OLYMPUS MONS / PLANÈTE MARS PHOTOGRAPHIÉ PAR NASA VIKING ORBITER 1

NASA VIKING ORBITER  (1975-1982)
Olympus Mons (21, 229 mètres soit 21, 2 km d'altitude)
Planète Mars (Voie Lactée)

D'après une photographie prise en 1979, à 5000 km de hauteur, retouchée par IA en 2020. 

Photo originale prise par la sonde NASA Viking Orbiter 1 en 1979.

Le  volcan
Olympus Mons (21, 2 km)  nom latin pour « mont Olympe », est un volcan bouclier de la planète Mars situé dans les quadrangles d'Amazonis et de Tharsis. C'est le plus haut relief connu du système solaire, culminant à 21 229 mètres au-dessus du niveau de référence martien selon les mesures très précises de l'altimètre laser de Mars Global Surveyor (ancienne mesure 22 500 mètres). Son impressionnant diamètre est de 648 km, c'est à dire qu'il couvrirait la plus grande partie du territoire français et Suisse s'étendant de Bordeaux à Genève et de Paris à Montélimar !
Il se trouve sur la bordure nord-ouest du renflement de Tharsis, immense soulèvement de la surface martienne, centré sur Noctis Labyrinthus et Syria Planum, dont l'extension occidentale concentre une douzaine de volcans majeurs..
L'édifice central s'élève à  deux fois et demie la hauteur de l'Everest par rapport au niveau de la mer et plus du double de celle du Mauna Kea (Hawaï) par rapport à sa base  Il possède à son sommet une caldeira complexe d'environ 80 × 60 kilomètres résultant de la coalescence d'au moins six cratères enchevêtrés, attestant de l'histoire mouvementée de la caldeira avec notamment la présence de grabens résultant de l'effondrement de la surface dans une faille.
Il est entouré d'une falaise formant un escarpement continu sur toute sa circonférence, d'une hauteur de 2 à 6 kilomètres. Au-delà de cet escarpement se trouve une zone souvent appelée « l'auréole » du volcan, constituée de crêtes et de grands blocs s'étendant jusqu'à un millier de kilomètres de la caldeira. Cela met en évidence l'expansion et la modification de la surface liées à l'activité glaciaire.
L'inclinaison des pentes du volcan est voisine de 5 degrés en moyenne, atteignant 30 degrés au niveau de l'escarpement périphérique.
À proximité de la caldeira se trouvent deux cratères d'impact. À une vingtaine de kilomètres au sud, le cratère Pangboche a un diamètre de 10,4 kilomètres. Il a été nommé par l'Union astronomique internationale en 2006 d'après une localité du Népal située à vingt kilomètres du sommet de l'Everest. C'est sur le rebord ouest de ce cratère que se trouve le point le plus haut d'Olympus Mons, à 21 229 mètres au-dessus du niveau de référence. Le cratère Karzok, situé à une quarantaine de kilomètres à l'est de la caldeira, a un diamètre de 15,6 kilomètres. Il a été nommé d'après une localité du Cachemire indien. D'autres cratères d'impact sont également visibles sur les flancs du volcan.
L'escarpement et l'auréole sont tous deux mal compris. La falaise résulterait de glissements de terrain, et l'auréole proviendrait des matériaux entassés au bas de ces glissements. Les coulées de lave s'étendent au-delà de l'escarpement. L'escarpement qui entoure la montagne à sa base aurait été formé par des glissements de terrain induits par une fonte massive du permafrost11 ou par un soulèvement tectonique. Les structures linéaires en forme de crêtes présentes autour du volcan au-delà de l'escarpement seraient, quant à elles, des dykes mis en place après les dernières coulées de lave ayant atteint la base du volcan. Son premier nom, Nix Olympica, en français « Neige de l'Olympe », lui avait été donné par l'astronome italien Giovanni Schiaparelli (1835-1910). 

La mission
NASA Viking Orbiter 1 était le premier des deux engins spatiaux (avec Viking 2) envoyés sur Mars dans le cadre du programme Viking de la NASA. Le 20 juillet 1976, il est devenu le deuxième vaisseau spatial à atterrir en douceur sur Mars, et le premier à réussir sa mission. (Le premier vaisseau spatial à atterrir en douceur sur Mars était le Mars 3 de l'Union soviétique le 2 décembre 1971, qui a cessé de transmettre après 14,5 secondes.) Viking 1 détenait le record de la plus longue mission de surface de Mars de 2307 jours (plus de 6 1⁄ 4 ans) ou 2245 jours solaires martiens, jusqu'à ce que ce record soit battu par le rover Opportunity le 19 mai 2010. Après le lancement à l'aide d'un lanceur Titan/Centaur le 20 août 1975 et une croisière de 11 mois vers Mars, l'orbiteur a commencé à renvoyer des images globales de Mars environ 5 jours avant l'insertion en orbite. L'orbiteur Viking 1 a été inséré dans l'orbite de Mars le 19 juin 1976 et ajusté à une orbite de certification de site de 1513 x 33 000 km, 24,66 h le 21 juin. L'atterrissage sur Mars était prévu pour le 4 juillet 1976, le bicentenaire des États-Unis, mais l'imagerie du site d'atterrissage principal a montré qu'il était trop difficile pour un atterrissage en toute sécurité. L'atterrissage a été retardé jusqu'à ce qu'un site plus sûr soit trouvé et a eu lieu à la place le 20 juillet, le septième anniversaire de l'alunissage d'Apollo 11. L'atterrisseur s'est séparé de l'orbiteur à 08:51 UTC et a atterri à Chryse Planitia à 11:53:06 UTC. C'était la première tentative des États-Unis d'atterrir sur Mars.
Les instruments de l'orbiteur se composaient de deux caméras vidicon pour l'imagerie (VIS), d'un spectromètre infrarouge pour la cartographie de la vapeur d'eau (MAWD) et de radiomètres infrarouges pour la cartographie thermique (IRTM). La mission principale de l'orbiteur s'est terminée au début de la conjonction solaire le 5 novembre 1976.
La mission prolongée a commencé le 14 décembre 1976, après la conjonction solaire. Les opérations comprenaient des approches rapprochées de Phobos en février 1977. Le périastre a été réduit à 300 km le 11 mars 1977. Des ajustements mineurs d'orbite ont été effectués occasionnellement au cours de la mission, principalement pour modifier le taux de marche - le taux auquel la longitude aréocentrique changé à chaque orbite, et le périastre a été porté à 357 km le 20 juillet 1979. Le 7 août 1980, Viking 1 Orbiter manquait de gaz de contrôle d'attitude et son orbite a été portée de 357 × 33943 km à 320 × 56000 km pour éviter l'impact avec Mars et une éventuelle contamination jusqu'en 2019. Les opérations ont pris fin le 17 août 1980, après 1485 orbites. Une analyse de 2009 a conclu que, même si la possibilité que Viking 1 ait eu un impact sur Mars ne pouvait être exclue, il était très probablement toujours en orbite. Plus de 57 000 images ont été renvoyées sur Terre.

