Towering storms, swirling clouds, and vortices are the cloud top manifestation of complex weather systems shaping the atmosphere of Jupiter. We use observations from Juno’s MicroWave Radiometer (MWR), the Karl G. Jansky Very Large Array, and the Hubble Space Telescope to probe for the first time the depth and impact of weather on Jupiter. We use ammonia, the main source of opacity at radio wavelengths on Jupiter, as the tracer for the weather by fitting ammonia anomalies to the MWR brightness temperature variations. We show that most of the weather—defined here as longitudinal deviations in ammonia concentration from the zonal mean—is concentrated in regions near cloud formation. Both the South Equatorial Belt and the Equatorial Zone have surprisingly shallow weather systems ( P < 2 bars), and even in the North Equatorial Belt most of the ammonia variations are above the water condensation level ( P ∼ 6 bars). This confirms that the water condensation layer plays a crucial role in controlling the dynamics and the weather on Jupiter. Three features, however, extend below the water condensation layer: a vortex in the northern hemisphere reaching down to 30 bars, an ammonia plume down to 20–30 bars, and the signature of ammonia fallout down to 20 bars. This work confirms that an interplay of large-scale processes (vortices, plumes) and small-scale processes (storms) is responsible for shaping the global atmospheric makeup of Jupiter.

Planetary-scale giant storms erupt on Saturn quasiperiodically. There have been at least six recorded occurrences of past eruptions, and the most recent one was in 2010, with its whole life span captured by the Cassini mission. In 2015, we used the Very Large Array to probe the deep response of Saturn’s troposphere to the giant storms. In addition to the remnant effect of the storm in 2010, we have found long-lasting signatures of all mid-latitude giant storms, a mixture of equatorial storms up to hundreds of years old, and potentially an unreported older storm at 70°N. We derive an ammonia anomaly map that shows an extended meridional migration of the storm’s aftermath and vertical transport of ammonia vapor by storm dynamics. Intriguingly, the last storm in 2010 splits into two distinct components that propagate in opposite meridional directions, leaving a gap at 43°N planetographic latitude.

Ground-based interferometry at mm-cm wavelengths provides a powerful tool for characterizing satellite surfaces and atmospheres.We present the science enabled by the ALMA (current) and ngVLA (proposed) arrays, including recent results as well as future work in the context of planned and proposed spacecraft missions.ALMA dishes on the Chajnantor Plateau in Chile (Credit: Ariel Marinkovic / X-Cam)

The deep atmospheres of the giant planets provide crucial constraints on their composition, an essential parameter in planet formation models.These deep atmospheres can only be probed remotely at radio wavelengths.The next-generation Very Large Array (ngVLA) will enable the highest sensitivity and spatial resolution observations at wavelengths of 0.25-26 cm (1.2-116 GHz), enabling one to derive the composition and atmospheric dynamics of the Ice Giants Uranus and Neptune from the stratosphere down to tens of bars, and constrain H 2 O at 100s of bars via mmspectroscopy of CO.A comparison of the ngVLA with a future Ice-Giant mission shows that the ngVLA will provide a spatial resolution at wavelengths 10 cm that is superior over radio instrumentation on an Ice-Giant mission.The ngVLA will provide unique scientific observations (e.g., full maps over a broad wavelength range, and mm-wavelength spectroscopy), providing invaluable support to space missions.It also is a potential ground station for spacecraft telemetry.

We present ALMA and VLA spatial maps of the Uranian atmosphere taken between 2015 and 2018 at wavelengths from 1.3 mm to 10 cm, probing pressures from $\sim$1 to $\sim$50 bar at spatial resolutions from 0.1'' to 0.8''. Radiative transfer modeling was performed to determine the physical origin of the brightness variations across Uranus's disk. The radio-dark equator and midlatitudes of the planet (south of $\sim$50$^\circ$ N) are well fit by a deep H$_2$S mixing ratio of $8.7_{-1.5}^{+3.1}\times10^{-4}$ ($37_{-6}^{+13}\times$ Solar) and a deep NH$_3$ mixing ratio of $1.7_{-0.4}^{+0.7}\times10^{-4}$ ($1.4_{-0.3}^{+0.5}\times$ Solar), in good agreement with literature models of Uranus's disk-averaged spectrum. The north polar region is very bright at all frequencies northward of $\sim$50$^\circ$N, which we attribute to strong depletions extending down to the NH$_4$SH layer in both NH$_3$ and H$_2$S relative to the equatorial region; the model is consistent with an NH$_3$ abundance of $4.7_{-1.8}^{+2.1} \times 10^{-7}$ and an H$_2$S abundance of $<$$1.9\times10^{-7}$ between $\sim$20 and $\sim$50 bar. Combining this observed depletion in condensible molecules with methane-sensitive near-infrared observations from the literature suggests large-scale downwelling in the north polar vortex region from $\sim$0.1 to $\sim$50 bar. The highest-resolution maps reveal zonal radio-dark and radio-bright bands at 20$^\circ$S, 0$^\circ$, and 20$^\circ$N, as well as zonal banding within the north polar region. The difference in brightness is a factor of $\sim$10 less pronounced in these bands than the difference between the north pole and equator, and additional observations are required to determine the temperature, composition and vertical extent of these features.

