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M.A.D.A.N.A.C Measurement And Discovery of
Asteroids and NEOs in AntarctiCa
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Physical characterization is losing the race
against discovery
(Data from Tedesco, private communication)
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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

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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?
• Internal structures?
• How many?
• Size and albedo distribution?
• Taxonomic distribution?

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PHOTOMETRY
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Thermal Radiometry
NEOs are bright in the thermal IR !
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.
(Courtesy of S. Price)
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THE (923) HERLUGA FIELD IN THE VISIBLE AND IR
(MSX Observations)
(Courtesy of S. Price)
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For D 1 km and pV 0.16
Microns 12 8.5 4.7 0.55
(Computations by E.F. Tedesco)
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Diameter in Km as a function of albedo (visible))
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(data from E.F. Tedesco)
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Advantages of mid-IR observations of NEOs

• Radiometry allows to obtain sizes and albedos
• Objects are bright at mid-IR wavelengths
• Stellar background substantially reduced, even
  at low galactic latitudes
• Modest dependence of IR luminosity on phase angle

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)
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POLARIMETRY
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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.
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Polarization curve of 1 Ceres
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The slope albedo relationship
(from Dollfus et al., 1989)
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Polarimetry in IR never done at this moment
Inputs to models A new way to classify taxonomy ?
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SPECTROSCOPY
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Asteroid Taxonomic Classes
(from Tholen and Barucci, 1989)
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a) Ni-Fe b) Olivine c) Ortopyroxene d)
Feldspar e) Spinel
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IR spectroscopy (or color-photometry) allows to
discriminate taxonomic types
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DETECTION
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Aten objects a lt 1, Q gt 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 lt 16 Medium dots 16 lt Mv lt
18 Small dots 18 lt Mv lt 20
(integrations made by Boattini and Carusi)
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IEOs a class of NEOs totally interior to the
Earths orbit
In addition to Atens, a new class of objects,
with orbits completely inside Earths orbit, have
been found to exist necessarily, through
numerical integrations of NEO orbits performed in
2000. These objects have been called IEOs
(objects Interior to Earths Orbit).
Where on earth can we make observations in
direction of the sun ?
These objects are extremely hard to discover, due
to 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.
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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.