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2023 - Gravir les montagnes en peinture...
Un blog de Francis Rousseau

 

OLYMPUS MONS (ON MARS) PHOTOGRAPHED BY NASA MARS GLOBAL SURVEYOR

NASA MARS GLOBAL SURVEYOR  (1996-2007)
Olympus Mons (21, 230m - 69,650ft)
Mars (Solar system)

The Volcano
Olympus Mons (21, 230m / 21, 2 km-  69,650 ft /1 3 mi) is a very large shield volcano located on the planet Mars,  the largest volcano in the solar system. The massive Martian mountain towers high above the surrounding plains of the red planet, and may be biding its time until the next eruption.By one measure, it has a height of nearly 22 km (13.6 mi). Olympus Mons stands about two and a half times as tall as Mount Everest's height above sea level. It is the youngest of the large volcanoes on Mars, having formed during Mars's Hesperian Period. It had been known to astronomers since the late 19th century as the albedo feature Nix Olympica (Latin for "Olympic Snow"). Its mountainous nature was suspected well before space probes confirmed its identity as a mountain.

The volcano is located in Mars's western hemisphere at approximately 18.65°N 226.2°E, just off the northwestern edge of the Tharsis bulge. The western portion of the volcano lies in the Amazonis quadrangle (MC-8) and the central and eastern portions in the adjoining Tharsis quadrangle (MC-9).

Two impact craters on Olympus Mons have been assigned provisional names by the International Astronomical Union. They are the 15.6 km (9.7 mi)-diameter Karzok crater (18°25′N 131°55′W) and the 10.4 km (6.5 mi)-diameter Pangboche crater (17°10′N 133°35′W). The craters are notable for being two of several suspected source areas for shergottites, the most abundant class of Martian meteorites. Olympus Mons and a few other volcanoes in the Tharsis region stand high enough to reach above the frequent Martian dust-storms recorded by telescopic observers as early as the 19th century. The astronomer Patrick Moore pointed out that Schiaparelli (1835–1910) "had found that his Nodus Gordis and Olympic Snow [Nix Olympica] were almost the only features to be seen" during dust storms, and "guessed correctly that they must be high". The Mariner 9 spacecraft arrived in orbit around Mars in 1971 during a global dust-storm. The first objects to become visible as the dust began to settle, the tops of the Tharsis volcanoes, demonstrated that the altitude of these features greatly exceeded that of any mountain found on Earth, as astronomers expected. Observations of the planet from Mariner 9 confirmed that Nix Olympica was not just a mountain, but a volcano. Ultimately, astronomers adopted the name Olympus Mons for the albedo feature known as Nix Olympica.

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.

The Mars Orbiter Laser Altimeter, or MOLA, is an instrument on the Mars Global Surveyor (MGS), a spacecraft that was launched on November 7, 1996. The mission of MGS was to orbit Mars, and map it over the course of approximately 3 years, which it did sucessfully, completing 4 1/2 years of mapping.
Determining the height of surface features on Mars is important to mapping it. To this end, MGS carried a laser altimeter on board. This instrument, MOLA, collected altimetry data until June 30, 2001. MOLA then operated as a radiometer until October 7, 2006.
This website will explain what MOLA is and how it works, and share some of the important discoveries about Mars that have been made using MOLA data.

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2021 - Wandering Vertexes...
by Francis Rousseau

ELYSIUM MONS BY NASA VIKING PROGRAM (1975-1982)

NASA VIKING PROGRAM (1975-1982)
Elysium Mons (13, 900m / 13, 9km - 46,000 ft / 8,6 mi)
MARS

Image from camera B (541A44, 541A46). Red filter used . Resolution is about 144 m/pixel. 

Approximate north is at top. taken on 10 December 1977, USGS Astrogeology Science Center 

The Mountain
Elysium Mons (13,900m / 13, 9km - 46,000 ft / 8,6 mi) is a volcano on Mars located in the volcanic province Elysium, at 25.02°N 147.21°E, in the Martian eastern hemisphere. It stands about above the surrounding lava plains, and about 16 km (52,000 ft) above the Martian datum. Its diameter is about 240 km (150 mi), with a summit caldera about 14 km (8.7 mi) across. It is flanked by the smaller volcanoes Hecates Tholus to the northeast, and Albor Tholus to the southeast.
A 6.5 km diameter crater at 29.674 N, 130.799 E, in the volcanic plains to the northwest of Elysium Mons has been identified as a possible source for the nakhlite meteorites, a family of similar basaltic Martian meteorites with cosmogenic ages of about 10.7 Ma, suggesting ejection from Mars by a single impact event. This implies that Martian volcanism had slowed greatly by that point in history.


