Science > Highlights > 2023 Science Highlights > Solar System and Planetary Science

Solar System and Planetary Science

The NRAO facilities remain the paramount tools of radio astronomy in the study of planetary science and Solar physics. Working in concert with space missions and ground-based facilities, the VLA, ALMA, and VLBA have contributed in the last year in areas ranging from the energy source of the Solar chromosphere, to winds, storms, and polar vortices in the atmospheres of Saturn, Uranus, Neptune, and Jupiter, to the surfaces of Kuiper belt objects and volcanos on Io.

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Figure 3. ALMA 343 GHz image of Callisto at 0.16” resolution with mean disk emission subtracted. Right: ALMA contours plus the albedo map from Voyager and Galileo imaging (Camarca et al. 2023). A few crater impact regions are indicated, showing higher albedo and cooler mm thermal emission.
Callisto is the least geologically active of the Galilean moons of Jupiter (Figure 3; Camarca et al. 2023). ALMA 343 GHz observations at 0.16” resolution find a mean disk thermal brightness temperature of 116 K. The data suggest a regolith with two very different thermal inertial components. They also identify several thermally anomalous regions, including spots ∼3 K colder than model predictions co-located with the Valhalla impact basin and a complex of craters in the southern hemisphere, indicating the presence of materials possessing either a higher thermal inertia or a lower emissivity. A warm region confined to the mid-latitudes may be indicative of regolith property changes due to exogenic sculpting.

 

 

 

 

 

 

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Figure 4. ALMA 12m and ACA 345 GHz images of the Didymous-Dimorphos binary asteroid system after impact of the DART deep space probe (Roth et al. 2023, arXiv:2306.05908).

 

ALMA played an important role as a ground facility in the Double Asteroid Redirection Test (DART; Figure 4; Roth et al. 2023)— a deep space probe designed to investigate the effect of satellite impact on asteroid orbits, as part of the kinetic impactor planetary defense technique program at NASA. ALMA detected thermal emission from the asteroid at 345 GHz both before and after impact. The comparison of the two observations provide the most sensitive measurement of mm-sized ejecta caused by the impact. Depending on the material composition, the ejecta mass was ~ few x107 kg, representing about 1% of Dimorphos’ total mass.

 

 

 

 

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