Environmental News

I joined there, but have not talked about why CO2 in eg. Mars does not trap heat well at that low density. It seems WRONG to interfere with joy. The few times I saw aurora were pure joy.

 

Epistemic language in news headlines shapes readers’ perceptions of objectivity

More jargon follows:
https://www.pnas.org/doi/10.1073/pnas.2314091121

But I link this for a reason. For me "scientists know" is not satisfactory either. "scientists understand" is just kinda self serving like they do and you don't. My favorite is clumsy "scientists recognize a concordance of evidence". Because it accurately describes how to reach a condition that is not belief, and not quite knowledge or understanding. Would appreciate how to convey that with fewer syllables.

it's all very epistemic ¯\_(ツ)_/¯

 

Boeing Starliner & ULA firestick & Will & Will did not go to ISS. Maybe Wednesday.

These resets require onboard batteries replaced. Those batteries can only be replaced when the assembly is returned to big rocket barn. How did it happen that Boeing (or ULA?) did not design such battery replacements doable 'in the field'? I want to call that an example of under engineering.

The wise guys have taken to calling it Boeing Stayliner.

 

Genomic sequencing began in 1996 with yeast, 1998 nematodes, and in 2000 for fruit flies. The are all lab rats in a way and easy to 'farm'. Indeed if you have a banana it is quite difficult to not also have fruit flies. Now 20,000 species of eukaryotes (cells more complex than bacteria) have been sequenced, which is quite a technological whoosh.

I want to compare it to exoplanet finding which has proceeded at same time with similar tempo. AFAIK no one else has drawn this comparo and I just threw it in because readers of this thread have to put up with so much

But the real topic is the diminutive New Caledonian fork fern:

This tiny fern has the largest genome of any organism on Earth

Which is pretty much ALL DNA, with some chlorophyll added for color.

No not really. But its 160 billion base pairs is the current record. Humans (for all their complexity) manage to bumble along with only 3.1 billion. So what's up with this, and why is it so common for green plants to engage in this excess? Take strawberries for example. They are ocotoploid meaning they haul around 8 complete sets of strawberry genes. They are the school project for learning DNA extraction because there is so dang much, it's hard to mess up the extraction.

It appears to be more or less accidental for DNA to get duplicated or extended during cell reproduction. For plants it does not seem to cause problems. For crops in particular, having more is related to having more of desired chemical traits, so we have ended up with many 4, 6 or 8 ploid crop species.

An absence of disadvantage may explain why plants have not evolved 'scissor' enzymes to keep things tidy. Bacteria in contrast are always snipping out viral DNA inserts. This is what CRISPR first was. Now converted to genomic editing in plants and animals and Nobel Prize medals.

There is just so much wonderfulness in DNA (and much more recently DNA tech) that I am not as excited about this fern's DNA, if unwound, would be 100 meters long from a single cell. The outside part of DNA (the D; deoxyribose) has parts that REALLY like to hydrogen bond with itself. It cannot be unwound it just coils back up again. Each 'D' hydrogen bonds to the nearest neighboring 'D' (10 base pairs away) that it can, limited by how tightly the whole thing can be twisted. This makes familiar helix!. It can't not.

==
Winners for smallest genomes appear to be bacteria that only live as symbionts inside insects. Having as few as 0.00001 billion base pairs. This may be the very definition of 'a simple life'.

 

So, there is a lot of DNA on Earth. A replicating cell cannot exist without it. Is DNA the most abundant biopolymer?

No, cellulose is and lignin (which makes wood wood) is second. I do not immediately find consistent reports for DNA's rank among 'our' biopolymers. May get back to you later. Meanwhile a few other abundant biopolymers merit mention.

Chitin is N-containing sugar polymer 'walling' crustaceans, insects and the like. Fungal and bacterial walls are not so different, but people do love to expand dictionaries, so those are not called chitin.

Marine critters live in a sea of bicarbonate and many wall with that. Braver ones wall with silicates of which there are less.

Animals do not have cell walls but their outsides are keratin. I call it a dumbed down protein polymer for including only the most abundant amino acids. Fingernails, scales, feathers and rhinoceros horns? Keratin.

Whole dang planet runs on photosynthesis, and proteins and energy-transfer molecules for that are abundant. Got ta be.

It might be useful to rank Earth's major biopolymers including DNA into a list of abundances. College profs can have exam questions. Perhaps more usefully examine polymer recycling into future life

 

We do not have a thread particular to Starlink satellites. We have mentioned their growing numbers, frequent re entries (now about 1 per day) and risk of initiating Kessler Syndrome mostly in LEO. But there is another aspect:

The Latest Threat to the Ozone Layer: Elon's Starlink Satellite Megaconstellation

That amount of aluminum re entering leads to formation of Al2O3 in stratosphere where it indirectly decomposes ozone. See there a linked publication for fuller summary.

Even when fully populated, Starlink and other LEO internet repeaters will be dumping much less aluminum than the amount of iron that micrometeoriods do (something like 40,000 tons/yr). It must be that Fe2O3 is less of an ozone problem. I guess. Something to ask authors of article.

 

Starlink full network later may de orbit ~7 units per day. I agree that only Al has been examined in that. Starlink's competing internet repeater networks may expand to 1/10 as large? And their units may have different chemistries? Those downplays have not yet been examined.

Something interesting may arise beyond shredding Al in the stratosphere. So stay tuned.