Spectroscopy Archives - The Sciku Project

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

Patches on Venus:

Atmosphere harbouring the

conditions for life?

In the hunt for extra-terrestrial life, Venus is rarely considered due to the high surface temperatures (~465 °C) and the intense atmospheric pressure (92 times that on Earth). Yet a new study by Limaye et al (2018) suggests that life off the surface of the planet may be possible since the lower cloud layer harbours conditions suitable for microbial life: water, solutes, ~60 °C and an atmospheric pressure roughly equivalent to Earth.

What’s more, observations of Venus have revealed dark patches in the atmosphere that change shape, size and position over time. These are made up of particles roughly the same size as common Earth bacteria and also absorb light of at a similar spectrum. The changes in patch patterns could therefore be the equivalent of algae blooms.

Venus is thought to have once had water on its surface, potentially for as long as 2 billion years providing enough time for life to evolve. As the surface water evaporated the microorganisms could have been transported to the clouds, in similar ways to how bacteria have been found in the atmosphere of Earth (although on Earth aerial microbes do not appear to remain aloft indefinitely). Life on the second planet from the sun therefore remains a possibility and only further observations and potentially even atmospheric sampling will reveal whether the changing dark patches are indeed patterns of microbial life.

Original research: https://doi.org/10.1089/ast.2017.1783