Hey Mars, Me Again
- Admin
- Feb 25, 2021
- 5 min read
Updated: Apr 11, 2021
I know. You've been asking yourself, "what does nucleosynthesis have to do with life on Earth"? And everyday you look in the mirror and think, "are there aliens under the surface of Mars"? Well, wonder no more! You've come to the right place. Without heavy elements from big huge exploding stars, there would be no you or me. Let's explore.
Mars vs Life
You might not know this about me but I'm obsessed with Mars. NASA's Perseverance Rover just touched down on Mars in the Jezero Crater on February 18, 2021. From the crater, Perseverance can collect rock samples to test if there has been life on Mars in the past. This new Mars mission has sparked my love for space again (R.I.P. astronomy Twitter account).
Like Mars, Earth's habitability is related to the whole solar system, the whole cosmos. The age of a galaxy and how long nucleosynthesis has been occurring in the cosmos determines the number of supernova that will occur, and therefore the amount of heavy elements present.
Heavy elements from supernovae are necessary to create oxygen for water, which is necessary to create compounds for life to exist. Where there's water, there's life.
Mars also has a very thin atmosphere and without a protective atmosphere the solar wind caused the water to dry right up. Atmosphere can either mean a dry, cold misery or a perfectly balanced greenhouse ecosystem. Small changes in the atmosphere of a planet can throw off this balance necessary for life to exist. I'm looking at you, climate change!
Whether the water is boiling hot or frozen, some sort of creature seems to thrive in it. Water makes it easier for organic molecules to swirl around and bump into each other to form interesting compounds. If water once flowed on Mars, maybe life once thrived there too. We already know that NASA has found water on the poles, and has confirmed finding evidence of flowing water on the surface. Maybe there's more flowing water on Mars underground. There could there be tiny life forms like bacteria on Mars even now.
The map of Mars below shows relative locations of three types of findings related to salt or frozen water, plus a new type of finding that may be related to both salt and water. Blue boxes are caches of water ice; white boxes are fresh craters that exposed water ice; red boxes are salt deposits that may be from salt water evaporation.
“Our quest on Mars has been to ‘follow the water,’ in our search for life in the universe, and now we have convincing science that validates what we’ve long suspected, this is a significant development, as it appears to confirm that water albeit briny is flowing today on the surface of Mars.” –John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington
The Age of Life
Detailed measurements of the expansion rate of the universe place the Big Bang at around 13.8 billion years ago, which is thus considered the age of the universe. In cosmology, Big Bang nucleosynthesis (BBN) is the production of nuclei other than those of the lightest isotope of hydrogen (hydrogen-1, 1H, having a single proton as a nucleus) during the early phases of the Universe.
If nucleosynthesis had occurred for only millions of years instead of 13.8 billion, the ratio of H/He would be different, density would be off in the whole cosmos, stars would be so small that supernovae couldn't occur, and there would be a bunch of baby stars/ gas giant planets beginning to form.
No supernovae = No heavy elements
No heavy elements = No oxygen
No oxygen = No water
No water = No life
A cycle is born. Intermediate and high mass stars wouldn’t have been created without heavy elements, which are supplied by supernovae, dead supermassive stars. A younger universe had no terrestrial planets and no water for life. It has aged to... perfection? Well, it has aged to... us, whatever we are. Supernovae wouldn’t have been able to occur which means no elements past lead are produced.
A young universe/ cosmos/ galaxy/ solar system would contain only gas giants, composed mainly of hydrogen and helium. Gas giants are sometimes known as failed stars because they contain the same basic elements as a star.
If supernovae never occurred, and if the only stars that came into being were low-mass, the only elements that would be present are those elements made in the big bang (helium and hydrogen) and the elements smaller stars are capable of forming like nitrogen and carbon. Elements that would not be present in this hypothetical galaxy are; aluminum, calcium, chlorine, copper, gold, iron, magnesium, mercury, nickel, oxygen, phosphorous, platinum, silicon, silver, sodium, sulfur, titanium, uranium and zinc.
The implication here is that life probably wouldn’t exist in this particular young galaxy. No oxygen means no H2O (water). In our hypothetical galaxy, only the slow process of nucleosynthesis would take place, not the rapid process. The slow type of heavy element nucleosynthesis produces nuclei with atomic masses as large as 209. Uranium and other very heavy naturally occurring elements are produced via the r-process. The rapid, r- process, chains of nuclear reactions occur during explosive nucleosynthesis for example, a core-collapse supernova.
In addition, Terrestrial planets wouldn’t have formed in a younger galaxy because there aren’t many elements heavy enough to coalesce and create terrestrial planets and therefore no way to generate an internal heat source in order to be geologically active. Terrestrial planets consist of mainly silicates ((Fe,Mg)SiO_4) and iron (plus FeS). The heavier metals are created in supernovae, which wouldn’t occur, in our hypothetical galaxy. Planets like Jupiter and Saturn would probably exist because they are mostly made of hydrogen and helium. Planets like Uranus and Neptune are too dense to be primarily H2/He and not dense enough to be rocky compounds.No heavy elements = No terrestrial planets, No terrestrial planets = No Earth.
Mars displays clear evidence of physical and chemical attributes that were created by liquid water suggesting that young Mars may have been as suitable for life, as was young Earth. To search for fossils on Mars, the best place to look is in dried lake and riverbeds.
Additionally, methane (the fart gas) has been reported in Mars’s atmosphere, and since methane is photo- chemically destroyed on a timescale of a few hundred years, there must be an active source responsible for its presence. Under the soil might be where the source of this methane is located. Aliens!
One meteorite from Mars, ALH 84001, has several chemical and morphological features that initially were attributed to possible traces of microbial life on ancient Mars. The rock was probably ejected into space by an impact about 16 Myr ago. Therefore, another place to search for life might be near large craters of a similar age, like the Jezero Crater, to find what else the impactor lifted up.
Thank you to my former CU Boulder professor, Nick Schneider, for teaching me this stuff (hopefully nothing is too amiss). His current work is focussed on CU's mission to Mars: MAVEN, (Mars Atmosphere and Volatile EvolutioN). He leads the Imaging UltraViolet Spectrograph (IUVS) which performs remote sensing of Mars upper atmosphere. MAVEN's goals are to (1) understand the current state of the Mars atmosphere; (2) determine how atmospheric escape depends on drivers such as the solar wind, solar radiation and dust storms; (3) extrapolate escape back in time to estimate the cumulative atmospheric loss to space.
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