Home \ ... Exploration Gallery \ Pioneer 10 and 11 - 1972/97 - "Pioneer Project"
Spacecraft and image details:
| Pioneer imaging system details: | |
| Pixel size: | 0.028º |
| Sampling: | 0.015º or 0.030º |
| "Vertical" imaging range: | 14º or 28º |
| "Horizontal" imaging range: | 151º |
| Reading time: | ~30 min per image |
Scan lenght: |
466 pixels |
Bit
depth: |
6 bits |
Sensor: |
Imaging
Photopolarimeter (IPP) |
Filters: |
Red (580-700um) and
Blue (390-490um) |
Pioneer 10 and 11 were the first spacecraft to explore Jupiter and Saturn. They were designed as simple probes with a limited number of instruments.
As such, they didn't cary a camera in a conventional sense, but an Image Photo-Polarimeter. This device works by measuring the amount of light coming from a single point of space in two wavelengths (Red and Blue). These measurements were encoded on 64 levels (6 bits). Therefore, to produce a picture, that single point must move and scan the planet step by step and line by line.
This movement was connected with Pioneer's spin rate. Each of these scans on each spin was converted to 466 pixels, covering a 14º or 28º portion of sky, depending of the actual sample rate selected. We can consider this scan to be the equivalent of a line on a computer display.
Therefore, a raw Pioneer image can have a maximum of 466 horizontal pixels. The vertical dimensions of each image are not constrained. After reading a "line" the instrument could be repositioned to scan a small amount bellow or above the previous position. This was done as needed in order to scan the full disk of a planet from a distance or zones of interest when the spacecraft was closer.
At closest approach, it took 30 minutes to scan a full image. This amount of time, combined with spacecraft motion through space and the target planet's rotation introduces severe distortions to the pictures.
Image processing:
The available images come in scanned format from printed paper or photographic sources. Where possible, I stacked several copies of the same image to reduce noise. Color RGB composites were generated from the separate red and blue data when available, with a synthethic green channel. Image orientation and proportions were corrected accounting for spacecraft distance and planet rotation. A dark gray planet outline was generated to place the parcial images with regard to the planet's disk. Some cylindrical maps were produced from the semi-global Jupiter coverage provided by both spacecraft's encounters with Jupiter. Positions of features on the maps are only aproximate, given the dificulty to correct all the geometrical distortions mentioned above in conjunction with the planet's rotation. The images are presented on the tabs below, in the correct sequence and with the same apparent size.
- Jupiter global maps
- P10 Jupiter encounter
- P11 Jupiter encounter
- P11 Saturn encounter
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Ganimedes
Europa
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Callisto
Ganimedes
Io
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(c) 2008 Webdesign, images and text by Ricardo Nunes