Jezero Sediment, TOI-715 b: Headlines and Extraterrestrial Life

Results from Google News search: 'exoplanet habitable'. (February 5, 2024)Last month ended with headlines hinting that our first glimpse of extraterrestrial life was just around the corner.

A week later, there’s the usual politics and pandemonium in the news: but no space aliens.

I’m not surprised. I’m not disappointed, either.

I am, however, excited about what we’ve found in Jezero crater, and a new world that’s not quite Earth 2.0.

Perseverance on Mars: Sediment and Speculation

From Paige et al., Science Advances, 2024), via ScienceAlert: 'Diagram of the depositional and erosional history of the Jezero western delta region.'
Jezero crater’s history of deposition and erosion, according to Paige et al., Science Advances. (2024)

ESA/DLR/FU-Berlin's photo, via NASA: Jezero Crater's delta, image from ESA Mars Express Orbiter. (September 21, 2020)The Mars 2020 mission hasn’t sent back snapshots of a Martian “EARTHERS GO HOME” protest, but we may have Martian microfossils in the sample tubes Perseverance has been collecting.

Scientists More Hopeful Than Ever That Perseverance Has Already Found Life on Mars
Carly Cassella, ScienceAlert (January 24, 2024)

“If signs of life really do exist on Mars, there’s a chance the Perseverance rover has already rolled over them.

“Underground radar images suggest it is searching in the perfect spot for fossilized microbial life….

“…Scientists strongly suspected the Jezero Crater once contained a delta system, as its surface holds the telltale signs of a dried-out lake bed, fed by an ancient river. That’s why a Mars rover was sent to investigate the crater in February of 2021.

“Now that researchers can peer beneath Jezero’s dusty exterior, they are more excited than ever by the possibility that Percy has already scooped up signs of extraterrestrial life….”

I’d planned on talking about RIMFAX, the Perseverance rover’s ground penetrating radar, and how recent data (apparently) confirms that flowing water built Jezero crater’s delta.

But that, and why “organic” and “alive” aren’t synonyms, will wait. Mainly because of the continuing family health situations. I’ve talked about that before.

Short version: it looks like sediment in the lake that filled Jezero crater very probably holds evidence of Martian life.1 If there ever was Martian life, that is.

Bacteria and Mars

NASA's high-resolution scanning electron microscope image of 'an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001. This structure was not part of the published research paper, but it is located in a similar carbonate glob in the sample.' (1996) see the last few decades, we’ve ruled out life on the Martian surface, microbial or otherwise, because several sorts of radiation and toxic chemicals would kill it.

If it wasn’t already dead from exposure to extremely low air pressure and pretty much no water.

Then, with people landing on Mars in the foreseeable future, some researchers checked out what would happen to some microcritters that make us sick: if they got loose on Mars.

Testing shows some bacteria could survive under Mars conditions
Bob Yirka, (February 7, 2024)

“An international team of radiation specialists, biologists and infectious disease experts has found four types of bacteria that are capable of surviving exposure to the hostile Mars environment. In their study, published in the journal Astrobiology, the group exposed four human-infectious bacteria to Mars-like conditions….

“…But they also found that all four survived to some extent when exposed to all that Mars would throw at them—three of them survived for 21 days, with one of them, P. aeruginosa, seeming to multiply and thrive.

“The research team concludes that bacteria carried inadvertently to Mars could pose a health risk to astronauts, particularly if the bacteria mutated to help them better survive the harsh conditions.”

I see at least two takeaways here.

First, this is a good example of why making sure Martian landers are thoroughly clean is a good idea.

As it is, if we do find living microorganisms on Mars, my guess is that someone will insist they must have originally come from Earth. Since nothing can live on Mars.

Second, and this is a point these scientists were making: being careful about what we bring along when we visit Mars in person is a good idea. Because microbes that make us sick can survive on or near the Martian surface. There’s no sense in adding hazards to an already-hazardous environment.

I don’t know what, if any, effect this latest study will have on discussions of things like the “chain structures resembling living organisms” scientists spotted in a Martian meteorite, back in 1996.

Last I heard, the consensus is that the “chain structures” weren’t microfossils. Partly because they are far too small to be alive, partly because non-living processes can produce similar shapes.

There are theoretical limits to how small critters can get. The chemical mechanisms in our cells take up a certain amount of room.2

If someone finds “chain structures resembling living organisms” that move, grow, and otherwise act like living critters — then it’ll be time to review those theoretical limits.

TOI-715 b: Habitable? Maybe — Worth Studying? Definitely!

Roger Sinnott's and Rick Fienberg's sky chart: constellation Volans; for IAU, Sky and Telescope magazine. (2011) Approximate location of TOI-715 marked with a red circle.The super-Earth last month’s headlines is TOI-715 b.

