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Contents
The Nordic Regional Planetary Image Facility of Astronomy of Oulu a part of the NASA's Regional Planetary Image Facility (RPIF) organisation. Viking and Voyager images with additional pictures from the Moon and Mercury as well as Venus radar imagery are located at NRIPF on CD-ROMs and/or as prints. Planetary data sets, being superiour in their resolution and coverage to telescopic observations, allow detailed studies on various astronomical, geological and geophysical aspects of planets. Being a regional centre NRPIF helps you to find and study the data acquired by the notable planetary missions of past few decades.
Cytherean studies based on Magellan data
Magellan radar data of the Venus' surface
structures is used to find clues of tectonic and geologic development of
the planet. Along this task we need to know more of the processes active on planets in general. Various volcanic and tectonic structures,
their distribution and special characteristics allow us to estimate
the internal development of a planet while impact craters give information of the age of the surface units as well as of
the past of the planets environment. Magellan data -based studies
are still in the process to materialize in the form of interpretations
and publications over several surface units: Planitiae, Coronae,
Tesserae, Dorsa etc.
Coronae are interpreted to be associated with mantle plume
responsible for the primary uplift and volcanism. Extension is related to active rift tectonics or ascending mantle when heated interiors produce elevated topography with tensional stresses and graben systems. Central collapse or updoming contributed on various phases of graben formation around coronae while many ridges surrounding corona ring bulge were controlled by circumferential compression radial to the corona centre, downslope surface movements or traction of internal flows. The central load-induced stresses then contributed on further bulge and ridge formation over an extended period of time.
Several separate tectonic phases are identified from within
planitiae. Polyphase ridge formation of Sigrun Fossae and Ausra Dorsa is are traced based on cross-cutting relations which give strong arguments for repeated, or superposed, deformation which still has to be put into the right context. The Sel-anya Dorsa is found to be deformed by Fortuna Tessera terrain as seen from the sharp discordance and the surface pattern. Ridge belt formation includes large-scale compression, its concentration into zones, and the moderation of deformation by lithospheric discordance(s). Ridge belts have been formed by repeated thrusting, faulting and folding of crustal units which moved relative to each other. Along some ridge belt -related scarps there are parallel troughs indicating additional flexural surface deformation. Both surface load and subduction-related stresses may have contributed to the crustal bending. Only few impact craters are cought within the process of disappearing bue to lava fill. Based on studies on other planets it should be possible to find some lava-buried craters.
Cytherean highland structures are mostly tensional faults
controlled by crustal block movements, relaxation and/or active mantle.
Parallel main faults of Meshkenet Tessera may be due to right-handed
strike-slip faults or by a dextral faults and anticlockwise rotation.
These faults as well as the possible chocolate tablet boudinage of the
area are still studied along the proceeding of the work which also
includes other small tesserae. The apparent lack of small impact crater
is also a mystery which has to be solved by further studies. One
possibility is thattectonic activity has been effective enough to
remowe, or deform, most of the small impact craters from highlands
and these processes are to identified and addressed in details.
Goal: Magellan data allow us to interpret planet's tectonics,
or how and whyits crustal plates have been deformed, broken, collided
and moved, what has been the driving force and which processes were
involved. Structures indicate that the share of asthenospheric effects
has been very important. To explain observed structures a new paradigm
of the global tectonics or asthenosphere-lithosphere interactions may
be needed. Impact craters and their deformation are used as a test
objects for the effectiveness of geologic forces in various environments.
We have studied Martian local tectonics and volcanism at several
locations. Partly this has been performed to find answers to certain
geologic problems but we have also located certain areas of interest
which can be studied from the future data. The loss of Mars Observer
and delay of Mars94 to Mars96 were real setbacks for all interests
but we will still pursue studies in order to be ready for the new
data when available. All the image data will be distributed for us
in the form of CD-ROMs.
