)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Near-Earth Objects: What We Would Like To
Know Better
• Inventory and Size Distribution
• Asteroidal/Cometary Contribution
• Origin, History and Evolution
• Composition
• Internal Structure: Density, Impact Strength, Macroscopic
Porosity
• Regolith Properties
• Spin rates
• Binarity
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
How to improve our knowledge on:
Statement from the conclusions of the Erice Space Chemistry School, July
2001 on “The Physical Properties of Potential Earth Impactors: Know Your
Enemy”
• The most crucial datum needed for assessing the NEO hazard is the size of the
objects. This information is lacking for the majority of known NEOs and is the
highest measurement priority after discovery and orbit determination.
• Masses and densities?
 In situ Exploration
• Internal structures?
 In situ Exploration
• How many?
• Size and albedo
distribution?
• Taxonomic distribution?
 Remote Observations
 Remote Observations
 Remote Observations
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
PHOTOMETRY
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
Thermal
Radiometry
Asteroids emit
both scattered
sunlight at
visible
wavelengths,
and thermal
radiation in the
IR.
Simultaneous
measurement of
V and thermal IR
fluxes lead to
determination of
albedo and size.
A. Cellino Osservatorio di Torino I.N.A.F
NEOs are
bright in
the thermal
IR !
(Courtesy of S. Price)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
THE (923) HERLUGA FIELD IN
THE VISIBLE AND IR (MSX Observations)
(Courtesy of S. Price)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
For D = 1 km
and pV= 0.16
Microns
12
8.5
4.7
0.55
(Computations by E.F.
Tedesco)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Diameter in Km as a function of albedo (visible))
1 UA
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
(data from E.F. Tedesco)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Advantages of mid-IR observations of
NEOs
Radiometryallows
allowstotoobtain
obtainsizes
sizesand
andalbedos
albedos
• •Radiometry
Objectsare
arebright
brightatatmid-IR
mid-IRwavelengths
wavelengths
• •Objects
Stellarbackground
backgroundsubstantially
substantiallyreduced,
reduced,even
evenatatlow
lowgalactic
galacticlatitudes
latitudes
• •Stellar
Modestdependence
dependenceofofIRIRluminosity
luminosityon
onphase
phaseangle
angle
• •Modest
… but from the ground, in recent years, no more than 10
NEOs per year on the average have been observed in the
thermal IR.
Most of the available IR data have been obtained
so far by space missions (IRAS, MSX)
Jon Lawrence and Michael Burton
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
POLARIMETRY
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Polarimetry
This technique is based on some empirical relationships
between the degree of linear polarization (measured through
the Stokes parameters Q and U) and the surface albedo.
What is usually measured is the parameter:
Pr = ( I- I ) / ( I + I//)
Where I and I are the intensities of the components linearly
polarized along the directions perpendicular and parallel to the
scattering plane, respectively.
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Polarization curve of 1
Ceres
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
The slope –
albedo
relationship
(from Dollfus et al.,
1989)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Polarimetry in IR : never done at this moment
Inputs to models
A new way to classify taxonomy ?
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
SPECTROSCOPY
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Asteroid
Taxonomic
Classes
(from Tholen and Barucci,
1989)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
a): Ni-Fe
b): Olivine
c): Ortopyroxene
d): Feldspar
e): Spinel
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
IR spectroscopy (or color-photometry)
allows to discriminate taxonomic types
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
DETECTION
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
Aten objects: a < 1, Q > 0.983 AU
Solar elongations vs. Earth distance
Orbital evolution of 21 Atens
(821 yrs). Solar elongations
vs. Earth distance every 40
days.
Large dots: Mv < 16
Medium dots: 16 < Mv < 18
Small dots: 18 < Mv < 20
(integrations made by Boattini and
Carusi)
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
IEOs: a class of NEOs totally
interior to the Earth’s orbit
In addition to Atens, a new class of objects, with orbits
completely inside Earth’s orbit, have been found to exist
necessarily, through numerical integrations of NEO
Where on earth can
orbits performed in 2000. These objects have been
called IEOs (objects
Interiorobservations
to Earth’s Orbit).
we make
These objectsinare
extremely
to discover,
due to
direction
of hard
the sun
…?
the difficulty of observing them from ground, since
they never are visible at large solar elongations.
The first IEO discovery has been made by LINEAR not
earlier than 2003.
M.A.D.A.N.A.C
Ph. Bendjoya L.U.A.N-U.N.S/C.N.R.S
A. Cellino Osservatorio di Torino I.N.A.F
There are things to do at Dome C for asteroids:
Discoveries :
NEOs, IEOS but also MBAs and TNOs
Measurements:
albedo, size, taxonomy: photometry, spectroscopy,
polarimetry
Great benefits of IR
M.A.D.A.N.A.C could (should ?) exist….