Venera-13, Venera-14 Lander Images, Images generated from raw digital telemetry Options

[Guest_DonPMitchell_*]

Here are images I generated from the 9-bit Venera-13 and Venera-14 data. Most of the work was spent combining three or four transmissions from the spacecraft, each with an independent set of digital noise. In some cases, scrambled regions of images were restored by recalculating the 10th parity bit, and shifting the bit stream. In particular, I resurrected a new section of the image on Venera-14 Camera II on the left side. I managed to distill out one very high quality copy of the full transmission from each of the four cameras.

Next, there is the problem of linearizing the camera response. The camera response curves published in Cosmic Research are wrong, or at least they do not extend into the darker range where a lot of the actual Venus imagery lies. You can prove they are wrong from the calibration wedges, viewed through the four different filters. Correct generation of true log response would result in wedge profiles that are exactly offset from one another. Some recent work on camera self-calibration in the computer-vision community points the way to reconstructing response curves, and when applied to the Venera images, the result is very pleasing. Round objects, like the elbow joint of the penetrometer, look round, not flat, details in shadows appears out of the blackness of the original Russian images, and some additional hills on the horizon appear out of the formerly white sky.

The full transmission consisted of several passes of the camera scanner, back and forth, across the scene. These four panoramas are combinations of up to five black-and-white images (clear filter), and a number of red, green, and blue-filter images. In Lab color coordinates, I extracted the ab channels from the red/green/blue images, and added them to the much higher quality B/W images. You can see that when making scans through the clear filter, the camera covered a wider area, the uncolored regions are just where the RGB data did not exist. Most of the blue images are black, due to a sudden drop-off in the camera response. There are probably a few areas near the bright horizon where the real RGB ratio can be extracted...a project for someone someday.

I've been too busy with my book and my company in Seattle to completely finish what I wanted to do. The color is still not correct on any Venera surface images. But the color filters in the camera were balanced with gray filters to be somewhat correct. I am awaiting one last key piece of data -- the spectral response of a color filter that was in front of the calibration wedge. With that in hand, an absolute color calibration would be possible.

Venear-13, Camera I (short program):



Venera-13, Camera II (long program):


Venera-14, Camera I:


Venera-14, Camera II:

[Guest_BruceMoomaw_*]

The Soviets were actually quite explicit on the fates of Veneras 4 through 6 -- after they finally got through grudgingly admitting that Venera 4's radar altimeter was incorrectly calibrated and that Mariner 5's S-band occultation measurement of Venus' real air pressure and temperature was correct. Venera 4's hull was only designed to withstand 20 atm of pressure. In the case of Venera 5 and 6, which were already scheduled for launch in 1969 (probably on the assumption that Venera 4 might be yet another failure) at the time that they finally accepted that Mariner 5 was corrrect, they hastily thickened the hulls a little to withstand 27 atm -- which they both did. Then they promptly designed Venera 7 to settle the question of surface atmospheric conditions once and for all by thickening its hull to withstand fully 150 atm, and equipping it only with temperature and pressure sensors (like the probe that Avco had proposed for Mariner 5, in fact). The pressure sensor failed, but the combination of the temperature measurments and the time it took for Venera 7 to land allowed an indirect estimate of pressure as well, fully confrming Mariner 5's results.

So then the Soviets, certain at last, moved on to designing Venera 8 -- a probe thick-hulled enough to withstand genuine Venusian surface conditions, but as well-instrumented as the earlier Veneras (and in fact better, given its gamma-ray spectrometer and its daytime landing with a light-level photometer). Given the fact, however, that they could have built and flown this craft in 1970, their insistence on flying Venera 7 first indicates either bizarre conservatism on the the part of the Soviet program, or the fact that they didn't have enough money to build and fly Venera 8 that early.

As for the true color of the Venusian surface, Carle Pieters did an excellent article all the way back in the Dec. 12, 1986 "Science" compensating for the orange sunlight to confirm that Venus' surface is actually an inspiring shade of flat gray.

[Guest_DonPMitchell_*]

The Soviets were actually quite explicit on the fates of Veneras 4 through 6 -- after they finally got through grudgingly admitting that Venera 4's radar altimeter was incorrectly calibrated and that Mariner 5's S-band occultation measurement of Venus' real air pressure and temperature was correct. Venera 4's hull was only designed to withstand 20 atm of pressure. In the case of Venera 5 and 6, which were already scheduled for launch in 1969 (probably on the assumption that Venera 4 might be yet another failure) at the time that they finally accepted that Mariner 5 was corrrect, they hastily thickened the hulls a little to withstand 27 atm -- which they both did. Then they promptly designed Venera 7 to settle the question of surface atmospheric conditions once and for all by thickening its hull to withstand fully 150 atm, and equipping it only with temperature and pressure sensors (like the probe that Avco had proposed for Mariner 5, in fact). The pressure sensor failed, but the combination of the temperature measurments and the time it took for Venera 7 to land allowed an indirect estimate of pressure as well, fully confrming Mariner 5's results.

So then the Soviets, certain at last, moved on to designing Venera 8 -- a probe thick-hulled enough to withstand genuine Venusian surface conditions, but as well-instrumented as the earlier Veneras (and in fact better, given its gamma-ray spectrometer and its daytime landing with a light-level photometer). Given the fact, however, that they could have built and flown this craft in 1970, their insistence on flying Venera 7 first indicates either bizarre conservatism on the the part of the Soviet program, or the fact that they didn't have enough money to build and fly Venera 8 that early.

As for the true color of the Venusian surface, Carle Pieters did an excellent article all the way back in the Dec. 12, 1986 "Science" compensating for the orange sunlight to confirm that Venus' surface is actually an inspiring shade of flat gray.

The relationship between Venera-4 and Mariner-5 was far more complex than that. To interpret the data correctly, you needed to know several facts:

1. The refractive index of the atmosphere (Venera-4's gas analysis)
2. Accurate temperature and pressure readings (Venera-4)
3. An absolute measurement of radio refraction at a fixed distance from the planet's center (Mariner-5)
4. The radius of Venus' hard surface (Kuz'min and Clark's 1964 experiment)

The fact that Venus's atmosphere was almost pure CO2 (which is highly refractive), changed a lot of things. Kuz'min quickly recalculated the surface temperature from microwave spectra (upgrading it from 600 to 700 K), and he corrected the radar measurements of the hard-surface radius.

As for what happened to Venera-4, nobody knows. I think Sagan's theory is plausible, but certainly not the dramatic macho failure mode the Russians would prefer to announce.

I refer to Pieters work above, see the posting with the color and white-light corrected panoramas. Unfortunately, they used an incorrect camera response function. The result could be improved with additional information that exists now.