| Piú votate - THE LUNAR EXPLORER ARCHIVES |
Martian_Pyramids.jpgMartian Pyramids (by Roberto Tremolada)112 visitenessun commentoMareKromium
(17 voti)
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Towers.jpgThe Ultimate Boundaries (by Roberto Tremolada)94 visitenessun commentoMareKromium
(17 voti)
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as13-60-8622.JPGAS 13-60-8622 - The "Silver Sphere"126 visite
(17 voti)
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Volcanoes-Arsia_Mons-E05-1721_1722_arsia100.jpgArsia Mons Volcano and "spiral clouds" (Natural Colors; credits: NASA/JPL/MSSS)112 visiteCaption NASA originale:"One of the benefits of the MGS-MOC Extended Mission is the opportunity to observe how the planet's weather changes during a second full martian year. This picture of Arsia Mons was taken on June 19, 2001; Southern Spring equinox occurred the same day. Arsia Mons is a volcano nearly large enough to cover the state of New Mexico. On this particular day (the first day of Spring), the MOC wide angle cameras documented an unusual spiral-shaped cloud within the 110 Km diameter caldera - such as 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".
(17 voti)
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Craters-Newton_Crater-00-39S_166W_30.jpgGullies inside Newton Crater - Terra Sirenum (Natural Colors; credits: NASA/MGS/MSSS)107 visiteCaption NASA originale:"Both pictures show gullies (gully--->plur.: gullies: "gole" o "crepacci scoscesi") on the walls of two different meteor impact craters that occur in Newton Basin in Sirenum Terra, Mars. This picture, showing gullies in a crater at 42.4°S, 158.2°W, exhibits patches (patch-->geol.: "placche" o "macchie") of wintertime frost on the crater wall and dark-toned sand dunes on the floor. Its resolution is 1,5 meters (5 feet) per pixel - objects the size of school buses can be resolved in the full size image. The gullies in these craters originate at a specific layer and may have formed by release of groundwater to the martian surface in geologically recent times".
(17 voti)
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Imagination-PIA07096_modest.jpgAnother Sun, another Time, another Place...152 visite"...Principio invento, facile est augere reliquum..."
(Aristotele)
"...Trovato l'inizio (di una qualsiasi opera), è facile completare tutto il resto..."
(17 voti)
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Crossway.jpgAlien Crossway... (by Roberto Tremolada)166 visitenessun commentoMareKromium
(16 voti)
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Martian_Dawn.jpgDawn on Mars (by Roberto Tremolada)122 visitenessun commentoMareKromium
(16 voti)
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WinterMorning-1.jpgWinter Morning, on Mars (by Dr Paolo C. Fienga)207 visitenessun commentoMareKromium
(16 voti)
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ZZ-ZZ-ZZ-ZZ-ZZ-ZZ-ZZ-ZZ-Sunset.gifThe "True Colors" of Mars (21)310 visite"...problemi per guadagnare tempo, quella circostanza appare per quello che è e cioè una gigantesca "sola". Dalle foto HST e da quelle Mariner scampate al cover-up sappiamo invece che l'aspetto di Marte era molto più complesso ed inquietante del previsto e andava diffuso col contagocce, cosa che in effetti si fece.
I colori tornarono in ballo col Viking e me lo ricordo bene. Subito dopo il landing del 1976 vennero diffuse ai media delle immagini di Marte con un bel cielo blu ed un terreno molto "terrestre". Dopo 48 ore passate a rispondere al telefono ad Americani preoccupati, la NASA cominciò a tingere di rosso le foto e da allora non si è più fermata. Altra piccola considerazione: possibile che nessuno si sia accorto che di sabbia asciutta non ce n'è proprio? Dalle impronte dei Rovers si vede benissimo che la consistenza del suolo è simile a quella della sabbia pressata ghiacciata e, dato che oltre tutto i granuli sono anche magnetizzati, è ovvio che essi non si solleverebbero neanche con un argano..."
