APOD: The Eagle Rises (2019 Jul 13)

[APOD Robot]

The Eagle Rises

Explanation: Get out your red/blue glasses and check out this stereo view from lunar orbit. The 3D anaglyph was created from two photographs (AS11-44-6633, AS11-44-6634) taken by astronaut Michael Collins during the 1969 Apollo 11 mission. It features the lunar module ascent stage, dubbed The Eagle, rising to meet the command module in lunar orbit on July 21. Aboard the ascent stage are Neil Armstrong and Buzz Aldrin, the first to walk on the Moon. The smooth, dark area on the lunar surface is Mare Smythii located just below the equator on the extreme eastern edge of the Moon's near side. Poised beyond the lunar horizon is our fair planet Earth.

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[Boomer12k]

Awesome 3D image...

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[orin stepanek]

Beautiful 3D imagery! I really like how well everything stands out!

[neufer]

Topography (top) and corresponding gravity (bottom) signal of lunar Mare Smythii containing a significant mascon.

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Under a spreading chestnut-tree
The village SMYTHII stands;
Admiral Smyth, a mighty man was he,
With large and sinewy hands;
And the muscles of his brawny arms
Are strong as iron bands.

<<In astronomy and astrophysics, a mass concentration (or mascon) is a region of a planet or moon's crust that contains a large positive gravitational anomaly. In general, the word "mascon" can be used as a noun to refer to an excess distribution of mass on or beneath the surface of an astronomical body (with respect to some suitable average), such as is found around Hawaii on Earth. However, this term is most often used to describe a geologic structure that has a positive gravitational anomaly associated with a feature (e.g. depressed basin) that might otherwise have been expected to have a negative anomaly, such as the "mascon basins" on the Moon. Since their identification in 1968, the origin of the mascons beneath the surface of the Moon has been subject to much debate, but is now regarded as being the result of the impact of asteroids during the Late Heavy Bombardment.

Typical examples of mascon basins on the Moon are the Imbrium, Serenitatis, Crisium and Orientale impact basins, all of which exhibit significant topographic depressions and positive gravitational anomalies. Examples of mascon basins on Mars include the Argyre, Isidis, and Utopia basins. Theoretical considerations imply that a topographic low in isostatic equilibrium would exhibit a slight negative gravitational anomaly. Thus, the positive gravitational anomalies associated with these impact basins indicate that some form of positive density anomaly must exist within the crust or upper mantle that is currently supported by the lithosphere. One possibility is that these anomalies are due to dense mare basaltic lavas, which might reach up to 6 kilometers in thickness for the Moon. While these lavas certainly contribute to the observed gravitational anomalies, uplift of the crust-mantle interface is also required to account for their magnitude. Indeed, some mascon basins on the Moon do not appear to be associated with any signs of volcanic activity. Theoretical considerations in either case indicate that all the lunar mascons are super-isostatic (that is, supported above their isostatic positions). The huge expanse of mare basaltic volcanism associated with Oceanus Procellarum does not possess a positive gravitational anomaly.

Because of its mascons, the Moon has only four "frozen orbit" inclination zones where a lunar satellite can stay in a low orbit indefinitely. Just before the Apollo 12 flight, it was noted that the Apollo 11 Eagle was still likely to be orbiting the Moon. Later NASA reports mentioned that Eagle's orbit had decayed, resulting in it impacting in an "uncertain location" on the lunar surface. Lunar subsatellites were released on two of the last three Apollo manned lunar landing missions in 1971 and 1972; the subsatellite PFS-2 released from Apollo 16 was expected to stay in orbit for one and a half years, but lasted only 35 days before crashing into the lunar surface. It was only in 2001 that the mascons were mapped and the frozen orbits were discovered.>>

[Chris Peterson]

Stereo Pair Versions

Straight:

Crossed:

[daddyo]

Thanks Chris for always posting these

[TheZuke!]

Topography (top) and corresponding gravity (bottom) signal of lunar Mare Smythii containing a significant mascon.

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Under a spreading chestnut-tree
The village SMYTHII stands;
Admiral Smyth, a mighty man was he,
With large and sinewy hands;
And the muscles of his brawny arms
Are strong as iron bands.

On "smith" by GK Chesterton
"“In most cases the name is unpoetical, although the fact is poetical. In the case of Smith, the name is so poetical that it must be an arduous and heroic matter for the man to live up to it. The name of Smith is the name of the one trade that even kings respected; it could claim half the glory of that arma virumque which all epics acclaimed. The spirit of the smithy is so close to the spirit of song that it has mixed in a million poems, and every blacksmith is a harmonious blacksmith.

Even the village children feel that in some dim way the smith is poetic, as the grocer and the cobbler are not poetic, when they feast on the dancing sparks and deafening blows in the cavern of that creative violence. The brute repose of Nature, the passionate cunning of man, the strongest of earthly metals, the weirdest of earthly elements, the unconquerable iron subdued by its only conqueror, the wheel and the ploughshare, the sword and the steam-hammer, the arraying of armies and the whole legend of arms, all these things are written, briefly indeed, but quite legibly, on the visiting-card of Mr. Smith.” "