October 19, 2015 | David F. Coppedge

Pounding Headaches for Solar System Dates

It’s hard to tell when things crashed into each other.

Moon

Dates for cataclysms on early moon, Earth questioned (Science Daily).  Two events that are “widely accepted but unproven” are (1) the impact that formed the moon out of the Earth, and (2) the so-called “Late Heavy Bombardment” that left many craters on the moon. This article casts doubt on the only empirical support for dating these imaginary events: zircons. Geologists have assumed that radiometric clocks were reset during the impacts. That may not be the case. A researcher at the University of Wisconsin-Madison says “to know that, you have to apply strict criteria, and that’s not what people have been doing.” His team’s work on zircons at the Vredfort Crater in South Africa “casts doubt on the methods used to date lunar impacts.

Planetary science: Carbon in the Moon (Nature Geophysics).  The moon recipe has been wrong, this paper says. “The Moon was once thought to be depleted in volatile elements. Analyses of the carbon contents of lunar volcanic glasses reveal that carbon monoxide degassing could have produced the fire-fountain eruptions from which these glasses were formed.” If the previous article casts doubt on dates of the moon and impacts, do scientists really know how long ago these eruptions took place?

Mound near lunar south pole formed by unique volcanic process (Science Daily). Not every circle on the moon is an impact crater. “A giant mound near the Moon’s south pole appears to be a volcanic structure unlike any other found on the lunar surface, according to new research by Brown University geologists.” It’s generally not a good idea to weave a theory around a unique, poorly-understood feature, but the article tries to tie this mound to the formation of the moon. “This unusual structure at the very center of the basin begs the question: What is this thing, and might it be related to the basin formation process?” Various “scenarios” are bandied about.

Earth’s Gravitational Pull Cracks Open the Moon (Live Science). One cannot assume that formations on the moon were all formed millions or billions of years ago. This article shares the surprise that Earth is forming cracks on the moon even now. The Lunar Reconnaissance Orbiter (LRO) has identified 3,200 fault scarps. The fact that they do not have random orientations led scientists to theorize that the Earth’s pull is responsible for their formation. “These cliffs are the most common tectonic feature on the moon, and are typically dozens of yards or meters high and less than about 6 miles (10 kilometers) long. Previous research had suggested they were less than 50 million years old, and are likely still actively forming today.” Fifty million years is roughly a hundredth the assumed age of the moon.

Ceres

What smacks into Ceres stays on Ceres, research suggests (Science Daily). Another puzzle at Ceres is the material brought in by impactors. Ceres has a mysteriously low density, making it porous. What happens when another body smacks into it? “The results were a bit of a surprise,” the article says about simulation experiments that showed 77% of the incoming material stays in or near the crater. “This is really contrary to previous estimates for small bodies,” the experimenter said. The article claims that “Over billions of years of such impacts, Ceres may have accumulated quite a bit of non-native material,” but wouldn’t that tend to make it less porous over time? Certainly the scientists have it all figured out, the next entry shows:

Fresh views of Ceres but ‘spots’ remain mysterious (BBC News).  Scientists on the Dawn mission team are puzzling over streaks and spots on asteroid Ceres. They still don’t have an explanation for the bright spots in Occator Crater, but that’s only one of the mysteries. The irregularly shaped craters are different from those on Vesta. “There is also a colour-enhanced mosaic image that offers clues about what the dwarf planet is made of – arguably asking more questions than it answers.” There’s a mysterious blue ring in one location; “We have absolutely no idea what that blue ring is due to” said one geologist, who revealed the degree of confidence they have about their explanations:

“And there are streaks across the surface that point back to the Occator Crater with its bright spots. We are poking at this, and we’re looking for ideas, but we haven’t solved the problem yet.

