[X] My Assistant

[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:

[tasp]

Really appreciate the newly processed pictures!

Additionally, it is my understanding the Vega 1 and 2 landers had their cameras removed as the Halley intercept trajectory required a night time landing.

My question:

Some of the early landers had lights on them for their cameras (the lights weren't needed and were deleted on subsequent landers. Why, oh why, didn't they put lights on Vega 1 and 2 instead of removing the cameras?!?!?!?!?!?!?

Seems like an opprotunity to get some nice pictures of the surface with a light source tested and calibrated on earth would generate the most accurate color pictures possible. That would be a 'good thing', right?



I am probably missing something, but I am really wondering about this.


Also, the list of missionsis really helpful, keep in mind though, there are a very large number of launch failures not mentioned in the Soviet era literature.

[Guest_DonPMitchell_*]

Some of the early landers had lights on them for their cameras (the lights weren't needed and were deleted on subsequent landers. Why, oh why, didn't they put lights on Vega 1 and 2 instead of removing the cameras?!?!?!?!?!?!?

That's an interesting question. And one actual surviving Russians can answer, so I will ask them!

[tedstryk]

That's an interesting question. And one actual surviving Russians can answer, so I will ask them!

I asked Sasha Basilevsky years ago (well, actually, I didn't ask him, I asked someone at Brown, and they forwarded my question to him and I got his reply). Basically, when the mission was designed, it was originally the next Venera mission, which morphed into the Ve-Ga (short for Venus-Halley - the Russians have no H in their alphabet). It was modified to fly by Venus and on to Halley. This was relatively late in the game, and the trajectory change left the landers no choice but to land on the night side. Adding lights would have been too much of a design change for the already built landers. It also left the balloons without a relay, which really damaged the science that they obtained (with direct to earth transmission, and with the help of the DSN, they managed to trickle back data at 4 bits/second which was so compressed, using very crude techniques by today's standards, that interpreting a lot of it is difficult, to say the least).

[Guest_DonPMitchell_*]

I asked Sasha Basilevsky years ago (well, actually, I didn't ask him, I asked someone at Brown, and they forwarded my question to him and I got his reply). Basically, when the mission was designed, it was originally the next Venera mission, which morphed into the Ve-Ga (short for Venus-Halley - the Russians have no H in their alphabet). It was modified to fly by Venus and on to Halley. This was relatively late in the game, and the trajectory change left the landers no choice but to land on the night side. Adding lights would have been too much of a design change for the already built landers. It also left the balloons without a relay, which really damaged the science that they obtained (with direct to earth transmission, and with the help of the DSN, they managed to trickle back data at 4 bits/second which was so compressed, using very crude techniques by today's standards, that interpreting a lot of it is difficult, to say the least).

I just talked to Sasha, and he suggested that weight was an issue too. Vega was loaded down with experiments and fuel. It had more instruments for the Halley encounter than the other two missions combined, it had the balloon aerostats, etc.

Speaking from my own research, Vega was really focused on answering a lot of open questions about the clouds of Venus. One of the camera positions was occupied by an ultraviolet spectrometer, and the landing ring was completely covered with devices, mostly for the analysis of cloud particles.

Direct broadcast from Venus is pretty slow. That was a probelm with the Pioneer Venus landers too. Venera-11 and 12 sent about 100 times as much data as the four Pioneer landing probes, because they had to do something similar to the aerostats. Not sure why they didn't try to use the Pioneer Venus Orbiter to relay data.

[mcaplinger]

Not sure why they didn't try to use the Pioneer Venus Orbiter to relay data.

Recall that the PV orbiter and probes/bus were separately launched; you wouldn't want to make one dependent on the other if you could avoid it.

[ljk4-1]

Recall that the PV orbiter and probes/bus were separately launched; you wouldn't want to make one dependent on the other if you could avoid it.

And in the mid-1980s, the US and USSR were going through another Cold War freeze.
They weren't very big on cooperating, though one US professor did get his dust
analyzer on the Vegas, the only US science instrument on a space probe aimed
for Comet Halley after an actual mission was canned.

Successful Veneras in a nutshell:

Venera-3: impact with no signal
Venera-4: analyzed atmosphere, batteries ran out

I thought Venera 3 stopped transmitting just days before reaching Venus,
just like its counterpart Venera 2 did. So other than being the first craft
to impact on Venus, how could it be called a success?

Even more interesting, I thought Venera 4 was crushed by the planet's
dense atmosphere before it could land. Carl Sagan relays a very humorous
story in his 1973 book, The Cosmic Connection, regarding how Soviet
scientists tried to defend their claim that Venera 4 did reach the planet's
surface still functioning.

So are you now saying Venera 4 actually lost battery power - and therefore
communications with Earth - before being crushed? At what altitude?

[Guest_DonPMitchell_*]

And in the mid-1980s, the US and USSR were going through another Cold War freeze.
They weren't very big on cooperating, though one US professor did get his dust
analyzer on the Vegas, the only US science instrument on a space probe aimed
for Comet Halley after an actual mission was canned.
I thought Venera 3 stopped transmitting just days before reaching Venus,
just like its counterpart Venera 2 did. So other than being the first craft
to impact on Venus, how could it be called a success?

Even more interesting, I thought Venera 4 was crushed by the planet's
dense atmosphere before it could land. Carl Sagan relays a very humorous
story in his 1973 book, The Cosmic Connection, regarding how Soviet
scientists tried to defend their claim that Venera 4 did reach the planet's
surface still functioning.

So are you now saying Venera 4 actually lost battery power - and therefore
communications with Earth - before being crushed? At what altitude?

Oops, Venera-3 wasn't really a success, except for its deep-space science. Well, it did hit its target though. :-)

Sagan believed Venera-4 ran out of battery power. It was rated for 100 minutes, and it transmitted for 93 minutes. Keep in mind, the atmosphere of Venus was much more dense than almost anyone expected. It doesn't seem to have reached the depth that it was designed for. The Russians never admitted this, but on Venera-5 and 6, the parachutes were made much smaller, and they went deeper. No one can be sure about this though.

Yes, I've read what Sagan and Kuz'min have had to say about this. I've been trying to gently coax Kuz'min into telling me more about that event. It was not actually unreasonable to believe Venera-4 landed, given what was expected about Venus. Radio altimeters have something called "ambiguity", so it was only really the Mariner-5 occultation data that let people figure out later that it stopped transmitting at 22 km.

With regard to mission failures, most were the result of Block-L failure -- lots of interesting planetary probes were just left in orbit. Escape stages are difficult. The Russians just started using Block-L right from the start. The Americans just waited (and waited...and waited...) for the Centaur stage to work right. It's not obvious the Russians did the wrong thing there. They managed to launch a number of big complex probes with Block-L, while the Americans were very limited by what they could do with Agena.

[Guest_DonPMitchell_*]

Getting back to the original topic for a minute, here is the true-color calibration that Brown Univerisity did some years ago:

[attachment=5473:attachment]

It's based on information about the sky spectrum from the lander's spectrometer, and from information about the color of the ground, particularly from the Venera-9 lander (from its photometer, not its camera).

The real solution to the color problem is yet to be done I think. Futhermore, given the known spectral response of the color camera filters, the right way to calculate color is by solving an integral equation, the so-called inverse method. Nobody ever does that, but the original Russian papers at least mention it (Those Russians know their math!).