Discovery Alert: A ‘Super-Earth’ in the Habitable Zone
Pat Brennan, News and Events, NASA (January 31, 2024)

The discovery: A ‘super-Earth’ ripe for further investigation orbits a small, reddish star that is, by astronomical standards, fairly close to us — only 137 light-years away. The same system also might harbor a second, Earth-sized planet.

Key facts: The bigger planet, dubbed TOI-715 b, is about one and a half times as wide as Earth, and orbits within the ‘conservative’ habitable zone around its parent star. That’s the distance from the star that could give the planet the right temperature for liquid water to form on its surface. Several other factors would have to line up, of course, for surface water to be present, especially having a suitable atmosphere….”

What makes a planet a super-Earth is usually its mass: something more than Earth’s, but less than the mass of planets like Uranus and Neptune.

The last I checked, we don’t know the mass of TOI-715 b. But we do have its radius/diameter: 1.55 times that of Earth, give or take 0.06.

I did see one article give a mass for TOI-715 b: roughly three and a half times Earth’s mass. Since a planet 1.55 times Earth’s diameter would have a volume 3.723875 times Earth, I’m guessing that’s where TOI-715 b’s reported mass came from.

Maybe TOI-715 b does have exactly the same density as Earth. But we don’t know that yet.

That NASA news release gave TOI-715 b’s distance as 137 light-years. I’ve also seen 138 and 139 light-years given as how far away the exoplanet and star are.

I don’t know where NASA got 137 light-years. The best number I’ve seen for distance is 42.46 parsecs, which works out to about 138.49 light-years.

That puts TOI-715 in the neighborhood of Zeta Volantis. It’s a binary star that passed within a couple dozen light-years of us, back when folks we call Neanderthals were living south of my ancestral homelands.

HD 76700 b is in the same general direction, too. A probe to TOI-715 would pass the L 98-59 planetary system, and I’m drifting off-topic.

What’s exciting about TOI-715 b is that it’s close, by cosmic standards. That, and the fact that TOI-715 b passes across the face of its star every 19 days, should give scientists a look at its atmosphere: if any.3

Extraterrestrial Life: Bat-People and Making Sense Anyway

'Nouvelles découvertes dans la Lune....' A lithograph from 'Great Astronomical Discoveries', The New York Sun, translated into French. (1835) Artwork probably by Benjamin Day. Part of the 'Great Moon Hoax of 1835'. 'Lunar animals and other objects Discovered by Sir John Herschel in his observatory at the Cape of Good Hope and copied from sketches in the Edinburgh Journal of Science.' Benjamin Henry Day, Library of Congress, via Wikipedia, used w/o permission.It’s been a while since I talked about the Great Moon Hoax of 1835.

Briefly — for me — The Sun, one of New York City’s serious newspapers, ran a series of six articles about Sir John Herschel’s “great astronomical discoveries”, starting in August of 1835.

Seems that Sir John had discovered life on the Moon: tiny zebras, unicorns, bipedal beavers with no tails: and winged humanoids. The latter, “Vespertilio-homo” built temples: but apparently hadn’t invented clothing.

The Sun mentioned that the articles were fiction in September of that year, never retracted them, and issued a reprint in 1836.

Scientists recognized hokum, hogwash, and hooey when they saw it. I don’t know how many other folks believed the articles. Or noticed the ‘we’re just fooling’ statement. And maybe never got word that bat-people weren’t flitting about on the Moon.

I suspect that the Great Moon Hoax, 1947’s flying disc craze,4 and assorted other screwball fads helped make “extraterrestrial life” seem silly. At best.

Evidence, Logic, and — Maybe — Extraterrestrial Life

NASA, ESA, CSA, and J. Olmsted (STScI)'s illustration: absorption lines from dark cloud Chamaeleon I, showing which substances are present within the molecular cloud. Spectral data from three of the James Webb Space Telescope's instruments. (2023)What impresses me is that outfits like NASA admit that they’re thinking about whether or not life may exist on other worlds: and taking astrobiology seriously.

Life, Here and Beyond
Marc Kaufman, About Astrobiology, Astrobiology at NASA (October 12, 2022)

“…While no clear signs of life have ever been detected, the possibility of extraterrestrial biology — the scientific logic that supports it — has grown increasingly plausible. That is perhaps the single largest achievement of the burgeoning field of astrobiology, the broad-based study of the origins of life here and the search for life beyond Earth….”

I don’t “believe in” extraterrestrial life. I’ll talk about that later. But I definitely agree that “the possibility of extraterrestrial biology … has grown increasingly plausible”.

We keep finding more-or-less-complex organic molecules on other worlds and in interstellar clouds. And the catalog of other worlds long since passed the 5,000 mark.

Granted, many of those other worlds never could and never will support life. But some are remarkably like the place we call home.

