Venera Images, VENERA 13 fully calibrated image Options

[Phil Stooke]

Good suggestion, but the areas covered by these reprojected images would span at most a few tens of pixels in Magellan images, and at locations in the images uncertain by many tens of kilometers, so it is very unlikely that we could do something like that.

Phil

[vikingmars]

A collection of surface panoramas: 180° for Venera 9 and 10, 360° for Venera 13 and 14. Reprojections are according to various suggestions on this forum. Horizon topography is probably not real, but due to inaccuracies of the reprojections (which are not strictly geometric anyway).

Thanks for your contribution. You did an interesting work.
The horizon of Venera 9 should be adjusted because the lander was sitting on a slope with a 20° tilt...

[4th rock from th...]

It's not easy to extrapolate much from the Venera images. I'm yet to see a good geometrical correction of all the distortions.

Those "U" shaped strips are approximations, and looking at them I always have the feeling that the spacecraft is on lower ground relating to the horizon. The imaging system is similar to that of Viking, but the scanning is made at an angle in relation to the horizon.
The Venera cameras were about 2m above the surface but, as you move from the center to the edges towards the horizon, the image looks like they were taken with a lower point of view (more like Pathfinder).
All of this makes the horizon interpretation much harder. What looks like a slope might be an horizontal feature...

[Hungry4info]

Ted Stryk has given the Venera 9 and 10 images a bit of a makeover.
http://planetimages.blogspot.com/2014/07/s...us-in-1975.html

[Explorer1]

Good catch! Why did I never notice the hills at Venera 9....

[4th rock from th...]

Interesting results with those horizon features.
My only fear is that the results look too good. Easy to mistake the generated images for the actual ones...
Other than that, I still see some geometric distortion in the vertical axis. But I know from self experience that this is a difficult dataset.

[tedstryk]

Interesting results with those horizon features.
My only fear is that the results look too good. Easy to mistake the generated images for the actual ones...
Other than that, I still see some geometric distortion in the vertical axis. But I know from self experience that this is a difficult dataset.

The problem is that there are less that 50,000 pixels showing the surface, and so I used somewhat distorted repeats to fill gaps in the case of Venera 9. The hills to the left can be seen at the edge of the original panorama. Many versions I've seen have the horizons so overexposed that the hills are lost. The middle hill is of course a creation created from cloned bits of the stuff on either corner...here was my thinking...there are relatively big hills on the left, and the ground is choppy on the right-hand horizon. Venera-9 is itself on a slope. So there is little chance that the horizon is flat between the two corners of the panorama. It took dozens of times going back to the drawing board before I got something that looked half-way decent. Venera 10 was much easier.
I was also trying to project it to look as though one is looking from one point rather than moving along the scene is the camera scanned...that improves some things, but creates other geometric issues.
As I said, everything is from cloned portions of the actual image data. Nothing is drawn outright. That might be an interesting experiment.

[4th rock from th...]

The idea of providing a "synthetic" scene is interesting.

You could to the same using elements from earth photos. As long as rock size, distribution, overall shape and composition are the same, it's a valid experiment. I'd go for that and totally skip the original imagery.

[tedstryk]

Venera 14 landed 33 years ago today. I wrote a new blog entry about it. http://planetimages.blogspot.com/2015/03/v...hy-we-need.html

[JRehling]

Very nice, Ted! Putting the images where they can be compared is very evocative. And yes, it's tantalizing to think of how much of Venus we haven't seen. One ground-buzzing airplane taking hi-definition video as it zoomed along a long ground swath could increase our ground-level imagery by a few orders of magnitude. If only the will were there...

[tedstryk]

Very nice, Ted! Putting the images where they can be compared is very evocative. And yes, it's tantalizing to think of how much of Venus we haven't seen. One ground-buzzing airplane taking hi-definition video as it zoomed along a long ground swath could increase our ground-level imagery by a few orders of magnitude. If only the will were there...

Thanks. I love the idea of a balloon that rises and falls with the day so that it touches down in multiple locations. I've added a second interpretation of the color in the combined image.

[Julius]

It's time to go back and explore!

[rlorenz]

My short paper just out in Icarus on the observed probability distribution of Venus surface winds (useful for lander design, as well as evaluation of aeolian transport) . It is remarkable that on only two ~hour long occasions when aeolian transport of regolith could possibly have been observed (by Venera landers), it was seen on one. Typically one has to wait months to see something happen on Earth or Mars - Venusian sediment is therefore probably always on the move, something that might be observable with radar interferometry, as well as lander observations...
(link to free pdf valid for 50 days)



http://authors.elsevier.com/a/1RvsN4L-YESvT

[nprev]

Thanks for sharing this with us, Ralph. In your estimation, were the Veneras on the high or low side of optimum landing configuration (if that makes sense) given your analysis?

[rlorenz]

In your estimation, were the Veneras on the high or low side of optimum landing configuration (if that makes sense) given your analysis?

None of them fell over, so the design can be claimed to be robust. But the question of optimality is meaningless without a stated success criterion (i.e. given an [unknown]
surface slope distribution and given an [unknown, but kindof handwavy-estimated here] wind distribution, and given a requirement for e.g. 99% success THEN a certain
design can be considered optimal)

The fundamental point is that any planetary landing entails uncertainty (qv Philae) and thus no finite-cost design can offer 100% reliability. Thus rational design and
evaluation entails the statement of an acceptable degree of risk. Where terrain (or meteorological) factors introduce an entirely stochastic element to the landing
dynamics, an optimal mission solution may be to build two 90% landers to achieve an overall 99% chance of safe landing.