The Mission
NASA Viking Orbiter 1 was the first of two spacecraft (along with Viking 2) sent to Mars as part of NASA's Viking program. On July 20, 1976, it became the second spacecraft to soft-land on Mars, and the first to successfully perform its mission. (The first spacecraft to soft-land on Mars was the Soviet Union's Mars 3 on December 2, 1971, which stopped transmitting after 14.5 seconds.) Viking 1 held the record for the longest Mars surface mission of 2307 days (over 6​1⁄4 years) or 2245 Martian solar days, until that record was broken by the Opportunity rover on May 19, 2010. Following launch using a Titan/Centaur launch vehicle on August 20, 1975, and an 11-month cruise to Mars, the orbiter began returning global images of Mars about 5 days before orbit insertion. The Viking 1 Orbiter was inserted into Mars orbit on June 19, 1976, and trimmed to a 1513 x 33,000 km, 24.66 h site certification orbit on June 21. Landing on Mars was planned for July 4, 1976, the United States Bicentennial, but imaging of the primary landing site showed it was too rough for a safe landing. The landing was delayed until a safer site was found, and took place instead on July 20, the seventh anniversary of the Apollo 11 Moon landing. The lander separated from the orbiter at 08:51 UTC and landed at Chryse Planitia at 11:53:06 UTC. It was the first attempt by the United States at landing on Mars.
The instruments of the orbiter consisted of two vidicon cameras for imaging (VIS), an infrared spectrometer for water vapor mapping (MAWD) and infrared radiometers for thermal mapping (IRTM). The orbiter primary mission ended at the beginning of solar conjunction on November 5, 1976.
The extended mission commenced on December 14, 1976, after solar conjunction. Operations included close approaches to Phobos in February 1977. The periapsis was reduced to 300 km on March 11, 1977. Minor orbit adjustments were done occasionally over the course of the mission, primarily to change the walk rate — the rate at which the areocentric longitude changed with each orbit, and the periapsis was raised to 357 km on July 20, 1979. On August 7, 1980, Viking 1 Orbiter was running low on attitude control gas and its orbit was raised from 357 × 33943 km to 320 × 56000 km to prevent impact with Mars and possible contamination until the year 2019. Operations were terminated on August 17, 1980, after 1485 orbits. A 2009 analysis concluded that, while the possibility that Viking 1 had impacted Mars could not be ruled out, it was most likely still in orbit. More than 57,000 images were sent back to Earth. 

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2021 - Wandering Vertexes...
by Francis Rousseau

RHEASILVIA PHOTOGRAPHED BY NASA DAWN MISSION (2007-2018)

NASA DAWN MISSION (2007-2018)

Rheasilvia (22,2500 m / 22.5 km - 73,8189 ft / 14 mi) 

Currently the tallest mountain known in the Solar System 

PROTOPLANET VESTA 

About this image

The black-and-white perspective view was made by laying a global image mosaic from Dawn's survey phase (1,700 miles or 2,750 kilometers in altitude) over a topographic shape model. 

The colorized view was made by laying a color-coded height map over the topography. Red indicates higher areas and blue indicates lower areas. 

A still image showing the black-and-white view from the Rheasilvia rim, with the corresponding colorized topography image, is also included here. 

The images used to create these vistas were obtained by Dawn's framing camera from Aug. 11 to Nov. 2, 2011.

The Mountain

Rheasilvia (22,2500 m / 22.5 km - 73,8189 ft / 14 mi) is the tallest mountain known in the Solar System and the most prominent surface feature on the asteroid/ proto planet Vesta. 

Rheasilvia is thought to be an impact crater. It is 505 km (314 mi) in diameter, which is 90% the diameter of Vesta itself, and is 95% the mean diameter of Vesta. However, the mean is affected by the crater itself. It is 89% the mean equatorial diameter of 569 km (354 mi), making it one of the largest craters in the Solar System.  The crater partially obscures an earlier crater, named Veneneia, that at 395 km (245 mi) is almost as large.
Rheasilvia was discovered in Hubble Space Telescope images in 1997, but was not named until the arrival of the Dawn spacecraft in 2011.
It is named after Rhea Silvia, a mythological vestal virgin and mother of the founders of Rome, Romulus and Remus.

The Mission
Dawn is a retired space probe launched by NASA in September 2007 with the mission of studying two of the three known protoplanets of the asteroid belt, Vesta and Ceres. 

It was retired on 1 November 2018 and it is currently in an uncontrolled orbit around its second target, the dwarf planet Ceres. 

Dawn is the first spacecraft to orbit two extraterrestrial bodies, the first spacecraft to visit either Vesta or Ceres, and the first to visit a dwarf planet, arriving at Ceres in March 2015, a few months before New Horizons flew by Pluto in July 2015.
Dawn entered orbit around Vesta on July 16, 2011, and completed a 14-month survey mission before leaving for Ceres in late 2012.It then entered orbit around Ceres on March 6, 2015.

NASA considered, but decided against, a proposal to visit a third target.

On October 19, 2017, NASA announced that the mission would be extended until the probe's hydrazine fuel supply was used up

On November 1, 2018, NASA announced that the Dawn spacecraft had finally exhausted all of its hydrazine fuel, thus ending its mission. The satellite is currently in an uncontrolled state about Ceres.
The Dawn mission was managed by NASA's Jet Propulsion Laboratory, with spacecraft components contributed by European partners from Italy, Germany, France, and the Netherlands. It was the first NASA exploratory mission to use ion propulsion, which enabled it to enter and leave the orbit of two celestial bodies. Previous multi-target missions using conventional drives, such as the Voyager program, were restricted to flybys.

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2019 - Wandering Vertexes...

by Francis Rousseau 

ARSIA MONS BY NASA MARS GLOBAL SURVEYOR

NASA MARS GLOBAL SURVEYOR (1996-2007) 

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

MARS 

1. In Arsia Mons Spiral Cloud, June 19, 2001 

2. In Possible caves of Arsia Mons, HiRISE image, Laszlo P. Keszthelyi, August 9, 2007  

The mountain
Arsia Mons (20,000 m / 20 km - 63, 360ft / 12mi) is the southernmost of three volcanos with Ascraeus Mons, and Pavonis Mons (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 was named by Giovanni Schiaparelli after the legendary Roman forest of Arsia Silva.
Arsia Mons is a shield volcano with a relatively low slope and a massive caldera at its summit. It is  large enough to cover the state of New Mexico.

