Transcript Immature lunar formations and palaeoregolith deposits as

Immature lunar formations and
palaeoregolith deposits as sources
of information about history of the
Solar System
Sinitsyn M.P.
Lunar and planetary investigations division
Sternberg Astronomical Institute
Moscow State University
Tree types of radiations(SW,SCR,GCR) affecting
the surface of the Moon
SW
- Energy of the nucleons
- Proton flux
(1/cm**2sek)
- ratio of the
protons/alpha particles
- penetration depth
of protons and alpha part.
heavy nuclides
- composition (%):
protons
alpha
more heavy
0.3-3 kev/u
3*10E8
~22
~micron
~micron
SCR
GCR
1-100Mev/u
0.1-10Gev/u
0-1*E6
2-4
~60
~7
centimeters meters
millimeters
centimeters
~ 85-90 %
~ 10 %
~1%
A typical shock formation structure
Immature impact melt as a possible source of information
about the last 200 million years of lunar history
• fresh impact in Oceanus
Procellarum. At the bottom of
the crater can be seen impact
melt.
•
Farside fresh impact. Visible
jet of the melt on the slopes
and close to the edge of the
crater.
(Images produced by LROC)
Impact melt at the edge of the immature craters
 Impact melt on the slope and at
the edge of crater rim (slope and
horizontal)

Impact melt of the Giordano
Bruno fresh crater about 6 km
away from edge (horizontal
surface)
(images of LROC)
Some impact melts
•
Impact melts on the Ticho crater floor
.
•
Blocked impact melt on the
Giordano Bruno crater floor. It is
possible to obtain a vertical column
of this melt without drilling
(LROC Images)
Increased hydrogen concentration of some
immature(fresh) impact craters by Lunar Prospector
Neutron Spectrometer results

Crater Proclus, 20-40 mil. yrs
Crater
Aristarchus, ~60 mil. yrs
Crater
Timocharis, ~80 mil. yrs
The hydrogen content in marine formations of the
Moon according to the LPNS
LROC image and hydrogen
distribution on the Mare Nectaris
neighborhood
Crater Cleomed (with the seabed) and
the north coast of Mare Crisium
Hydrogen distribution on the border
of highland and Mare Crisium
Mare Crisium
Highland
Some additional features of the distribution
of hydrogen
Distribution of hydrogen
Hydrogen anomaly in the vicinity
Distribution of hydrogen in in the Appeniny
of Fra- Mauro (~ 200 ppm)
the Caucasus mountains mountains
The vertical column of the lunar regolith, delivered
by Apollo-12 spacecraft
• digging depth of 3 meters
• this depth corresponds to 3
billion years of lunar
history...
• ...but, regolith is
considerably mixed
• there is a large number of
tracks
• Is it possible to detect not
mixed regolith?
Palaeoregolith
•
Any regolith, located between the two lava flows at a depth
of 3 meters can be considered closed to cosmic radiation
•
Traces of Cosmic Rays in palaeoregolite have very precise
information relating to a specific time period.
• One of the possible problems of the LROC is to determine
the locations of places of occurrence of palaeoregolith
layers.
Palaeoregolith on Bessel crater’ slope
•
Creter Bessel
Mare Serenitatis,
Diameter 16 km
Depth 1,7 km.
•
Location basalt layers one above
the other on the wall of Bessel
crater. The palaeoregolith layers
are clearly visible between the
layers of basalt.
(LROC Images)
Palaeoregolith on Euler crater’ slope
•
Creter Euler
Mare Imbrium,
Diameter 28 km
Depth
2.2 km.
•
The palaeoregolith between
basalt layer on the slope of
Euler crater.
(LROC Images)
Possible source of palaeoregolith on terraces of
Necho and Burg craters
•
Necho crater with terraces
Mare Imbrium,
Diameter 30 km
Depth 2.1 km.
•
Possible source of
palaeoregolith on terraces
of Burg crater (d=40 km.
depth =1.8 km)
(LROC Images)
Tectonic and volcanic extended objects are
Possible source of palaeoregolith
• As a result of tectonic
forces generated any
breaks the surface
(faults).
• Some faults can expose
deposits of
palaeoregolith.
New formation of modern palaeoregolith
(preserved regolith) layers.
• Formation preserved
regolith under new
volcanic lava.
The volcanic lava of
resent volcano of
Tsiolkovsky crater.
• Formation preserved
regolith under impact
melt flow on edges of
any craters rims.
Potential information about Solar System history that possible
to obtain from an impact melt and palaeoregolith
•
•
•
Concentration of volatile isotopes (H,He,Ar,Ne,Xe,N) in the lunar regolith make
it possible to trace the changes of the solar wind for up to 4 billion years.
There are serious reasons to believe that the ancient solar wind flow was 2-3
times higher. This is indicated by the steady increase in the ratio of nitrogen
isotopes 15 N /14N .
7
7
Changes in the depth of penetration of solar wind to the minerals give the
opportunity to explore the change of energy of solar wind protons.
•
Studies of galactic cosmic rays for a period of up to 4 billion years, will provide
an opportunity to reconstruct the history of motion of solar system around the
galactic center (the periods of passage through galactic arms).
•
Studies of galactic cosmic rays over the period to 200 million years will provide
an opportunity to reconstruct the history of galactic events around the Solar
System (eg supernova explosions).
• Correlation of galactic events with periods of evolution of life.
Summary