Coalition of the Confused

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Confused malcontents swilling Chardonnay while awaiting the Zombie Apocalypse.

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The Solar System   Science

Started 5/17/18 by Jenifer (Zarknorph); 31743 views.
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From: Jenifer (Zarknorph)

6/9/18

Curiosity hits pay dirt at Mt Sharp

NASA's rover hasn't just been sniffing the air as it's trundled across the Gale Crater — it has also been drilling just below the surface of the 3.5 billion-year-old lakebed in search of organic molecules.

In 2013, it confirmed organic compounds in rocks in a deep part of the crater called Yellowknife Bay, said Jennifer Eigenbrode, who led the organic molecule study published in Science.

But the deposits were much smaller than they had anticipated.

"A lot of us were left scratching our heads trying to figure out, 'What does this mean?' Then we turned around and realised, 'Let's just go and find more'," said Dr Eigenbrode of NASA's Goddard Space Flight Centre.

They hit pay dirt about 6.5 kilometres away, at two sites near Pahrump Hills at the base of Mt Sharp.

"The rock powder was dark grey. Oh that was such a great feeling when we found those," Dr Eigenbrode said.

Thimble-sized samples of material baked slowly in temperatures of between 500–840 degrees Celsius, revealed the grey mudstone contained different carbon-based molecules to those found at Yellowknife Bay.

These molecules appeared to come from a much larger molecule, and contained high levels of sulfur.

"Those two features are very important for the preservation of organic material in rock on Earth," Dr Eigenbrode said.

Although there is not enough information to know whether the carbon molecules were created by biological or non-biological processes, it is possible that they could be a source of methane, Dr Eigenbrode said.

"They could be changed from something like we've observed at the base of the mountain into methane that eventually makes its way back in to the atmosphere," she said.

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From: Jenifer (Zarknorph)

6/9/18

And Now Pluto!

Image result for Pluto

For a minor planet, Pluto throws up some pretty big surprises. The icy world has dunes, but unlike Earth's sandy versions, Pluto's seem to be composed of flecks of methane ice.

Key points:

  • Dune-like features were spotted on Pluto after the New Horizons mission flew past in 2015
  • Planetary scientists thought the icy world lacked the atmosphere to generate dune-building winds
  • Modelling shows how methane ice grains from mountain slopes and moderate winds could produce dunes

Published today in the journal Science, it's the latest in a swag of new discoveries uncovered by NASA's New Horizons spacecraft.

When New Horizons flew past Pluto in July 2015, it sent back detailed images of the icy world's surface.

Matt Telfer at the University of Plymouth in the United Kingdom was one of many planetary scientists and geologists who scoured the pictures for interesting features such as dunes.

One location stood out: a north-west patch of Pluto's vast heart-shaped plain of ice dubbed Tombaugh Regio.

New Horizons took photos of dune-like ripples roughly a kilometre wide and tens of kilometres long on the plain, nestled against mountain peaks standing more than 3 kilometres tall.

"There were a few areas that looked interesting," said Dr Telfer, who co-authored the paper.

"But this one spot, the more we looked at it, we thought 'they really, really do look like dunes'."

Upon closer examination, their location, orientation and spacing all pointed to them being dunes.

But there was a problem: planetary scientists thought Pluto's atmosphere was too thin to sustain the winds needed to sculpt the ripples that were visible.

So how did they appear?

Continued

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From: Jenifer (Zarknorph)

6/9/18

How to build a dune on Pluto

Think of dunes, and you probably picture sweeping swathes of hot sandy desert. Winds whisk sand grains into the air, which fall to the ground in ordered ridges.

On Earth, this happens largely because our atmosphere is thick enough to keep the wind blowing.

But Pluto has a comparatively thin atmosphere — only 0.001 per cent of what we have on Earth. Little atmosphere means weak winds.

Pluto is extremely cold — around minus 230 degrees Celsius — and orbits the sun at an average distance of 6 billion kilometres.

But even the meagre solar energy that falls on its icy surface is enough to warm nitrogen ice on its frosty mountains.

The nitrogen ice turns into a gas in a process called sublimation. Still-frozen methane grains from the slopes are shaken loose and lofted into the atmosphere.

"On the order of a stiff Earth breeze, methane grains around a quarter of a millimetre across will blow around," Dr Telfer said.

Size wise, the methane grains are "on the order of typical Australian dune sand from the Simpson or Strzelecki [deserts]", he added.

Temperature differences in the atmosphere trigger "thermal winds", which keep the methane grains moving along and eventually dump them on the plain below.

Those grains, in turn, kick up more grains and so on, to eventually produce long, thin dunes.

It turns out that Pluto's thin atmosphere, plus its low gravity, may help the dune-forming process. With little gravity or wind resistance to drag or slow them down, methane grains can stay airborne longer.

The dunes are no more than half a million years old, because that's how long it takes the slab of ice they sit on to completely turn over.

But Dr Telfer suspects the dunes are much younger — perhaps on the scale of hundreds of Earth years.

And that particular site is, at the moment, the only place known on Pluto that ticks all the dune-building boxes: a supply of granular material, enough wind to push them around and atmosphere — even a little bit.

