Month: May 2021

Planning ahead is something that sets astronomy and space exploration apart. Decadal surveys and years of technical effort for missions give the field a much longer time horizon than many others. In the near future, scientists know that there will be many ways to search for biosignatures anywhere from nearby ocean worlds (i.e. Titan) to distant potentially habitable exoplanets. However, it is not clear what these biosignatures would look like. After all, there is only Earth’s biosphere to study at the moment, and it would be unfortunate to miss any clues about another just because it didn’t look like those found on Earth. Now, a team led by researchers from the Santa Fe Institute (SFI) has developed a framework that could help scientists look for biosignatures that may be completely different from those on Earth.

This framework is based on stoichiometry. Stoichiometry is a common characteristic of high school chemistry classes and the study of chemical relationships. There are some obvious stoichiometric ratios on earth that are clearly formed by life as we know it. The generalization of these relationships to be applicable everywhere was the focus of the SFI paper. There were three main principles that together make up the new framework.

UT video about biosignatures.

The first principle is that stoichiometric values ​​change with the cell size of individual cells. For example, as bacteria get larger, the concentration of RNA increases while the concentration of individual proteins decreases. When these cells die, their size would help determine what concentration of molecules is being released into the environment.

The environmental distribution is also influenced by the second principle – that the number of cells in a neighborhood follows a power law distribution with respect to their size. For example, according to the simplest power law distribution curve, there are most likely many more small cells than large ones. This size ratio, together with the stoichiometries associated with these different sizes, then led to the third principle.

Example of a power law distribution. Lower values ​​on the x-axis (in this case particle sizes) lead to large quantities (y-axis).
Credit – Hay Cranes / PD / Wikipedia

Further application of this stoichiometric principle leads to a result that can be applied more generally to biospheres. In this case, the size of a particular particle is a determining factor in its relationship to the liquid that surrounds it.

Let’s keep using RNA and proteins as an example. RNA is an order of magnitude larger than a protein. According to the first principle, it is also found more frequently in larger cells. However, according to the second principle, larger cells are less widespread in the environment. Therefore, in a biologically active system, proteins that are smaller are more likely to have a higher concentration in a surrounding fluid than RNA, which is larger. Hence the third principle that its size determines the concentration of a particle in a surrounding liquid.

UT video about the possibility of life on Titan.

The immediate application of this framework is the study of ocean worlds like Titan or Enceladus, which are likely to contain liquid bodies that could contain concentrations of biological molecules. Unfortunately, there are currently no systems that can accurately measure the particle size and that could launch missions into these worlds. But that doesn’t mean there won’t be any in the future. The potential for using this framework now requires a little more technical expertise to develop such a system. And it’s already clear how good the astronomy and space research community is at this.

Learn more:
SFI – Origins of Life researchers develop a new ecological biosignature
Journal of Mathematical Biology – Generalized Stoichiometry and Biogeochemistry for Astrobiological Applications
Astrobiology – Exoplanet Biosignatures: A Framework for Their Evaluation
UT – What does it take to find life? Search the universe for biosignatures

Mission statement:
Artistic idea of ​​life on another planet
Photo credit: NASA

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Reposted from the NoTricksZone

By P. Gosselin on May 28, 2021

A team of scientists believe they have made a breakthrough in forecasting, suggesting that the NAO is indeed very predictable.

Winter temperatures in Europe in particular are modulated by the North Atlantic atmospheric pressure pattern known as the North Atlantic Oscillation (NAO).

As the name suggests, it describes the natural fluctuations in the difference in air pressure at sea level between the Icelandic low and the Azores high. These fluctuations control the strength and direction of the westerly winds and the location of the storm tracks over the North Atlantic and thus much of the European weather. It has nothing to do with CO2.

Promise of greater skill in seasonal forecasts

The ability to predict these fluctuations in the months ahead would of course be a very useful tool for agriculture, trade, and general preparedness.

Now the German Die kalte Sonne reports in its 40th video how researchers have achieved a “breakthrough” in predicting the NAO. In a recent article in Nature entitled, “The North Atlantic Climate Is Far More Predictable Than Models Suggest,” by Smith et al.

Breakthrough: NAO very predictable

The large research team evaluated climate model predictions from the past six decades and showed that “decadal fluctuations in the North Atlantic winter climate are actually very predictable, despite the lack of agreement between individual model simulations and the poor predictability of raw model results. ”

The authors say current models underestimate the predictable signal of the North Atlantic Oscillation by a full order of magnitude.

Image: Smith et al., Nature.

The scientists now hope to “deliver robust NAO forecasts in the future,” reports Die Kalte Sonne. No connection with trace gas CO2 is mentioned.

In September 2020, an article by Lüdecke et al. The correlation of AMO, NAO and sunspots with European temperatures for the period 1901–2015 and found a strong relationship between the NAO and temperatures in Central / Northern Europe from December to March.

In April 2021, another paper by Luedecke et al., “Decadal and multidecadal natural variability of African precipitation” showed how climate variability in Africa is related to natural oceanic and solar cycles.

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Symmetry in nature is pleasing to look at, and even more so when that symmetry is new. There is a lot to see on earth as biological processes have a penchant for patterns. But finding it out of the world is more difficult and sometimes more noticeable. This is why a HiRISE picture of some Martian dunes is so spectacular.

The picture was actually taken in 2010 in a crater in Noachis Terra in the southern hemisphere of the red planet with a latitude / longitude of 38 by -42.5 degrees. The Mars Reconnaissance Orbiter HiRISE he is traveling in was about 252 km above the surface of the planet when it captured the image, which covers an area of ​​about 25 square kilometers.

Reduced view of the dunes with their size compared to the rest of the surface.
Photo credit: NASA / JPL / University of Arizona

Even at this relatively large size, the image resolves objects that are less than a meter tall. However, the most striking feature of the images is the similarity between the dunes, which are actually the thin dark lines. The area between them, the slightly lighter reddish material, is covered with boulders that appear as points in the picture.

Mars and Earth aren’t the only worlds in the solar system with these fascinating types of dunes. In fact, Titan has the largest linear dune field in the solar system. We might get a high-resolution look at these when Dragonfly visits Saturn’s largest moon in 2034.

Learn more:
UA – dune symmetry
Flicker – dune symmetry

Mission statement:
Symmetrical dunes on Mars.
Photo credit: NASA / JPL / University of Arizona

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