planetary science references

Morbidelli et al., 2025

Pebble accretion predicts terrestrial planets should become more CC rich as they grow which isn't supported by isotopic data

Morbidelli et al., 2025

NC and CC reservoirs are unmixed and isotopic anomalies haven't been altered

Schiller et al., 2018

Calcium isotopes are positively correlated with masses of parent bodies providing evidence for pebble accretion

Schiller et al., 2018

Assumes we know the masses of parental bodies and that masses of bodies can be used as a proxy for accretion timescale

Steller et al., 2018

We can see from zinc isotopes that most of earth's volatiles come from the inner solar system (70% is NC)

Steller et al., 2018

Zinc isn't very volatile

Onyett et al., 2023

Silicon isotopes correlate with accretion ages and are consistent with rapid pebble accretion in <3ma

Onyett et al., 2023

cyclical assumption that mass = accretion timescale

Burkhardt et al., 2021

Earth and mars predominantly accreted material from NC reservoir suggesting a persistent dust barrier and both planets incorporate unsampled material

Burkhardt et al., 2021

reliance on martian meteorites to represent bulk mars, only analysed some isotopes

McDonough and Sun, 1995

5 - 15% light elements in the core. Bulk composition of earth doesnt match any known group of meteorites

McDonough and Sun, 1995

model relies on upper mantle samples as we cannot sample deeper

Wood et al., 2006

conditions of core formation became more oxidised as the earth grew. crystallisation of bridgemanite in the lower mantle also drove oxidation. core segregation stopped when oxidisation conditions rose above iron-wustite buffer

Wood et al., 2006

core formation conditions are hard to recreate in the lab. compositional assumptions

Olson et al., 2025

model earth accretion to 0.6 earth mass as pebbles to see effect on core. partitioning of moderately siderophile elements is sensitive to mass of pebbles accreted. pebbles of chondritic components under reducing conditions is best fit

Olson et al., 2025

assumes proto-earth and pebbles are homogenous mixtures of silicate and metal. full equilibrium between mantle and core

Li and Agee, 1996

there is more Ni and Co in the mantle than we would expect because they become less siderophile with pressure. right ratio is reached at 28GPa/750km depth.

Carlson et al., 2014

outlines whole solar system and earth evolution

Carlson et al., 2014

relies on indirect modelling and models because we lack many ancient rocks

Halliday, 2012

earth and moon have same Hf/W ratios, moon has higher FeO, W suggests formation @30Myr which is late compared to size, evidence for magma ocean despite no short lived nuclides.

Cuk and Stewart, 2012

modelled a small impactor hitting a fast-spinning proto earth to form moon mainly from earth mantle. angular momentum lost through evection resonance

Cuk and Stewart, 2012

do not model mixing of lower mantle. may be unrealistic for earth to be spinning that fast. dont show how moon formed from disk

Canup, 2012

modelled an impact with an impactor half the size of earth. impactor contributes to earth and moon so compositions are similar. angular momentum removed through evection resonance

Canup, 2012

modelled the system without having the earth or impactor rotating, only use a model with 300,000 particles. does not model moon formation from the disk

Canup and Asphaug, 2001

model moon formation with 20,000 particles

Melosh, 2001

Appraisal of Canup and Asphaug 2001 smooth particle hydrodynamic model compared to cameron et al., 1986 with only 3000 particles

Wang and Jacobsen, 2016

moon rocks are enriched in heavy potassium compared to earth suggesting moon formation included condensation and evaporation, supporting a high energy impact model

Wang and Jacobsen, 2016

assume the main control on potassium fractionation is pressure. extrapolate low pressure information to high pressures.

Young et al., 2016

earth and moon have indistinguishable oxygen isotope ratios supporting vigorous mixing during moon-forming impact. also limits impactor isotopes to similar to earth

Young et al., 2016

simplified 2 component mixing model. assumes no isotope fractionation during moon formation

wade and wood, 2016

Bist fit moon formation for chemistry is for an impactor of 10 - 20% ME, which is reduced (mantle FeO 0.3%), hitting an oxidised proto-earth (10.7% mantle FeO) to resolve slightly higher moon FeO than earth

Wade and Wood, 2016

doesnt consider geophysics and only considers varying oxidation state not any other chemistry.

