Photons x Force: Differentiable Radiation Pressure Modeling
Pith reviewed 2026-05-16 03:38 UTC · model grok-4.3
The pith
Neural networks serve as fast differentiable proxies for radiation pressure forces after training on Monte Carlo simulations.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We introduce neural networks as a representation of forces from design parameters. This neural proxy model, learned from simulations, is inherently differentiable and can query forces orders of magnitude faster than a full MC simulation. We demonstrate optimizing inverse radiation pressure designs, such as finding geometry, material or operation parameters that minimizes travel time, maximizes proximity given a desired end-point, minimize thruster fuel, trains mission control policies or allocated compute budget in extraterrestrial compute.
What carries the argument
A neural network proxy that takes design parameters as input and outputs radiation pressure forces, trained on data from a parallel Monte Carlo simulator using importance sampling and next-event estimation.
If this is right
- Spacecraft geometry and materials can be optimized directly to minimize travel time under radiation pressure.
- Design parameters can be adjusted to maximize proximity to a target point while respecting radiation forces.
- Thruster fuel budgets can be reduced by gradient searches over the differentiable force model.
- Mission control policies can be trained end-to-end using the fast, differentiable force queries.
- Compute resources for extraterrestrial operations can be allocated on the basis of rapid force evaluations.
Where Pith is reading between the lines
- The same training-plus-proxy pattern could accelerate other expensive physics-based design loops in aerospace.
- Combining the proxy with additional differentiable simulators would enable complete mission-level optimization pipelines.
- Real-time force estimates from the network might improve tracking models used in space situational awareness.
Load-bearing premise
The neural network must approximate the true Monte Carlo radiation pressure forces closely enough across the design space that optimization does not settle on wrong parameters.
What would settle it
Take the final designs produced by optimization with the neural proxy, run independent full Monte Carlo simulations on them, and check whether the force values differ by more than the tolerance needed to change the optimum.
Figures
read the original abstract
We propose a system to optimize parametric designs subject to radiation pressure, \ie the effect of light on the motion of objects. This is most relevant in the design of spacecraft, where radiation pressure presents the dominant non-conservative forcing mechanism, which is the case beyond approximately 800 km altitude. Despite its importance, the high computational cost of high-fidelity radiation pressure modeling has limited its use in large-scale spacecraft design, optimization, and space situational awareness applications. We enable this by offering three innovations in the simulation, in representation and in optimization: First, a practical computer graphics-inspired Monte-Carlo (MC) simulation of radiation pressure. The simulation is highly parallel, uses importance sampling and next-event estimation to reduce variance and allows simulating an entire family of designs instead of a single spacecraft as in previous work. Second, we introduce neural networks as a representation of forces from design parameters. This neural proxy model, learned from simulations, is inherently differentiable and can query forces orders of magnitude faster than a full MC simulation. Third, and finally, we demonstrate optimizing inverse radiation pressure designs, such as finding geometry, material or operation parameters that minimizes travel time, maximizes proximity given a desired end-point, minimize thruster fuel, trains mission control policies or allocated compute budget in extraterrestrial compute.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes a Monte Carlo simulation for radiation pressure on parametric spacecraft designs that supports families of designs and uses importance sampling, a neural network surrogate trained on MC outputs to provide fast differentiable force queries, and demonstrations of its use for inverse optimization tasks such as minimizing travel time, maximizing proximity, or reducing fuel use.
Significance. If the neural proxy proves sufficiently accurate, the work could enable scalable gradient-based optimization of spacecraft under radiation pressure, a dominant force beyond low Earth orbit, by replacing expensive MC evaluations with fast differentiable queries. This combination of physics-based MC simulation and learned surrogates addresses a practical bottleneck in design and space situational awareness applications.
major comments (2)
- [Abstract] Abstract: the claim that the neural proxy 'can query forces orders of magnitude faster' and enables optimization of geometry, material, and operation parameters is unsupported by any error metrics, held-out validation accuracy, or re-evaluation of proxy-optimized designs against full MC ground truth.
- [Optimization demonstrations] Optimization demonstrations: the pipeline uses the neural proxy for gradient-based search on objectives such as travel-time minimization, yet no quantitative assessment is given of how approximation error propagates into the discovered optima or whether re-simulating those optima with the original MC simulator recovers comparable performance.
minor comments (2)
- Provide the neural-network architecture details, training-set size, loss function, and regularization used to fit the proxy to MC data.
