Venus and Earth have remarkably diferent surface conditions, yet the lithospheric thickness and heat fow on Venus may be Earth-like. This fnding supports a tectonic regime with limited surface mobility and dominated by intrusive magmatism.

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https://doi.org/10.1038/s41561-022-01104-z
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Planetary science
Estrangedplanetarytwins
Diogo L. Lourenço
VenusandEarthhaveremarkablydifferent
surfaceconditions,yetthelithospheric
thicknessandheatflowonVenusmaybe
Earth-like.Thisfindingsupportsatectonic
regimewithlimitedsurfacemobilityand
dominatedbyintrusivemagmatism.
Venus is often called Earth’s twin. These neighbouring planets have
similar sizes and compositions, and should have been formed in a
similar way. Hence, we could expect their subsequent evolution and
present-day state to be alike. This is not the case: in fact, their surface
conditions are extraordinarily different. While Earth has surface
conditions that allow life, Venus has a mean surface temperature
of around 737 K (464°C, 867°F) and an average surface pressure of
about 92 times that at Earth’s surface1
. This means that Earth and
Venus must have evolved differently over the past 4.5 billion years.
Writing in Nature Geoscience, Smrekar and colleagues2
find that,
despite other differences in present-day state, the heat flow and the
thickness of the lithosphere (the crust and uppermost mantle) of
Venus are comparable to those of Earth, constraining its evolution
and interior dynamics.
The surface of a planet is intrinsically connected to its interior
dynamics. On Earth, amenable surface conditions are closely linked
to the fact that its surface is split into mobile plates, which results
in a dynamic tectonic regime that facilitates efficient heat loss. The
tectonic regime on Venus is still an enigma. The traditional models3
are (1) ‘stagnant lid’ (Fig. 1a), characterized by an immobile, thick,
cold lithosphere that covers the planet, and through which heat is
conducted inefficiently from the interior to the atmosphere, and (2)
‘episodic lid’ (Fig. 1b), characterized by bursts of surface mobility
because of episodic overturns of an unstable stagnant lid. An over-
turn or a resurfacing event is the process where (almost) all the litho-
sphere of a planet descends into the mantle within tens of millions
of years. Both regimes imply minimal surface geological activity
duringmostofVenus’history,whichisnotsupportedbyrecentmodels
(e.g.,ref.4)anddataanalysis(e.g.,ref.5).
Smrekaretal.2
aimtounderstandthemysterioustectonicregime
andevolutionofVenusbydeterminingthethicknessoftheplanet’slitho­
spherethatbehaveselasticallyonshorttimescales.Theauthorscom-
putethislithosphericthicknessbymeasuringthetopographicflexure
at 75 coronae — abundant (>500), quasi-circular volcano–tectonic
surfacefeaturesthatspanawiderangeofdiameters(60to>1,000km)6
—
using altimetry data from the Magellan mission. They calculate an
averagelithosphericthicknessthatissimilartooceaniclithosphereon
Earth.Fromthis,theyestimatetheheatflowonVenus,findingthatthe
averageisalsosimilartoEarth’sinactivelyextendingareas.Therefore,
Venus seems to have Earth-like lithospheric thickness and heat flow,
which is consistent with Venus having a geologically active surface,
evenifEarth-likeplatetectonicsisnotactive.
Instead of one of the two traditional models, Smrekar et al.2
sug-
gestthattheconvectiveandtectonicregimethatbestfitstheirresults
Check for updates
a Stagnant lid b Episodic lid c Plutonic-squishy lid
Fig.1|Schematicillustrationsofsomeoftheglobaltectonicregimes
proposedforVenus. a,‘Stagnantlid’.b,‘Episodiclid’.c,‘Plutonic-squishy
lid’,whichisthesuggestedregimeactiveonVenusinSmrekaretal.2
.Crustis
indicatedbydarkbeige,lithosphericmantlebygreen,ambientmantlebylight
grey,andthesurfaceagebytheshadeofpurpleanddensityofimpactcraters
(lighterisolder,andthereforehasmorecraters).Thecoreistheyellowsphere
inthecentre,fromnearthesurfaceofwhichplumes/upwellings(inorange)rise
throughthemantle.Figureisadaptedfromref.12,SpringerNatureLtd.