Alexander et al., 2012

CI chondrites were the primary source of N and H, and asteroids were the primary source of water, rather than comets, from isotopes

Alexander et al., 2012

isotopic composition of chondrites has changed over time, so they have to estimate original composition

Altwegg et al., 2015

wide range of D/H ratios in JFC challenging the idea that JFCs have similar water to earth's oceans

Altwegg et al., 2015

accuracy of D/H measurements relies on accurate background subtraction, they assume no fractionation during volatile delivery which may not be accurate

Marty et al., 2011

N and H isotopes similar to chondrites. Solar neon in the mantle. Xenon depletion due to ionisation from early sun

Marty et al., 2011

assumes mantle derived lavas are representative samples of volatile compositions of different mantle reservoirs

Mukhopadhyay, 2012

deep mantle has solar wind volatiles and upper mantle has accreted volatiles, mixing lines dont meet

Mukhopadhyay, 2012

assumes DICE 10 samples preserved unfractionated mantle isotopic ratios. assume limited mixing of upper and lower mantle

Clay et al., 2017

reanalysis of meteorite samples showing earth is not actually depleted in halogens, just contaminated outer rims of meteorites had been sampled with halogen contamination

Clay et al., 2017

assumes chondritic samples are representative of all chondrites

Avice et al., 2018

Xenon is ionised in the early atmosphere and escapes with hydrogen. after GOE xenon preferentially bonds with oxygen rather than being ionised so stops escaping

Avice et al., 2018

assumes fluid inclusions are accurate samples of the early atmosphere

Zahnle et al., 2019

xenon is easily ionised and so escapes from the atmosphere along polar magnetic field lines with hydrogen. this process extends xenon loss into the archean suggesting a hydrogen atmosphere persisted for longer than previously thought

Zahnle et al., 2019

used 1D models. unrepresentative samples. dont consider other xenon loss mechanisms

Zahnle et al., 2013

time delay between origin of photosynthesis and GOE. atmosphere needed to become oxidised enough that oxygen could out compete reducing methane. methane produced through organic matter decay had to be lost through UV splitting in upper atmosphere before GOE

Zahnle et al., 2013

assumes mantle was reducing through all earth history. simplified representation of redox chemistry

Young et al., 2023

used thermodynamic model to show that earth's water content, core density and oxidation can be a result of equilibrium between hydrogen rich early atmosphere and magma ocean.

Young et al., 2023

assumes ideal mixing between atmosphere and silicate melt. assumes early atmosphere was hydrogen rich. makes a model and then tries to force the data to fit it. assumes pebble accretion because planetary accretion has to occur quickly to have lots of hydrogen.

Catling and Zahnle, 2009

different role of hydrodynamic escape on different planets explains atmospheric differences. venus was close to sun so water was vapour, hydrogen escaped and oxygen was left and formed CO2. earth has water which prevented build up of CO2. loss of hydrogen leaves planet oxidised.

Catling and Zahnle, 2009

assumptions about initial atmospheric composition. long timescales of atmospheric loss make models hard to validate with short term observations

Catling and Zahnle, 2020

history of archean atmopshere

Catling and Zahnle, 2020

exact levels of gases is limited by proxy data

Way et al., 2016

modelled venus' climate with a slow rotation rate and lowlands filled with water. slow rotation = clouds = high albedo. showed despite having up to 70% more solar flux than earth it could have average temperatures of 11-15C until 0.715Ga

Way et al., 2016

topography of early venus is uncertain, and model is very sensitive to topography. initial rotation is uncertain. had to have been substantial volatile delivery.

wade et al., 2017

water on earth remained close to surface and is recycled by plate tectonics because of hot geothermal gradients. mars had stagnant lid and was colder so hydrated crust sunk and was locked into mantle. Higher FeO in mars basalt allow it to hold 25% more water

Wade et al., 2017

assumes mars cooled 3x quicker than earth. assumes fluid saturated metamorphism. martian meteorites are not representative samples of mars.

Nittler et al., 2011

mercury is low in plag and iron and high in sulfur showing mercury formed from highly reduced precursors. high sulphur suggests mercury is not depleted in volatiles, so its high density cannot be explained by an impactor removing silicate

Nittler et al., 2011

messenger spacecraft sampling is not high resolution and so doesnt capture heterogeneities

Gunnet et al., 2018

the magnetic field on earth sized planets leads to more volatile loss than if it had no magnetic field. magnetic fields are only protective when a planet is jupiter sized.

