Dr. Raphael Marschall
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Dr. Raphael Marschall
@spacemarschall.net
4K followers 330 following 750 posts
#asteroids #comets #protoplanetarydisks #planetaryScience 🧪🔭🚀🛰️☄️
Science Programme Manager @issibern.ch. Co-I of ESA's Comet Interceptor, collaborator on NASA's Lucy and ESA's Rosetta missions.
www.spaceMarschall.net
(he/him)🇨🇭🇺🇸🇫🇷
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spacemarschall.net
I am delighted to finally announce that I have accepted an offer to become a Professor of Experimental Physics and Planetology at the @unibe.ch in Bern, Switzerland.
A huge thank you to everyone who believed in me and supported me over all these years! So excited for all that is to come 🚀🛰️🪨🪐
Historic university building with ornate architecture and arched windows at the University of Bern in Switzerland, photographed on a clear sunny day with green lawn in the foreground.
October 8, 2025 at 3:22 PM
spacemarschall.net
On my way to Helsinki for #EPSCDPS. If you want to help build the planetary science community here on Bluesky, you could include this QR code on your poster or show it during your talk.
QR Code for the starter pack of people at the EPSC-DPS conference in Helsinki 2025.
September 7, 2025 at 8:17 AM
spacemarschall.net
I’m in beautiful Asiago (Italy) this week giving some lectures at the INAF PhD School Francesco Lucchin. Really enjoying the discussions with all the students! Such a wonderful environment!
Main square of Asiago, Italy. On the left there is a big church. In the foreground there is a water fountain surrounded by circular patches of grass. On the right there are town buildings one of them with a tower. The sky is blue with light clouds.
May 28, 2025 at 9:09 AM
spacemarschall.net
ORIGO will visit a comet with a dedicated lander that will examine the subsurface down to several meters. The instruments will characterise the interior's physical and chemical properties to discriminate between existing formation theories.

🧵4/5 #planetSci
Mission logo of ORIGO: A dark blue circle with a white border. Inside the circle, there is a comet with a tail and two spacecraft (one orbiter and one lander). The background features some stylised stars. The text at the bottom of the circle reads "ORIGO, proposal in response to ESA's M8 call".
May 21, 2025 at 11:44 AM
spacemarschall.net
Examining undisturbed interior material can answer this big open question in planetary science.

Where can we find such material? In the interiors of comets!

Because of intense comet activity (up to 10m erosion per orbit), pristine material is close to the surface (within 1st metre).

🧵3/5
Illustration of the stratigraphy of the southern hemisphere of comet 67P at aphelion and the amount of erosion around perihelion. Panel a & b show a zoom-in of potential subsurface structure of homogeneous pebbles (a) and larger heterogeneous hierarchical sub-units (b). A further zoom-in shows potential sub-micron structure of icy and refractory monomers (i) and ice encases refractories (ii).
May 21, 2025 at 11:43 AM
spacemarschall.net
Why is this important?
There are currently two end-member theories for how planetesimals form: hierarchical accretion (2a in the figure below) or through the gravitational collapse of pebble clouds (2b in Fig). The two theories predict very different properties for the interior.

🧵2/5 #planetSci
A schematic illustrating the leading theories of planetesimal formation. First particles grow from sub-micrometre to cm. They then continue growing in a hierarchical manner to km-sized bodies. Alternatively, the cm-sized particles, when concentrated sufficiently, can gravitationally collapse to directly form 100 km bodies.
May 21, 2025 at 11:39 AM
spacemarschall.net
Today, I submitted a proposal called ORIGO in response to ESA's M8 call for missions!

ORIGO would collect crucial ground truths to understand the first step in planet formation: forming the first (100 km-ish) solid bodies called planetesimals.