We present spatially resolved (0.″1–1.″0) radio maps of Neptune taken from the Very Large Array and Atacama Large Millimeter/submillimeter Array between 2015 and 2017. Combined, these observations probe from just below the main methane cloud deck at ∼1 bar down to the NH 4 SH cloud at ∼50 bar. Prominent latitudinal variations in the brightness temperature are seen across the disk. Depending on wavelength, the south polar region is 5–40 K brighter than the mid-latitudes and northern equatorial region. We use radiative transfer modeling coupled to Markov Chain Monte Carlo methods to retrieve H 2 S, NH 3 , and CH 4 abundance profiles across the disk, though only strong constraints can be made for H 2 S. Below all cloud formation, the data are well fit by 53.8 − 13.4 + 18.9 × and 3.9 − 3.1 + 2.1 × protosolar enrichment in the H 2 S and NH 3 abundances, respectively, assuming a dry adiabat. Models in which the radio-cold mid-latitudes and northern equatorial region are supersaturated in H 2 S are statistically favored over models following strict thermochemical equilibrium. H 2 S is more abundant at the equatorial region than at the poles, indicative of strong, persistent global circulation. Our results imply that Neptune's sulfur-to-nitrogen ratio exceeds unity, as H 2 S is more abundant than NH 3 in every retrieval. The absence of NH 3 above 50 bar can be explained either by partial dissolution of NH 3 in an ionic ocean at GPa pressures or by a planet formation scenario in which hydrated clathrates preferentially delivered sulfur rather than nitrogen onto planetesimals, or a combination of these hypotheses.

We observed Jupiter four times over a full rotation (10 h) with the upgraded Karl G. Jansky Very Large Array (VLA) between December 2013 and December 2014. Preliminary results at 417 GHz were presented in de Pater et al. (2016); in the present paper we present the full data set at frequencies between 3 and 37 GHz. Major findings are: i) The radio-hot belt at 8.511 degrees N latitude, near the interface between the North Equatorial Belt (NEB) and the Equatorial Zone (EZ) is prominent at all frequencies (337 GHz). Its location coincides with the southern latitudes of the NEB (717 degrees N). ii) Longitude-smeared maps reveal belts and zones at all frequencies at latitudes less than or similar to vertical bar 20 degrees vertical bar. At higher latitudes numerous fainter bands are visible at frequencies greater than or similar to 7 GHz. The lowest brightness temperature is in the EZ near a latitude of 4 degrees N, and the NEB has the highest brightness temperature near 11 degrees N. The bright part of the NEB increases in latitudinal extent (spreads towards the north) with deceasing frequency, i.e., with depth into the atmosphere. In longitude-resolved maps, several belts, in particular in the southern hemisphere, are not continuous along the latitude line, but broken into small segments as if caused by an underlying wave. iii) Model fits to longitude-smeared spectra are obtained at each latitude. These show a high NH3 abundance (volume mixing ratio similar to 4 x 10(-4) ) in the deep (P > 810 bar) atmosphere, decreasing at higher altitudes due to cloud formation (e.g., in zones), or dynamics in combination with cloud condensation (belts). In the NEB ammonia gas is depleted down to at least the 20 bar level with an abundance of . The NH3 abundance at latitudes > vertical bar 50 vertical bar degrees is characterized by a relatively low value (similar to 1.75 x 10(-4)) between similar to 1 and 10 bar. iv) Using the entire VLA dataset, we confirm that the planet is extremely dynamic in the upper layers of the atmosphere, at P < 23 bar, i.e., at the altitudes where clouds form. At most latitudes the relative humidity within and above the NH3 cloud is considerably sub-saturated. v) The radiative transfer models that best fit the longitude-smeared VLA data at 425 GHz match the Juno PeriJove 1 microwave data extremely well, i.e., the NH3 abundance is high in the deep atmosphere, and either remains constant or decreases with altitude. vi) Hot spots have a very low, sub-saturated NH3 abundance at the altitudes of the NH3-ice cloud, gradually increasing from an abundance of similar to 10(-5) at 0.6 bar to the deep atmosphere value (similar to 4 x 10(-4)) at 8 bar. vii) We previously showed the presence of large ammonia plumes, which together with the 5-mu m hot spots constitute the equatorially trapped Rossby wave. Observations of these plumes at 1225 GHz reveal them to be supersaturated at similar to 0.80.5 bar, which implies plumes rise similar to 10 km above the main clouddeck. Numerous small ammonia plumes are detected at other locations (e.g., at 19 degrees S and interspersed with hot spots). viii) The Great Red Spot (GRS) and Oval BA show relatively low NH3 abundances throughout the troposphere (similar to 1.51.8 x 10(-4)), and the GRS is considerably sub-saturated at higher altitudes.

