Harrison Agrusa @harrisonagrusa.bsky.social · 25/08/2026A very nice paper by @raducan.bsky.social. I had a fun time playing a small part! 030
Harrison Agrusa @harrisonagrusa.bsky.social · 08/07/2026It’s mainly due to the debris field’s self-gravity which causes it to collapse into filaments which look like rays. But you may notice some symmetry about the x-y plane which is due to the initial conditions being symmetric, so it may be partially artificial. 100
Reposted by Harrison AgrusaMichael Busch @michael-w-busch.bsky.social · 07/07/2026For #ACM2026, @harrisonagrusa.bsky.social suggests up to 30% contact binaries in the asteroids resulting from large collisions. Radar samples of near-Earth asteroids have counted fewer than that - but not all of the contact binaries would be recognized. 072
Harrison Agrusa @harrisonagrusa.bsky.social · 06/07/2026I’ve been exploring gravitational reaccumulation after asteroid catastrophic disruptions and am finding contact binaries are super common outcomes! I can’t help but notice how similar Torifune looks compared to this fragment from one of my simulations, which I will present tomorrow at #ACM2026 1306
Harrison Agrusa @harrisonagrusa.bsky.social · 27/04/2026This is with 1 km diameter spheres, hence the long time span. And the coefficient of restitution is 0.99 so 1% of the energy is lost in each collision. 000
Harrison Agrusa @harrisonagrusa.bsky.social · 27/04/2026I've been working on a new N-body code and wanted a fun way to demonstrate that the contact physics is correct (at least qualitatively). So here is a self-gravitating Newton's cradle! 110
Reposted by Harrison AgrusaSabina Raducan @raducan.bsky.social · 12/12/2025New paper out 🥳 Using data from #NASA #Lucy mission and a series of numerical simulations, we show that #Selam, the moon of #Dinkinesh, likely formed through a series of at least four low-velocity collisions between similarly sized moonlets. www.nature.com/articles/s41...nature.comMultiple moonlet mergers as the origin of the Dinkinesh-Selam system - Nature CommunicationsSpace missions imaging small asteroid moons revealed the variety in shapes. Here, the authors show that repeated low-speed collisions can explain the shape of Selam, which is the smaller component in ... 6248
Harrison Agrusa @harrisonagrusa.bsky.social · 25/06/2025Current status: gardening with a view. Had to harvest ~1/4 of my onions early because somebody has a habit of trampling on them in search of the ball… 020
Harrison Agrusa @harrisonagrusa.bsky.social · 07/05/2025If you don't read the paper, at least enjoy this movie of our Figure 2! In this simulation, q is the particle's pericenter, normalized to the primary's long axis. The point is that you need q>1 to avoid reimpacting the primary during pericenter passage, and that is not always easy! 140
Harrison Agrusa @harrisonagrusa.bsky.social · 07/05/2025Had a fun time being a part of this paper where we used a combination of SPH and N-body simulations to explore how asteroid satellites form from collisions. arxiv.org/abs/2505.03325arxiv.orgSatellite formation around the largest asteroidsSatellites around large asteroids are preferentially found among those with the most rapid rotation and elongated shape. The taxonomic statistics are similarly skewed; in total, 13 asteroids larger th... 161
Reposted by Harrison AgrusaDr. Raphael Marschall @spacemarschall.net · 20/04/20252 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 15414
Harrison Agrusa @harrisonagrusa.bsky.social · 04/04/2025In Japan for the next 10 days for a few exciting meetings. Today and tomorrow, I am at JAXA’s ISAS for a Hayabusa2# science team meeting. What a great excuse to visit when the cherry blossoms are in full bloom! 030
Reposted by Harrison AgrusaDr. Nick Attree @nickattree.eurosky.social · 24/03/2025Working up here at the Obervatoire de la Côte d'Azur, #Nice today and gave a talk on #Comet activity modelling this morning #PlanetSci. Thanks to everyone who came and thanks very much to @harrisonagrusa.bsky.social for hosting me! 181
Harrison Agrusa @harrisonagrusa.bsky.social · 21/03/2025I just compute the orbital elements, then calculate the corresponding xyz positions over 360 degrees of true anomaly. Then it’s a simple ax.plot(x,y,z). I wanted to have the lines fade away like in Rebound but it was a bit more work. 120
Harrison Agrusa @harrisonagrusa.bsky.social · 21/03/2025Playing around with some renderings of DART impact ejecta simulations. It’s amazing what you can do with @matplotlib.org and @reboundbot.bsky.social ! 1427
Harrison Agrusa @harrisonagrusa.bsky.social · 27/02/2025Happy to announce that I’ve been selected as a participating scientist on NASA’s Lucy mission. I can’t wait to join the team and explore the Trojans! science.nasa.gov/uncategorize...science.nasa.govNASA Selects Participating Scientists to Join Lucy Asteroid Mission - NASA ScienceNASA has selected eight participating scientists to join its Lucy mission to the Jupiter Trojan asteroids. These asteroids are remnants of our early 010
Harrison Agrusa @harrisonagrusa.bsky.social · 27/12/2024Just wait until the garden is up and running. You’re gonna hate me 030
Harrison Agrusa @harrisonagrusa.bsky.social · 27/12/2024New (to me) handmade table and chairs found at a flea market in Nice. Restoring it now with some beeswax. €100 and will probably outlive me. This room is finally coming together! 150
Harrison Agrusa @harrisonagrusa.bsky.social · 13/12/2024This image should be properly credited. It was made by Yun Zhang for her paper on 'Oumuamua: arxiv.org/abs/2004.07218 000
Harrison Agrusa @harrisonagrusa.bsky.social · 05/12/2024I saw and would totally apply but this I think New Zealand is outside the allowable parameter space of my two-body problem :) 010
Harrison Agrusa @harrisonagrusa.bsky.social · 05/12/2024I also installed mods to include Jupiter Trojans and KBOs, so maybe New Horizons or Lucy are next on the list. Or maybe I get back to work... 020
Harrison Agrusa @harrisonagrusa.bsky.social · 05/12/2024I launched in 1978 (a year late) so I ended up having to skip Saturn. But my flybys of Jupiter, Uranus, and Neptune needed less than ~50 m/s of mid-course corrections. Maybe I am a real rocket scientist?? I forgot how great this game is! 120
Harrison Agrusa @harrisonagrusa.bsky.social · 05/12/2024I decided it would be a good idea to procrastinate on job applications and play some Kerbal Space Program instead. Using a mod to play with a 1/9 scale real solar system, did a nice Voyager style mission. Here are my Jupiter and Neptune/Triton flybys :) 210
Harrison Agrusa @harrisonagrusa.bsky.social · 22/01/2024Another one. This paper is “The feasibility of deflecting asteroid 2017 PDC using neutral beam propulsion” by DeCicco et al., 2019 (Don’t worry, 2017 PDC is not a real asteroid!) 030
Harrison Agrusa @harrisonagrusa.bsky.social · 22/01/2024In fact there was a line in the show where they mentioned all of the DART results were published openly! 140
Harrison Agrusa @harrisonagrusa.bsky.social · 22/01/2024I found a fun Easter egg in For All Mankind. They used real DART papers as props for a scene related to altering the orbit of an asteroid! On the left is Rivkin et al. 2021 and on the right is Hirabayashi et al. 2022. 4293
Harrison Agrusa @harrisonagrusa.bsky.social · 28/12/2023Thanks!! That is if I ever end up posting anything :) 010
