Mathieu Lapôtre

Our results suggest that on Mars, values of the aerodynamic roughness length may reach up to 1 cm—up to two orders of magnitude larger than typically assumed. #NASA Ames, @stanforddoerr.bsky.social, @marslogander.bsky.social

Aerodynamic roughness of rippled beds under active saltation at Earth-to-Mars atmospheric pressures - Nature Communications Low-pressure wind tunnel experiments suggest that the aerodynamic roughness length on Mars, over rippled beds and under active saltation, may be dominated by form drag, reaching values up to two order...

Excited to share our latest publication in @natcomms.nature.com, where we analyze the aerodynamic roughness length over equilibrated rippled sand beds with active saltation under atmospheric pressures intermediate between those of Earth and Mars.
www.nature.com/articles/s41...

Best wishes to you and your family, Laurie!

Ripples formed in low-pressure wind tunnels suggest Mars’s large windblown ripples are not impact ripples - Nature Communications Low-pressure wind tunnel experiments suggest that large sand ripples on Mars are drag ripples, not impact ripples. Windblown drag ripples constitute an untapped record of atmospheric evolution under t...

Postdoc Carlos Alvarez shows that Mars’s large #aeolian #ripples are not impact ripples through low-pressure #wind tunnel experiments at #NASA Ames. Very excited about this one!
@stanforddoerr.bsky.social

www.nature.com/articles/s41...

New paper by PhD student @mcolinmarvin.bsky.social uses #patterns formed by #dunes to better understand sources, pathways, and sinks of #sand on #Titan. Spoiler: #Xanadu has outsized influence on #eolian sediments, and sand travels far!!

@stanforddoerr.bsky.social

I'm giving a talk at Stanford tomorrow! If you're around, come join us. I think Zoom is an option too—details here:
events.stanford.edu/event/earth-...

Congrats @jtuttlekeane.bsky.social !!!!!

Final stop with postdoc Carlos Alvarez on the "Aerodynamic #roughness of rippled beds under active #saltation at low atmospheric #pressure" (EP54A-03, 146 B).

Fr 4:20-4:30 pm.

#Wind tunnel work reveals impact of #bedforms and #saltation on #Mars.

#AGU24

(10/10)

Back to #Mars with PhD student Claire Blaske asking "Were #boulder fields along Mars' putative #ocean paleoshoreline deposited by a #tsunami?" (EP51B-06, 146
B).

Fr 9:25-9:35 am.

Or perhaps #floods? #glaciers? #impacts?

#AGU24

(9/10)

Collaborator @alvitello.bsky.social from U. Padua next will show that " #Vegetation leaves measurable imprints on the #morphodynamics or #meandering #rivers"
(EP51F-1434).

Fr 8:30 am-12:20 pm.

All about how #plants affect #meander shape!

#AGU24

(8/10)

PhD student Timmy Lui will take us to #Mars for his " #Segmentation of #dune crestlines using #convolutional #neural #networks"
(EP51D-1378, hall B-C).

Fr 8:30 am-12:20 pm.

A challenging task with potential to reveal much about #Mars #climate!

#AGU24

(7/10)

Kicking off Fr, PhD student Vittorio Colicci will present his MS work at MIT, "Examining the influence of early #tree #root geometry on #soil cohesion and anchoring strength using 3D-printed reconstructions" (EP51F-1439, hall B-C)

Fr 8:30 am-12:20 pm

#AGU24

(6/10)

Alternatively, undergrad Brian Amaro will talk about his "Automatic characterization of the size distribution of small #rocks on the #Moon and implications for orbiter-based extrapolations" (P44C-06, Liberty M at Marriott).

Th 4:52-5:02 pm.

#AGU24

(5/10)

Then former postdoc @agunn.bsky.social (now faculty at Monash) and recipient of #AGU24 's Luna Leopold award will deliver the Sharp lecture (Ballroom B). #Dunes galore on the horizon!

Th 4-5:30 pm.

(4/10)

Next: #Precambrian #Earth with PhD student @mcolinmarvin.bsky.social, with "Zircon microtextures: A record of Earth's earliest surface environments" (EP43F-03, 146 C).