The caldera of Arsia Mons was formed when the mountain collapsed in on itself after its reservoir of magma was exhausted. There are many other geologic collapse features on the mountain's flanks.
The caldera floor formed around 150 millions years ago.
One of the benefits of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is the opportunity to observe how the planet's weather changes during a second full martian year. The picture  of Arsia Mons  (photo 1 above) was taken June 19, 2001  southern spring equinox occurred the same day. On this particular day (the first day of Spring), the MOC wide angle cameras documented an unusual spiral-shaped cloud within the 110 km (68 mi) diameter caldera- the summit crater- of the giant volcano. Because the cloud is bright both in the red and blue images acquired by the wide angle cameras, it probably consisted mostly of fine dust grains. The cloud's spin may have been induced by winds off the inner slopes of the volcano's caldera walls resulting from the temperature differences between the walls and the caldera floor, or by a vortex as winds blew up and over the caldera. Similar spiral clouds were seen inside the caldera for several days; we don't know if this was a single cloud that persisted throughout that time or one that regenerated each afternoon. Sunlight illuminates this scene from the left/upper left.

Dark pits on some of the Martian volcanoes have been speculated to be entrances into caves . A HiRISE image (cf. photo 2 above), looking essentially straight down, saw only darkness in this pit. This time the pit was imaged from the west. Since the picture was taken at about 2:30 p.m. local (Mars) time,  August 9, 2007, the sun was also shining from the west. We can see the eastern wall of the pit catching the sunlight. This confirms that this pit is essentially a vertical shaft cut through the lava flows on the flank of the volcano. Such pits form on similar volcanoes in Hawaii and are called "pit craters." They generally do not connect to long open caverns but are the result of deep underground collapse. From the shadow of the rim cast onto the wall of the pit NASA could calculate that the pit is at least 178 meters - 584 feet deep. The pit is 150 x 157 meters (492 x 515 feet) across. 

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.

___________________________________________

2019 - Wandering Vertexes...

by Francis Rousseau 

ELYSIUM MONS BY NASA MARS ODYSSEY

NASA MARS ODYSSEY  (2001- 2010/2025) 

Elysium Mons  (13,900m / 13, 9km - 46,000 ft / 8,6 mi)

MARS

The Mountain 

Elysium Mons  (13,900m / 13, 9km - 46,000 ft / 8,6 mi) is a volcano on Mars located in the volcanic province Elysium, at 25.02°N 147.21°E, in the Martian eastern hemisphere. It stands about  above the surrounding lava plains, and about 16 km (52,000 ft) above the Martian datum. Its diameter is about 240 km (150 mi), with a summit caldera about 14 km (8.7 mi) across. It is flanked by the smaller volcanoes Hecates Tholus to the northeast, and Albor Tholus to the southeast.

A 6.5 km diameter crater at 29.674 N, 130.799 E, in the volcanic plains to the northwest of Elysium Mons has been identified as a possible source for the nakhlite meteorites, a family of similar basaltic Martian meteorites with cosmogenic ages of about 10.7 Ma, suggesting ejection from Mars by a single impact event. This implies that Martian volcanism had slowed greatly by that point in history.

The Mission 

NASA Mars Odyssey was launched April 7, 2001, on a Delta II rocket from Cape Canaveral Air Force Station, and reached Mars orbit on October 24, 2001, at 02:30 UTC (October 23, 19:30 PDT, 22:30 EDT). By December 15, 2010, it broke the record for longest serving spacecraft at Mars, with 3,340 days of operation. It is currently in a polar orbit around Mars with a semi-major axis of about 3,800 km or 2,400 miles. It has enough propellant to function until 2025.
Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and a thermal imager to detect evidence of past or present water and ice, as well as study the planet's geology and radiation environment.  It is hoped that the data Odyssey obtains will help answer the question of whether life existed on Mars and create a risk-assessment of the radiation that future astronauts on Mars might experience. It also acts as a relay for communications between the Mars Exploration Rovers, Mars Science Laboratory, and previously the Phoenix lander to Earth. The mission was named as a tribute to Arthur C. Clarke, evoking the name of 2001: A Space Odyssey.

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.

EUROBEA MONS BY NASA VOYAGER 1 MISSION

NASA VOYAGER I MISSION (1977-2012)

Eurobea Montes (10, 500 m /34, 448 ft -  10, 5 km -  6,5 mi) 

Io (Jupiter's moon)

1.  In Voyager 1 view of Euboea Montes; the main massif is to upper right of center;  the dark oval to its lower left is Creidne Patera. North is at top,   from NASA's image PIA00328, 1 march 1979

 2  In Voyager 1 view of two of Io's ten highest peaks, Euboea Montes, just below upper left, and Haemus Montes, at lower right  © NASA's image PIA00328, 1 march 1979

The mountain 

Eurobea Montes (10, 500 m /34, 448 ft -  10, 5 km -  6,5 mi)  is a mountain on Io, on of the moons of Jupiter. Its coordinates are at 48.89°S 338.77°W.  Euboea Montes is rugby ball shaped (175 km by 240 km), located about 40 kilometers east of Creidne Patera caldera.  There is a curved ridge crest which divides Euboea Montes into two sections: the steep, southern flank with an uneven surface of rounded mounds and the smoother, northern flank sloping about 6° to the northwest. At the base of the northern flank is a thick, ridged deposit with rounded margins.

Schenk and Bulmer used their observations of NASA Voyager 1 images, measurements of heights on the digital elevation map generated from the images, and analogies to Earth structures to characterize Euboea Montes. According to them, the mountain is one block of crustal material, due to its polygonal, relatively intact shape. The block was raised and tilted (by about 6°) by thrust faulting. This uplift led to a massive landslide along the mountain's northern flank.
This scenario is directly tied to the recycling of Io's crust. Older crustal pieces are forced to sink as newer material is thrust above them. This old volcanic crustal material is compressed laterally as it sinks. Schenk and Bulmer argue that this global compression on Io is at least partially relieved by thrust faulting and uplift of large crustal blocks. On Earth, a similar mechanism exists, for example in the Black Hills of Dakota.