- Clarify the exact sampling strategy and next-event estimation implementation in the MC simulator, including any variance-reduction parameters.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback. We agree that the current manuscript lacks quantitative support for the neural proxy claims and optimization reliability. We will revise to include held-out validation metrics, speedup measurements, error propagation analysis, and MC re-evaluation of optimized designs.
read point-by-point responses
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Referee: [Abstract] Abstract: the claim that the neural proxy 'can query forces orders of magnitude faster' and enables optimization of geometry, material, and operation parameters is unsupported by any error metrics, held-out validation accuracy, or re-evaluation of proxy-optimized designs against full MC ground truth.
Authors: We accept this criticism. The revised manuscript will report specific held-out validation accuracy (MAE and relative error on force vectors), query-time benchmarks showing the speedup factor versus MC, and re-simulation of proxy-optimized designs with the original MC simulator to confirm recovered performance. revision: yes
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Referee: [Optimization demonstrations] Optimization demonstrations: the pipeline uses the neural proxy for gradient-based search on objectives such as travel-time minimization, yet no quantitative assessment is given of how approximation error propagates into the discovered optima or whether re-simulating those optima with the original MC simulator recovers comparable performance.
Authors: We agree this assessment is missing. In revision we will add: (1) sensitivity analysis showing how proxy error affects the discovered optima, and (2) direct MC re-evaluation of the final designs to compare objective values and verify that the proxy-guided optima remain competitive under ground-truth simulation. revision: yes
Circularity Check
No significant circularity in surrogate-based optimization pipeline
full rationale
The paper's chain runs from an independent Monte Carlo radiation pressure simulator (physics-based, parallelized with importance sampling) to training a neural network surrogate on its outputs, then using the differentiable surrogate for inverse design optimization. This is standard surrogate modeling; the MC outputs constitute external data generation rather than a self-referential loop. The optimization result is not equivalent to the training inputs by construction, nor does any step rename a fit as a first-principles prediction. No self-citations, uniqueness theorems, or ansatzes imported from prior author work appear in the abstract or description to bear load on the central claims. The pipeline remains self-contained against the MC benchmark.
Axiom & Free-Parameter Ledger
free parameters (1)
- Neural network weights and biases
axioms (2)
- domain assumption Monte Carlo ray tracing with importance sampling and next-event estimation produces accurate radiation pressure forces
- domain assumption Neural networks can represent the mapping from design parameters to forces with sufficient fidelity for optimization
Reference graph
Works this paper leans on
-
[1]
Moritz Bächer, Emily Whiting, Bernd Bickel, and Olga Sorkine-Hornung
Physical design using differentiable learned simulators.arXiv preprint arXiv:2202.00728(2022). Moritz Bächer, Emily Whiting, Bernd Bickel, and Olga Sorkine-Hornung
-
[2]
Spin- it: Optimizing moment of inertia for spinnable objects.ACM Trans. Graph. (Proc. SIGGRAPH)33, 4 (2014), 1–10. Jeremy Banik and Paul Hausgen
work page 2014
-
[3]
Santosh Bhattarai, Marek Ziebart, Tim Springer, Francisco Gonzalez, and Guillermo Tobias
Demonstrating developments in high-fidelity analytical radiation force modelling methods for spacecraft with a new model for GPS IIR/IIR-M.J Geodesy93 (2019), 1515–1528. Santosh Bhattarai, Marek Ziebart, Tim Springer, Francisco Gonzalez, and Guillermo Tobias
work page 2019
-
[4]
High-precision physics-based radiation force models for the Galileo spacecraft.Advances in Space Research69, 12 (2022), 4141–4154. James Bradbury, Roy Frostig, Peter Hawkins, Matthew James Johnson, Chris Leary, Dougal Maclaurin, George Necula, Adam Paszke, Jake VanderPlas, Skye Wanderman- Milne, and Qiao Zhang. 2018.JAX: composable transformations of Pyth...
