"Ask an Astrobiologist" with Dr. Britney Schmidt

Event Details

"Ask an Astrobiologist" with Dr. Britney Schmidt

Time: April 19, 2017 from 10:30am to 11:30am
Location: http://saganet.org/page/saganlive
Event Type: live, interview
Organized By: SAGANet
Latest Activity: Apr 20, 2017

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Event Description

lease join us if you can Wednesday April 19th at 10:30am US Pacific Time (5:30pm GMT)!

"Ask an Astrobiologist" is a live interview with a renowned astrobiologist! This format is interactive and allows participants to ask questions on Twitter & SAGANet! Use #askastrobio to submit your questions before the event! Questions will still be taken via SAGANet chat!

We welcome to SAGANet Dr. Britney Schmidt, Assistant Professor of Earth and Atmospheric Sciences at Georgia Tech, USA! Dr. Schmidt is an expert in Icy & Ocean Worlds. You can find out more about her work here!

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Comment by Teemu Gröhn on April 13, 2017 at 12:54am

Oh, and many plants do have multiple cells, but I get your meaning (photo- versus chemosynthesis). Here on Earth I would like to learn more about permafrost and the methane release from biomass locked under it. The latest work that I have read indicates that it will not doom us all in the short term at least (results that also go against the clathrate gun hypothesis), but we shall see. How does the Arctic compare to Mars in terms of permafrost depth and area? I remember reading that Mars might warm up sometimes on long time scales due to orbital characteristics. Anything you know about that? I am talking about periodic warming, not the billion-year future warming.

Comment by Teemu Gröhn on April 13, 2017 at 12:22am

If a cave was cut off from the outside atmosphere and hosted anaerobic lithotrophs, wouldn't their metabolism lead to a gaseous atmosphere inside the cave with pressure determined by the pressure of the rocks and water surrounding them? I am talking about very deep caves here, below any ice layers close to the surface. Supposing there is continued volcanism on Mars, the conditions down there could harbor extremophiles. Your points against any hypothesis for multicellular life on Mars are exactly the kind of expert opinion I want to know, but that still leaves the mystery of what I am looking at in the pictures. Perhaps some astronaut will visit the site in a few decades and take a look. Until then, I will keep wondering.

Comment by Sanjoy Som on April 12, 2017 at 4:57pm

Water-based organisms like fish and other animals get their oxygen from dissolved gas that is in the water solvent. They don't break the water molecules. Photosynthesis is a process in which oxygen is liberated by breaking down the water molecule, but no multi-cellular organism does that (and it requires light). My sense is that a lava tube would protect from radiation, but little less. The tube is still exposed to the thin atmosphere that has been around for billions of years. I feel that Mars never had an environment clement enough for long enough time to allow the evolution of complex multi-cellular animals like the ones you describe. If life does exist on Mars, it's probably single-celled like the ones you suggest (e.g. methanogens).

Comment by Teemu Gröhn on April 12, 2017 at 1:34am

I am curious to know more about hydrogenosomes and methanotrophic archaea and what role they might play in a hypothetical subterranean cave/groundwater ecosystem. Assuming the presence of H2O, CO2, methane, minerals like olivine and geothermal energy sources, could more complex organisms have evolved and survived in lava tubes or other caves by consuming the energy produced anaerobically by numerous smaller organisms, without any photosynthesis or atmospheric oxygen present? A very slow-going metabolism without plentiful oxygen to power the ATP synthesis I assume. Unless oxygen was somehow dissolved in the underground water by chemical reactions. The sporadic methane readings in the Martian atmosphere are interesting in this regard. Metabolites or chemical reactions? I would love to know.

Comment by Teemu Gröhn on April 11, 2017 at 10:57pm

Good points, Sanjoy. Earth lifeforms do show a strong correlation between size and oxygen levels in the atmosphere. Subterranean water sources do however have oxygen in the form of H2O, do they not? I do not know nearly enough about the metabolism of deep burrowing organisms to estimate the viability of any such critter in the deep underground layers. What do you think of the requirements for colonial organisms then? Could such micro-organisms join together on Mars to form macroscopic structures visible on camera? And what is your best hypothesis for the photo I linked? You can send email to me if you prefer.

Comment by Sanjoy Som on April 11, 2017 at 10:01am

Thinking out of the box is certainly encouraged, and you should keep thinking of ways to test your hypothesis. Multicellular organisms like the one you describe require a fair bit of oxygen, which is certainly absent from the planet today, and was certainly absent throughout the planet's history. Mars' atmosphere has been strongly dominated by CO2 over most of its history, and it's been a fairly tenuous atmosphere, to say the least, challenging the long term stability of water on the planet's surface. The energy you get by breathing CO2 is just not enough for a multi-cellular organism like the one you describe. But again, keep researching biological requirements for multi-cellular organisms, and environmental contexts in which those requirements are found, to help convince yourself one way or the other. Another interesting question to ponder is at what point did tentacle-like animals appear on Earth, versus the age of the lake deposit on Mars.

Comment by Teemu Gröhn on April 9, 2017 at 1:44am


Some other questions for the participants, take your pick:

-What are the deepest endolith micro-organisms ever found?

-What is the estimated volume of subsurface brine/water on different planets/moons in the solar system?

-What is estimated to be the total or relative subsurface biomass on Earth in various environments (cave ecosystems, under the seafloor, aquifers?)

-Any interesting discoveries relating to lake Vostok and other lakes in Antarctica?

-How stable are cave ecosystems over long periods of time? Assuming total cutoff from outside, what happens to the organisms?

Comment by Teemu Gröhn on April 7, 2017 at 11:55pm

If you look up "Hidden Valley" (the rough area of the photos, not necessarily the exact spot) on JPL's site you will find (quote): "A variety of mudstone strata in the area indicate a lakebed deposit, with river- and stream-related deposits nearby." To me that indicates a good chance of subterranean water. Imagine what evolution would do in underground layers like that over the course of hundreds of millions of years, if there was any simple life there to begin with. Opinions?

Comment by Teemu Gröhn on April 7, 2017 at 11:33pm

The circular symmetry of the thing in the photo is one big point in making it look lifelike. The roots, tentacles or what have you seem to radiate outwards from a central stalk. I have not seen a mineral formation that would mimic that feature, but many earth lifeforms that do (some worms, plants, sea cucumbers). I am curious to hear your opinions, Sanjoy, as well as others. Like I said, I can be wrong but a good debate of possibilities is necessary. What do you think of the geology of the region? Odds for subsurface water sources, based on the overhead map imagery? How big can burrowing lifeforms get on Earth, for example? A lively discussion is what I am after.

Comment by Teemu Gröhn on April 7, 2017 at 10:35pm

I myself can NOT guarantee that there is no life form on Mars that might have "tentacles". It is not good scientific practice to dismiss seemingly unlikely hypotheses offhand. Take a look at the photo and tell me what you think you're looking at. Maybe it is a mineral formation? Maybe it is a trick of the light? Or maybe it is something that was once alive. We can only advance scientific discovery by being open to possibilities and not ignoring what seems unlikely at first, Sanjoy. My mind sees a possible lifeform that needs to be looked at more closely, if I am wrong then so be it. What is your best hypothesis for the thing in the photo?

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