2. naturegeoscience
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Venus and Earth are so similar yet so different will give us more clues
astowhatmakesaplanethabitable.
Diogo L. Lourenço
Institute of Geophysics, Department of Earth Sciences, ETH Zürich,
Zürich, Switzerland.
e-mail: diogo.lourenco@erdw.ethz.ch
Published online: xx xx xxxx
References
1. De Pater, I. & Lissauer, J. Planetary Sciences 2nd edn (Cambridge University Press, 2015).
2. Smrekar, S., Ostberg, C. & O’Rourke, J. Nat. Geosci. https://doi.org/10.1038/s41561-022-
01068-0 (2022).
3. Armann, M. & Tackley, P. J. J. Geophys. Res. Planets 117, E12003 (2012).
4. O'Rourke, J. G., Wolf, A. S. & Ehlmann, B. L. Geophys. Res. Lett. 41, 8252–8260 (2014).
5. Brossier, J., Gilmore, M. & Toner, K. Icarus 343, 113693 (2020).
6. Stofan, R. et al. J. Geophys. Res. 97, 13347–13378 (1992).
7. Lourenço, D. L., Rozel, A. B., Ballmer, M. D. & Tackley, P. J. Geochemistry, Geophys.
Geosystems 21, e2019GC008756 (2020).
8. Lourenço, D. L., Rozel, A. B., Gerya, T. & Tackley, P. J. Nat. Geosci. 11, 322–327 (2018).
9. Garvin, J. B. et al. Planet. Sci. J. 3, 117 (2022).
10. Ghail, R. et al. EnVision: Understanding why Earth’s closest neighbour is so different
(ESA, 2021); https://sci.esa.int/documents/34375/36249/EnVision_YB_final.pdf
11. Smrekar S. et al. VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and
Spectroscopy): A Discovery Mission. In 2022 IEEE Aerospace Conference (AERO) 1–20
(IEEE, 2022).
12. Lourenço, D. L. & Rozel, A. B. in Dynamics of Plate Tectonics and Mantle Convection 1st edn
(ed. Duarte, J. C.) (Elsevier, 2022).
Competing interests
The author declares no competing interests.
and other observations — such as a young surface age and abundant
volcanism — is a ‘plutonic-squishy lid’ regime7
(Fig. 1c). This regime
is dominated by intrusive magmatism, small-scale plumes, and lith-
ospheric delaminations, which result in a relatively thin lithosphere,
highsurfaceheatflow,andsomelimitedsurfacemobility.Importantly,
astheauthorsnote,thisisalsoconsistentwithformationofthecoro-
nae by both upwelling and downwelling. If the plutonic-squishy-lid
regime is active on Venus, then we will need to reframe the way we
have been thinking about the planet, such as the interpretation of
observations of surface ages and geological features. Notably, this
regime has implications for the thermal and chemical evolution of
Venus’ mantle: for example, a plutonic-squishy lid is dominated by
intrusions,whicharecapableofcoolingdowntheinteriorofaplanet
more efficiently than eruptions8
.
The Magellan spacecraft was launched in 1989 and was active for
4.5 years. The data collected are still being used and providing new
insights, as exemplified by Smrekar et al.2
. Nevertheless, these data
pale in comparison to the resolution and quality of those collected
by modern spacecraft. Fortunately, there should be three missions
headingtoVenusinthenextdecadeorso9–11
,whichwillbeabletoverify
the findings of Smrekar et al.2
using higher-resolution altimetry and
gravity data. These missions should also enable a leap forward in our
understandingofgeologicalfeaturesandtheinnerworkingsofVenus,
whichmayprovidevaluableinsightsonEarth’sevolutionandeventhe
workingsoftheSolarSystem.ThestudybySmrekaretal.2
isanimpor-
tant step in understanding the dynamics and evolution of Venus, and
inpreparingforthescheduledmissionsthere.Furtherinsightsonwhy