Observing with Street Lights

Observing with Street Lights
Dark sky sites not always necessary to see the Milky Way (This image was taken ouside of a B&B in Julian, CA)

Wednesday, July 24, 2019

Ninth International Mars Conference at Caltech; What have we learned about Mars, Dust and Biosignatures and where is the water?

Greetings from Palmia Observatory

Well just as soon as the Astrobiology for Astronomers Workshop ended, it is now time for the Ninth International Mars Conference held at Caltech.  I'm already exhausted and hoped to spend at least a couple of days on Mars.

Ok, so I'm all badged up for the conference and ready to get started.  I started off with a lot of enthusiasm, but soon tired out and played hooky the second day.  Sorry about that if you were hoping to find some additional little tidbits here, but I will make some "student, physicist wannabe" type comments.
Resident Astronomer picks up badge and coffee and heads to Caltech Beckman Auditorium (Source: Palmia Observatory)
Resident Astronomer picks up badge and coffee and heads to Beckman Auditorium (Source: Palmia Observatory)


The plenary sessions and breakout sessions were held in the Caltech Beckman Auditorium and Ramo Auditorium.  Here we see eager Martians milling about until the front doors open up.  
Martians gather at the Caltech Beckman Auditorium for the Ninth International Mars Conference (Source: Palmia Observatory)
Martians gather at the Beckman Auditorium for the Ninth International Mars Conference (Source: Palmia Observatory)


I sat in on three major topics: What we learn by studying Mars, Is Dust Controlling the Martian Atmosphere, and Biosignatures.  A key point to remember is that we have had over 50 years of space based exploration of Mars.  Initially the investigation was to follow the water, reminiscent of the "canals on Mars" way of thinking, but at least now there is geological evidence of water at one time in Mars' history.  Then there were missions to look at habitability and evidence for life at least in some previous era on Mars.  Now, we are preparing for the transition from robot investigation of Mars to human astronaut exploration of Mars. 
Earthlings have over 50 years of space based investigation of Mars (Source: Source: Sarah Johnson, Georgetown U)
Earthlings have over 50 years of space based investigation of Mars (Source: Source: Sarah Johnson, Georgetown U)


Many of the speakers discussed the geological history of Mars and how Mars is a complex planetary system where water and carbon dioxide are continuously in circulation in the atmosphere.  Some liquid water or frozen water is still identified as being below the surface or frozen in the polar caps.  Working out all of these interactions and especially how water on the surface years ago resulted in formation of mineral species, observable today, that could only have formed in the presence of water.  Again we see the interdisciplinary nature of these studies where astronomers have to identify how the amount of sunlight due to varying obliquity and solar variation impact the amount of solar radiation heating the planet and how early on high carbon dioxide levels helped warm the planet and maintain an atmospheric pressure capable of supporting liquid water, which the geologists then describe how the mineral evidence visible now helped shape the surface of the planet.
Mars is a complex planetary system (Source: Bruce Jakosky, U of Colorado - Boulder)
Mars is a complex planetary system (Source: Bruce Jakosky, U of Colorado - Boulder)


The evidence for previous climate history comes from landed missions as well as orbiting missions.  This chart below shows the main missions sent to Mars and how early missions, such as Viking, had limited spatial resolution, but later missions had greater spatial resolution, measured in meters not hundreds or thousands of meters.  Likewise the wavelength of spectroscopic measurements have increased to such an extent that mineral species can be detected from orbit.
Investigating Mars needs missions with high spatial & wavelength resolution  (Source: Wendy Calvin, U of Nevada - Reno)
Investigating Mars needs missions with high spatial & wavelength resolution  (Source: Wendy Calvin, U of Nevada - Reno)


The geologists and their robotic surveyors have looked and found rock structures consistent with an early history of water and lakes, if not oceans, on Mars.
Landed Mars missions identify geological history (Source: Ray Arvidson, Washington U in St. Louis)
Landed Mars missions identify geological history (Source: Ray Arvidson, Washington U in St. Louis)

Now, examination of the Martian surface finds little water and the storms on Mars now are dry and cold dust storms.  This slide shows over 11 Martian years of observation of dust in the atmosphere.  You can see regions and time during the year when dust is present in giant storms that cover large portions of the Martian surface.  Professor Montabone explained that even though this is a long period of coverage it is not nearly long enough to develop good climate models of dust circulation and the current data does not contain enough data over the solar maximums in the 11-year solar cycle to be able to predict if these storms are the worst or just normal.
Dust storms as seen over 11 Martian years of observations (Source: L. Montabone, Space Science Institute)
Dust storms as seen over 11 Martian years of observations (Source: L. Montabone, Space Science Institute)

