[X] My Assistant

[Webscientist]

I'm looking for data regarding the snapshot taken by the Huygens probe once it had landed.
I would like to known from what height, precisely, did the camera of the Huygens probe obtain the view.
I also would like to know what the field of view was horizontally and vertically.

If an expert has the answer!
Thank you in advance for your answer or suggestions.

[Juramike]

The intial article: Tomasko et al. Nature 438 (2005) 765-778. “Rain, winds and haze during the Huygen probe’s descent to Titan’s surface.” Doi: 10.1038/nature04126
FREELY AVAILABLE AT: http://www.chem.hawaii.edu/Bil301/Titan Related Publications/Nature 438 775 2005.pdf://http://www.chem.hawaii.edu/Bil301/T...38 775 2005.pdf

A detailed article on the surface image:
Karkoschka et al., Planetary and Space Science 55 (2007) 1896-1935. “DISR imaging and the geometry of the descent of the Huygens probe within Titan’s atmosphere.” Doi: 10.1016/j.psss.2007.04.019
(pay-for article) Abstract available here: http://www.sciencedirect.com/science?_ob=A...f2954e263aa752f

Another paper on DISR imaging: Keller et al. Planetary and Space Science (2008) “The reflectance spectrum of Titan’s surface at the Huygens landing site determined by the Descent Imager/Spectral Radiometer.” Doi: 1.01016/j.psss.2007.10.011
FREELY AVAILABLE (preprint) here: http://www.mps.mpg.de/homes/schroder/Publi...Keller_2008.pdf



Some details on DISR instrument: Tomasko et al., LPSC 36 (2005) Abstract 2194. “First results from the descent imager/spectral radiometer (DISR) experiment on the Huygens entry probe of Titan.”
Freely available at: http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2194.pdf


Hopefully something in there has all the information you are looking for..

[Webscientist]

Thanks for this wealth of relevant links!
If I read correctly in this ocean of technical data, the Medium Resolution Imager was about 46 cm above the soil and the width of the field of view was 7°.

I can deduce the following things:
If the height of the camera is 46 cm with a field of view of 7°, I can advance that the theoretical horizon point (assuming the hypothesis of the perfect sphere) is 1.539 km (0.962 miles) from the camera and the width of the skyline in the image is 188 m. It's theoretical because the relatively flat terrain has some irregularities.
If you consider that the maximum height of hills in that area is 200m, the farthest topographic element visible beyond the horizon point won't exceed 33.633 km.

(On Earth, the previous data would be 2.422 km for the horizon point, 296 m for the width of the skyline and 52.931 km for the 200m hill).

If you were standing in front of Kraken Mare, from a height of 170 cm, the horizon point would be 2.959 km (1.838 miles) from you (Earth:4.657 km or 2.893 miles). You could't see topographic elements farther than 35.051 km assuming that hills in that area don't exceed 200 m. (On Earth, the data would be 55.165 km). The width of the horizon in your field of view (120°) would be 6.404 km ( on Earth, 10.078 km).

I didn't calculate all these data. I used a program to bring you this set of data and finally, it shows that you wouldn't see so much difference from the Terrestrial landmark regarding distances if you were walking on this exotic moon (A tiny change in your perception of the land may however be bewildering, to be checked! ).