Martian tectonics and volcanism have been studied, partly
in order to make optimal approaches within such areas where some new
understanding can be gained with our limited resources from the
future mission data. New details are critical in understanding
tectonics and development of Tharsis bulge. The formation of Tharsis-
radial grabens may offer evidences of ascending mantle. Claritas
Fossae
and Alba Patera are defined for further studies in order to find to
which extent they represent rift tectonics and evidences of active-
passive rifting. Circumferential wrinkle ridge formation may have
depended on downslope slide, vertical intrusions & extrusions, mantle
flow traction, load-induced isostacy stresses, changes in internal
temperature and phase changes. The extent of how much ridge morphology,
location and orientation are controlled by Tharsis-related forces
evidende deformation processes.
The abundance of highland wrinkle ridges on Mars indicates
that during Martian global development crustal shortening has been
much more important than on the Moon but less important than on Mercury.
Highland ridges are controlled by contraction of Martian interiors,
volcanic loads or ancient impact basins. Although later events have
masked the original thermal, pressure and phase change-related
deformation the high-resolution data gives further details revealing
terra development due to surface loading and large-scale volume
decrease(s) of interiors. Secular cooling of the interiors, drying-up
of the magma, phase transitions, and differentiation must be taken
into account in explaining the formation of the compressional
structures of Mars.
Structures of Alba Patera are found to indicate tension,
rifting and asthenosphere effects. Many faults have been active
after main volcanism. Details of faults and their cross-cutting
relations with each other and lava flows give information of the
deformation sequence. Peripheral lava flows seem to have had
extremely low viscosity and high effusion rate and they may have
extruded directly from a primary source. These lava flows may be
rather original in their composition (komatitic?) and thus
indicative of Martian internal development. Various dimensions and
fractality of the lava lobes have been measured and mapped related
to their environment. The long-term caldera development has been
due to the lava load and withdraval and cooling of the magma. Mare
ridges of Syrtis Major Planum indicate compressional environment and
areal changes in compressional stress directions.
Goal: When being in the process to identify problems to
be studied and solved from future data we have concentrated into
a few aspects of Martian development. This allows us to make optimal
approaches to get better understanding of areology.
We are studying planetary craters from space imagery and Magellan radar data and we also sample and study
Fennoscandian and other
impact craters with local geologists. Planetary impact craters
are studied from space-borne remote sensing imagery
in order to find their usefulnes for various tasks such as event timing and defining space, time and target -related variations in craters and thus in amounts of impacted bodies. Several Cytherean impact craters display impact-induced lava flows, fractures and tectonics related to high-temperature environment. On the other hand some terrestrial crater impactites and target rocks are sampled in order to study details of impact processes and the effects impact explosion -related phenomena in the target rocks.
Jänisjärvi, Lappajärvi rocks display target geology, partial melting, milling and shock-metamorphosis due to high temperature-pressure regime. Samples from impact craters have revealed some compositional post-impact changes taken place in impact-resistant minerals. Very old
Suavjarvi rocks are only remains of ancient impactite breccias suffered of later regional metamorphosis.
Goal: Impacts have had an extremely important role on the
deformation of planetary surfaces. Such craters are studied from space imagery in order to find their usefulnes for various tasks such as event timing and defining space, time and target -related variations in craters and thus in amounts of impacted bodies. On the other hand the old Fennoscandian basement allows us to make hands-on search, sample and study work on various
impact-related processes which are otherwise unable to be reached.
The previous Clementine fight
produced only middle-resolution data of the Moon. Lunar Prospector did not have any imaging device.
The MORO (Moon ORbiting Observatory) proposal of
ESA was intended to give the necessary global data on Moon geology, geophysics, geochemistry and tectonics. MORO with its hi-res instruments was targeted for a 2000+ launch but failed in political issues.
High-resolution multispectral data of lunar surface would allow
to study its geological units and events and find evidences of the local
and global history of the body. Such detailed composition-related data
over various fault surfaces together with similar information of walls
and central peaks of impact craters on the Moon's surface allow limited
3-dimensional mapping of the crustal units. The surface units have also
to be studied in order to find their usefulnes for various purposes and
tasks in furter utilization of the Moon.
Goal: All the existing data have to be studied in details in
order to define the most appropriate areas and problems which have to
be approached by the future lunar program.
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