🧵 1/5 #planetSci
Mission logo of ORIGO: A dark blue circle with a white border. Inside the circle, there is a comet with a tail and two spacecraft (one orbiter and one lander). The background features some stylised stars. The text at the bottom of the circle reads "ORIGO, proposal in response to ESA's M8 call".
May 21, 2025 at 11:35 AM
spacemarschall.net
Got the warmest welcome on my first day at @issibern.ch! Thank you @antonellanota.bsky.social and the entire team for helping me with this transition and making me feel a part of the team! I can’t wait for all the great things will do together 🤩
Office plack of office 101 with the text: Dr. Raphael Marschalt Science Program Manager The text is on a blue background with colorful confetti and the inscription "Welcome!!!“.
May 5, 2025 at 5:19 PM
spacemarschall.net
I love the Psyche mission trajectory and made an interactive dashboard to examine it on www.whereis.space/psyche/
May 4, 2025 at 1:11 PM
spacemarschall.net
There is also the asteroid Toutatis.

Image from doi.org/10.1038/srep...
Photo of asteroid 4179 Toutatis taken by Chinese probe Chang'e 2 during a flyby mission.
April 21, 2025 at 7:14 PM
spacemarschall.net
Asteroid Donaldjohanson appears to be larger than originally estimated, about 8 km long and 3.5 km wide at the widest point.

Image credit: NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab science.nasa.gov/image-articl...

#PlanetSci #SciComm 🧪
The asteroid Donaldjohanson as seen by the Lucy Long-Range Reconnaissance Imager (L’LORRI). This is one of the most detailed images returned by NASA’s Lucy spacecraft during its flyby. This image was taken at 1:51 p.m. EDT (17:51 UTC), April 20, 2025, near closest approach, from a range of approximately 660 miles (1,100 km). The spacecraft’s closest approach distance was 600 miles (960 km), but the image shown was taken approximately 40 seconds beforehand. The image has been sharpened and processed to enhance contrast. NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab
April 21, 2025 at 6:51 PM
spacemarschall.net
A time-lapse of some images of asteroid (52246) Donaldjohanson during the encounter by Lucy!

Images taken on April 20, 2025, from a distance of 1,600 to 1,100 km.

Credit: NASA/Goddard/SwRI/Johns Hopkins APL

science.nasa.gov/image-articl...

#PlanetSci #SciComm 🧪
April 21, 2025 at 6:48 PM
spacemarschall.net
Here is asteroid (52246) Donaldjohanson as seen by Lucy’s LORRI camera! It’s a contact binary/bi-lobate asteroid 🎉🎊

Image taken on April 20, 2025 from a range of approximately 1100 km.

Credit: NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab

urldefense.com/v3/__https:/...

#PlanetSci #SciComm 🧪
April 21, 2025 at 6:26 PM
spacemarschall.net
Closest approach of Lucy with #asteroid (52246) Donaldjohanson [DJ] 🥳 🎉 🎈

↔️ current distance to DJ: 960 km
☀️ current phase angle: 75°

▶️ www.whereIsLucy.space
#PlanetSci #SciComm
The image presents a dark background dominated by a series of concentric circles representing distances in thousands of kilometers (km). These circles are subtly colored in shades of teal/blue. A bright white line cuts across these circles diagonally, representing the path or trajectory of the Lucy spacecraft. A small green dot marks the "point of closest approach" of the Lucy with asteroid Donaldjohanson. At the top right, a light gray line shows the trajectory of asteroid Donaldjohanson (DJ). At the top left, text indicates the "Encounter Mode" with a small red dot possibly showing "live updates." Further text displays the name of the asteroid (Donaldjohanson), data about the encounter, including the date and time, the distance, and the phase angle. A rectangular box in the lower right contains additional information about the observation, specifically the field of view of the L'LORRI instrument and the apparent size of the object in pixels. The box also clarifies that the object's shape and exact size are not precisely known, providing an estimated diameter of 3-5 km, citing a source ("Masiero et al. 2011").
April 20, 2025 at 5:51 PM
spacemarschall.net
15 min to the closest approach of Lucy with #asteroid (52246) Donaldjohanson [DJ].

