Eagle is a 22-metre long
impact crater
An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...
located on the
Meridiani Planum
The Meridiani Planum (alternately Meridiani plain, Meridiani plains, Terra Meridiani, or Terra Meridiani plains) is either a large plain straddling the equator of Mars and covered with a vast number of spherules containing a lot of iron oxide or ...
extraterrestrial plain, situated within the
Margaritifer Sinus quadrangle
The Margaritifer Sinus quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Margaritifer Sinus quadrangle is also referred to as MC-19 (Mars Chart-19) ...
(MC-19) portion of the planet
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
. 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
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.
The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
.
This crater should not be confused with the other, much larger Martian crater ''
Eagle
Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
'', which was officially named by IAU's
Working Group for Planetary System Nomenclature
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
in 1976.
Name
![Oppland02a](https://upload.wikimedia.org/wikipedia/commons/f/f1/Oppland02a.jpg)
The name is a triple reference: in honor of the first crewed spacecraft to land on the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
in 1969; in honor of the launching country, the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, whose symbol is an
eagle
Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
; and in reference to the golf term ''
eagle
Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
'', 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".
Discoveries in the crater
![Opportunity - Cratera Eagle](https://upload.wikimedia.org/wikipedia/commons/e/ed/Opportunity_-_Cratera_Eagle.jpg)
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,
"Reports Detail Rover Discoveries of Wet Martian History"
(2 Dec 2004) JPL. Retrieved 22 August 2011. 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
Endurance (also related to sufferance, resilience, constitution, fortitude, and hardiness) is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from a ...
to the east.
The hematite
Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...
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
Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' within the genus ''Vaccinium''. ''Vaccinium'' also includes cranberries, bi ...
. 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 Capitan
El Capitan ( es, El Capitán; "the Captain" or "the Chief") is a vertical Rock formations in the United States, rock formation in Yosemite National Park, on the north side of Yosemite Valley, near its western end. The El Capitan Granite, granit ...
, another layered outcrop
* Last Chance, another layered outcrop
The locations of these rocks and outcrops can be seen in the panorama below:
See also
* Geography of Mars
Areography, also known as the geography of Mars, is a subfield of planetary science that entails the delineation and characterization of regions on Mars. Areography is mainly focused on what is called physical geography on Earth; that is the di ...
* List of craters on Mars
__NOTOC__
This is a list of craters on Mars. Impact craters on Mars larger than exist by the hundreds of thousands, but only about one thousand of them have names. Names are assigned by the International Astronomical Union after petitioning by ...
References
Further reading
*
*
*
External links
Official Mars Rovers website
Geology of Eagle Crater
'Lion King' Panorama of Eagle Crater
(NASA)
{{Portal bar, Solar System
Impact craters on Mars
Mars Exploration Rover mission
Margaritifer Sinus quadrangle