Gunnet et al., 2018

other volatile escape processes also act on planets so just looking at magnetism is incomplete

Leone, 2020

argues no water on mars: fluvial deposits too high for liquid water, satellites show little serpentine and not associated with topographic lows, terrestrial analogues of water deposits may not be valid

Leone, 2020

many counter arguments debunking his points (Mitra et al., 2022, manganese oxide needs water to oxidise; Tutolo and Tosca, 2023, not looking for the right serpentines; thicker ancient atmosphere would change water stability at topographic highs)

Mitra et al., 2022

manganese oxide on mars which can only be formed in water, especially given acidic atmosphere. there must be at least shallow groundwater

Mitra et al., 2022

groundwater does not equate to having large oceans

Tutolo and Tosca, 2023

the serpentine on mars is different to earth (hisingerite) because of high silicate iron, so satelites werent looking for the right things. there are actually large terrains of hisingerite. formation of hisingerite produced 5 times more hydrogen than earth serpentines

Tutolo and Tosca, 2023

assumes all iron in samples was initially Fe2+ and assumes all Fe3+ was produced by serpentinization

Wandsworth et al., 2021

impossible amounts of hydrogen are needed to sustain a temperate climate on mars

Wandsworth et al., 2021

calculated hydrogen production through volcanism, bolide impacts and serpentinization, but used earth serpentines, despite the fact that Tutolo and Tosca show martian serpentines produce 5 times more hydrogen than terrestrial

Adams et al., 2025

to sustain a temperate climate on mars hydrogen loss needs to be modulated by trapping of hydrogen by glaciation; volcanism producing excess hydrogen; or fresh volcanic rock increasing serpentinisation

Adams et al., 2025

1D climate model, assumes terrestrial serpentine despite more hydrogen produced in martian serpentinisation. unknow initial atmosphere composition

Tosi et al., 2017

stagnant lid tectonics can host habitable climates because melt production replenishes lost atmospheric gases enough to host liquid water for billions of years. width of habitable zone is dependent on volcanic outgassing

Tosi et al., 2017

habitability is defined by the ability to host liquid water. model assumes that the planet has an earth like mass, radius and composition, despite the fact that outgassing depends on oxidation state. cloud free atmosphere

Sasselov et al., 2020

HCN is produced through high energy processing of N2-CO2 atmospheres. it is concentrated in shallow water bodies in salt where it can create biomolecules

Sasselove et al., 2020

assumes a N2-CO2 atmosphere. doesnt look at how these biomolecules then form life

Ehlmann et al., 2016

mars' crust hasnt been recycled or overprinted giving an insight on what a young habitable planet looks like. early mars would have hosted a thicker atmosphere, liquid water and a warmer climate

Ehlmann et al., 2016

use liquid water as the primary base of habitability. they assume mars is a good analogue for all terrestrial planets

Lane and Xavier, 2024

Experimental findings with regards to the origin of life can be correct, but when they stand alone and aren't integrated into a wider picture of life evolution they are pointless.

Wade et al., 2021

the aim of life is to acquire iron and the abundance of bioavailable iron drives evolution. oxidation of iron after GOE locks away iron and catalyses development of multicellular organisms and predation

Wade et al., 2021

assumes that iron has always been am important element for life

Barrett et al., 2025

It has been thought that enstatite chondrites are dry, but recent measurements suggest they main contain enough hydrogen to account for the amount of water on earth, found at H-S. sulphur from contaminated areas was in a different form. Earth’s water could be intrinsic to its formation rather than from late delivery.

Barrett et al., 2025

Just talks about hydrogen and doesn’t talk about the oxygen needed and how this H-S hydrogen became water. Noisy composition spectra.

Muller et al., 2024

The final water mass fraction of a planet, when recycling is considered, depends on the envelope opacity and the incoming flux of pebbles, which is influenced by the drift behaviour of pebbles in the disk. Accounting for water recycling reduces the amount of water accreted. Water is an intrinsic product of planetary formation.

Muller et al., 2024

Considering water recycling makes it difficult to accurately predict the amount of water. they assume the terrestrial planets formed by pebble accretion

Loroch et al., 2024

Looked at resulting planetary characteristics (core size and composition) from varying meteorite materials and partitioning conditions (sulphur content, pressure and temperature).

