3.2- Meteorites And CHNOPS Flashcards
What is the backbone to all biomolecules?
Carbon
What does Carbon do with HNOPS?
It forms a wide variety of stable bonds with HNOPS
What does Carbon give molecules?
The versatility to break down and form other or more complex molecules
Are the C to HNOPS bonds stable?
They are stable but not so stable that a large amount of energy is required to break them
What bonds to carbon form?
Carbon forms single (C-C), double (C=C), And triple bonds, increasing the diversity of molecules that can be made
What does CHNOPS stand for?
Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorous, Sulfur
What are the 4 classes of macromolecules found in living cells?
Carbohydrates, lipids, proteins, nucleic acids
How do we know about CHNOPS elements and compounds on the earth and other planets?
Meteorites found on earth, lunar samples and cosmic rays are the few pieces of the universe in which elements can be directly separated and measured chemically
How much of the solar system mass is in the sun?
99.86%
How much of the solar systems mass is in the earth?
0.0003%
What elements did or universe start out with?
Around 75% H, 24% He and traces of other elements
What is stellar nucleosynthesis?
Fusion inside stars creates heavier and heavier elements
How are elements released into the universe?
When stars explode, die or merge, elements are released into the universe
What happened when the sun ignited?
The remaining 1% of material was vapourised
What does temperature differences in the disk do?
It fixes the location of where different solids condense
What can condense closer to the sun?
Only refractory material can condense closer to the sun
How did condensation form the planets?
The particles that clumped together to make the planets, moons and other objects condensed from a hot gas. More volatile compounds such as water, ammonia, methane and carbon dioxide condensed into solid ice grains in the outer solar system. - This produced the 4 rocky inner planets and the 4 outer gas giants
What are volatiles and where are they found?
Chemical elements and compounds with low boiling points. They are mostly found in a planets or moons crust or atmosphere.
What are some examples of volatiles?
Ammonia (NH3), Carbon dioxide, Methane (CH4), Sulfur dioxide (S02) and water
What is planetary accretion?
Most models invoke the formations of volatile-rich planetesimals and planets beyond the ‘snow line’ and rocky (volatile poor) planets sunward of this
Why is earth known as a water world?
It has extensive oceans, a global water cycle, abundance of water gives earth its blueness as seen from space
Does earth have a lot of water for its size?
It has very little water in comparison to its size and other planets and moons in the solar system.
What do Asteroids provide us with?
Meteorites
What are the 3 categories the majority of asteroids fall into?
C-type (carbon rich), M-type (Metal rich), and S-type (Stony)
What do asteroids contain?
Amino acids and other organic compounds
What is poorly understood about asteroids?
Their physical structure is poorly understood
What is the panspermia theory?
It poses that asteroid impacts brought life itself to earth (implying we are all aliens)
Meteorites are rocks from space and before the moon landing were our only form of evidence of rocks from space
What are the different stages of a meteoroid?
A meteoroid is whilst in space, once it passes through the atmosphere is is known as a meteor, once it hits earth it is known as a meteorite
What does our meteorite collection contain?
It contains a wide range of rocks with different chemistries and mineralogies which represent the chemically heterogenous nature of our solar system
What are stony meteorites?
Made of >50% silicates
What are iron meteorites?
Made of mostly FE-Ni alloys
What are stony-iron meteorites
Contain both silicates and Fe-Ni alloys
What are chondrites?
Most abundant type of meteorite and are our main source of information about solar system chemistry. They contain mainly silicates, with some metals and sulphides and are known as ‘Undifferentiated’
What are achondrites?
They contain a wider range of mineralogy and are meteorites that have experienced some degree of igneous processing. They are known as ‘Differentiated’
What are chondritic meteorites useful for?
They provide the best clues to the origin of the solar system as contain the oldest pieces of our solar system (4.567Ga)
How many groups are chondritic meteorites split into?
Split into 15 groups and are mostly made of Fe, Mg, Si, and O
What are the 3 classes of chondritic meteorites?
Carbonaceous, Ordinary and Enstatite
What are chondrules?
The most abundant constituent in most chondrites (there are some exceptions). They are mostly composed of olivine and pyroxene.
What are the characteristics of chondrules?
Mostly 0.1-10mm diameter spherules. The volume and abundance of chondrules in a meteorite is characteristic of chondrite groups. They have igneous quench textures- crystallised from a melt.
What can the primitive chondritic meteorites contain?
Can contain the whole range of equilibrium condensates- including the volatile compounds in their matrix
What is not changed in chondritic meteorites even after being thermally or aqueosly altered?
Their chemistries have not been subsequently changed even if they have been thermally or aqueously altered
What do chondritic meteorites represent?
They represent the ‘bulk’ composition of their parent asteroid
What are carbonaceous chondrites?
They are carbon and water rich, and contain many different organic compounds made from CHNOPS elements. They are thought to have formed in the outer solar system (beyond Jupiter)
What are carbonaceous chondrites responsible for?
As with water, they are responsible for delivering other volatile compounds, including prebiotic molecules, to earth during its formation and soon afterward
Where did the CHNOPS elements come from?
They came from space, and ultimately are atoms that were forged in the heart of various stars before our own sun was even born (make up everything even us)
What is an example of a carbonaceous chondrite that fell to earth?
Murchison landed in Australia in 1969. It was over 100kg and its organic content could be well studied as it has very little contamination from earth as had an observed fall
Murchison carbonaceous chondrite compounds found
Even if only a small fraction of the molecules delivered during the impact prove to be biologically relevant, they would have had a significant impact on the prebiotic chemistry of the earth.
Are all meteorites from asteroids?
No
Are comets a source of CHNOPS elements?
Comets comprise mainly of water ice and C02 ice, plus a variety of less abundant volatile compounds made from CHNOPS elements
What are examples of missions to comets?
Stardust launched in 1999 and returned to earth in 2006. It collected tail particles, and also IDP particles, and pre solar grains.
Rosetta launched in 2004 and reached comet 67P in 2014. It found water vapour and also identified 16 different organic molecules and lots of macro molecular carbon.
What did the analysis of water on comet 67P in 2014 show?
It showed to be very different to earths water
What does hydrogen contain?
It has 3 naturally occurring isotopes, of which hydrogen and deuterium are stable. Tritium is the other isotope (3H)
The ratio of 1H to 2H (“D/H”) in water can provide a chemical ‘fingerprint’ to help trace where the water has come from
How was water formed on the earth?
There are 2 theories.
1) Earths water arrived after the formation of the earth from extraterrestrial sources (ie. Water-rich asteroids and/or comets)
2) Earth’s water was already part of the newly formed Earth, delivered during accretion, and later expelled to the surface via volcanism
St. Andrews study showed what about zinc isotopes on chondrites
Zinc isotope anomalies in primitive meteorites identify the outer solar system as an important source of earths volatiles.
30% of earths sinc must have CC (outer solar system) origin
CHNOPS elements creating and formation on earth
The delivery of CHNOPS elements and compounds to Earth can be understood using a number of solar system materials.
It is likely that early solar system processes formed prebiotic chemicals and then distributed these throughout the solar system even to the inner (volatile poor) planets.
What is special about life
Life is self replicating and so even a small amount of material can generate a large amount of life
Where are volatiles mostly found?
Found mostly in a planet or moons crust or atmosphere
