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Life on Venus? Intriguing molecule phosphine spotted in planet's clouds
again
By Robert Lea published 1 day ago
There's a new chapter in the Venus phosphine debate.

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illustration of phosphine molecules floating in space near venus and the sun
Artist's illustration of phosphine molecules floating in space near
Venus. (Image credit: NASA/ Robert Lea)
The Venus phosphine saga continues.

In September 2020, a team of scientists led by Jane Greaves of Cardiff
University in Wales reported the detection of phosphine, a possible
indicator of life, in the clouds of Venus. The announcement sparked a
heated debate and a surge of follow-up studies, which have generally
failed to spot the intriguing molecule in the Venusian atmosphere.

Now there's a new twist. Speaking at the Royal Astronomical Society's
National Astronomy Meeting 2023 in Cardiff this week, Greaves revealed
the discovery of phosphine deeper in the atmosphere of Venus than it had
been spotted before. Using the James Clark Maxwell Telescope (JCMT) at
the Mauna Kea Observatory in Hawaii, Greaves and her colleagues delved
into the atmosphere of Venus, down to the top and even the middle of the
planet's clouds.

The team thinks that the phosphine could be coming from lower in Venus'
atmosphere. But, as Greaves pointed out in the talk, the real question
is, What does the phosphine mean? Could it be evidence of alien life on
Venus?

Related: The phosphine discovered in Venus' clouds may be a big deal.
Here's what you need to know.

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Greaves said that, on Earth, phosphine is generated by microorganisms
living in a very low-oxygen environment. She explained that phosphine is
generally not made in other ways on our planet, as Earth lacks an
abundance of "loose" hydrogen. This suggests that phosphine, if detected
on other worlds, is a potential biosignature.

That's why the putative Venus phosphine find caused such a stir three
years ago. And the thought of life on Earth's "sister planet" isn't as
far-out as you might think: While Venus' surface is incredibly
inhospitable, reaching temperatures around 900 degrees Fahrenheit (475
degrees Celsius), conditions about 30 miles (50 kilometers) up in the
clouds are much more temperate and Earth-like.

However, even if there is phosphine in the Venusian atmosphere, it
doesn't necessarily mean the planet hosts life. Abiotic processes, some
of which we don't fully understand, could also be generating the stuff
on Venus.

"There’s a big school of thought that you can make phosphine by lobbing
phosphorus-bearing rocks up into the high atmosphere and kind of eroding
them with water and acid and stuff and getting phosphine gas," Greaves
said during her talk.

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2020: When all hell broke loose on Venus
Greaves may be wary of sparking a furor like the one that resulted from
the initial detection of phosphine by her team three years ago.

She reflected on how the search for phosphine in the atmosphere of Venus
was prompted and how that led to the 2020 situation. She said the
decision to investigate Venus resulted from the study of other solar
system worlds like Saturn and improved telescope technology that allowed
for the probing of the atmospheres of smaller planets.

"I vaguely remembered Venus is supposed to have this potential habitat
in the high clouds, which is anaerobic, and we eventually got telescope
time, so I thought, 'Why don’t we have a very quick look and see if
there’s some phosphates in Venus clouds, an analog to things living on
the surface of the Earth?'" Greeaves said. "Astonishingly, we found it,
and all hell broke loose!"

The potential detection sparked a flurry of follow-up research, some of
which was conducted by teams consisting of scientists involved in the
initial phosphine detection, that failed to turn up the molecule. And
these new findings from Greaves and her team are likely to prompt even
more follow-up investigations.

The debate could be settled in the not-too-distant future, for Venus has
emerged as a planetary science and astrobiology priority. For example,
two NASA missions, called VERITAS and DAVINCI, and Europe's EnVision
orbiter are scheduled to launch toward the planet in the next decade.
DAVINCI will carry a descent probe, which will study the Venusian
atmosphere up close as it plunges through it.

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Robert Lea
Robert Lea
Contributing Writer
Robert Lea is a science journalist in the U.K. whose articles have been
published in Physics World, New Scientist, Astronomy Magazine, All About
Space, Newsweek and ZME Science. He also writes about science
communication for Elsevier and the European Journal of Physics. Rob
holds a bachelor of science degree in physics and astronomy from the
U.K.’s Open University. Follow him on Twitter @sciencef1rst.