Eagle (crater)

MarsGeo-Crater
name=Eagle Crater


region=Meridiani Planum
latitude = 1.94
N_or_S = S
longitude = 354.47
E_or_W = E
diameter=Approx. 30 m
depth=Approx. 5 m
discoverer=Opportunity rover
eponym=See list below

Eagle Crater is the small impact crater in which the Mars Exploration Rover "Opportunity" found itself after landing on Mars in 2004.

The crater is located on Meridiani Planum. Scientists are 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 Moon 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 Eagle crater as "a hole in one."

Discoveries in the crater

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 then a finger, it was confirmed that Meridiani Planum was once the location of an ancient, somewhat acidic and salty [http://marsrovers.jpl.nasa.gov/newsroom/pressreleases/20041202a.html sea] , though much more information on the history of this area would start being collected more than 3 months later, when Opportunity visited the much larger Endurance crater 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".

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, another layered outcrop
* Last Chance, another layered outcrop

These can be seen in context in the high resolution version of the panorama above.

Further reading

*cite journal|author=Squyres, et al|title=In Situ Evidence for an Ancient Aqueous Environment at Meridiani Planum, Mars|journal=Science|date=2004|volume=306|pages=1709-1714|doi=10.1126/science.1104559
*cite journal|author=Squyres, et al|title=Soils of Eagle Crater and Meridian Planum at the Opportunity Rover Landing Site|journal=Science|date=2004|volume=306|pages=1723-1726|doi=10.1126/science.1105127
*cite journal|author=Squyres, et al|title=The Opportunity Rover's Athena Science Investigation at Meridiani Planum, Mars|journal=Science|date=2004|volume=306|pages=1698-1703|doi=10.1126/science.1106171

ee also

*List of craters on Mars
*Geography of Mars

Other craters visited by "Opportunity"

*Fram Crater
*Endurance Crater
*Argo Crater
*Vostok Crater
*Erebus Crater
*Beagle Crater
*Emma Dean Crater
*Victoria Crater

External links

* [http://marsrovers.jpl.nasa.gov Official Mars Rovers website]