↔️ current distance to DJ: 12 thousand km
☀️ current phase angle: 10°
🪨 estimated size on L'LORRI camera: 50-83 pixels

Time to head over to www.whereIsLucy.space and activate "encounter mode"...
#PlanetSci #SciComm
The image presents a dark background dominated by a series of concentric circles representing distances in thousands of kilometers (km). These circles are subtly colored in shades of teal/blue. A bright white line cuts across these circles diagonally, representing the path or trajectory of the Lucy spacecraft. A small green dot marks the "point of closest approach" of the Lucy with asteroid Donaldjohanson. At the top right, a light gray line shows the trajectory of asteroid Donaldjohanson (DJ). At the top left, text indicates the "Encounter Mode" with a small red dot possibly showing "live updates." Further text displays the name of the asteroid (Donaldjohanson), data about the encounter, including the date and time, the distance, and the phase angle. A rectangular box in the lower right contains additional information about the observation, specifically the field of view of the L'LORRI instrument and the apparent size of the object in pixels. The box also clarifies that the object's shape and exact size are not precisely known, providing an estimated diameter of 3-5 km, citing a source ("Masiero et al. 2011").
April 20, 2025 at 5:36 PM
spacemarschall.net
ONE hour to the closest approach of Lucy with #asteroid (52246) Donaldjohanson [DJ].

↔️ current distance to DJ: 48 thousand km
☀️ current phase angle: 13.41°
🪨 estimated size of DJ on L'LORRI camera: 12-21 pixels

▶️ www.whereIsLucy.space
The image presents a dark background dominated by a series of concentric circles representing distances in thousands of kilometers (km). These circles are subtly colored in shades of teal/blue. A bright white line cuts across these circles diagonally, representing the path or trajectory of the Lucy spacecraft. A small green dot marks the "point of closest approach" of the Lucy with asteroid Donaldjohanson. At the top right, a light gray line shows the trajectory of asteroid Donaldjohanson (DJ). At the top left, text indicates the "Encounter Mode" with a small red dot possibly showing "live updates." Further text displays the name of the asteroid (Donaldjohanson), data about the encounter, including the date and time, the distance, and the phase angle. A rectangular box in the lower right contains additional information about the observation, specifically the field of view of the L'LORRI instrument and the apparent size of the object in pixels. The box also clarifies that the object's shape and exact size are not precisely known, providing an estimated diameter of 3-5 km, citing a source ("Masiero et al. 2011").
April 20, 2025 at 4:51 PM
spacemarschall.net
2 hours and 4 minutes to the closest approach of Lucy with #asteroid (52246) Donaldjohanson [DJ].

↔️ current distance to DJ: 100 thousand km
☀️ current phase angle: 13.98°
🪨 estimated size of DJ on L'LORRI camera: 6-10 pixels

▶️ www.whereIsLucy.space
#PlanetSci #SciComm
The image presents a dark background dominated by a series of concentric circles representing distances in thousands of kilometers (km). These circles are subtly colored in shades of teal/blue. A bright white line cuts across these circles diagonally, representing the path or trajectory of the Lucy spacecraft. A small green dot marks the "point of closest approach" of the Lucy with asteroid Donaldjohanson. At the top right, a light gray line shows the trajectory of asteroid Donaldjohanson (DJ). At the top left, text indicates the "Encounter Mode" with a small red dot possibly showing "live updates." Further text displays the name of the asteroid (Donaldjohanson), data about the encounter, including the date and time, the distance, and the phase angle. A rectangular box in the lower right contains additional information about the observation, specifically the field of view of the L'LORRI instrument and the apparent size of the object in pixels. The box also clarifies that the object's shape and exact size are not precisely known, providing an estimated diameter of 3-5 km, citing a source ("Masiero et al. 2011").
April 20, 2025 at 3:47 PM
spacemarschall.net
This is why I think we're in for another surprise tomorrow and that DJ will have a very weird shape or even be another binary system. Soon we can fill in this image! So excited!

