Astronomical Observations in Support of Planetary Entry-Probes to the Outer Planets

Abstract

A team of Earth-based astronomical observers supporting a giant planet entry-probe event substantially enhances the scientific return of the mission. An observers' team provides spatial and temporal context, additional spectral coverage and resolution, viewing geometries that are not available from the probe or the main spacecraft, tracking, supporting data in case of a failure, calibration benchmarks, and additional opportunities for education and outreach. The capabilities of the support program can be extended by utilizing archived data. The existence of a standing group of observers facilitates the path towards acquiring Director's Discretionary Time at major telescopes, if, for example, the probe's entry date moves. The benefits of a team convened for a probe release provides enhanced scientific return throughout the mission. Finally, the types of observations and the organization of the teams described in this paper could serve as a model for flight projects in general.

Keywords: Jupiter; Neptune; Planetary probes; Saturn; Uranus.

Fig. 1

An infrared (4.85 μm) image obtained of Jupiter at the IRTF 16 days before the entry of the Galileo probe. The X is the location of the probe’s entry. Based on Orton et al. (1996)

Fig. 2

An image from the Hale Telescope at Palomar Mountain Observatory of the Deep Space 1 spacecraft obtained on November 16, 1998, 23 days after its launch from Cape Canaveral. The spacecraft is marked with a red arrow. Observers were B. Buratti, A. Doressoundiram, M. Hicks, and P. Weissman

Fig. 3

Various images of the ice giants, including some obtained by the authors. A. An image of Uranus obtained with the Palomar Adaptive Optics system on the Hale Telescope on 20 September 2007, with 1.55 μm, 1.65 μm, & K-band in the RGB bands. Three moons and the rings are visible. B. An image of Uranus obtained with the same equipment on July 19, 2021, with the J-filter image in the R-Band, the CH₄ long band image in the G-band, and the CH4 short filter image in the B-band (the CH₄ long band filter has a spectral range of 1.64-1.74 μm and a central wavelength of 1.69 μm, while the CH₄ short band filter has a spectral range of 1.52-1.62 μm and a central wavelength of 1.57 μm). C. Visible (0.47 μm) images of Neptune obtained by HST in 2020 tracking the evolution of a dark vortex (Space Telescope Science Institute 2022). The headings describe a co-adding and difference scheme to accentuate the feature. D–E. Images of Neptune obtained with the Palomar Adaptive Optics system in July 2021. The left image has the JHK filter images placed in the RGB planes, while the right image has the CH₄(short), CH₄(long) and K(short, with a central wavelength of 2.145 μm and a range of 1.99-2.30 μm) placed in these planes. These images suggest the possibility of doing compositional analyses (as described in the text) as well as tracking of cloud formation and motion through a seasonal cycle