Saturn Moons

Surface ages of mid-size saturnian satellites (Icarus). In this paper, Sisto and Zanardi apply the crater-count dating technique to Saturn’s moons and find problems. One highlight: “The number of observed small craters is less than model calculations; probably due to crater saturation or E-ring flux.” Well, which is it? Those are very different scenarios. “Crater counting from high definition images is very important and could serve for the determination of the age of the surfaces.” Maybe someone should remind them of the problems with that dating method (5/22/12). Looking at their data and earlier estimates, “we have noted that the number of observed small craters is less than our calculated theoretical number,” they say, going into theory repair mode.

Pluto

The Pluto system: Initial results from its exploration by New Horizons (Science).  Some quotes in this historic paper cast severe doubt on what scientists think they know about the solar system in general, and Pluto-Charon in particular.

Varying crater abundances indicate wide-ranging surface ages on Pluto, in the sense that numerous large craters are seen on certain regions (such as CR [Cthulhu Regio]), whereas no craters with diameters of >10 km can be identified on SP [Sputnik Planum]. Model ages for SP derived from estimates of Kuiper Belt bombardment (see the discussion of Charon crater counts below) imply active geomorphic processes within the last few hundred million years and possibly continuing to the present. Such resurfacing can occur via surficial erosion/deposition (as at Titan), crater relaxation (as at Enceladus), crustal recycling or tectonism (as at Europa), or some combination of these processes. For icy satellites, resurfacing is generally associated with eccentricity tides, but these are not a viable heat source today for Pluto or Charon, whose orbital eccentricities are fully damped (Table 1); as such, the young surface units on Pluto present a puzzle regarding the energy source(s) that power such resurfacing over time scales of billions of years.

While pondering this puzzle, planetary scientists should remember that they are not so confident about the processes and dates at Titan, Enceladus or Europa either. Those are all puzzles, too. What do you get when you create a “combination of these processes”? Puzzle soup.

Exoplanets

Astrophysics: Surprisingly fast motions in a dust disk (Nature).  Scientists are really confused about the dust disk surrounding the star AU Microscopii. Observations made over ten years show pieces are flying out of the system rapidly! On the 20th anniversary of the first exoplanet discovery, they didn’t expect to see such rapid changes in a disk thought to be creating planets slowly over millions of years. Marshall D. Perrin writes,

What was definitely not expected, however, was what they saw around AU Mic: the clumpy dust clouds that extend across much of the disk to the southeast of the star have moved outwards over the past few years, by between 3 and 8 AU each (see Fig. 1 of the paper).

This unexpected result led the team to revisit some of the earlier Hubble data with more careful analysis. By separately analysing two data sets that had previously been combined, they found that the outward motion could also be seen in the Hubble data between 2010 and 2011. Although it is well understood that individual dust grains would be gradually blown out of the system, this would be expected to be a fairly continuous, steady-state process — not something that would produce a chain of discrete clouds of dust, stretching across an apparent distance equal to the diameter of our Solar System and moving outward as a coherent pattern. Furthermore, the observed speed increases roughly linearly with apparent distance from the star, from 4 to 10 kilometres per second; the motion of the outermost clumps is fast enough for bound orbits around the star to be ruled out. These clouds seem to be blowing out into interstellar space.

The authors readily admit that they do not have a good explanation for what is going on. They present several potential hypotheses, from resonant waves of dust induced by an unseen planet, to debris from massive asteroid collisions, to material ejected from the debris ring as a result of periodic stellar flares. But none of these is fully satisfactory.

This is clearly a destructive process, not something that can be trusted to create planets. That it’s happening before the eyeballs of humans in just years is really astonishing.

Puzzles can only be solved when you have some solid pieces to work with. How confident will you be solving a crossword puzzle with pieces that flow over time like putty? The main problem with planetary science is that they have the wrong box cover. The moyboys are not only trying to solve it with pieces made out of Silly Putty, they are trying to fit the pieces into the wrong picture. Millions of years & billions of years is not helping. It’s stretching the Silly Putty to the breaking point.

 

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