Earth-like planets can form from known meteorite materials through accretion and core formation processes, with volatile-depleted carbonaceous chondrites being a likely primary source. However, the abundances of some volatile elements, like sulfur and silver, might require additional processes beyond simple metal-silicate partitioning to match Earth's composition

Loroch et al., 2024

Know meteorite samples are unlikely to be representative of all the types of bodies that helped form the earth. Uncertainties in element concentrations affects results.

Zhou et al., 2024

Reconstructed the earth-moon system dynamics including distance apart and rotation rate using cyclostratigraphy. The distance apart was closer and earth days were shorter during the Mesoproterozoic. This could be combined with moon formation models to see if the angular moment evolution through time works out with this geological evidence.

Zhou et al., 2024

They assume the cycles seen are driven by Milankovitch cycles. Relies on the accuracy of the Bayesian inversion model and the chosen parameters.

Fu and Jacobsen, 2024

Examined a broad range of Lunar Magma Ocean (LMO) crystallization models. They forward-modelled the element-ratio evolution of the residual LMO liquids and flotation cumulates for different crystallization models, starting from a common near-chondritic LMO initial refractory element ratio. The study found excellent agreement between the refractory element data of lunar samples and the forward modelling starting from a BSE-like composition for most elements, suggesting the Moon-forming disk was thoroughly mixed, implying significant material exchange between the proto-Earth and the lunar disk

Fu and Jacobsen, 2024

Modelling relies on the accuracy of the mineral-melt partition coefficients used. The initial LMO composition is assumed to be near-chondritic with a uniform enrichment. Focuses on refractory trace elements.

Turner et al., 2025

A plagioclase-rich protocrust would have formed relatively early in the cooling history of the Earth's magma ocean due to the buoyancy of plagioclase in the melt and that the composition of this protocrust is distinct from modern crust. The trace-element signature of the Hadean protocrust mimics that of modern subduction-zone magmas without requiring subduction. This suggests that the geochemical arguments for when and how plate tectonics began, which often assume subduction is needed to produce the continental trace-element signature, are severely compromised if this signature was already present in the Hadean protocrust

Turner et al., 2025

Relies on equilibrium crystallisation and perfect separation of crystals from the melt. The chosen crystallization sequence and the mineral-melt partition coefficients used are based on experimental studies, which may not perfectly replicate Hadean conditions

Madhusudhan, 2025

Habitability requires environments to meet four key requirements based on Earth life: liquid water, bio-essential elements (CHNOPS), an energy source, and suitable environmental conditions (pressure, temperature). The location and extent of the habitable zone are not static and depend on various factors such as the host star's properties and the planet's atmospheric composition and albedo. A more stringent concept, the continuous habitable zone (CHZ), refers to the region where a planet could sustain liquid water over geological timescales. Many things affect habitability: magnetic field, chemical cycling, orbit, phototroph/chemotroph and extremophiles show life can exist in unusual settings.

Madhusudhan, 2025

Focuses on habitability from hat we understand on earth but different forms of habitability may exist in very different environments.

Kong et al., 2024

The presence of an outer gas giant can significantly affect the number and properties of the formed terrestrial planets. The outer gas giant is more likely to eject planetary embryos from the system due to gravitational slingshot effects

Kong et al., 2024

The study uses a specific model and set of initial conditions for the protoplanetary disk and the giant planet

Liu and Jing, 2024

Performed first-principles molecular dynamics (FPMD) simulations to study the properties of iron alloys with various light elements (H, C, Si, O, S) under Earth's core conditions (high pressure and temperature). They find hydrogen and silicon are the best light elements for reproducing the seismological properties of earth’s core. The presence of hydrogen significantly reduces the density and sound velocities of iron, other light elements like oxygen, sulfur, and especially carbon are less likely to be major constituents of the core based on their effects on density and sound velocities

Liu and Jing, 2024

This is the result of theoretical modelling. It is hard to experimentally reproduce the conditions of core formation. The analysis only considers single light elements added to iron, when in reality it is more likely to be a mixture.

Grewal and Manilal, 2025

The study suggests that a differentiated late veneer can deliver significant amounts of volatiles to the BSE, and the composition of these volatiles depends on the size and differentiation state of the impactors.