work page 2022
-
[5]
Ricky TQ Chen, Yulia Rubanova, Jesse Bettencourt, and David K Duvenaud
Machine learning in orbit estimation: A survey.Acta Astronautica(2024). Ricky TQ Chen, Yulia Rubanova, Jesse Bettencourt, and David K Duvenaud
work page 2024
-
[6]
Neural ordinary differential equations.NeurIPS31 (2018). Charles Constant, Shaylah M. Mutschler, Santosh Bhattarai, and Marcin Pilinski
work page 2018
-
[7]
End-to-end differentiable physics for learning and control.NeurIPS31 (2018). Per K Enge
work page 2018
- [8]
-
[9]
Geometric Calibration of the Orion Optical Navigation Camera using Star Field Images,
Space Weathering Experiments on Spacecraft Materials.J Astronautical Sciences66 (2019), 210–223. doi:10.1007/s40295- 019-00175-2 Michael Fischer and Tobias Ritschel
-
[10]
ZeroGrads: Learning Local Surrogates for Non-Differentiable Graphics.ACM Trans Graph (Proc. SIGGRAPH)43, 4 (2024), 1–15. S. C. Fisher and K. Ghassemi
work page 2024
-
[11]
GPS IIF-the Next Generation. 87, 1 (1999), 24–47. Moritz Geilinger, David Hahn, Jonas Zehnder, Moritz Bächer, Bernhard Thomaszewski, and Stelian Coros
work page 1999
-
[12]
Add: Analytically differentiable dynamics for multi-body systems with frictional contact.ACM Trans. Graph. (Proc. SIGGRAPH Asia)39, 6 (2020), 1–15. Peter E Glaser
work page 2020
-
[13]
Jeffrey Goldsmith and John Salmon
Power from the sun: Its future.Science162, 3856 (1968), 857–861. Jeffrey Goldsmith and John Salmon
work page 1968
- [14]
-
[15]
Neuroanima- tor: Fast neural network emulation and control of physics-based models. InProc. SIGGRAPH. 9–20. A Rupert Hall. 2012.From Galileo to Newton. Courier Corporation. Isadore Harris and Wolfgang Priester
work page 2012
-
[16]
Time-dependent structure of the upper atmosphere.Journal of Atmospheric Sciences19, 4 (1962), 286–301. Gerald S Hawkins
work page 1962
-
[17]
NA Hładczuk, Jose van den IJssel, Timothy Kodikara, Christian Siemes, and Pieter Visser
Stonehenge decoded.Nature200, 4904 (1963), 306–308. NA Hładczuk, Jose van den IJssel, Timothy Kodikara, Christian Siemes, and Pieter Visser
work page 1963
-
[18]
Philipp Holl, Vladlen Koltun, and Nils Thuerey
GRACE-FO radiation pressure modelling for accurate density and crosswind retrieval.Advances in Space Research73, 5 (2024), 2355–2373. Philipp Holl, Vladlen Koltun, and Nils Thuerey
work page 2024
-
[19]
Learning to control PDEs with differentiable physics.ICLR(2020). Yuanming Hu, Luke Anderson, Tzu-Mao Li, Qi Sun, Nathan Carr, Jonathan Ragan- Kelley, and Frédo Durand
work page 2020
-
[20]
DiffTaichi: Differentiable programming for physical simulation.ICLR(2020). International GNSS Service
work page 2020
-
[21]
http: //acc.igs.org/orbits/ Accessed: 2025-01-23
IGS Orbits - Analysis Center Coordinator. http: //acc.igs.org/orbits/ Accessed: 2025-01-23. Victor Isakov. 2006.Inverse problems for partial differential equations. Vol
work page 2025
-
[22]
Les Johnson, Roy Young, Edward Montgomery, and Dean Alhorn
Optimality principles in spacecraft neural guidance and control.Science Robotics9, 91 (2024). Les Johnson, Roy Young, Edward Montgomery, and Dean Alhorn
work page 2024
-
[23]
Gary Johnston, Anna Riddell, and Grant Hausler
Status of solar sail technology within NASA.Adv Space Res48, 11 (2011), 1687–1694. Gary Johnston, Anna Riddell, and Grant Hausler
work page 2011
-
[24]
Springer Handbook of Global Navigation Satellite Systems(2017), 967–982
The International GNSS Service. Springer Handbook of Global Navigation Satellite Systems(2017), 967–982. Tero Karras and Timo Aila
work page 2017
-
[25]
Fast parallel construction of high-quality bounding volume hierarchies. InProc. High-Performance Graphics. 89–99. Patrick William Kenneally. 2019.Faster than Real-Time GPGPU Radiation Pressure Modeling Methods. Ph. D. Dissertation. University of Colorado at Boulder. Patrick W Kenneally and Hanspeter Schaub
work page 2019
-
[26]
Fast spacecraft solar radiation pressure modeling by ray tracing on graphics processing unit.Advances in Space Research65, 8 (2020), 1951–1964. Pyotr N Lebedev
work page 2020
-
[27]
Experimental examination of light pressure.Ann. Phys6, 433 (1901), 10–1002. Jaakko Lehtinen, Jacob Munkberg, Jon Hasselgren, Samuli Laine, Tero Karras, Miika Aittala, and Timo Aila
work page 1901
-
[28]
Tzu-Mao Li, Miika Aittala, Frédo Durand, and Jaakko Lehtinen
Noise2Noise: Learning image restoration without clean data (2018).ICML(2018). Tzu-Mao Li, Miika Aittala, Frédo Durand, and Jaakko Lehtinen. 2018a. Differentiable Monte Carlo ray tracing through edge sampling.ACM Trans. Graph. (Proc. SIG- GRAPH Asia)37, 6 (2018), 1–11. Zhen Li, Marek Ziebart, Santosh Bhattarai, David Harrison, and Stuart Grey. 2018b. Fast ...