Thermal observations of minor bodies in the Solar System, and in particular centimeter-wave measurements probing across the diurnal skin depth, are strongly indicative of fundamental properties of their surfaces. We describe how the sensitivity provided by the ngVLA is necessary to achieve thermal detections on a large number of small bodies.

We present multi-wavelength VLA observations in the microwave of Saturn's rings. The data were obtained over two observational windows and cover a range from the Q to S bands (0.7–13 cm). Key ring particle properties are determined in the C and B rings such as particle porosity and non-icy material fraction in order to compare them directly with previously derived results using the 2-cm Cassini RADAR radiometry data (Zhang et al., 2017a, b). We confirm that these new data are consistent with the particles in the C ring being quite porous with porosity values of roughly 75–90% depending on different scattering phase functions, as well as the presence of a “hot band” in the middle C ring which is associated with both an anomalously high non-icy material fraction and low opacity relative to the rest of the C ring. Furthermore, with our multi-wavelength study we find that the amount of intrinsic thermal emission is almost constant with wavelength, which is unexpected since particles tend to become more absorbing at higher frequencies. If we assume that the non-icy material in the rings is intramixed within the ring particles, this result suggests a corresponding decrease in the imaginary part of the non-icy material dielectric constant at higher frequencies, which is most noticeable in the middle C ring. We do not see evidence for such decrease in the B ring particles. If true, this supports the idea that the non-icy material in the middle C ring has a different origin, and that the larger particles in the middle C ring may be composed of a rocky core covered by a porous, icy mantle. If the non-icy materials in the middle C ring are embedded as large chunks, a core-mantle model for the ring particles there naturally explains this almost constant intrinsic thermal emission. Furthermore, because the VLA has more complete azimuthal angle coverage than the Cassini radiometry observations, we are able to investigate the ring brightness in more detail. In particular, we notice a flatter scattering profile than that predicted by using a pure Mie phase function at higher frequencies (Q and K bands; 0.7–1.3 cm) for azimuthal angles between |40|o and |60|o. We can match the observed scattering profile better by introducing a semi-empirical phase function for large particles to account for nonsphericity effects. Finally, the non-icy material fraction in the B ring is less than 1%, which is in agreement with that derived from Cassini observations. The frequency-dependence of the B ring thermal emission sets the lower limit of B ring particle porosity. We confirm that the B ring particles are likely over 80% porous, which at the same time explains the high opacity in the B ring as measured from density waves. Because we are limited by the signal-to-noise ratio, the optical depth of the middle B ring could be higher than the currently accepted values. However, we found that even if the middle B ring is six times more optically thick than the value measured from UVIS occultations, the surface mass density is still likely to be less than 300 g/cm^2, while the exposure time to non-icy pollutants due to micrometeoroid bombardment is less than 200 Myr.

