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

[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.

[tedstryk]

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.

It probably wasn't capable. Remember, it was the Bus that relayed the multiprobe data back, not PVO.

[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!).

[tedstryk]

I do think the general appearance is roughly accurate in the top version - blue is so weak on the surface. The color under more earthlike lighting conditions is the real question.

[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.

[Bob Shaw]

Don:

Great images - it's a joy to see old data given new life!

Bob Shaw

[rogelio]

In the upper left hand corner of DonPMitchell's Venera 13, Camera 1 (short program) photo, there appears to be the distant, blurred flank of a mountain or hill visible on the horizon... Is this an artifact or are we truly seeing a hill some distance away?

[Guest_DonPMitchell_*]

In the upper left hand corner of DonPMitchell's Venera 13, Camera 1 (short program) photo, there appears to be the distant, blurred flank of a mountain or hill visible on the horizon... Is this an artifact or are we truly seeing a hill some distance away?

Yes its a hill in the distance. They just blew out the pixels when they stretched the contrast, in the Russian versions. It's very clearly there in the raw data.

You also see some hills in the color-filter images, in the camera-II images, because the gain blew out the pixels in the clear-filter images.

[Rem31]

How will it really look when i am standing on the surface of Venus? Like grey or like a orange color.

[helvick]

How will it really look when i am standing on the surface of Venus? Like grey or like a orange color.

It might look orange for a while but if you could stay there for a while your eyes would adjust and you would begin to find the orange increasingly less noticable.

You can see a limited similar effect by wearing 3D anaglyph specs for an extended period of time and then taking them off. If you alternately close one eye and then the next everything will appear to be alternately blue\red tinged.

[ljk4-1]

It might look orange for a while but if you could stay there for a while your eyes would adjust and you would begin to find the orange increasingly less noticable.

You can see a limited similar effect by wearing 3D anaglyph specs for an extended period of time and then taking them off. If you alternately close one eye and then the next everything will appear to be alternately blue\red tinged.

Remember when they used to claim that the Venusian atmosphere
was so refracted that you could technically see all the way around
the planet and right to the back of your head (or whatever special
helmet was shielding it)?

http://www.cosmographica.com/gallery/portf...fraction%20.htm