Schenk and M. H. Bulmer identify the deposit of a possible landslide off Euboea Montes. The thick deposit at the northern flank is interpreted to be from a landslide, and they further point to the shape of the northern flank as evidence for slope failure. The estimated volume of the debris apron is about 25,000 km3. If this is true, then Euboea Montes has arguably one of the largest debris aprons in the Solar System, of a size similar to those formed by landslides in Valles Marineris, around Olympus Mons on Mars, or submarine landslides on Earth.

The imager 
The Voyager program is a continuing American scientific program that employs two robotic probes, Voyager 1 and Voyager 2, to study the outer Solar System. They were launched in 1977 to take advantage of a favorable alignment of Jupiter, Saturn, Uranus, and Neptune, and are now exploring the outer boundary of the heliosphere in interstellar space. Although their original mission was to study only the planetary systems of Jupiter and Saturn, Voyager 2 continued on to Uranus and Neptune, and both Voyagers are now tasked with exploring interstellar space. Their mission has been extended three times, and both probes continue to collect and relay useful scientific data. Neither Uranus nor Neptune has been visited by any probe other than Voyager 2.
On August 25, 2012, data from Voyager 1 indicated that it had become the first human-made object to enter interstellar space, traveling "further than anyone, or anything, in history".
As of 2013, Voyager 1 was moving with a velocity of 17 kilometers per second (11 mi/s) relative to the Sun. Voyager 2 is expected to enter interstellar space by 2016, and its plasma spectrometer should provide the first direct measurements of the density and temperature of the interstellar plasma.
Data and photographs collected by the Voyagers' cameras, magnetometers, and other instruments revealed previously unknown details about each of the giant planets and their moons. Close-up images from the spacecraft charted Jupiter’s complex cloud forms, winds, and storm systems and discovered volcanic activity on its moon Io. Saturn’s rings were found to have enigmatic braids, kinks, and spokes and to be accompanied by a myriad of "ringlets." At Uranus Voyager 2 discovered a substantial magnetic field around the planet and 10 additional moons. Its flyby of Neptune uncovered three complete rings and six hitherto unknown moons as well as a planetary magnetic field and complex, widely distributed auroras. Voyager 2 is still the only spacecraft to have visited the ice giants.
The Voyager spacecrafts were built at the Jet Propulsion Laboratory in Southern California, and they were funded by the National Aeronautics and Space Administration (NASA), which also funded their launchings from Cape Canaveral, Florida, their tracking, and everything else concerning the space probes due the radioactive materials on board the spacecraft.

ASCRAEUS MONS SEEN BY NASA MARS RECONNAISSANCE ORBITER

NASA MARS RECONNAISSANCE ORBITER (2005-2015) 

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

Planet Mars

1.  In Ascraeus mons, HiRISE camera ,Mars Reconnaissance Orbiter (MRO); November 2010

2.  In  Colorized MOLA topography of Ascraeus Mons, 2006   

The mountain 
Ascraeus mons (18, 225m / 18kms- 50, 793 ft / 11, 1mi)  is a large shield volcano located in the Tharsis region of the planet Mars. It is the northernmost and tallest of three shield volcanoes collectively known as the Tharsis Montes. The volcano's location corresponds to the classical albedo feature Ascraeus Lacus.
Ascraeus Mons was discovered by the Mariner 9 spacecraft in 1971. The volcano was originally called North Spot because it was the northernmost of only four spots visible on the surface due to a global dust storm that was then enshrouding the planet. As the dust cleared, the spots were revealed to be extremely tall volcanoes whose summits had projected above the dust-laden, lower atmosphere.
The volcano is located in the southeast-central portion of the Tharsis quadrangle at 11.8°N, 255.5°E in Mars' western hemisphere.  Ascraeus Mons is roughly 480 km in diameter and is the second highest mountain on Mars, with a summit elevation of 18.1 km ! The volcano has a very low profile with an average flank slope of 7°. Slopes are steepest in the middle portion of the flanks, flattening out toward the base and near the top where a broad summit plateau and caldera (collapse crater) complex are located.
Volcanic vents, located on the northeastern and southwestern edges of the volcano, are sources for broad lava aprons, or fans, that bury nearby portions of the volcano and extend over 100 km out into the surrounding plains.  The southwest-northeast orientation of the aprons matches the orientation of the Tharsis Montes, suggesting that a major fissure or rift in the Martian crust is responsible for the orientation of both the aprons and the Tharsis Montes chain. The presence of the lava aprons causes some disagreement in the actual dimensions of the volcano.
Like most of the Tharsis region, Ascraeus Mons has a high albedo (reflectivity) and low thermal inertia, indicating that the volcano and surrounding areas are covered with large amounts of fine dust.  The dust forms a mantle over the surface that obscures or mutes much of the fine-scale topography and geology of the region. Tharsis is probably dusty because of its high elevations. The atmospheric density is too low to mobilize and remove dust once it is deposited.
Ascraeus Mons is surrounded by lava flow plains that are mid to late Amazonian in age. The elevation of the plains averages about 3 km above datum (Martian "sea" level), giving the volcano an average vertical relief of 15 km.  However, the elevation of the plains varies considerably. The plains northwest of the volcano are less than 2 km in elevation. The plains are highest (>3 km) southeast of the volcano.
The lava plains northwest of Ascraeus Mons are notable for having two dark collapse pits photographed by the HiRISE camera on the Mars Reconnaissance Orbiter (MRO) in November 2010 (image above) . The pits resemble those imaged around Arsia Mons by the Mars Odyssey spacecraft. The two pits measure about 180 and 310 m wide, and the larger pit is approximately 180 meters deep. The eastern walls of the pits consist of steep, overhanging ledges. The bottoms of both pits contain sediments and large boulders.  These rimless pit craters are believed to form by collapse of surface material into a subsurface void created either by a dike or lava tube. They are analogous to volcanic pit craters on Earth, such as the Devil's Throat crater on the upper east rift zone of Kilauea Volcano, Hawaii.  In some cases, they may mark skylights/entrances to subsurface lava caves.