Earth 2.0, Reality, and an Op-Ed

NASA/JPL-CalTech/R. Hurt's illustration: comparison of Kepler-186, Kepler-452, and (inner) Solar planetary systems. (2015)
Kepler-452 b: not quite ‘Earth 2.0’, but close. (2015)

Kepler-452 b’s sun is a whole lot like ours: pretty much the same size and color, maybe a billion years older.

Kepler-452 b is almost exactly the same size as TOI-715 b: half again Earth’s diameter, and almost certainly a rocky world, like ours. That’s why reporters called it ‘Earth 2.0’ and ‘Earth’s cousin’ when it was discovered, back in 2015.5

I still see the occasional headline with “Earth 2.0” in it: generally when scientists spot another exoplanet that’s not wildly unlike ours. But I haven’t run across other op-eds like this one, not recently:

Earth 2.0: Bad News for God
Jeff Schweitzer, Huffington Post (July 23, 2015)

“…I would like here to preempt what will certainly be a re-write of history on the part of the world’s major religions. I predict with great confidence that all will come out and say such a discovery is completely consistent with religious teachings. My goal here is to declare this as nonsense before it happens. I am not alone in this conclusion that religion will contort to accommodate a new reality of alien life.

“Let us be clear that the Bible is unambiguous about creation: the earth is the center of the universe, only humans were made in the image of god, and all life was created in six days. All life in all the heavens. In six days….”

At the risk of being marked as one of the “all” who will spout “nonsense” about religion and reality: here’s why I don’t fear the discovery of new worlds and extraterrestrial life.

‘Because Aristotle Says So’?!

NASA/JPL-Caltech/R. Hurt's artist's concept: how rocky, potentially habitable planets might appear. (April 13, 2022)
R. Hurt’s illustration: hypothetical habitable worlds. (2022)

Schematic diagram of Peter Apian's (Petrus Apianus) cosmology, largely reflecting Aristotelian physics and cosmology. From Peter Apian's 'Cosmographia,' annotated by Gemma Frisius. (1524) Reproduced in Edward Grant's 'Celestial Orbs in the Latin Middle Ages.' (1987)First, we’ve been through this before, at least in principle.

About a thousand years back, Aristotle was making a big impression on European academics; which was good news and not-so-good news.

The good news — my opinion — was that Aristotelian logic helped us think about how we think.

The not-so-good news was that many academics became entirely too respectful, regarding Aristotle’s views.

That came to a head in the 13th century. One of the many topics getting attention was speculation that we might not be standing on the only world.

Some scholars said that other worlds could exist. Others said that wasn’t possible: because Aristotle had said there was only one world, and we’re standing on it.

That’s when the Bishop of Paris got involved. His Condemnation of 1277 said, at least by implication, that God’s God and Aristotle’s not.

Not even if what Aristotle said didn’t line up with what God does.6

One of the prohibited claims from the Bishop’s list:

27A. That the first cause cannot make more than one world.
Selections from the Condemnation of 1277“, Gyula Klima, Fordham University (November 23, 2006)

This is a very oversimplified version of socio-philosophical-political concerns in 13th century Europe, but it’s what I have time — and mental focus — for this week.

Belief, Preference, and God

NASA/ESA/STScI's Hubble image: Abell 2744 galaxy cluster, in the constellation Sculptor. (2014) from JPL News Release see don’t “believe in” extraterrestrial life.

I don’t not believe in extraterrestrial life.

I’m quite sure that we have not found solid, clear, unmistakable evidence that life exists anywhere except on Earth. And places we’ve carried it, like Earth’s moon.

On the other hand —

We’re finding life’s chemical components scattered throughout the universe.

Insisting that life can’t, or mustn’t, exist elsewhere strikes me as silly.

I’d prefer that we find life which unequivocally began on another world: even Martian microbes would do.

But I won’t insist that there must be Martian microbes: or that we must have neighbors in this vast and ancient universe.

That sort of decision is up to God.


  • God’s God
  • I’m not
  • I’m okay with that

The idea that God is large and in charge isn’t new:

“Our God is in heaven and does whatever he wills.”
(Psalms 115:3)

I’ve talked about this before, and almost certainly will again:

1 Mars, rocks, and microfossils:

2 A microscopic Martian meteorite mystery:

3 Exoplanets, life, and all that:

4 In the news:

5 2015: Earth 2.0, but not quite:

6 Aristotelian enthusiasm and a reality check:

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About Brian H. Gill

I was born in 1951. I'm a husband, father and grandfather. One of the kids graduated from college in December, 2008, and is helping her husband run businesses and raise my granddaughter; another is a cartoonist and artist; #3 daughter is a writer; my son is developing a digital game with #3 and #1 daughters. I'm also a writer and artist.
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