(16 voti)
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North_Polar_Features-Cl-louds-Mars_Weather-PIA05079.jpgWeather Patterns over the North Pole of Mars (Natural Colors; credits: NASA/MGS/MSSS)102 visiteMars Global Surveyor entered Mars orbit on 12 September 1997. The 8 Earth Years that MGS has been in orbit span portions of 5 Martian Years. One of the critical science activities that the MOC has been engaged in for the past 8 years has been to document daily changes in the Martian Weather. Each day that MOC is operating, the red and blue wide angle cameras are used to build up a daily global map. These maps provide a record of the Planet's changing meteorological conditions. One important discovery that has been made is that the Red Planet has "repeatable weather patterns". In light of weather-related problems and disruptions that occur every year on Earth, one can only imagine how nice it would be if our planet followed a similar, repeated pattern. The 4 pictures shown here provide an example of one of the weather phenomena that repeat each MY. Each picture shows the North Polar Region of Mars during the Northern Summer Season. Each picture is a composite of several images acquired at different visible wavelengths to give a color view of the planet. Each picture was taken about 1 Mars year apart, and each shows an annular (circular) cloud located over the same terrain each summer.
The first picture, acquired in April 1999, is actually not from the MGS MOC instrument. It was obtained by the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) and was originally released by the Space Telescope Science Institute on 19 May 1999. The reason there is no MOC image for April 1999 is a product of the MGS spacecraft's 8-year history at Mars. MGS was certainly in orbit at the time, and it was taking data during the month of April. However, the camera did not obtain any images between 17 and 28 April because the spacecraft encountered, and then had to be recovered from, a problem. It was at this time that the spacecraft team realized that there is something obstructing the full movement of MGS's high gain antenna. A work-around was created and the mission has continued, ever since, but the down-side was that MOC did not have the opportunity in 1999 to provide detailed observations of the north polar, summertime, annular cloud.
The remaining three pictures show MGS MOC views of the cloud feature, as it appeared in the subsequent 3 Mars years. Each year, the cloud appeared at about the same time or slightly earlier than in the previous year. Despite its superficial resemblance to a hurricane or cyclone on Earth, the northern summer annular cloud does not rotate. The cloud forms as different currents of air merge in the morning hours in the polar region; by afternoon, the annular cloud typically dissipates or breaks up into smaller clouds.
MGS MOC has observed other repeated phenomena over the course of its 8-year mission orbiting Mars. These include dust storms that repeat, year after year, in the same location within a week or two of the time it occurred in the previous year. They also include dust devils in northern Amazonis, which start up shortly after the first day of spring, and keep occurring nearly every afternoon until a few days into the autumn season. MOC is continuing its mission to monitor the planet -- in 2006, MOC's weather observations will be used to provide guidance for the aerobraking maneuvers of the Mars Reconnaissance Orbiter (MRO). MOC images will show whether dust storms are occurring, and whether the dust suspended by these storms will impact the density of the atmosphere at the altitudes that MRO is passing through to slow the spacecraft and change its orbit to the one desired for the MRO primary mission.
(16 voti)
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Volcanic_Features-Plume-Tharsis-PIA04285.jpgAn isolated "Water Ice Cloud" over Tharsis or a volcanic "Plume"? (Saturated Natural Colors; credits: NASA/JPL/MSSS)155 visiteOriginal caption:"This composite of red and blue MGS-MOC daily global images acquired on 6 July 2005 shows an isolated water ice cloud extending more than 30 Km (more than 18 miles) above the Martian surface. Clouds such as this are common in late Spring over the terrain located South-West of the Arsia Mons volcano. Arsia Mons is the dark, oval feature near the limb, just to the left of the "T" (in the "Tharsis Montes" label).
The dark, nearly circular feature above the "S" (in "Tharsis") is the Pavonis Mons Volcano and the other dark circular feature, above and to the right of "S" in "Montes," is Ascraeus Mons.
Illumination is from the left/lower left.
Season: Northern Autumn/Southern Spring".
Nota: purtroppo non ci sono vulcanologi nel Gruppo Lunar Explorer, ma la sensazione (nulla di più) che la "isolata nuvola di ghiaccio d'acqua", come la chiama la NASA sia, in realtà, il residuo di un evento vulcanico, è molto intensa (confrontate la sua forma con qualcuna delle "volcanic plumes" di Io...).
(16 voti)
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