The camera
The image above, has been captured by the HiRISE  (High Resolution Imaging Science Experiment) camera aboard NASA’s Mars Reconnaissance Orbiter. The 65 kg (143 lb), $40 million USD instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp. It consists of a 0.5 m (19.7 in) aperture reflecting telescope, the largest so far of any deep space mission, which allows it to take pictures of Mars with resolutions of 0.3 m/pixel (about 1 foot), resolving objects below a meter across.
HiRISE has imaged Mars landers on the surface, including the ongoing Curiosity and Opportunity rover missions.
HiRISE was designed to be a High Resolution camera from the beginning. It consists of a large mirror, as well as a large CCD camera. Because of this, it achieves a resolution of 1 microradian, or 0.3 meter at a height of 300 km. (For comparison purposes, satellite images on Google Mars are available to 1 meter). It can image in three color bands, 400–600 nm (blue-green or B-G), 550–850 nm (red) and 800–1,000 nm (near infrared or NIR).
HiRISE incorporates a 0.5-meter primary mirror, the largest optical telescope ever sent beyond Earth's orbit. The mass of the instrument is 64.2 kg.
Red color images are at 20,048 pixels wide (6 km in a 300 km orbit), and Green-Blue and NIR are at 4,048 pixels wide (1.2 km). These are gathered by 14 CCD sensors, 2048 x 128 pixels. HiRISE's onboard computer reads out these lines in time with the orbiter's ground speed, meaning the images are potentially unlimited in height. Practically this is limited by the onboard computer's 28 Gbit (3.5 GByte) memory capacity. The nominal maximum size of red images (compressed to 8 bits per pixel) is about 20,000 × 126,000 pixels, or 2520 megapixels and 4,000 × 126,000 pixels (504 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image uses up to 28 Gbit. However, these images are transmitted compressed, with a typical max size of 11.2 Gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000.
To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter.
The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible. It has provided a closer look at fresh martian craters, revealing alluvial fans, viscous flow features and ponded regions of pitted materials containing breccia clast.  This allows for the study of the age of Martian features, looking for landing sites for future Mars landers, and in general, seeing the Martian surface in far greater detail than has previously been done from orbit. By doing so, it is allowing better studies of Martian channels and valleys, volcanic landforms, possible former lakes and oceans, and other surface landforms as they exist on the Martian surface.
The general public is allowed to request sites for the HiRISE camera to capture (see HiWish). For this reason, and due to the unprecedented access of pictures to the general public, shortly after they have been received and processed, the camera has been termed "The People's Camera".
 The pictures can be viewed online, downloaded, or with the free HiView software.

IAPETUS RIDGE BY NASA CASSINI MISSION

NASA CASSINI MISSION (1997-2017)

Iapetus equatorial ridge (20,000 m - 65,6168 ft)  or (20 km - 12, 43 mi)

Saturn planet (Iapetus moon) 

1. Iapetus equatorial ridge on 10/09/2007 

2. Photomosaic of the Iapetus moon  from NASA Cassini Spacecraft  on 31/12/2004

Assembled by Matt McIrvin  

The mountain 

Iapetus is one of the numerous Saturn's moon which has a 10 to 20 kilometers high (20,000 m - 65,6168 ft)  ridge above the surrounding plains, running along most of its equator, making them some of the tallest mountains in the Solar System.  Iapetus's equatorial ridge was discovered when the NASA Cassini spacecraft imaged Iapetus on 31 December 2004, during the NASA Cassini Mission to Saturn.  The ridge forms a complex system including isolated peaks, segments of more than 200 km and sections with three near parallel ridges. There are bright areas on the sides of the equatorial ridge near Iapetus's bright trailing hemisphere, which were already visible in Voyager Missions images appearing like mountains and were nicknamed the "Voyager Mountains". Within the bright regions there is no ridge, but there are a series of isolated 10 km (6 miles) peaks along the equator. The ridge system is heavily cratered, indicating that it is ancient. 

The prominent equatorial bulge gives Iapetus a walnut-like appearance. 

It is not clear how the ridge formed. One difficulty is to explain why it follows the equator almost perfectly. There are at least four current hypotheses, but none of them explains why the ridge is confined to Cassini Regio.

1. A team of scientists associated with the Cassini mission have argued that the ridge could be a remnant of the oblate shape of the young Iapetus, when it was rotating more rapidly than it does today.  The height of the ridge suggests a maximum rotational period of 17 hours. 

2. The ridge could be icy material that welled up from beneath the surface and then solidified. 

3. Iapetus may have had a ring system during its formation due to its large Hill sphere, and the equatorial ridge could have then been produced by collisional accretion of this ring.

4. The ridge and the bulge could be the result of ancient convective overturn. This hypothesis states that the bulge is in isostatic equilibrium typical for terrestrial mountains. 

Source:

- NASA Cassini mission Page at Iapetus  

The Mission

Cassini sails low over the surface of Iapetus on approach to its close encounter with the enigmatic moon on Sept. 10, 2007. Its flight takes it over the rugged, mountainous ridge along the moon's equator, where ancient, impact battered peaks - some topping 10 kilometers (6 miles) in height -- are seen rising over the horizon and slipping beneath the spacecraft as it flies.
Frames used in this movie were acquired with the Cassini wide-angle camera on Sept. 10, 2007, as the intrepid robot soared past Iapetus (1,468 kilometers - 912 miles across), within a few thousand kilometers of the surface. Additional simulated images were inserted between the Cassini images in this movie in order to smooth the appearance of the movement, a scheme called interpolation.
The Cassini mission was launched on  October 15, 1997 at 8:43 UTC. This 20 years mission was programmed to end on September 15, 2017 by what is called The Grande Finale.
Source:
- NASA Cassini mission Page at Iapetus  

SKADI MONS BY NASA MAGELLA MISSION

NASA MAGELLAN MISSION (1989-1994)

Skadi Mons (11, 500m or 11, 5 km -  37,730 ft or 7 miles) 

Venus planet (Maxwell Montes)

Photographed on 7 march 1996  

The mountain 

Skadi Mons 10,700m or 10, 7 km -  35,105 ft or 6, 65 mi) is a mountain on planet Venus, in Maxwell Montes, at the center of Ishtar Terra. It is the highest point of the planet with an altitude of about 10,700 meters above the mean planetary radius. On this image it is located along the right hand part. 

