Ice Archives - The Sciku Project

September 16, 2022September 17, 2022

Diamond Rain

Does Neptune ever
feel lonely, with a wall of
diamonds round it’s heart?

Diamonds might be precious but they’re composed of carbon, an element that’s common here on Earth and throughout the universe.

Under the right conditions (pressure and heat) carbon turns into diamonds. Marvin Ross predicted in 1981 that such conditions might be found in the mantels of the Solar System’s ice giants, Neptune and Uranus.

Recent research has supported this, with laser shock experiments on polystyrene performed by Kraus et al. (2017) replicating the conditions approximately 10,000km below the surfaces of Neptune and Uranus. Their experiments created nanodiamonds, supporting evidence that diamond precipitation occurs in the mantels of these planets.

Now further research has strengthened this evidence. The earlier studies used pure hyrdrocarbon systems (polystyrene is C₈H₈) but the interiors of Neptune and Uranus are more complex than that, consisting mainly of a dense fluid mixture of water (H₂O), methane (CH₄), and ammonia (NH₃).

To understand diamond formation under more complex conditions similar to those found on Neptune and Uranus, Zhiyu et al. (2022) investigated diamond formation using polyethylene terephthalate (PET) plastics (C₁₀H₈O₄). The researchers found that diamond formation is likely to be enhanced by the presence of oxygen, which in their research accelerated the splitting of the carbon and hydrogen.

Under the conditions found on Neptune and Uranus it’s likely that much larger diamonds would be formed, potentially millions of carats in weight. Over millennia these vast diamonds are predicted to sink slowly through the icy layers of the mantel before melting near the cores, creating an ever changing layer of diamonds around the cores of the planets.

The latest research may also explain another peculiarity about Neptune and Uranus: their unusual magnetic fields. Under the conditions that form diamonds in the mantel, the researchers also found evidence that superionic water might be created. Superionic water conducts electric current and is likely to impact the planets’ magnetic fields.

In addition to learning more about the Universe, there are practical implications for us on Earth resulting from the research too. Nanodiamonds have a range of important uses, including in medical sensors, non-invasive surgery, sustainable manufacturing, and quantum electronics. This latest research points the way towards a new way of fabricating nanodiamonds for such uses.

Glacier Mice by Dr. Jon Hare

unexplained movements
of a moss ball herd
island bioglaciology
By Jon Hare

My brother sent me an NPR story about a herd of fuzzy green “glacier mice”. The concept is crazy – small rocks, covered in moss, on a glacier, moving in tandem like a herd of miniature muskox. Hotaling et al. (2020) studied moss balls on an Alaskan glacier. They tagged the balls and tracked them for 54 days to understand their movement and then revisited the site over the next three years to understand persistence.

Photo credit – Tim Bartholomaus (http://tbartholomaus.org)

The moss balls moved in unison at approximately 2 cm day-1. Speed of movement was related to rate of ablation of the glacier surface: more ice melting, greater speed of movement. The direction of movement, however, was not related to ablation, nor slope, wind direction, or direction of solar radiation. Further, the moss balls persisted over years with an annual survival rate of 0.86, which equates to a greater than 6 year life span. It is hard to imagine a herd of moss balls surviving six Alaskan winters to move around together in subsequent summers.

These moss balls are also hotspots of biological diversity – they provide an island-like habitat for an array of organisms. How the biodiversity survives the winter is also unknown, as are the rates of colonization and extinction on the moss balls – raising questions of island biogeography on a glacier.

Original research: Hotaling, S, T. C. Bartholomaus and S. L. Gilbert (2020). Rolling stones gather moss: movement and longevity of moss balls on an Alaskan glacier. Polar Biology. https://doi.org/10.1007%2Fs00300-020-02675-6

Dr. Jon Hare is a scientist who works in Woods Hole, Massachusetts. His research background is fisheries oceanography and climate change impacts on marine fisheries. Check out Jon’s other sciku ‘Owls of the Eastern Ice’, ‘Varves’, ‘Signs of Spring’ and ‘Cobwebs to Foodwebs’.

August 21, 2019August 21, 2019

Dust

Iron-60 falls,
sprinkling stardust on pure snow.
Is this Philip’s Dust?

Particles of extraterrestrial dust enter the Earth’s atmosphere all the time, coming from asteroids or comets. Yet some is thought to come from supernova explosions and could help us understand the history of our solar neighbourhood. How can researchers detect these particles?

The key lies in a rare isotope, iron-60, that has no natural sources on Earth. But measuring abundance of iron-60 is easier said than done. One previous study has found iron-60 in deep sea sediment deposits but new research by Koll et al (2019) suggests that pure, untouched Antarctic snow is another viable source.

The team collected pure snow that was less than 20 years old, melted it, filtered out the solids and incinerated the residues. They then used mass spectrometry to measure the presence of iron-60 and manganese-53. By comparing the relative abundances of these two isotopes the researchers were able to demonstrate that the source of the iron-60 was interstellar dust, ruling out other potential sources such as cosmic radiation, nuclear weapons tests or reactor accidents.

The process opens the way for researchers to measure iron-60 abundance in older snow samples to get an idea of where and when the supernova occurred and when our Solar System entered the local interstellar cloud.

The final line of this sciku is a reference to Philip Pullman’s His Dark Materials, in a scene near the very start of the trilogy where Lord Asriel shows images of Dust taken in the Arctic:

“And the streams of Dust…”
” – Come from the sky, and bathe him in what looks like light.”
Chapter 2, The Northern Lights by Philip Pullman.

Original research: http://dx.doi.org/10.1103/PhysRevLett.123.072701

February 6, 2018February 6, 2018

On a knife edge

Life on a knife edge:

The metabolic demands

facing polar bears.

Polar bears rely on marine mammals such as seals which are high-fat prey. Despite the richness of their diet however, new research suggests that a reduction in the prey availability can have severe consequences on polar bear survival.

Pagano et al (2018) monitored nine free-ranging female polar bears over 2 years, measuring their metabolic rates, daily activity patterns, body condition and foraging success. They found that more than half of the bears had an energy deficit resulting from a high metabolic rate (1.6 times higher than previously assumed) and a low intake of the high-fat prey. As fragmentation of sea ice continues and seals become harder to catch the high metabolic requirements of polar bears is likely to become increasingly catastrophic for the species.

Original research: https://doi.org/10.1126/science.aan8677

November 10, 2017November 10, 2017

What lurks beneath?

What lurks beneath the

‘Mountains of Madness’? Maybe

it’s a mantle plume?

Antarctica has numerous subsurface lakes and rivers under its glaciers. Over 30 years ago it was hypothesised that there might be a mantle plume under West Antarctica which might be in part responsible for these subglacial water bodies.

Now there is increased evidence that such a mantle plume might actually exist: Seroussi et al (2017) wrote a three-dimensional ice flow model to understand how much geothermal heat would be needed to create the conditions observed at Marie Byrd Land in West Antarctica. They then compared this model with observations collected by a Nasa satellite. Their results lend support to the theory that there may indeed be a mantle plume under Antarctica.

Original research: https://doi.org/10.1002/2017JB014423