THE THREE THARSIS MONTES BY NASA VIKING 1 ORBITER

NASA VIKING PROGRAM (1975-1982) 

The three Tharsis Montes:

Ascraeus Mons (18, 225m / 18, 1 kms - 50, 793 ft / 11, 1mi)  

Pavonis Mons (14, 000m / 14km - 46, 000ft / 8,7 mi) 

Arsia Mons (17, 761 m  17 / - 58, 721ft / 11 mi)

MARS 

1. The Three Tharsis montes  photographed in 1980 by Viking1 orbiter 

2. Arsia Mons,  Viking mosaic showing the massive side lobes on the southwest (top) and northeast (bottom) sides of the volcano

The volcanoes 
The three Tharsis Montes (Fountains mountains in latin) are three large shield volcanoes in the Tharsis region of the planet Mars. From north to south (up to down on the image), the volcanoes are:  : Ascraeus Mons,  Pavonis Mons and Arsia Mons named by Giovanni Schiaparelli after the legendary Roman forest of Arsia Silva.
Arsia Mons (17, 761 m  17 / - 58, 721ft / 11 mi) is the southernmost of three volcanos (collectively known as Tharsis Montes) on the Tharsis bulge near the equator of the planet Mars, the tallest volcano in the solar system, Olympus Mons, is to its northwest.
Arsia Mons (down left on the  first photo) is a shield volcano with a relatively low slope and a massive caldera at its summit.
The three Tharsis Montes, together with some smaller volcanoes to the north, form a rather straight line. It has been proposed that these are the result of plate tectonics, which on Earth makes chains of "hot spot" volcanoes.
The Tharsis Montes volcanoes lie near the equator, along the crest of a vast volcanic plateau called the Tharsis region or Tharsis bulge.
The three Tharsis Montes volcanoes are evenly spaced about 700 km (430 mi) apart from peak to peak, in a line oriented southwest-northeast. This alignment is unlikely to be coincidental.

The mission 
Viking 1 Orbiter color mosaic of the eastern Tharsis region on Mars. At left, from top to bottom, are the three 25 km high volcanic shields, Ascraeus Mons, Pavonis Mons, and Arsia Mons. The shield at upper right is Tharsis Tholus. The canyon system at lower right is Noctis Labyrinthus, the westernmost extension of Valles Marineris. The smooth area at bottom center is Syria Planum. The distance between the calderas of Ascraeus and Pavonis Mons is 800 km. North is up. The images used to produce this mosaic were taken during orbit 1334 on 22 February 1980.

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2018 - Wandering Vertexes...
by Francis Rousseau 

PAVONIS MONS BY NASA MARS GLOBAL SURVEYOR

 NASA MARS GLOBAL SURVEYOR  (1996-2007), 

Pavonis Mons (14,000m / 14km - 46,000ft / 8,7 mi) 

MARS

The mountain 

Pavonis Mons (14,000m / 14km - 46,000ft / 8,7 mi)  latin for "peacock mountain" is a large shield volcano located in the Tharsis region of the planet Mars. It is the middle member of a chain of three volcanic mountains (collectively known as the Tharsis Montes) that straddle the Martian equator between longitudes 235°E and 259°E. The volcano was discovered by the Mariner 9 spacecraft in 1971 and was originally called Middle Spot. Its name formally became Pavonis Mons in 1973.

Using NASA Mars Global Surveyor  and Odyssey data, combined with developments in the study of glaciers, scientists suggest that glaciers once existed on Pavonis Mons and probably still do to some extent.  Evidence for this includes concentric ridges (moraines "dropped" by glaciers), a knobby area (caused by ice sublimating), and a smooth section that flows over other deposits (debris-covered glacial ice). The ice could have been deposited when the tilt of Mars changed the climate, thereby causing more moisture to be present in the atmosphere. Studies suggest the glaciation happened in the Late Amazonian period, the most recent period in Mars chronology. Multiple stages of glaciation probably occurred. The ice present today represents one more resource for possible future colonization of the planet.

The mission
Mars Global Surveyor (MGS) was an American robotic spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 7, 1996. Mars Global Surveyor was a global mapping mission that examined the entire planet, from the ionosphere down through the atmosphere to the surface.  As part of the larger Mars Exploration Program, Mars Global Surveyor performed monitoring relay for sister orbiters during aerobraking, and it helped Mars rovers and lander missions by identifying potential landing sites and relaying surface telemetry.
It completed its primary mission in January 2001 and was in its third extended mission phase when, on 2 November 2006, the spacecraft failed to respond to messages and commands. A faint signal was detected three days later which indicated that it had gone into safe mode. Attempts to recontact the spacecraft and resolve the problem failed, and NASA officially ended the mission in January 2007.
The Mars Orbiter Camera (MOC) science investigation used 3 instruments: a narrow angle camera that took (black-and-white) high resolution images (usually 1.5 to 12 m per pixel) and red and blue wide angle pictures for context (240 m per pixel) and daily global imaging (7.5 km per pixel). MOC returned more than 240,000 images spanning portions of 4.8 Martian years, from September 1997 and November 2006.[6] A high resolution image from MOC covers a distance of either 1.5 or 3.1 km long. Often, a picture will be smaller than this because it has been cut to just show a certain feature. These high resolution images may cover features 3 to 10 km long. When a high resolution image is taken, a context image is taken as well. The context image shows the image footprint of the high resolution picture. Context images are typically 115.2 km square with 240 m/pixel resolution.