Gale (crater)

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Gale Crater
Curiosity Cradled by Gale Crater.jpg
Aeolis Mons rises from the middle of the crater - the green dot marks the Curiosity rover landing site in Aeolis Palus - North is down.
Planet Mars
Coordinates 5°24′S 137°48′E / 5.4°S 137.8°E / -5.4; 137.8Coordinates: 5°24′S 137°48′E / 5.4°S 137.8°E / -5.4; 137.8
Diameter 154 km (96 mi)[1]
Eponym Walter Frederick Gale

Gale is a crater on Mars near the northwestern part of the Aeolis quadrangle at 5°24′S 137°48′E / 5.4°S 137.8°E / -5.4; 137.8.[2] It is 154 km (96 mi) in diameter[1] and estimated to be about 3.5-3.8 billion years old.[3] The crater was named after Walter Frederick Gale, an amateur astronomer from Sydney, New South Wales, Australia, who observed Mars in the late 19th century.[4] Aeolis Mons is a mountain in the center of Gale Crater and rises 5.5 km (18,000 ft) high.[5][6] Aeolis Palus is the plain between the northern wall of Gale Crater and the northern foothills of Aeolis Mons.[5][6] Peace Vallis,[7] a nearby outflow channel, 'flows' down from the Gale Crater hills to the Aeolis Palus below and seems to have been carved by flowing water.[8][9][10]

The NASA Mars rover, Curiosity, of the Mars Science Laboratory (MSL) mission, landed in "Yellowknife" Quad 51[11][12][13][14] of Aeolis Palus in Gale Crater at 05:32 UTC August 6, 2012.[15] NASA named the landing location Bradbury Landing on August 22, 2012.[16] Curiosity is expected to explore Aeolis Mons and surrounding areas.

Characteristics[edit]

An unusual feature of Gale is an enormous mound of "sedimentary debris"[17] around its central peak, officially named Aeolis Mons[5][6] (popularly known as "Mount Sharp"[18][19]) rising 5.5 km (18,000 ft) above the northern crater floor and 4.5 km (15,000 ft) above the southern crater floor - slightly taller than the southern rim of the crater itself. The mound is composed of layered material and may have been laid down over a period of around 2 billion years.[3] The origin of this mound is not known with certainty, but research suggests it is the eroded remnant of sedimentary layers that once filled the crater completely, possibly originally deposited on a lakebed.[3] However, debate exists around this issue.[20][21] Observations of possible cross-bedded strata on the upper mound suggest aeolian processes, but the origin of the lower mound layers remains ambiguous.[22]

Gale crater is located at about 5°24′S 137°48′E / 5.4°S 137.8°E / -5.4; 137.8 on Mars.[23]

Description at NASA[edit]

Colorized shaded relief map of Gale Crater. The general landing area for Curiosity on the northwestern crater floor, named Aeolis Palus, is circled. (HRSC data)

At 10:32 p.m. PDT on Aug. 5, 2012 (1:32 a.m. EDT on Aug. 6, 2012), the Mars Science Laboratory rover, Curiosity, landed on Mars at 4°30′S 137°24′E / 4.5°S 137.4°E / -4.5; 137.4, at the foot of a layered mountain inside Gale Crater. The crater is named for Walter F. Gale (1865-1945), an amateur astronomer from Australia.

Gale Crater formed when a meteor hit Mars in its early history, about 3.5 to 3.8 billion years ago. The meteor impact punched a hole in the terrain, and the subsequent explosion ejected rocks and soil that landed around the crater. Scientists chose Gale Crater as the landing site for Curiosity because it has many signs that water was present over its history. Water is a key ingredient of life as we know it.

Minerals called clays and sulfates are byproducts of water. They also may preserve signs of past life. The history of water at Gale, as recorded in its rocks, is giving Curiosity lots of clues to study as it pieces together whether Mars ever could have been a habitat for small life forms called microbes. Gale is special because both clays and sulfate minerals, which formed in water under different conditions, can be observed.