Maxwell Montes is a mountain massif on the planet Venus, located on Ishtar Terra, the more northern of the planet's two major highlands. The western slopes are very steep, whereas the eastern slopes descend gradually into Fortuna Tessera. Due to its elevation it is the coolest (about 380 °C or 716 °F) and least pressurised (about 45 bar or 44 atm) location on the surface of Venus. 

By using radar to probe through the permanent and thick clouds in the Venusian atmosphere and make observations of the surface, scientists at the American Arecibo Radio Telescope in Puerto Rico discovered the extensive highland on Venus that came to be called Maxwell Montes in 1967.
In 1978, the space probe Pioneer Venus 1 went into orbit around Venus for the purpose of making radar observations of the Venusian surface. These observations made possible the creation of the first topographic map of the surface of Venus, and confirmed that a point within Maxwell Montes is the highest point above the average level of the planet's surface.
Maxwell Montes, Alpha Regio, and Beta Regio are the three exceptions to the rule that the surface features of Venus are to be named for females.
Maxwell Montes is named for James Clerk Maxwell whose work in mathematical physics predicted the existence of radio waves, which made radar, and thus the surface observations of Venus, possible.
The name, originally given by Ray Jurgens in 1970 on the urging of Tommy Gold, was approved by the International Astronomical Union's Working Group for Planetary System Nomenclature (IAU/WGPSN) between 1976 and 1979.
Source: 
- NASA Jet Propulsion Laboratory / CalTech

The image capturer
This Magellan full resolution radar image is centered at 65 degrees north latitude, zero degrees east longitude, along the eastern edge of Lakshmi Planum and the western edge of Maxwell Montes and its highest peak,  Skadi Mons. The plains of Lakshmi are made up of radar-dark, homogeneous, smooth lava flows. Maxwell is made up of parallel ridges 2 to 7 km (1.2 to 4.2 miles) apart and is interpreted to have formed by compressional tectonics. The image is 300 km (180 miles) wide.
The Magellan spacecraft, named after the 16th century Portuguese explorer whose expedition first circumnavigated the Earth, was launched May 4, 1989, and arrived at Venus on August 10, 1990. Magellan's solid rocket motor placed it into a near-polar elliptical orbit around the planet. During the first 8-month mapping cycle around Venus, Magellan collected radar images of 84% of the planet's surface, with resolution 10 times better than that of the earlier Soviet Venera 15 and 16 missions. Altimetry and radiometry data also measured the surface topography and electrical characteristics.
During the extended mission, two further mapping cycles from May 15, 1991 to September 14, 1992 brought mapping coverage to 98% of the planet, with a resolution of approximately 100m.
Precision radio tracking of the spacecraft will measure Venus' gravitational field to show the planet's internal mass distribution and the forces which have created the surface features. Magellan's data will permit the first global geological understanding of Venus, the planet most like Earth in our solar system.
Magellan Synthetic Aperture Radar (SAR) data is combined with radar altimetry to develop a three-dimensional map of the surface. The vertical scale in this perspective has been exaggerated 22.5 times. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey, are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory.
Source: 

- NASA Jet Propulsion Laboratory / CalTech

OLYMPUS MONS (MARS) BY NASA VIKING PROGRAM

NASA VIKING PROGRAM (1975-1982)

Olympus Mons (21, 230m -  69,650ft) 

Planet Mars - Solar system  

1.  Image of Olympus Mons from NASA Viking 1 Orbiter in 1974 

2.  Olumpus Mons caldera from Mars Express camera on 26 May 2004 

The mountain 

Olympus Mons (21, 230m -  69,650 ft) is a very large shield volcano located on the planet Mars. By one measure, it has a height of nearly 22 km (13.6 mi). Olympus Mons stands about two and a half times as tall as Mount Everest's height above sea level. It is the youngest of the large volcanoes on Mars, having formed during Mars's Hesperian Period. It is currently the largest volcano discovered in the Solar System and had been known to astronomers since the late 19th century as the albedo feature Nix Olympica (Latin for "Olympic Snow"). Its mountainous nature was suspected well before space probes confirmed its identity as a mountain.

The volcano is located in Mars's western hemisphere at approximately 18.65°N 226.2°E, just off the northwestern edge of the Tharsis bulge. The western portion of the volcano lies in the Amazonis quadrangle (MC-8) and the central and eastern portions in the adjoining Tharsis quadrangle (MC-9).

Two impact craters on Olympus Mons have been assigned provisional names by the International Astronomical Union. They are the 15.6 km (9.7 mi)-diameter Karzok crater (18°25′N 131°55′W) and the 10.4 km (6.5 mi)-diameter Pangboche crater (17°10′N 133°35′W). The craters are notable for being two of several suspected source areas for shergottites, the most abundant class of Martian meteorites.

Olympus Mons and a few other volcanoes in the Tharsis region stand high enough to reach above the frequent Martian dust-storms recorded by telescopic observers as early as the 19th century. The astronomer Patrick Moore pointed out that Schiaparelli (1835–1910) "had found that his Nodus Gordis and Olympic Snow [Nix Olympica] were almost the only features to be seen" during dust storms, and "guessed correctly that they must be high".
The Mariner 9 spacecraft arrived in orbit around Mars in 1971 during a global dust-storm. The first objects to become visible as the dust began to settle, the tops of the Tharsis volcanoes, demonstrated that the altitude of these features greatly exceeded that of any mountain found on Earth, as astronomers expected. Observations of the planet from Mariner 9 confirmed that Nix Olympica was not just a mountain, but a volcano. Ultimately, astronomers adopted the name Olympus Mons for the albedo feature known as Nix Olympica.

