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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Articles avec #planetary volcanism catégorie

Publié le par Bernard Duyck
Publié dans : #Planetary volcanism
 Cassini-Huygens' missions from 1977 to 2017 - a click on image to enlarge - doc. Nasa / JPL / Caltech

Cassini-Huygens' missions from 1977 to 2017 - a click on image to enlarge - doc. Nasa / JPL / Caltech

The space probe Cassini, part of the Earth in 1997, will soon be out of fuel, after twenty years of services around Saturn, its rings and its moons.
Last April, the probe changes its last trajectory. Its new orbit will send it between the inner rings and less than 2,000 km from Saturn. While analyzing what it perceives, it will run to its programmed loss on September 15, entering and consuming itself in the Saturnian atmosphere.
This suicide is a necessary passage because NASA does not want that, if its probe remains in orbit, it does not end up crashing on one of the moons and deposits microbes and terrestrial bacteria in a place potentially sheltering an extraterrestrial life.

 
- Sept. 15: Cassini's Final Entry into Saturn's Atmosphere begins at 10:44 a.m. UTC (3:44 a.m. PDT). Spacecraft loss of signal comes one minute later at 10:45 a.m. UTC (3:45 a.m. PDT).
- Sept. 15: Final signal received on Earth at about 5 a.m. PDT
Synthesis of the Cassini mission - 2004/2017

Synthesis of the Cassini mission - 2004/2017

Synthesis of the Cassini mission - 2004/2017

During these two decades, the orbiter Cassini allowed the exploration of Saturn, its rings and its moons. Among the most astonishing discoveries, the mission allowed to follow a mega storm on the giant gaz planet, caught by astonishing clichés of the planet and its rings, revealed the existence of ice plumes on the surface of Enceladus, and the number of moons; thanks to its passenger, the European probe Huygens, it has made discover the wonderful world of Titan, where rivers of methane enters a sea of ​​the same composition.
 
Source: Nasa / Jet Propulsion Laboratory / Caltech

Crashing into Saturn / via Nat Geo

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Publié le par Bernard Duyck
Publié dans : #Planetary volcanism

Water vapor traces were detected in November 2012 by Herschel Space Telescope, from ESA, on the surface of Ceres.

With 950 km in diameter, Ceres is the smallest dwarf planet in our solar system, but the biggest space object in the main asteroid belt between Mars and Jupiter.

Released in 2007, the Dawn spacecraft of NASA revealed in January 2015 strange white spots on the surface of Ceres. In gradual descent toward the dwarf planet, Dawn will spend from 46,000 km, altitude of revelation the white spots, to 375 km, its lowest altitude at the end of the mission in December 2015.

 

Ceres position in our solar system between Mars and Jupiter

Ceres position in our solar system between Mars and Jupiter

Bright spots on Ceres photographed by the Dawn probe on 6 June 2015 - Doc. NASA / JPL Caltech / UCLA / MPS / DLR / IDA

Bright spots on Ceres photographed by the Dawn probe on 6 June 2015 - Doc. NASA / JPL Caltech / UCLA / MPS / DLR / IDA

Ceres, another clearer picture and more precise (1 pixel = 140 meters) taken in September 2015 - Doc. NASA / JPL Caltech / UCLA / MPS / DLR / IDA

Ceres, another clearer picture and more precise (1 pixel = 140 meters) taken in September 2015 - Doc. NASA / JPL Caltech / UCLA / MPS / DLR / IDA

Image analysis will show the largest craters and a large conical mountain, called Ahuna Mons.

This is one of many bright spots intriguing the scientists since the early observations; it is supposed to be a great cryovolcano, a "cold volcano", which stretches over 17 km and dominates 
the surrounding land of 4,000 meters ... it would be older than a hundred million years.

Instead of spitting lava, as effusive volcanoes, Ahuna eject actually ice, which gradually formed the dome with smooth, shiny walls.

Take a flight over dwarf planet Ceres in this video made with pictures from NASA's Dawn spacecraft. The simulated flyover Was Made by the Mission's camera team at Germany's national aeronautics and space research center (DLR).

A second mystery : by modeling the asteroid collisions that would have occurred during the 4.5 billion years of history of Ceres, the scientists conclude that the dwarf planet should have 10-15 craters over 400 km wide and at least 40 of over 100 km.

But the observations by the Dawn spacecraft show only six craters over 100 km and less than 280 km wide. The explanation of erosion craters come from the structure of the planet : the top layers of Ceres contain ice mixed with salt, likely to "relax with the times" and to soften the reliefs. The  internal heat released shortly after the formation of the planet would have helped the ice in surface to erase the impacts.

 

Reconstituted view of the "cryovolcano" Ahuna Mons - Doc. NASA / JPL Caltech / UCLA / MPS / DLR / IDA

Reconstituted view of the "cryovolcano" Ahuna Mons - Doc. NASA / JPL Caltech / UCLA / MPS / DLR / IDA

The scientific interest of Ceres has strengthened since the Dawn probe joined her, and NASA has just extend the mission around the dwarf planet rather than sending it to another asteroid.

 

Sources :

- Nasa Jet Propulsion Laboratory – Dawn – Ceres' geological activity, ice revealed in new research – 01.09.2016

- Nasa Jet Propulsion Laboratory – Dawn – The case of the missing Ceres craters – 26.07.2016

- Notre planète : Découverte de mystérieuses taches lumineuses à la surface de la planète naine Cérès. fév.2015 / fév.2016

- L'OBS – les cratères disparus, le deuxième mystère de Cérès.

- Futura-Sciences : l'Europe ira-t-elle se poser sur Cérès ?

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