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From: Jenifer (Zarknorph)

6/21/18

Mysterious mountain waves in Venus's atmosphere put new spin on a day

Magellan: Venus False-Color Terrain

This visualization is a brief tour of the global terrain of the planet Venus as revealed by radar onboard the Magellan spacecraft. The height of the terrain ...

A mysterious bow-shaped "gravity" cloud that hovers over mountains on Venus could speed up the planet's day by a couple of minutes, according to a study.

Key points

  • We don't know exactly how long it takes Venus to complete a single rotation.
  • New modelling shows fleeting formation of massive mountain waves in atmosphere may speed up rotation at surface
  • Understanding rotation rate can help us understand other mysteries such as what lies at Venus's core

The study, published today in Nature Geoscience, may help explain variations in the planet's rotation seen by different spacecraft over the years.

Venus spins at a leisurely pace, taking an average of 243 Earth days to complete one full rotation.

Measurements taken 16 Earth years apart by the Magellan and Venus Express missions differ by up to seven minutes, said Thomas Navarro, a planetary scientist at the University of California, Los Angeles.

"It is very difficult to measure the rotation rate because Venus rotates very slowly," Dr Navarro said.

"We have to average the displacement over a long period of time to get an estimate.

"We kind of know what the average duration of the day is, what we don't know very well is how the fluctuations of the rotation rate could make the day vary."

Slow planet vs super-fast atmosphere

Venus is also hard to study because it is shrouded in thick clouds of sulfuric acid.

Unlike the leisurely pace taken by the planet itself, these clouds rip right around Venus in just four to five Earth days.

"We do not understand much about why the atmosphere is super rotating," Dr Navarro said.

But not all the atmosphere appears to super rotate.

Recently, the Japane
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From: Jenifer (Zarknorph)

7/25/18

The Quest for the Holy Grail continues

Image result for ice age on mars

In a massive shot in the arm for the search for life on Mars, a giant lake of liquid water seems to be buried beneath the ice near the Red Planet's south pole.

Key points:

  • The search for liquid water on Mars has, so far, been unsuccessful
  • What appears to be a 20-kilometre-wide subsurface "lake" near Mars's south pole has been detected by the MARSIS ground-penetrating radar instrument on the Mars Express spacecraft
  • If the lake is part of a wider network, life in microbial form could theoretically survive there today

Using ground-penetrating radar on an orbiting spacecraft, an Italian team picked up signs of a 20-kilometre-wide body of liquid water, hidden 1.5 kilometres under the ice cap.

They published their observations in Sciencetoday.

Whether that body of water is a relic of past oceans or part of a bigger network of subterranean lakes is still a mystery, said Roberto Orosei, a planetary scientist at the Italian National Institute of Astrophysics and lead author of the paper.

"We need to determine if this discovery is unique or if it's something that exists elsewhere on Mars," he said.

Whether it's a one-off or not, he added, has important implications for finding life lurking on Mars today.

Image result for mars ice caps

"This [bright reflection] is what you see in places like Antarctica, over Lake Vostok and other subglacial lakes," Dr Orosei said.

But whether the Martian subsurface lake is mostly pure water or sludgy sediment remains to be seen.

The MARSIS instrument can't tell us how deep the water is or how much stuff is mixed with it.

It could be pure water, maybe a metre deep or so, or water-saturated sediments tens of metres thick, Dr Orosei said. Both scenarios would produce the same radar signal.

So what can we deduce about the lake?

To stay liquid in such frigid conditions, the lake must be salty.

Dissolved salts lower water's freezing point — seawater on Earth, for instance, freezes at minus 2 degrees Celsius.

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From: Jenifer (Zarknorph)

7/28/18

Blood Moon last night, but I missed it

The lunar eclipse seen around 4:00am on Saturday morning.

Curiosity and awe have greeted a complete lunar eclipse, the longest one of this century and visible in much of the world.

The so-called "blood moon," when it turns a deep red, was visible at different times in Australia, Africa, Asia, Europe and South America when the sun, Earth and moon lined up perfectly, casting Earth's shadow on the moon.

The total eclipse lasted one hour, 42 minutes and 57 seconds, though a partial eclipse preceded and followed it, meaning the Moon spent a total of three hours and 54 minutes in the Earth's umbral shadow, according to NASA.

A total lunar eclipse occurs when the Earth's shadow moves across the Moon, blocking out light from the Sun.

"What it actually shows is the solar system in action, and it gives you a bit of a better perspective of your own place in the scheme of things, in the universe," he said.

Astrophysicist at the Australian National University Brad Tucker said a total lunar eclipse is something even experts get excited about.

"The Moon passes into the Earth's shadow and that red colour really is the atmosphere of our Earth covering the light to bed.

"So you're actually seeing … the sunrise and the sunset of the Earth simultaneously," he said.


Pictures to follow

Di (amina046)

From: Di (amina046)

8/12/18

Jenifer (Zarknorph)
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From: Jenifer (Zarknorph)

8/12/18

I heard it got delayed at the last minute..

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