work page 2018
-
[29]
doi:10.2514/1.62986 Matthew M Loper and Michael J Black
Space Object Shape Characterization and Tracking Using Light Curve and Angles Data.J of Guidance, Control, and Dynamics37, 1 (2014), 13–25. doi:10.2514/1.62986 Matthew M Loper and Michael J Black
-
[30]
Reparameterizing discontinuous integrands for differentiable rendering.ACM Trans. Graph. (Proc. SIGGRAPH Asia)38, 6 (2019), 1–14. J David MacDonald and Kellogg S Booth
work page 2019
-
[31]
Luc Maisonobe and Veronique Pommier-Maurussane
Heuristics for ray tracing using space subdivision.The Visual Computer6 (1990), 153–166. Luc Maisonobe and Veronique Pommier-Maurussane
work page 1990
-
[32]
High-fidelity geometry models for improving the consistency of CHAMP, GRACE, GOCE and Swarm thermospheric density data sets.Adv Space Res63 (2019), 213–238. Darren McKnight, Rachel Witner, Francesca Letizia, Stijn Lemmens, Luciano Anselmo, Carmen Pardini, Alessandro Rossi, Chris Kunstadter, Satomi Kawamoto, Vladimir Aslanov, et al
work page 2019
-
[33]
Antoine McNamara, Adrien Treuille, Zoran Popović, and Jos Stam
Identifying the 50 statistically-most-concerning derelict objects in LEO.Acta Astronautica181 (2021), 282–291. Antoine McNamara, Adrien Treuille, Zoran Popović, and Jos Stam
work page 2021
-
[34]
Fluid control using the adjoint method.ACM Trans. Graph.23, 3 (2004), 449–456. Sharon K. R. Miller and Bruce A. Banks
work page 2004
-
[35]
Degradation of Spacecraft Materials in the Space Environment.MRS Bulletin35, 1 (2010), 20–24. doi:10.1557/mrs2010.612 O. Montenbruck and E. Gill. 2000.Satellite Orbits: Models, Methods, and Applications. Springer Berlin Heidelberg. Oliver Montenbruck, Ralf Schmid, Flavien Mercier, Peter Steigenberger, Carey Noll, Roman Fatkulin, Satoshi Kogure, and Aiylam...
- [36]
-
[37]
Physics- Based Approach to Thermospheric Density Estimation Using CubeSat GPS Data. Space Weather21, 1 (2023). Nvidia. 2023.NVIDIA H100 Tensor Core GPU Architecture. Daniel J O’Shaughnessy, James V McAdams, Peter D Bedini, Andrew B Calloway, Kenneth E Williams, and Brian R Page
work page 2023
-
[38]
Ryan S Park, William M Folkner, James G Williams, and Dale H Boggs
MESSENGER’s use of solar sailing for cost and risk reduction.Acta Astronautica93 (2014), 483–489. Ryan S Park, William M Folkner, James G Williams, and Dale H Boggs
work page 2014
-
[39]
The JPL planetary and lunar ephemerides DE440 and DE441.The Astronomical J161, 3 (2021),
work page 2021
-
[40]
David Pérez and Riccardo Bevilacqua
The development and evaluation of the Earth Gravitational Model 2008 (EGM2008).J of geophysical research: solid earth117, B4 (2012). David Pérez and Riccardo Bevilacqua
work page 2008
-
[41]
Matt Pharr, Wenzel Jakob, and Greg Humphreys
Neural Network based calibration of atmospheric density models.Acta Astronautica110 (2015), 58–76. Matt Pharr, Wenzel Jakob, and Greg Humphreys. 2023.Physically based rendering: From theory to implementation. MIT Press. L.S. Pontryagin, V. G. Boltyanskii, R. V. Gamkrelidze, and E. F. Mishchenko. 1962.The mathematical theory of optimal processes.Wiley, NY....
