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Zodiacal-Light Two-Color Photopolarimetry

NSSDCA ID: 1973-019A-15

Mission Name: Pioneer 11
Principal Investigator:Dr. Jerry L. Weinberg


The Imaging Photopolarimeter (IPP) experiment was used to obtain maps of the zodiacal light distribution in two colors, blue (3900 to 4900 A) and red (5800 to 7000 A). In each color, the maps were constructed out of the integrated-detector-response (1/64 of a roll period), spin-scan point-imaging data obtained by viewing through a 40- by 40-mrad field-stop aperture. This work was performed during the cruise portion of the mission. In detail, simultaneous radiometric and polarimetric maps of the sky in both colors were made as the spacecraft swept out a 360-deg clock angle swath, and the telescope and optics were stepped in cone angle (the angle between spacecraft spin axis and the telescope optical axis). At each discrete cone angle, a 20-roll measurement cycle occurred, consisting of 10 rolls for the accumulation of the data and for calibration, alternated with 10-roll periods used for the telemetry of the data. During a data roll, the signals from four detectors (2/color) were integrated over a time interval equal to 1/64 of the roll period. The four channels provided simultaneous measurements at two orthogonal polarization azimuths in the two spectral bands. The polarization was sampled parallel and perpendicular to the plane containing the spacecraft spin axis and the optical axis of the telescope. Radioactive calibration was provided by a radioisotope-activated phosphor source. All such data were formatted to produce a sky map, 360 deg in clock angle by 141 deg in cone angle. The experimental train for the IPP package consisted of the following elements: (1) a near-diffraction-limited 2.54-cm Maksutov catadioptric telescope (f/3.4); (2) a focal plane wheel containing field-of-view apertures, depolarizers, calibration source, etc.; (3) a Wollaston prism to split the light into two orthogonally polarized beams, (4) a 45-deg dichromatic mirror that reflected wavelengths less than 5500 A (blue beam) and transmitted all light of greater wavelength (red beam), (5) for each spectral beam (two polarizations) a filtering, coated relay lens and folding mirrors, and (6) for each spectral beam, two Bendix channeltron detectors (blue - bialkali S-11 photocathodes, red - S-20 photocathodes) to register the intensity in each polarization component. (Note: a similar experiment was also aboard Pioneer 10.) Data include the interplanetary region.

Alternate Names

  • Pioneer11/Zodiacal-LightTwo-ColorPhotopolarimetry

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science: Small Bodies
  • Astronomy: Visible

Additional Information

Questions and comments about this experiment can be directed to: Dr. John F. Cooper



NameRoleOriginal AffiliationE-mail
Dr. Martha S. HannerOther InvestigatorNASA Jet Propulsion
Dr. Jerry L. WeinbergPrincipal InvestigatorUniversity of

Selected References

  • Hanner, M. S., and C. Leinert, The zodiacal light as seen from the Pioneer F/G and Helios probes, Space Res., 12, Pt. 1, 445-455, 1972. (Proc. of the 14th COSPAR Plenary Meeting, Seattle, Wash., June 18-July 2, 1971).
  • Pellicori, S. F., et al., Pioneer imaging photopolarimeter optical system, Appl. Opt., 12, No. 6, 1246-1258, doi:10.1364/AO.12.001246, June 1973.
  • Hanner, M. S., et al., Zodiacal light and the asteroid belt: The view from Pioneer 10, J. Geophys. Res., 79, No. 25, 3671-3675, doi:10.1029/JA079i025p03671, Sept. 1974.
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