So, we are left wondering what has happened in Mars' history to go from a planet with water on its surface to the dry and cold low pressure atmosphere that is there today?  Previously, I had mostly just accepted that Mars lost its atmosphere when its molten core froze out and it lost its magnetic field, when then allowed the solar wind and solar radiation to photoionize the atmospheric water and blow the hydrogen and other molecules off into space.  But, this theory of magnetic field loss is apparently now being questioned and the total reasons for atmospheric loss remain unclear.  We will have to keep following up on this idea.
Mars climate observations indicate warm wet environment 3.7Ga (Source: D.M. Kass, JPL - Caltech)
Mars climate observations indicate warm wet environment 3.7Ga (Source: D.M. Kass, JPL - Caltech)


After lunch, I split up from Math Whiz, Dave, and elected to spend some of the remaining sessions hearing more about biosignatures.  So, even though we spent most of last week hearing about that topic at the Astrobiology for Astronomers Workshop, also held at Caltech, it was time to listen in a bit more at this Mars specific conference.  In fact, we heard that most NASA future missions are now being designed and/or upgraded to include more specific search for biosignatures as a design goal and requirement.
NAS study calls for more search for life and astrobiology in NASA mission stages  (Source: Ray Arvidson, Washington U in St. Louis)
NAS study calls for more search for life and astrobiology in NASA mission stages  (Source: Ray Arvidson, Washington U in St. Louis)
As we saw from the previous workshop, the topic of habitability goes much deeper than having a planet in the habitability zone near the sun.  Looking at bacteria here on Earth that is able to adapt and grow and divide in very harsh environments can lead to a better definition of habitability and better identification of a biosignature.  Some Earth based members of the Archaea bacteria class, including the methanogens and halophiles, can live in very harsh environments and help define better biosignatures and what constitutes habitability.
Studying extremophiles on Earth as analog for Mars (Source: S. DasSama, U of Maryland School of Medicine)
Studying extremophiles on Earth as analog for Mars (Source: S. DasSama, U of Maryland School of Medicine)



In in a presentation on how manganese can get incorporated in biological material and how the metal helps stabilize the survival of biological material in extreme environments, we hear about the importance of these trace elements to life.  This was just one of many presentations that talked about the importance of these rare small amounts of metals, like manganese, and of the value to life and the survival of biological molecules.  There was a lot of chemistry here which I did not completely follow, but I did recognize the presenter in this case, which is Dr. Nina Lanza.
Manganese as an indicator of habitable exoplanet biosignature (Source: Nina Lanza, LANL)
Manganese as an indicator of habitable exoplanet biosignature (Source: Nina Lanza, LANL)


If you follow the TV series, "How the Universe Works" you probably have seen Nina Lanza in many of the episodes where she speaks as a geologist and planetary scientist.  She also can be found on twitter, when she has a free moment, as @marsninja.  Hmm, maybe I should be following her in that she always seems to explain things pretty clearly and I always pay attention when I see she is on!
Scientist Nina Lanza is familiar to "How the Universe Works" viewers (Source: Nina Lanza, @marsninja)
Scientist Nina Lanza is familiar to "How the Universe Works" viewers (Source: Nina Lanza, @marsninja)



Finally, in other presentations that returned to the idea of biosignatures and how they can apply to search for life on Mars and perhaps even more significantly how they can apply to searches for life on exoplanets.  I really like Dr. Sarah Johnson's introductory slide showing a scientist pointing a flashlight at the night sky as a symbol for our search for life detection in the universe.
Making search for life approaches agnostic to Earth biology (Source: Sarah Johnson, Georgetown U)
Making search for life approaches agnostic to Earth biology (Source: Sarah Johnson, Georgetown U)


Dr. Johnson and team are advocates of biosignatures that are agnostic about what we constitutes life and strive to develop biosignatures that are as independent as possible from what we already know about life here on Earth.  This is our single and only example of life in the universe.  But, she has identified four major categories that hopefully lead to more general biosignatures that will of course identify life here on Earth, but also work to hopefully not miss other life on exoplanets because it was a life form, but was so different than what we have on Earth, that we just missed it.  The four features are shown in the slide below.  She talked how complexity of molecules can be used as a biosignature.  Life on Earth makes complex molecules that resemble nothing like other molecules that form in random non-life bearing regions of the Earth.  Leaving out the case of large polymers of chains of smaller molecules, which apparently can show up in non-living nature, the rise of more structurally complex molecules like ribosomes, and their much smaller cousins, seems to track very well with a living source.  So maybe, just finding some strange grouping of complex molecules, might indicate life of some unknown form.  The other signatures include pathway complexity, chemical fractionation (the preference for lighter isotopes and chirality) and disequilibria and energy transfer.  Life changes its environment and maintains itself in disequilibria with the surrounding environment.  Hmm, it is strange that life can do things in making complexity that other natural chemical processes in the world cannot do, and yet, life is a natural process, itself, that can generate the means by which to make this un-natural complexity!
Making search for life approaches agnostic to Earth biology (Source: Sarah Johnson, Georgetown U)
Making search for life approaches agnostic to Earth biology (Source: Sarah Johnson, Georgetown U)



Until next time,
Resident Astronomer George



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