The program

The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts: an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down.
The Viking program grew from NASA's earlier, even more ambitious, Voyager Mars program, which was not related to the successful Voyager deep space probes of the late 1970s. Viking 1 was launched on August 20, 1975, and the second craft, Viking 2, was launched on September 9, 1975, both riding atop Titan III-E rockets with Centaur upper stages. Viking 1 entered Mars orbit on June 19, 1976, with Viking 2 following suit on August 7.
After orbiting Mars for more than a month and returning images used for landing site selection, the orbiters and landers detached; the landers then entered the Martian atmosphere and soft-landed at the sites that had been chosen. The Viking 1 lander touched down on the surface of Mars on July 20, 1976, and was joined by the Viking 2 lander on September 3. The orbiters continued imaging and performing other scientific operations from orbit while the landers deployed instruments on the surface.
The project cost roughly 1 billion USD in 1970s dollars, equivalent to about 11 billion USD in 2016 dollars. It was highly successful and formed most of the body of knowledge about Mars through the late 1990s and early 2000s.
Source :
 - NASA- JPL-CALTECH

BOÖSAULE MONTES AND PELE IMAGED BY NASA VOYAGER 1

NASA VOYAGER I MISSION (1977-2012)

Boösaule Montes (17, 500 m or 17, 5 km - 57, 400 ft or 10, 9 miles) 

Io (Jupiter's moon) - Solar system 

as imaged by Voyager I Mission in March 1979 

© NASA / Jet Propulsion Lab / USGS 

NASA comment for images

Image 1 :  " The eruption of Pele on Jupiter's moon Io. The volcanic plume rises 300 kilometers above the surface in an umbrella-like shape. The plume fallout covers an area the size of Alaska. The vent is a dark spot just north of the triangular-shaped plateau (right center). To the left, the surface is covered by colorful lava flows rich in sulfur. "

Image 2  :  detail from image 1: Boösaule Montes on the left side of image

The mountain

Boösaule Montes (17, 500 m or 17, 5 km - 57, 4147 ft or 10, 9 miles)  is the highest mountain of Jupiter's moon Io, and one of the tallest mountains in the Solar System. It is located in the north-west from the volcano Pele ( on right in the first image), in the mountain range Boösaule.
The highest (southern) peak of the Boösaule Montes, which is the highest peak on Io, as imaged by Voyager 1. North is to the upper left. This image was created from PIA00323 by cropping and sharpening. NASA's description of the uncropped image is as follows:
The official name of the mountain range was given in honor of the cave in Egypt where Io gave birth to Epaphus, and approved by the IAU in 1985.
Mountains are widely distributed across the surface of Io, the innermost large moon of Jupiter. There are about 115 named mountains; the average length is 157 km (98 mi) and the average height is 6,300 m (20,700 ft). The longest is 570 km (350 mi), and the highest is Boцsaule Montes, at 17,500 metres (57,400 ft), taller than any mountain on Earth. Ionian mountains often appear as large, isolated structures; no global tectonic pattern is evident, unlike on Earth, where plate tectonics is dominant.
Io is exceptional for the strong tidal heating it undergoes, caused by the eccentricity of its orbit (which results from its resonance with Europa and Ganymede) in conjunction with the proximity and great mass of Jupiter. This leads to widespread and intensive volcanism. Most volcanoes on Io have little relief; those that can be considered mountains are generally smaller than the mountains formed by tectonic processes, averaging only 1,000 to 2,000 metres (3,300 to 6,600 ft) in height and 40 to 60 kilometres (25 to 37 mi) in width. Several geodynamic models of Io exist but the tectonic mountain-building process is still obscure and debatable. However, it is thought to be related to stresses caused by the rapid volcanic resurfacing of the body.
To explore the origin of Io's mountains, classification of morphological types and description of morphological features are necessary. Five morphological types of mountains have been identified.
- Mesa: a mountain with flat top and relatively smooth surface. It may be difficult to distinguish mesas from eroded layered plains. Ethiopia Planum is a good example of this morphological type.
1 mountains on Io are classified as mesas.
- Plateau : an elevated plain with a rugged surface. There is no steep or prominent peak on plateau. Iopolis Planum is a good example of this type. About 46% of Ionian mountains belong to this morphological type.
- Ridge: an elevated structure dominated by one or more linear or arcuate rises. 28 mountains on Io (or 24%) have been cataloged into this type.
- Massif: an elevated structure dominated by rugged or complex surface and has one or more peaks. Boösaule Montes and Tohil Mons are good examples.
Sources :  
- Io mountains database
- NASA
- Jet Propulsion Laboratory 

The imager 
The Voyager program is a continuing American scientific program that employs two robotic probes, Voyager 1 and Voyager 2, to study the outer Solar System. They were launched in 1977 to take advantage of a favorable alignment of Jupiter, Saturn, Uranus, and Neptune, and are now exploring the outer boundary of the heliosphere in interstellar space. Although their original mission was to study only the planetary systems of Jupiter and Saturn, Voyager 2 continued on to Uranus and Neptune, and both Voyagers are now tasked with exploring interstellar space. Their mission has been extended three times, and both probes continue to collect and relay useful scientific data. Neither Uranus nor Neptune has been visited by any probe other than Voyager 2.
On August 25, 2012, data from Voyager 1 indicated that it had become the first human-made object to enter interstellar space, traveling "further than anyone, or anything, in history".
As of 2013, Voyager 1 was moving with a velocity of 17 kilometers per second (11 mi/s) relative to the Sun. Voyager 2 is expected to enter interstellar space by 2016, and its plasma spectrometer should provide the first direct measurements of the density and temperature of the interstellar plasma.
Data and photographs collected by the Voyagers' cameras, magnetometers, and other instruments revealed previously unknown details about each of the giant planets and their moons. Close-up images from the spacecraft charted Jupiter’s complex cloud forms, winds, and storm systems and discovered volcanic activity on its moon Io. Saturn’s rings were found to have enigmatic braids, kinks, and spokes and to be accompanied by a myriad of "ringlets." At Uranus Voyager 2 discovered a substantial magnetic field around the planet and 10 additional moons. Its flyby of Neptune uncovered three complete rings and six hitherto unknown moons as well as a planetary magnetic field and complex, widely distributed auroras. Voyager 2 is still the only spacecraft to have visited the ice giants.
The Voyager spacecrafts were built at the Jet Propulsion Laboratory in Southern California, and they were funded by the National Aeronautics and Space Administration (NASA), which also funded their launchings from Cape Canaveral, Florida, their tracking, and everything else concerning the space probes due the radioactive materials on board the spacecraft.