A view of a transparent FLUIDICS sphere aboard space station. The FLUIDICS 

investigation studies the dynamics of liquid sloshing to better understand turbulence 

in spacecraft tanks and to optimize fuel use. NASA ID: iss066e146914. 
Publication Highlights

Physical Science

 

The presence of gravity greatly influences our understanding of physics and the development of fundamental 

mathematical models that reflect how matter behaves. The space station is the only laboratory where 

scientists can study long-term physical effects without the complications of gravity-related processes such 

as convection and sedimentation. This unique environment allows different physical properties to dominate 

systems, and scientists are harnessing these properties for a wide variety of investigations in the physical 

sciences. From the beginning of station to date, more than 700 articles have been published in the area of 

Physical Science. 

The investigation The 

Materials International 

Space Station 

Experiment-13-NASA 

(MISSE-13-NASA) 

encompasses a group of 

experiments that examine the 

effect of the space environment on material 

quality. MISSE experiments fly similar 

materials on multiple missions to better 

understand degradation, predict durability, 

ensure feasibility of in-space manufacturing, 

and prepare for long-term use of materials in a 

harsh environment. 

For 10 months, a promising low-cost, highperforming semiconductor material known as 

Metal Halide Perovskites (MHP) that absorbs 

sunlight and converts it into electrical energy 

was exposed to the space environment as 

encapsulated thin films. Confocal microscopy 

analysis conducted postflight on the ground 

showed localized surface defects (i.e., 

bubbles) that resulted from trapped moisture, 

and 13 percent of its surface was optically 

inactive. However, the surface flaws, carrier 

recombination lifespan, and response to solar 

exposure were repaired or improved after 15 

hours of solar illumination of the sample 

(Figure 18). 

These results demonstrate that MHPs in microgravity have a stable response to solar light, 

can be restored, and have a good charge 

lifespan that assists in overcoming the known 

longevity issues of MHP devices. Improved 

MHPs could lead to enhancements in solar 

cells, light emitting diodes, and optoelectronFigure 18. Confocal flourescence images of Earth control samples (A and B, with 

and without a layer of silicon dioxide, repectively), fligh (C) and flight sample after 

light exposure (D). Images adopted from Delmas, Advanced Energy Materials. 

ic devices, which could in turn assist in the 

development of life support systems, telecommunications, and electric propulsion systems 

to support space exploration. 

The JAXA investigation Hourglass examines the behavior 

of granular materials in 

various low-gravity environments aiming to enhance the 

design of spacecraft, landers, 

and other mobility systems. 

The Moon, Mars, and asteroids in our solar 

system can be covered by a layer of loose 

material known as regolith. To ensure the 

Delmas W, Erickson S, Arteaga J, Woodall M, Scheibner M, et al. Evaluation of hybrid perovskite prototypes after 10-month space flight on 

the International Space Station. Advanced Energy Materials. 2023 May 19; 13(19): 2203920. DOI: 10.1002/aenm.202203920. 

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Publication Highlights

Physical Science

proper functioning of the equipment developed 

for use on the celestial surface, it is essential to 

conduct a ground test that verifies the reaction 

force and the sinkage caused by loose regolith. 

Previous research has employed computerized 

simulations to predict equipment performance 

in the most challenging environments. 

A recent study published in npj Microgravity 

provides verification of the hypothesis of granular flows by analyzing data from experiments 

conducted on the station under various levels 

of artificial gravity (0.063 to 2.0 times Earth’s 

gravity). 

The hourglass device was designed to control 

the flow of alumina beads, silica sand, 

Toyoura sand, and five variations of regolith 

simulants as analogous grains (Figure 19). 

Stable gravitational fields were generated 

by rotating a centrifuge and flipping an hourFigure 19. The state of Deposition after the hourglass is inverted and the 

granular particles have moved through the neck. Image provided by 

Hourglass research team. 

glass-shaped instrument in the Japanese 

Experiment Module (JEM). 

The researchers found that the low-gravity 

behavior of grains generally follows 

previously postulated physical laws of flow 

rate, but with some differences. And the 

researchers presumed that the bulk density of 

the flow is unstable but decreases with gravity. 

In addition, the researchers observed that the 

specific type of granular material and slant 

angle in the hourglass influenced the flow rate, 

with powder-like material adhering, depositing, 

and aggregating in the device. 

These findings can improve simulations and 

inform the development of advanced technologies for successful roving on extraterrestrial 

bodies. 

The ESA investigation FSL 

Soft Matter Dynamics -

Hydrodynamics of Wet 

Foams (FOAM) examines 

changes to liquid foams, 

(e.g., soap and champagne) 

in microgravity. On Earth, 

bubbles in liquids rapidly rise to the top and the 

liquid moves to the bottom of a container due 

to gravity. In microgravity, however, changes to 

the liquid foam are slower and can be studied 

in detail. Through this station research, investigators enhance the understanding of liquid 

foams to design better liquid systems in agriculture, brewery, detergent, and oil industries. 

In a new study published in Soft Matter, 

researchers observed changes to the size and 

distribution of bubbles created in microgravity 

by mixing water with a pure and chemically 

stable foaming agent. Researchers tested 

several mixed samples using 11 different liquid 

amounts (e.g., 15 percent water, 20 percent 

water, up to 50 percent water) to identify which 

liquid percentage most effectively led to the 

growth and dispersion of the bubbles 

(transitioning from a soft gel-like network of 

packed bubbles to a more liquefied solution). A

camera recorded the changes in the samples, 

and manual analyses of the images occurred 

on Earth. 

Researchers revealed that small bubbles 

shrank and large bubbles grew even larger 

over time because of pressure dynamics 

in the bubbles (Figure 20). Additionally, 

Ozaki S, Ishigami G, Otsuki M, Miyamoto H, Wada K, et al. Granular flow experiment using artificial gravity generator at International Space 

Station. npj Microgravity. 2023 August 8; 9(1): 1-13. DOI: 10.1038/s41526-023-00308-w. 

26
Publication Highlights

Physical Science

researchers identified that 

bubbles transitioned from 

a crowded to a scattered 

arrangement when 

the mixture contained 

39 percent liquid. This 

finding differed from their 

theoretical prediction 

of 31 percent liquid to 

observe such transition in 

microgravity. As packed 

bubbles separated 

Figure 20. Changes in bubble size in a mixture of foaming agent and 25 percent liquid after approximately five and a half 

hours. Image adopted from Pasquet, Soft Matter. 

and diffused, distorted 

polyhedral-shaped bubbles became more 

spherical and uniform. Weak interactions 

and reduced contact forces among bubbles 

may explain their separation and dispersion. 

Despite the uniqueness of these results, 

researchers also acknowledge similarities 

to phase separation in alloys and capillary 

pressure changes observed in biology. 

By studying the mechanical properties of 

liquid foams, researchers can learn how to 

stabilize and enhance their shelf life. This 

research not only improves liquid systems but 

also contributes to the improvement of foam 

solidification in applications such as packaging, 

insulation, and car-collision prevention through 

metallic foams. 

Pasquet M, Galvani N, Requier A, Cohen-Addad S, Hohler R, et al. Coarsening transitions of wet liquid foams under microgravity conditions. Soft Matter. 2023 August 8; 19(33): 6267-6279. DOI: 10.1039/d3sm00535f. 

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