What might aliens look like?
Nothing like us, possibly.
Hey guys, Amy here with DNews.
We haven’t found extraterrestrial life just yet, but that might be because we’re looking
for entirely the wrong thing.
Let’s start with a recap of life as we know it on Earth.
Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur are the six basic building blocks
of all life forms on Earth, at least that we know of.
Phosphorus is an integral part of DNA and RNA, the structures that carry all the genetic
instructions for life.
Carbon, meanwhile, is the main component of sugars, proteins, fats, DNA, muscle tissue…
pretty much everything that makes up your body.
Life on Earth also requires something called a phospholipid bilayer membrane, a strong,
permeable, water-based membrane that houses the organic matter inside every cell, vesicles
made of which are called liposomes.
So these are the things astronomers look for on other planets and in alien environments
to find life.
And because all life on Earth needs water, we tend to look for water in the search for
extraterrestrial life.
But there’s increasingly more research to suggest that life on other worlds won’t
necessarily have the same makeup as life does here.
In 2010, a team of researchers released a study saying they’d discovered the first
known microorganism able to thrive and reproduce using arsenic, a toxic chemical.
In a laboratory setting, researchers successfully grew a strain of Gammaproteobacteria microorganisms
on a diet lean on phosphorus and heavy on arsenic before removing the phosphorous entirely.
The microbes didn’t die.
Instead, they thrived, with later generations substituting arsenic for phosphorus in its
DNA and other cellular components.
The arsenic became a building block for a new strain of cells.
When this news came out it was massively exciting for the astrobiology and space world, but
the discovery was eventually debunked.
The phosphate-free medium in which the microbes thrived with arsenic in their DNA turned out
to have just enough phosphate in it to support life as we know it.
But it didn’t turn out to be the nail in the coffin of finding interesting alien life.
Just last month, scientists at Cornell University modeled a cell that could exist on Saturn’s
moon Titan.
Titan, Saturn’s largest moon, has a thick atmosphere, liquid ethane and methane seas,
and organic-rich chemistry somewhat reminiscent of a frozen early Earth.
Titan couldn’t support organic cells as they exist on Earth, but it could support
methane-based, oxygen-free cells.
The researchers theorized a cell membrane called an “azotosome.”
It’s a membrane analogous to the liposomes we know exist in Earthly life; it has the
same stability and flexibility.
But these azotosomes are made from nitrogen, carbon and hydrogen molecules, molecules we
know exist in Titan’s seas.
So it’s possible that carbon-free life could exist on Titan, or else on some exoplanet
or exomoon with a similar structure.
So, to be fair, the arsenic-based bacteria was eventually disproved and the possible
cell that could exist on Titan is only a model.
But still, the definition of life keeps expanding and that makes the ongoing search for extraterrestrial
life that much more interesting.
And switching gears just a little, we are really happy that our new channel Seeker launched
this week!
Here on DNews, we take a look at the news from a science angle, and they take a look
at the news from a human side!
Like this video here about the fight to save New York subway dancers...
So make sure you check that video out, it’s the first link in the description, and subscribe
to Seeker so you never miss a video!
So what do you guys think about non carbon-based life forms?
Cool science fact or unlikely science fiction?
Let us know in the comments below or you can let me know directly on Twitter as @astVintageSpace.
And don’t forget to subscribe for more DNews every day of the week.