Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Pseudoscience-is-malarkey on 02/03/2017 08:06:57

Title: How does NASA know that the Moon's South Pole-Aitken Basin is its oldest crater?
Post by: Pseudoscience-is-malarkey on 02/03/2017 08:06:57
How does NASA know that the Moon's South Pole-Aitken Basin is its oldest crater simply by looking at it? I also have confusion about how they acquired this knowledge when there are a lot of Moon craters, as you say in Britain, about.
Title: Re: The South Pole-Aitken Basin
Post by: Colin2B on 02/03/2017 09:40:47
I would imagine by looking at the overlay of debris and subsequent hits. Newest craters have fewer overlays.
Title: Re: How does NASA know that the Moon's South Pole-Aitken Basin is its oldest crater?
Post by: jeffreyH on 03/03/2017 10:38:41
Both crater counting and the aging of lunar samples were used to develop methods of determining the age planetary surfaces. Ultimately it was Bill Hartmann who refined the methodology. (

Title: Re: How does NASA know that the Moon's South Pole-Aitken Basin is its oldest crater?
Post by: chris on 02/12/2017 10:20:11
Put simply, if a crater has no craters then it must, on balance of probability, be younger than a crater with craters; similarly, a crater with more craters is older than a crater with fewer craters...

[Try saying that when you've had a few!]
Title: Re: How does NASA know that the Moon's South Pole-Aitken Basin is its oldest crater?
Post by: Zer0 on 05/12/2017 20:01:08
Subject - How does NASA know that the Moon's South Pole-Aitken Basin is its oldest crater?

The South Pole Aitken basin or SPA was stated to be the largest, deepest and Assumed to be oldest basin recognized on the Moon.

Here is info/data referring in relation to the Subject.

The composition of this basin, as estimated from the Galileo, Clementine and Lunar Prospector missions, show that it is different from typical highland regions. Most importantly, none of the samples obtained from the American Apollo and Russian Luna missions, nor the handful of identified lunar meteorites, have a composition that is comparable.

The orbital data indicate that the floor of this basin has slightly elevated abundances of iron, titanium, and thorium. In terms of mineralogy, the basin floor is much richer in clinopyroxene and orthopyroxene than the surrounding highlands that are largely anorthositic.

Reasons for Assuming it as Oldest.

Several possibilities exist for this distinctive chemical signature. One is that this composition might simply represent lower crustal materials that are somewhat more rich in iron, titanium and thorium than the upper crust.

Another possibility is that this composition reflects the widespread distribution of ponds of iron-rich basalts, similar to those that make up the lunar maria.

Alternatively, the rocks here could contain a component from the lunar mantle if the basin excavated all the way through the crust.

The origin of the anomalous composition of this basin is not known with certainty at this time, however, and a sample return mission will most likely be required to settle this debate.

Complicating matters is the fact that all three of the above hypotheses could contribute to the anomalous geochemical signature of this giant crater.

Furthermore, it is possible that a large portion of the lunar surface in the vicinity of this basin was melted during the impact event, and differentiation of this impact melt sheet could have given rise to additional geochemical anomalies.

Source - Wikipedia.–Aitken_basin#cite_note-Petro-1

Scientific Knowledge is Dynamic in Nature, new theories n concepts keep popping up n old views are often bubbles waiting to be popped.

Considering the Subject questions views of a specific Agency, it would only be fair to put forward their latest data.

Shortly after the Moon formed, an asteroid smacked into its southern hemisphere and gouged out a truly enormous crater, the South Pole-Aitken basin, almost 1,500 miles across and more than five miles deep.
This is the biggest, deepest crater on the Moon.

Fortunately, a crater on the edge of the South Pole-Aitken basin may provide just such a view. Called the Apollo Basin and formed by the later impact of a smaller asteroid, it still measures a respectable 300 miles across.

Petro and his team made the discovery with the Moon Mineralogy Mapper (M3), a NASA instrument on board India’s Chandrayaan-1 lunar-orbiting spacecraft. Analysis of the light (spectra) in images from this instrument revealed that portions of the interior of Apollo have a similar composition to the impact melt in the South Pole-Aitken (SPA) basin.

The asteroid that created the SPA basin probably carved through the crust and perhaps into the upper mantle. The impact melt that solidified to form the central floor of SPA would have been a mixture of all those layers. We expect to see that it has slightly more iron than the bottom of Apollo, since it went deeper into the crust. This is what we found with M3.

However, we also see that this area in Apollo has more iron than the surrounding lunar highlands, indicating Apollo has uncovered a layer of the lunar crust between what is typically seen on the surface and that in the deepest craters like SPA," said Petro.

The lower crust exposed by Apollo survived the impact that created SPA probably because it was on the edge of SPA, several hundred miles from where the impact occurred, according to Petro.

Both SPA and Apollo are estimated to be among the oldest lunar craters, based on the large number of smaller craters superimposed on top of them. As time passes, old craters get covered up with new ones, so a crater count provides a relative age; a crater riddled with additional craters is older than one that appears relatively clean, with few craters overlying it. As craters form, they break up the crust and form a regolith, a layer of broken up rock and dust, like a soil on the Earth.

Source of Info/Data & Credits - NASA

If you Observe closely, the views stated above are a new set of assumptions/estimates.

In my Personal opinion/view stratigraphic, gamma spectral, or crater counting all help build up a technically sound logically right conclusion but I would still wait for an actual recovery of sample obtained from the Aitken n Apollo basins n have them measured by radiometric dating techniques.
On second thought samples could still be contaminated or geological events misunderstood on basis of time sequences n patterns misleading.