The Imaging Photopolarimeter Experiment on Pioneer 11

Baker, A. L.; Baker, L. R.; Beshore, E. C.; Blenman, C.; Castillo, N. D.; Chen, Y.-P.; Doose, L. R.; Elston, J. P.; Fountain, J. W.; Gehrels, T.; Kendall, Joseph; Kenknight, C. E.; Norden, R. A.; Swindell, W.; Tomasko, M. G.; Coffeen, D. L.

doi:10.1126/science.188.4187.468

Cited by 20 publications

(5 citation statements)

References 17 publications

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“…The Pioneer 10/11 (launched 1972;Baker et al 1975;Gehrels 1976;Ingersoll et al 1976;Kliore & Woiceshyn 1976) and Voyager 1/2 missions (launched 1977;Kohlhase & Penzo 1977;Hanel et al 1977) enabled the initial exploration of key approaches to analyzing spacecraft flyby data for many Solar System worlds. Instruments and techniques for either acquiring or interpreting spatially-resolved observations of planets and moons using photometry or spectroscopy at wavelengths spanning the ultraviolet through the infrared were among the important developments.…”

Section: Earth As a Planet: The Galileo Experimentsmentioning

confidence: 99%

Earth as an Exoplanet

Robinson¹,

Reinhard²

2005

Planetary Astrobiology

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Earth is the only planet known to harbor life and, as a result, the search for habitable and inhabited planets beyond the Solar System commonly focuses on analogs to our planet. However, Earth's atmosphere and surface environment have evolved substantially in the last 4.5 billion years. A combination of in situ geological and biogeochemical modeling studies of our planet have provided glimpses of environments that, while technically belonging to our Earth, are seemingly alien worlds. For modern Earth, observations from ground-based facilities, satellites, and spacecraft have yielded a rich collection of data that can be used to effectively view our planet within the context of exoplanet characterization. Application of planetary and exoplanetary remote sensing techniques to these datasets then enables the development of approaches for detecting signatures of habitability and life on other worlds. In addition, an array of models have been used to simulate exoplanet-like datasets for the distant Earth, thereby providing insights that are often complementary to those from existing observations. Understanding the myriad ways Earth has been habitable and inhabited, coupled with remote sensing approaches honed on the distant Earth, provides a key guide to recognizing potentially life-bearing environments in other planetary systems.Look again at that dot. That's here. That's home. That's us. [. . . ] [E]very saint and sinner in the history of our species lived there -on a mote of dust suspended in a sunbeam. -Carl Sagan 1 "Sun-like" typically refers to main sequence stars with spectral type F, G, or K. Such stars range from 30% larger and 6× more luminous than our Sun down to 30% smaller and 13× less luminous than the Sun. Sun-like stars are often contrasted to "late type" stars, which are red, cool main sequence M stars that can be smaller than 10% the size of our Sun and can have luminosities as small as 1-2% that of the Sun.

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Section: Earth As a Planet: The Galileo Experimentsmentioning

confidence: 99%

Earth as an Exoplanet

Robinson¹,

Reinhard²

2005

Planetary Astrobiology

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“…Spatially resolved flyby data from the Pioneer 10/11 (Bender et al 1974;Baker et al 1975;Gehrels 1976;Ingersoll et al 1976;Kliore & Woiceshyn 1976) and Voyager 1/2 (Hanel et al 1977;Kohlhase & Penzo 1977) missions in the 1970s initiated the exploration of key concepts for the characterization of planetary bodies other than Earth in our solar system. The photometric and spectroscopic observations, ranging from the ultraviolet to infrared (IR), allowed planetary scientists to infer unprecedented details for these worlds such as planetary energy balance, surface, and atmospheric chemical, thermal, and composition properties including cloud and aerosol formation and distribution (for an extensive review see Robinson & Reinhard 2018).…”

Section: Introductionmentioning

confidence: 99%

Earth as an Exoplanet. II. Earth’s Time-variable Thermal Emission and Its Atmospheric Seasonality of Bioindicators

Mettler

Quanz

Helled

et al. 2023

ApJ

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We assess the dependence of Earth’s disk-integrated mid-infrared thermal emission spectrum on observation geometries and investigate which and how spectral features are impacted by seasonality on Earth. We compiled an exclusive data set containing 2690 disk-integrated thermal emission spectra for four different full-disk observing geometries (North and South Pole-centered and Africa and Pacific-centered equatorial views) over four consecutive years. The spectra were derived from 2378 spectral channels in the wavelength range from 3.75–15.4 μm (nominal resolution ≈1200) and were recorded by the Atmospheric Infrared Sounder on board the Aqua satellite. We learned that there is significant seasonal variability in Earth’s thermal emission spectrum, and the strength of spectral features of bioindicators, such as N2O, CH4, O3, and CO2 depends strongly on both season and viewing geometry. In addition, we found a strong spectral degeneracy with respect to the latter two indicating that multi-epoch measurements and time-dependent signals may be required in order to fully characterize planetary environments. Even for Earth and especially for equatorial views, the variations in flux and strength of absorption features in the disk-integrated data are small and typically ≤ 10%. Disentangling these variations from the noise in future exoplanet observations will be a challenge. However, irrespectively of when the planet will be measured (i.e., day or night or season) the results from mid-infrared observations will remain the same to the zeroth order, which is an advantage over reflected light observations.

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“…Furthermore, the trajectories of Voyager, Cassini, Galileo, and New Horizons spacecraft through or in the Jupiter system remained rather close to Jupiter's equatorial plane, resulting in similar viewing limitations. Pioneer 11 passed over the north pole of Jupiter but could not measure winds due to limitations in the imaging system and to the very large distance of the observations (Baker et al, ; Orton et al, ). On 4 July 2016 the Juno spacecraft entered into a polar orbit around Jupiter, providing the opportunity to acquire the best view of its polar regions achieved so far (Bolton et al, ).…”

Section: Introductionmentioning

confidence: 99%

First Estimate of Wind Fields in the Jupiter Polar Regions From JIRAM‐Juno Images

et al. 2018

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We present wind speeds at the ~ 1 bar level at both Jovian polar regions inferred from the 5‐μm infrared images acquired by the Jupiter InfraRed Auroral Mapper (JIRAM) instrument on the National Aeronautics and Space Administration Juno spacecraft during its fourth periapsis (2 February 2017). We adopted the criterion of minimum mean absolute distortion (Gonzalez & Woods, 2008) to quantify the motion of cloud features between pairs of images. The associated random error on speed estimates is 12 m/s in the northern polar region and 9.8 m/s at the south. Assuming that polar cyclones described by Adriani et al. (2018, https://doi.org/10.1038/nature25491) are in rigid motion with respect to System III, tangential speeds in the interior of the vortices increase linearly with distance from the center. The annulus of maximum speed for the main circumpolar cyclones is located at approximatively 1,000 km from their centers, with peak cyclonic speeds typically between 80 and 110 m/s and ~50 m/s in at least two cases. Beyond the annulus of maximum speed, tangential speed decreases inversely with the distance from the center within the Southern Polar Cyclone and somewhat faster within the Northern Polar Cyclone. A few small areas of anticyclonic motions are also identified within both polar regions.

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The Imaging Photopolarimeter Experiment on Pioneer 11

Cited by 20 publications

References 17 publications

Earth as an Exoplanet

Earth as an Exoplanet

Earth as an Exoplanet. II. Earth’s Time-variable Thermal Emission and Its Atmospheric Seasonality of Bioindicators

First Estimate of Wind Fields in the Jupiter Polar Regions From JIRAM‐Juno Images

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