More about the encounter in my thread here: bsky.app/profile/spac...
and on whereIsLucy.space

🧵 3/3
#PlanetSci #SciComm
Gallery of 5 small asteroids (each smaller than 1 km) compared to the estimated size of asteroid Donalsjohanson (4 km).
April 19, 2025 at 11:43 AM
spacemarschall.net
Fun fact: Asteroid (52246) Donaldjohanson is named after the paleoanthropologist who discovered the Lucy fossil.

Below is the encounter insignia: Interlaced silhouettes of Donald Johanson and the Lucy fossil.

Credit: Goddard/SwRI

🧵 5/6
The Donaldjohanson encounter insignia, interlaced silhouettes of Donald Johanson and the Lucy fossil. Credit: Goddard/SwRI.
April 18, 2025 at 5:49 PM
spacemarschall.net
Some key numbers about the encounter:
↔️ closest approach distance: 960 km
⏩ encounter speed: 13.4 km/s
🌍 distance from Earth: 1.5 AU (223 million km, 12 light-minutes)
☀️ inbound phase angle: 14° (E-1d)
☀️ outbound phase angle: 165° (E+1d)

▶️ Animation from www.whereIsLucy.space sped up by 500x

🧵 4/6
April 18, 2025 at 5:47 PM
spacemarschall.net
Here are some of the things we know about DJ:
1️⃣ estimated diameter: 3-5 km
2️⃣ C-Type asteroid (carbonaceous)
3️⃣ dark (albedo ~ 0.1)
4️⃣ slow rotator (period = 251 h)
Lucy will give us the first resolved images of this object!

🧵 3/6
Artist's impression of asteroid Donaldjohanson Credit: NASA; https://www.youtube.com/watch?v=OL9_0sagfBg&embeds_referring_euri=https%3A%2F%2Fscience.nasa.gov%2F&embeds_referring_origin=https%3A%2F%2Fscience.nasa.gov&source_ve_path=MjM4NTE
April 18, 2025 at 5:45 PM
spacemarschall.net
Asteroid (52246) Donaldjohanson is located between Mars and Jupiter in the Main Asteroid Belt. It's a member of the Erigone family, meaning it's a fragment from a massive collision that produced the family roughly 150 million years ago (fairly recently on astronomical timescales).

🧵 2/6
Top-down view of the Solar System with planets Earth and Jupiter. The trajectory of the Lucy spacecraft is shown as it flies from Earth through the main asteroid belt to the Jupiter Trojans. Jupiter's Trojan asteroids orbit 60 degrees ahead and behind Jupiter. The location of further targets of the Lucy mission in the Trojan region is also shown.
April 18, 2025 at 5:43 PM
spacemarschall.net
🚨 Two days to Lucy's encounter with asteroid Donaldjohanson (DJ) 🚨

NASA's Lucy spacecraft will fly by DJ on Sunday, April 20, 2025 at 17:51 UTC (2:51 a.m. JST/10:51 a.m. PDT/11:51 a.m. MDT/1:51 p.m. EDT/19:51 CEST).

You can follow the encounter on whereIsLucy.space

🧵 1/6
#PlanetSci #SciComm
April 18, 2025 at 5:42 PM
spacemarschall.net
That's great news! 🎉 And Juice is almost seven light minutes from Earth right now.

I've built a dashboard to follow and examine the Juice trajectory on whereis.space/juice/
January 14, 2025 at 10:10 AM
spacemarschall.net
I was wondering about these ⬇️

I’m not a geologist so was just using „streaks“ but i guess they are ridges or faults.
Mercury’s north polar region as seen by the BepiColombo spacecraft.
January 14, 2025 at 8:59 AM