work page 2015
-
[42]
Make it stand: balancing shapes for 3D fabrication.ACM Trans Graph. (Proc. SIG- GRAPH)32, 4 (2013), 1–10. Jacqueline A Reyes and Darren Cone
work page 2013
-
[43]
CJ Rodriguez-Solano, U Hugentobler, and P Steigenberger. 2012a. Adjustable box-wing model for solar radiation pressure impacting GPS satellites.Adv Space Res49, 7 (2012), 1113–1128. CJ Rodriguez-Solano, U Hugentobler, and P Steigenberger. 2012b. Impact of albedo radiation on GPS satellites. InProc. Geodesy for Planet Earth. Springer, 113–119. Carlos Javie...
work page 2012
-
[44]
XLA: Compiling machine learning for peak performance.Google Res(2020). Hanspeter Schaub and John L. Junkins. 2018.Analytical Mechanics of Space Systems (4th ed.). American Institute of Aeronautics and Astronautics, Reston, VA. Thomas Schildknecht
work page 2020
-
[45]
Optical surveys for space debris.The Astronomy and Astrophysics Review14 (2007), 41–111. Sheldahl. 2015.Sheldahl Optical Properties Handbook. Sheldahl, Northfield, Minnesota, USA. Revision E. Commonly known as "The Red Book". TA Springer, G Beutler, and M Rothacher
work page 2007
-
[46]
Marc A Toussaint, Kelsey Rebecca Allen, Kevin A Smith, and Joshua B Tenenbaum
A new solar radiation pressure model for GPS satellites.GPS solutions2 (1999), 50–62. Marc A Toussaint, Kelsey Rebecca Allen, Kevin A Smith, and Joshua B Tenenbaum
work page 1999
-
[47]
Robotics: Science and systems foundation(2018)
Differentiable physics and stable modes for tool-use and manipulation planning. Robotics: Science and systems foundation(2018). Slava G Turyshev, Viktor T Toth, Gary Kinsella, Siu-Chun Lee, Shing M Lok, and Jordan Ellis
work page 2018
-
[48]
Support for the thermal origin of the Pioneer anomaly.Physical Review Letters108, 24 (2012). Eric Veach. 1998.Robust Monte Carlo methods for light transport simulation. Stanford University. Delio Vicini, Sébastien Speierer, and Wenzel Jakob
work page 2012
-
[49]
SIGGRAPH)40, 4 (2021), 108:1–108:14
Path Replay Backpropagation: Differentiating Light Paths using Constant Memory and Linear Time.ACM Trans Graph (Proc. SIGGRAPH)40, 4 (2021), 108:1–108:14. Pascal Vincent, Hugo Larochelle, Yoshua Bengio, and Pierre-Antoine Manzagol
work page 2021
-
[50]
Ray tracing deformable scenes using dynamic bounding volume hierarchies.ACM Trans. Graph.26, 1 (2007). Gerhard Wanner and Ernst Hairer. 1996.Solving ordinary differential equations II. Vol
work page 2007
-
[51]
Clouds and the Earth’s Radiant Energy System (CERES): An earth observing system experiment.Bulletin of the American Meteorological Society77, 5 (1996), 853–868. W Wollenhaupt
work page 1996
-
[52]
Temperature aware workload management in geo-distributed datacenters.ACM SIGMETRICS performance evaluation review41, 1 (2013), 373–374. Radosław Zajdel, Salim Masoumi, Krzysztof Sośnica, Filip Gałdyn, Dariusz Strugarek, and Grzegorz Bury
work page 2013
-
[53]
Combination and SLR validation of IGS Repro3 orbits for ITRF2020.Journal of Geodesy97, 10 (2023),
work page 2023
-
[54]
Adv Space Res36, 3 (2005), 424–430
Combined radiation pressure and thermal modelling of complex satellites: Algorithms and on-orbit tests. Adv Space Res36, 3 (2005), 424–430. ACM Trans. Graph., Vol. 45, No. 4, Article
work page 2005
-
[55]
Publication date: July 2026
work page 2026
discussion (0)
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