Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry
The Galileo spacecraft had distant encounters with Earth in 1990 and 1992. Limited Solid State Imager (SSI) data acquired during these encounters has been previously presented, but the majority of the data from these Earth flybys have not been presented in the literature. Observations of Earth taken...
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| Format: | Article |
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IOP Publishing
2024-01-01
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| Series: | The Astronomical Journal |
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| Online Access: | https://doi.org/10.3847/1538-3881/ad1bd1 |
| _version_ | 1797336272689168384 |
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| author | Ryder H. Strauss Tyler D. Robinson David E. Trilling Ryan Cummings Christopher J. Smith |
| author_facet | Ryder H. Strauss Tyler D. Robinson David E. Trilling Ryan Cummings Christopher J. Smith |
| author_sort | Ryder H. Strauss |
| collection | DOAJ |
| description | The Galileo spacecraft had distant encounters with Earth in 1990 and 1992. Limited Solid State Imager (SSI) data acquired during these encounters has been previously presented, but the majority of the data from these Earth flybys have not been presented in the literature. Observations of Earth taken from afar are both rare and directly relevant to the development of any future exo-Earth direct imaging mission. Here we present a pipeline that vets, calibrates, and measures the disk-integrated brightness of the Earth, in multiple filters, from the complete SSI data sets from both the 1990 and 1992 Galileo flybys. The result is over 1500 usable photometric measurements for Earth as an analog for an exoplanet. The 1990 data set includes full rotational lightcurves in six bandpasses spanning the optical range. The 1992 data set is more limited, with lightcurves only spanning 14 hr. Time-averaged photometry for both encounters is presented while variability and color are discussed relative to findings from NASA’s EPOXI mission (which also provided photometric lighturves for Earth). The new Galileo/SSI data are used to further validate the Virtual Planetary Laboratory 3D spectral Earth model, which often serves as a stand-in for true disk-integrated observations of our planet. The revived Galileo/SSI data for Earth is a testament to the ability of NASA’s Planetary Data System to maintain data over decades-long timescales. The disk-integrated products derived from these data add to a very short list of calibrated and published whole-disk observations of the Pale Blue Dot. |
| first_indexed | 2024-03-08T08:51:52Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1538-3881 |
| language | English |
| last_indexed | 2024-03-08T08:51:52Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj.art-fa4f36a6712f4ef789602d349b54c0062024-02-01T09:26:27ZengIOP PublishingThe Astronomical Journal1538-38812024-01-0116738710.3847/1538-3881/ad1bd1Exoplanet Analog Observations of Earth from Galileo Disk-integrated PhotometryRyder H. Strauss0https://orcid.org/0000-0001-6350-807XTyler D. Robinson1https://orcid.org/0000-0002-3196-414XDavid E. Trilling2https://orcid.org/0000-0003-4580-3790Ryan Cummings3Christopher J. Smith4Department of Astronomy and Planetary Science, Northern Arizona University , Box 6010, Flagstaff, AZ 86011, USA ; rhs72@nau.eduDepartment of Astronomy and Planetary Science, Northern Arizona University , Box 6010, Flagstaff, AZ 86011, USA ; rhs72@nau.edu; Lunar and Planetary Laboratory, Department of Planetary Sciences, University of Arizona , Tucson, AZ 85721, USA; Habitability, Atmospheres, and Biosignatures Laboratory, University of Arizona , Tucson, AZ 85721, USA; NASA Nexus for Exoplanet System Science Virtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USADepartment of Astronomy and Planetary Science, Northern Arizona University , Box 6010, Flagstaff, AZ 86011, USA ; rhs72@nau.eduDepartment of Astronomy and Planetary Science, Northern Arizona University , Box 6010, Flagstaff, AZ 86011, USA ; rhs72@nau.eduDepartment of Astronomy and Planetary Science, Northern Arizona University , Box 6010, Flagstaff, AZ 86011, USA ; rhs72@nau.eduThe Galileo spacecraft had distant encounters with Earth in 1990 and 1992. Limited Solid State Imager (SSI) data acquired during these encounters has been previously presented, but the majority of the data from these Earth flybys have not been presented in the literature. Observations of Earth taken from afar are both rare and directly relevant to the development of any future exo-Earth direct imaging mission. Here we present a pipeline that vets, calibrates, and measures the disk-integrated brightness of the Earth, in multiple filters, from the complete SSI data sets from both the 1990 and 1992 Galileo flybys. The result is over 1500 usable photometric measurements for Earth as an analog for an exoplanet. The 1990 data set includes full rotational lightcurves in six bandpasses spanning the optical range. The 1992 data set is more limited, with lightcurves only spanning 14 hr. Time-averaged photometry for both encounters is presented while variability and color are discussed relative to findings from NASA’s EPOXI mission (which also provided photometric lighturves for Earth). The new Galileo/SSI data are used to further validate the Virtual Planetary Laboratory 3D spectral Earth model, which often serves as a stand-in for true disk-integrated observations of our planet. The revived Galileo/SSI data for Earth is a testament to the ability of NASA’s Planetary Data System to maintain data over decades-long timescales. The disk-integrated products derived from these data add to a very short list of calibrated and published whole-disk observations of the Pale Blue Dot.https://doi.org/10.3847/1538-3881/ad1bd1PhotometryExoplanet detection methodsDirect imaging |
| spellingShingle | Ryder H. Strauss Tyler D. Robinson David E. Trilling Ryan Cummings Christopher J. Smith Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry The Astronomical Journal Photometry Exoplanet detection methods Direct imaging |
| title | Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry |
| title_full | Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry |
| title_fullStr | Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry |
| title_full_unstemmed | Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry |
| title_short | Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry |
| title_sort | exoplanet analog observations of earth from galileo disk integrated photometry |
| topic | Photometry Exoplanet detection methods Direct imaging |
| url | https://doi.org/10.3847/1538-3881/ad1bd1 |
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