Evaluation of the potential landing sites for Venus Entry Probe Mission.

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Evaluation of the potential landing sites for
Venus Entry Probe Mission.

• J.Leitner1, M.Aittola2, V-P.Kostama2, T.Törmänen2
  and M.G. Firneis1.
• 1Dept. of Astronomy, University of Vienna,
  Austria, 2Division of Astronomy, Department of
  Physical Sciences, P.O. Box 3000, 90014
  University of Oulu, Finland (marko.aittola_at_oulu.fi
  ),

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Criteria for selecting the landing sites

• When selecting the landing sites we have to
  consider several important aspects
• The primary scientific goals of the VEP
  initiative regarding the surface and interior.
• The data provided by Venera mission
• We have to reckon with the fact that we do not
  yet know the final instrumentation of the descent
  probe. Therefore, we should select the target
  sites, which would serve the versatile scientific
  goals.
• To take into an account the impact craters and
  possible airfall material produced by the
  cratering events.

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Proposed target types

• Uplands
• The main reasons to select the higher plateaus as
  the areas to be studied by descent probes, are
  the age and the nature of tessera terrains.
• It is accepted that the tessera areas are among
  the oldest units in the Venusian surface
  although not necessarily formed simultaneously.
• Furthermore, the composition of tessera material
  is still unknown not studied by the Venera
  landers - and rather pristine compared to the
  other surface, which is covered by younger mafic
  lava flows.
• It should be extremely important to sample this
  still unknown material of the Venusian surface.
• Tessera terrains should be ranked first when
  selecting the landing sites.

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Proposed target types

• Alternative landing sites
• In the case of several (4) landers, we should be
  able to determine landing site, which provide
  divergent surface characteristics.
• We have to consider the altitude differences
  (highland-lowland weathering conditions),
  divergences in target ages, good coverage
  (north-south) etc.
• In contrast to supposedly old tessera terrain, we
  should also find the landing site on the
  fresh-looking lava-flow.
• If we can define the source for the lava flow, we
  can analyze the properties of certain type of
  volcanic feature.
• This landing site could be for example in
  connection to high-standing corona(volcano)-featur
  e with fresh lava flows.
• Depending the instrumentation, also good site to
  study the heat balance of the planet

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Proposed target types

• Alternative landing sites
• To sample the lavas of older volcanic activity
  and to have a sample from lower altitudes, the
  destination of one descent probe could be in the
  lowlands, where there is no evidence of recent
  lava flows.
• The last landing site could represent an example
  of probable more exotic Venusian surface
  composition to have an idea how heterogeneous the
  surface is.
• Steep sided domes, pancake volcanoes,
• high reflectance area, e.g. in Ishtar Terra.
• Also, regarding the quality of the camera
  onboard, the micro-dune fields could provide
  important information from the interaction of the
  loose material and the low-altitude wind as well
  as the composition.

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Detailed landing sites

• Ovda Regio.
• Defines the western part of Aphrodite Terra
• The largest crustal plateau on Venus.
• Located mostly on the equator from 50E to 110E
  and from 5N to 15S, covering 1.5 x 107 km2.
• Why this region would be good landing site?
• It is a good example of tessera terrain,
• It is not studied by Venera landers,
• Tesserae could represent the areas of
  non-basaltic crust? (at least can be something
  different than analyzed by Venera landers),
• We have relative good topographic data from the
  region
• It is located on high altitude (weathering
  conditions),
• It is large enough to find a appropriate landing
  site,
• We have geologic map from the Eastern side of the
  Ovda (e.g. Carter Crater).

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Detailed landing sites
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Detailed landing sites

• Pavlova Corona (14N/40E Eastern Eistla Regio).
• The landing site from where we can sample the
  young lava flows inside a corona structure.
• Relatively high elevation (corona itself 6052.88
  km and the nova 6053.06 km) and represent rather
  young volcanic activity.
• The size and the topography will make it easy
  target, because it is relatively large (360 x 400
  km) and flat, excluding the radial structure on
  the western part of the corona.
• There is only one small crater to the NWW from
  the target site, and no evidence that its airfall
  deposit would overlay the young lava flows.

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Detailed landing sites

• Pavlova Corona (14N/40E)
• corona floor altitude 6052.88 km
• 6053.26 km

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Detailed landing sites

• Mbokomu Mons (15S/215).
• Same kind of target than Pavlova corona
• Alternative landing site of this type.
• Also located on highland and represents young
  volcanism.
• hybrid structure (characteristic of both
  volcano and corona),
• The lack of the impact craters on the eastern
  side of it
• no disturbing airfall material, and also the
  lava flows which provide relative smooth landing
  site.
• These both corona structures (Pavlova and Mbokomu
  Mons) are rather well studied ? general interest

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Detailed landing sites

• Mbokomu Mons (15S/215)
• Highest point 6053,16 km
• Floor 6052,65 km

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Detailed landing sites

• Neyterkob-Cerridwen (49,5N/203)
• As a site to sample the lowland material and
  older lava fields as well as to get good global
  coverage
• Is located on Ganiki Planitia.
• Consists of two circular components (double
  corona)
• Both of which are ? 200 km wide with the floor
  altitude of 6051.1 km.
• Located in lowlands as a rather isolated feature.
  
• Relative easy to land due to the large size and
  rather smooth interiors. (small shields)
• The structure is located close to the impact
  crater the southwest of it.
• The airfall deposit can cover the western part of
  the structure, but there are no impact craters to
  the east of the area.
• In the case that instrumentation enable the
  studies of heat balance, the double corona target
  would be useful

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Detailed landing sites

• Neyterkob-Cerridwen (49,5/203)
• Floor altitude 6051.1 km

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Detailed landing sites

• Steep-sided domes pancake volcanoes
• On Venus the shape of the shield volcanoes,
  length of the lava flows and the data received by
  the Venera landers all suggest that the volcanism
  is basaltic.
• The pancakes are circular flat-topped volcanic
  domes on the Venusian surface
• Their unusual morphology suggests that they may
  have a composition different from that of shield
  volcanoes on Venus.
• Possible area of this kind is located on Eistla
  Regio (Carmenta Farra 13N/8E), which includes
  group of pancake domes.
• The largest of these domes is 65 kilometers
  across.
• Small impact crater to the east of them ?
  Possible airfall deposits?
• Other possibe site is the pancakes related to
  Aine Corona (59S/169E)

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Detailed landing sites
100 km

• Pancake volcano
• Located on Eistla Regio (Carmenta Farra)
  (13N/8E)

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Detailed landing sites

• Pancake volcano
• Located at 13N/8E, on the annulus of Aine
  Corona

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Detailed landing sites
Ishtar Terra
Neyterkob-Cerridwen old lowland
Pavlova Corona young lava flow
Carmenta Farra pancakes
Ovda Regio tessera
Mbokomu Mons young lava flow
Aine Corona pancakes
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Summary

• The most important target type for landing site
  is tessera terrain (1).
• Possible other landing sites should selected so
  that they would represent as versatile properties
  of the Venusian surface as possible.
• The landing sites of this kind could be for
  example
• Young lava flows in association with e.g. corona
  structure (2),
• Older lava fields in lowlands (3)
• Some target that would represent unusual
  properties of the surface, e.g. so called
  pancakes (4).