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Eagle (crater)
Encyclopedia
Eagle is a 22-metre impact crater
located on Mars
on Meridiani Planum
. The Opportunity rover
came to rest inside Eagle crater when it landed in 2004. Scientists were delighted that the rover landed there, as the crater contains rocky outcroppings that helped prove that Meridiani was once an ocean floor.
in 1969; in honor of the launching country, the United States
, whose symbol is an eagle
; and in reference to the golf term eagle, referring to sinking a ball two strokes under par. The third reference extended the golf metaphor begun with a description of landing in the crater as "a hole in one
".
Mission scientists were intrigued by the abundance of rock outcrops dispersed throughout the crater, as well as the crater's soil, which appeared to be a mixture of coarse gray grains and fine reddish grains. Upon closer, in-situ examination of the outcrops, whose layers are no thicker than a finger, it was confirmed that Meridiani Planum was once the location of an ancient, somewhat acidic and salty sea, though much more information on the history of this area would start being collected more than three months later, when Opportunity visited the much larger crater Endurance
to the east. The hematite
observed from orbit, whose presence decided the landing site in the first place, was found to be encased in millions of tiny hematite spherules
, nicknamed "blueberries", by mission scientists, due to their shape, although they are actually much smaller than real blueberries. These concretions were found soon to be covering not just the outcrops in Eagle crater, but covered the plains beyond as well. The origin of the blueberries was quickly discovered. They appeared to be being eroded out of the outcrops by wind. Images from the rover's microscope discovered blueberries at several stages of this process, with most completely separated, but some still attached by a thin "stalk".
These can be seen in context in the high resolution version of the panorama above.
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
located on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
on Meridiani Planum
Meridiani Planum
Meridiani Planum is a plain located 2 degrees south of Mars' equator , in the westernmost portion of Terra Meridiani. It hosts a rare occurrence of gray crystalline hematite...
. The Opportunity rover
Opportunity rover
Opportunity, MER-B , is a robotic rover on the planet Mars, active since 2004. It is the remaining rover in NASA's ongoing Mars Exploration Rover Mission...
came to rest inside Eagle crater when it landed in 2004. Scientists were delighted that the rover landed there, as the crater contains rocky outcroppings that helped prove that Meridiani was once an ocean floor.
Name
The name is a triple reference: in honor of the first manned spacecraft to land on the MoonMoon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
in 1969; in honor of the launching country, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, whose symbol is an eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
; and in reference to the golf term eagle, referring to sinking a ball two strokes under par. The third reference extended the golf metaphor begun with a description of landing in the crater as "a hole in one
Hole in one
In golf, a hole in one or hole-in-one is when a player hits the ball directly from the tee into the cup with one shot. This is most possible on a par 3 hole. Longer hitters have accomplished this feat on shorter par 4 holes...
".
Discoveries in the crater
Endurance
Endurance is the ability for a human or animal to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from, and have immunity to trauma, wounds, or fatigue. In humans, it is usually used in aerobic or anaerobic exercise...
to the east. The hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
observed from orbit, whose presence decided the landing site in the first place, was found to be encased in millions of tiny hematite spherules
Martian spherules
Martian spherules are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars...
, nicknamed "blueberries", by mission scientists, due to their shape, although they are actually much smaller than real blueberries. These concretions were found soon to be covering not just the outcrops in Eagle crater, but covered the plains beyond as well. The origin of the blueberries was quickly discovered. They appeared to be being eroded out of the outcrops by wind. Images from the rover's microscope discovered blueberries at several stages of this process, with most completely separated, but some still attached by a thin "stalk".
Rocks and outcrops in the crater
A number of rocks and outcrops were investigated with Opportunity's Instrument Deployment Device (IDD). They were given informal names by mission scientists. These include:- Berry Bowl, an outcrop rich in Martian spherules
- Carousel, a layered outcrop most likely to have been formed in a wet environment
- Cookies 'N' Cream, a dark soil target near Carousel
- El CapitanEl Capitan (Mars)El Capitan is a layered rock outcrop found on Mars by the Mars Exploration Rover Opportunity in February 2004. The rock outcrop was named for El Capitan, a mountain in Texas.- External links :*...
, another layered outcrop - Last ChanceLast Chance (Mars)Last Chance is a layered rock outcrop found on Mars, discovered by the Mars Exploration Rover Opportunity in March 2004. The rock lies within the outcrop near the rover's landing site at Meridiani Planum, Mars....
, another layered outcrop
These can be seen in context in the high resolution version of the panorama above.