Gale Crater spans 154 km (96 mi) in diameter and holds a mountain, Aeolis Mons (previously informally named "Mount Sharp" to pay tribute to geologist Robert P. Sharp) rising higher from the crater floor than Mount Rainier rises above Seattle. Gale is about the combined area of Connecticut and Rhode Island.

Curiosity landed within a landing ellipse approximately 7 km (4.3 mi) by 20 km (12 mi). The landing ellipse is about 4,400 m (14,400 ft) below Martian "sea level" (defined as the average elevation around the equator). The expected near-surface atmospheric temperatures at the Gale Crater landing site during Curiosity's primary mission (1 Martian year or 687 Earth days) are from −90 °C (−130 °F) to 0 °C (32 °F).

Layering in the central mound (Aeolis Mons) suggests it is the surviving remnant of an extensive sequence of deposits. Some scientists believe the crater filled in with sediments and, over time, the relentless Martian winds carved Aeolis Mons, which today rises about 5.5 km (3.4 mi) above the floor of Gale Crater—three times higher than the Grand Canyon is deep.[24]

Spacecraft exploration[edit]

Numerous channels eroded into the flanks of the crater's central mound could give access to the layers for study.[3] Gale is the landing site of the Curiosity rover, delivered by the Mars Science Laboratory spacecraft,[25] which was launched 26 November 2011 and landed on Mars at Gale Crater on the plains of Aeolis Palus[26] on 6 August 2012.[27][28][29][30] Gale was previously a candidate landing site for the 2003 Mars Exploration Rover mission, and has been one of four prospective sites for ESA's ExoMars.[31]

In December 2012, scientists working on the Mars Science Laboratory mission announced that an extensive soil analysis of Martian soil performed by the Curiosity rover showed evidence of water molecules, sulphur and chlorine, as well as hints of organic compounds.[32][33][34] However, terrestrial contamination, as the source of the organic compounds, could not be ruled out.

On September 26, 2013, NASA scientists reported the Mars Curiosity rover detected "abundant, easily accessible" water (1.5 to 3 weight percent) in soil samples at the Rocknest region of Aeolis Palus in Gale Crater.[35][36][37][38][39][40] In addition, the rover found two principal soil types: a fine-grained mafic type and a locally derived, coarse-grained felsic type.[37][39][41] The mafic type, similar to other martian soils and martian dust, was associated with hydration of the amorphous phases of the soil.[41] Also, perchlorates, the presence of which may make detection of life-related organic molecules difficult, were found at the Curiosity rover landing site (and earlier at the more polar site of the Phoenix lander) suggesting a "global distribution of these salts".[40] NASA also reported that Jake M rock, a rock encountered by Curiosity on the way to Glenelg, was a mugearite and very similar to terrestrial mugearite rocks.[42]

On December 9, 2013, NASA reported that, based on evidence from Curiosity rover studying Aeolis Palus, Gale Crater contained an ancient freshwater lake which could have been a hospitable environment for microbial life.[43][44]

Images[edit]

Surface images[edit]

Evidence of water on Mars in Gale Crater[8][9][10]

Peace Vallis and related alluvial fan near the Curiosity rover landing ellipse and landing site (noted by +).
"Hottah" rock outcrop on Mars - an ancient streambed viewed by the Curiosity rover (September 14, 2012) (close-up) (3-D version).
"Link" rock outcrop on Mars - compared with a terrestrial fluvial conglomerate - suggesting water "vigorously" flowing in a stream.
Curiosity rover on the way to Glenelg (September 26, 2012).


Curiosity's view of "Mount Sharp" (September 20, 2012; white balanced) (raw color).
Curiosity's view of the "Rocknest" area - South is center/North at both ends; "Mount Sharp" at SE horizon (somewhat left-of-center); "Glenelg" at East (left-of-center); rover tracks at West (right-of-center) (November 16, 2012; white balanced) (raw color) (interactives).
Curiosity's view of Gale Crater walls from Aeolis Palus at "Rocknest" looking eastward toward "Point Lake" (center) on the way to "Glenelg Intrique" - Aeolis Mons is on the right (November 26, 2012; white balanced) (raw color).
Curiosity's view of Mars sky at sunset (February 2013; sun simulated by artist).


See also[edit]


References[edit]

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External links[edit]