Open AccessObservation of Cassini’s Entry into Saturn: No Detection, and Lessons Learned
Author(s) -
Ralph D. Lorenz,
F. J. Crary,
Laurent Lamy,
Peter Jenniskens,
Lijuan Ge,
Xiliang Zhang,
JianYang Li,
Masataka Imaï,
T. Ono,
Matthew R. Arnison,
Lee Spitler
Publication year - 2021
Publication title -
research notes of the aas
Language(s) - English
Resource type - Journals
ISSN - 2515-5172
DOI - 10.3847/2515-5172/ac072d
Subject(s) - saturn , spacecraft , astronomy , planet , astrobiology , physics , meteor (satellite) , atmosphere (unit) , event (particle physics) , transit (satellite) , atmospheric entry , remote sensing , aperture (computer memory) , geology , environmental science , meteorology , astrophysics , engineering , public transport , transport engineering , acoustics
The mission of the 2000 kg Cassini spacecraft concluded on 2017 September 15, by its deliberate entry into Saturn’s atmosphere at some 31.1 km s −1 . Observations, using Hubble and groundbased observatories, to attempt optical detection of this 0.25 kT “artificial meteor” are summarized. No signatures were identified. A challenge with observing the event is that due to atmospheric drag, its timing was not completely deterministic months or even days in advance, a particular problem for space observatories. While imaging observations needed no geometric specification more than “Saturn,” observations with spectrometers required pointing the instrument aperture or slit at the specific impact site. Since giant planet longitude systems are not always familiar, distribution of an unambiguous “finder chart” showing the location of the predicted entry site on the disk is essential, as is clarity on whether stated times are spacecraft event time, or Earth received time (light-travel time, 83 minutes, later).