We obtained the first maps of Jupiter at 1-3 mm wavelength with the Atacama Large Millimeter/Submillimeter Array (ALMA) on 3-5 January 2017, just days after an energetic eruption at 16.5S jovigraphic latitude had been reported by the amateur community, and about 2-3 months after the detection of similarly energetic eruptions in the northern hemisphere, at 22.2-23.0N. Our observations, probing below the ammonia cloud deck, show that the erupting plumes in the SEB bring up ammonia gas from the deep atmosphere. While models of plume eruptions that are triggered at the water condensation level explain data taken at uv-visible and mid-infrared wavelengths, our ALMA observations provide a crucial, hitherto missing, link in the moist convection theory by showing that ammonia gas from the deep atmosphere is indeed brought up in these plumes. Contemporaneous HST data show that the plumes reach altitudes as high as the tropopause. We suggest that the plumes at 22.2-23.0N also rise up well above the ammonia cloud deck, and that descending air may dry the neighboring belts even more than in quiescent times, which would explain our observations in the north.

The solar system’s satellites include worlds with ongoing geological processes, complex atmospheric chemistry, and high astrobiological potential. Data at 1-100 GHz with high spatial resolution and sensitivity such as the ngVLA will provide would significantly advance our understanding of these bodies’ atmospheres and surface-interior exchange.

Radio wavelength observations of solar system bodies are a powerful method of probing many characteristics of those bodies. From surface and subsurface, to atmospheres (including deep atmospheres of the giant planets), to rings, to the magnetosphere of Jupiter, these observations provide unique information on current state, and sometimes history, of the bodies. The ngVLA will enable the highest sensitivity and resolution observations of this kind, with the potential to revolutionize our understanding of some of these bodies. In this article, we present a review of state-of-the-art radio wavelength observations of a variety of bodies in our solar system, varying in size from ring particles and small near-Earth asteroids to the giant planets. Throughout the review we mention improvements for each body (or class of bodies) to be expected with the ngVLA. A simulation of a Neptune-sized object is presented in Section 6. Section 7 provides a brief summary for each type of object, together with the type of measurements needed for all objects throughout the Solar System.

Using the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP BETA), we have carried out the first z = 0-1 survey for HI and OH absorption towards the gravitationally lensed quasars PKS B1830-211 and MGJ0414+ 0534. Although we detected all previously reported intervening systems towards PKS B1830-211, in the case of MG J0414+ 0534, three systems were not found, indicating that the original identifications may have been confused with radio frequency interference. Given the sensitivity of our data, we find that our detection yield is consistent with the expected frequency of intervening HI systems estimated from previous surveys for 21-cm emission in nearby galaxies and z similar to 3 damped Lyman alpha absorbers. We find spectral variability in the z = 0.886 face-on spiral galaxy towards PKS B1830-211 from observations undertaken with the Westerbork Synthesis Radio Telescope in 1997/1998 and ASKAP BETA in 2014/2015. The HI equivalent width varies by a few per cent over approximately yearly time-scales. This long-term spectral variability is correlated between the north-east and south-west images of the core, and with the total flux density of the source, implying that it is observationally coupled to intrinsic changes in the quasar. The absence of any detectable variability in the ratio of HI associated with the two core images is in stark contrast to the behaviour previously seen in the molecular lines. We therefore infer that coherent opaque HI structures in this galaxy are larger than the parsec-scale molecular clouds found at mm-wavelengths.

The Boolardy Engineering Test Array is a 6 x 12 m dish interferometer and the prototype of the Australian Square Kilometre Array Pathfinder (ASKAP), equipped with the first generation of ASKAP's phased array feed (PAF) receivers. These facilitate rapid wide-area imaging via the deployment of simultaneous multiple beams within a 30 square degree field of view. By cycling the array through 12 interleaved pointing positions and using 9 digitally formed beams we effectively mimic a traditional 1 hour x 108 pointing survey, covering 150 square degrees over 711 - 1015 MHz in 12 hours of observing time. Three such observations were executed over the course of a week. We verify the full bandwidth continuum imaging performance and stability of the system via self-consistency checks and comparisons to existing radio data. The combined three epoch image has arcminute resolution and a 1-sigma thermal noise level of 375 micro-Jy per beam, although the effective noise is a factor 3 higher due to residual sidelobe confusion. From this we derive a catalogue of 3,722 discrete radio components, using the 35 percent fractional bandwidth to measure in-band spectral indices for 1,037 of them. A search for transient events reveals one significantly variable source within the survey area. The survey covers approximately two-thirds of the Spitzer South Pole Telescope Deep Field. This pilot project demonstrates the viability and potential of using PAFs to rapidly and accurately survey the sky at radio wavelengths.