Th 2:30-2:40 pm.

Tiny scratches pack much info on first ~90% of Earth's history!

#AGU24

(3/10)

First stop: #Earth with PhD student Michael Hasson for " #Vegetation alters the migration trajectory of #meander bends"
(EP41E-1245, hall B-C).

Th 8:30 am-12:20 pm.

Cool implications for river evolution in the #Paleozoic!

#AGU24

(2/10)

#Rivers, #winds, #waves, and #impacts are all on the program for Stanford EPSP at #AGU24! Come along with us to explore #landscapes through #space (#Earth, #Moon, #Mars) and #time ( #Archean / #Hesperian to #future)

All times EST.

(1/10)

Last but not least, @stanforddoerr PhD student @mhasson7 will present a new depositional model for meandering #rivers that form in landscapes devoid of vegetation on Fr pm. Critical to deciphering rock record and paleoenvironments of the early #Earth and #Mars! EP56A-06 (6/6).

Th pm, @stanforddoerr #SURGE student Emiliano Gonzalez will show how rock type influences sizes and distribution of boulders created by meteor impacts on the #Moon, and how they degrade through time, with implications for cratering mechanics and dating. P45A-04 (5/6)

Next, I’ll be presenting @Liorruba’s recent @NatureComms paper, showing that the mechanics of dune formation are strongly affected by #Mars’ thin atmosphere, creating ripples that are analogous to those forming on Earth’s riverbeds!EP43A/06 (4/6)

nature.com/articles/s4146…

This afternoon, @stanforddoerr undergrad @b_amaro_ will present his findings applying boulder-detection #AI model to HiRISE imagery on #Mars, with implications for surface processes and evolution. P25A-64 (2/6)

Mars’ thin atmosphere makes large windblown sand ripples, like water shapes ripples on Earth’s riverbeds!
New paper by @stanforddoerr postdoc @Liorruba, with colleagues R. Ewing @TAMUGeosciences, @LoriKFenton @SETIInstitute, and former postdoc @_algunn now @MonashUni

x.com/NatureComms/st…

Congratulations to @mhasson7 for a brilliant qualifying exam!!! First PhD candidate from @StanfordEarth EPSP 🎉🥳 Time to celebrate with @Liorruba, @nilscp, @mcolinmarvin, and @b_amaro_!

A long time coming - “#Mars as a Time Machine to Precambrian Earth” - now open access in J. @GeolSoc! Was such a fun one to write with inspiring coauthors @KirstenSiebach @smtikoo + others not on Twitter.
@StanfordEarth

jgs.lyellcollection.org/content/early/…

Active saltation at Great Sand Dunes NP with @mcolinmarvin and @Liorruba!

@GreatDunesNPS

x.com/mcolinmarvin/s…

Just off the press: new paper by former @StanfordEarth postdoc @_algunn, now lecturer @MonashEAE analyzing spatial and temporal patterns in sand accumulation in impact craters on #Mars. Suggests enhanced sediment production in L. Noachian-E. Hesperian!

doi.org/10.1130/G49936…

Link to the #OpenAccess paper:@theAGU

doi.org/10.1029/2021GL…

Loved working with @mike_malaska and @starsarecalling on my first #Titan paper! We propose that a global sedimentary cycle, driven by seasons, could explain the distribution of Titan’s landscapes. Model inspired by how ooids form on Earth (cc: @lizzy_t)
@StanfordEarth @NASAJPL

x.com/stanforddoerr/…

A really cool study led by Dave Rubin I’ve had a lot of fun participating in. We showed that Mars’ atmosphere had thinned (at least temporarily) before the last episode of subaqueous deposition in Gale crater!
#Mars @MarsCuriosity @StanfordEarth

x.com/jgrplanets/sta…

Finally, check out #SANDE Mars-analog mission in #Iceland: abstracts # 2319 (Sinha), 2817 (Bedford @bedford_candice), 2409 (Champion), 2252 (Rudolph @rudolpa), and 2844 (Bedford) - results of collab with @TAMUGeosciences @PurdueEAPS @StanfordEarth @NASA @MissionCtrlSS (6/6)