Venus Science Options

[Guest_BruceMoomaw_*]

A few comments on the Russian probes:

Venera-1 - the temperature control system did not fail, but photosensitive element in the precision solar sensor overheated. It automatically put itself into a backup mode of spin stabilization, but contact was lost after the third telemetry session.

They made an attempt to send a Mars-1 style photo-flyby in 1962, and two attempts to send a Zond-3 style probe in 1965. Two failed to leave parking orbit, Venera-2 lost communication just before it was to relay all of its recorded data, including the photos. It may have actually performed its mission objectives, we will never know.

Mars-1 - a faulty valve caused a slow leak of its attitude control nitrogen. Before loss of control, it was placed in a backup mode of spin stabilization, and space science was performed for about half its flight, until contact was lost. If I was going to guess, I'd say it wobbled out of alighnment or the Earth just passed out of the funnel-shaped radiation pattern of its semi-directional antennas.

Zond-1 lost internal pressurization. From attitude pertubations, Soviets calculated that the window of its astronavigation sensor cracked. The ground crew then made a fatal mistake -- they switched on the radio transmitter before the craft was completely evaculated, and corona discharges destroyed the radio in the main bus. A back-up system switched over the main antenna to the transmitter in its landing capsule, and it continued for quite some time after that. Several midcourse corrections were performed, space science data was returned, but they lost contact before it reached Venus. In theory, it could have achieved its primary objective (landing) if they had not lost contact.

Zond-2 a photoflyby, not a lander. Its solar panels only half deployed, and lack of power ruined the mission. Zond-2, Zond-3 and Venera-2 were essentially identical spacecrafts.

Could you give your information source for this? Some of it is entirely new to me (although all of it at least sounds plausible).

[Guest_BruceMoomaw_*]

A couple comments on Mariner -2 and -5

I think it was a good call that NASA put the radio occultation experiment on Mariner-5. That ended up being the key experiment that mattered. In particular, it gave an important sanity check to the Venera-4 results about the depth of the atmosphere. Due to altimeter ambiguity, it was believed at first that Venera-4 had landed, and nobody would have disputed that without the occultation data. I think this was more valuable than noisy 256x256 television pictures, which probably wouldn't have shown much.

There is a nice little book about the Mariner-2 mission published by JPL (Mariner: Mission to Venus), and lots of scuttlebutt about it. Mariner-2 just barely made it to Venus, and the inside joke then was that JPL stood for "Just Plain Lucky".

Mariner-2 was a refurbished Ranger probe, a notoriously unreliable spacecraft. It's ironic that one of them made it to Venus two years before the first one succeeded in a lunar mission. The failure of about a dozen Lunar probes by that time was the cause of a congressional investigation and management shake-ups at NASA. Of course, the Russians had similar probems, and Korolev was called on the carpet at the Kremlin about the same time. They had a series of failures in their even more ambitious program to soft land on the Moon (Luna-4 to 8).

Politicians and the public just didn't understand how difficult and fundamentally new all of this work was.

By the time Mariner-2 reached Venus, the temperature of its body was unknown because it had exceeded the range of its sensors. Somewhere in excess of 100 C. The radiometer was so hot (60 C) that it almost couldn't function. One of its two solar panels had failed, its astro-navigation sensor was going blind and was only at a few percent of signal by then, etc. Yup, just plain lucky! But nevertheless a milestone in space history.

The main occultation experiment on Mariner 5 (the S-band occultation) was never in any danger of getting the boot -- it was, in fact, officially rated by JPL as the single most important experiment on the mission. The fight was over whether to fly a second occultation experiment -- the Twin-Frequency Radio Propagation experiment, which operated on two additional frequencies and used earth-to-Mariner transmissions rather than vice versa -- or the TV camera (with one visible and one UV filter). JPL recommended the camera; NASA HQ overrode them. The fight over that, believe it or not, is still going on; Bruce Murray, in his 1977 book "Flight to Mercury", denounces the choice on the grounds that the second occultation experiment (which focused mainly on ionospheric structure) didn't tell us that much more, while some writer in a 1980s "Icarus" article that I once saw praises it.

Apparently the plan for the TV was to get entirely closeup photos of Venus, rather than long-distance photos that would have revealed good details about its overall cloud patterns. This seems puzzling at first -- but I actually have a copy of the document in which JPL made its payload recommendations, and it makes it fairly clear that they were hoping for chinks in the clouds through which Mariner 5 just might be able to see Venus' surface directly.

As for Mariner 2 being lucky: damn straight. It was a Perils of Pauline mission of a sort we didn't see again among planetary probes until the downright embarrassing flight of Mariner 10. I've always marveled that the US got a successful probe to Venus -- 150 times farther away -- 19 months before it got one to the Moon. Any SF writer who had stated that as a possibility would have been laughed out of business. Keep in mind, though, that all 8 of the first US lunar probe failures -- the Pioneers -- were pure booster failures, and in some cases remarkable episodes of bad luck with rocket stages that, by that time, were usually working right. It wasn't until Ranger 3 that US lunar spacecraft themselves started breaking down in ways that roused Congress' ire against JPL.

Finally: we've had quite a detailed discussion of the Soviet 1963-66 lunar landers down in (of all places) the "I'm back from the Europa Focus group meeting" thread in the "Europa" section (which should give you some idea of how disciplined this group is). The Journal of the British Interplanetary Society has, in recent years, had at least two splendidly detailed long pieces on the 1958-60 and 1963-68 Soviet lunar probes; I'll have to check out what else they have in their periodic special issues on the history of Soviet astronautics. You're certainly right that the Soviets were losing even more missions than the US was early on, and they continued doing so at a much higher rate than us later -- while managing to conceal most of their launch failures. Being a tyranny means never having to say you're sorry...

[Guest_DonPMitchell_*]

Finally: we've had quite a detailed discussion of the Soviet 1963-66 lunar landers down in (of all places) the "I'm back from the Europa Focus group meeting" thread in the "Europa" section (which should give you some idea of how disciplined this group is). The Journal of the British Interplanetary Society has, in recent years, had at least two splendidly detailed long pieces on the 1958-60 and 1963-68 Soviet lunar probes; I'll have to check out what else they have in their periodic special issues on the history of Soviet astronautics. You're certainly right that the Soviets were losing even more missions than the US was early on, and they continued doing so at a much higher rate than us later -- while managing to conceal most of their launch failures. Being a tyranny means never having to say you're sorry...

I think it's difficult to compare failure rates when different things are being attempted. For example the Luna-4 to Luna-8 missions were trying to soft land, and with Pioneer/Able and Ranger, they were just trying to hit the damn Moon.

With regard to Venus probes, there was a vast improvement when NPO Lavochkin, a mature aviation engineering firm, took over planetary missions from OKB-1. They did a more professional job of testing, with vibration, centrafuge, thermal vacuum chambers, etc. For example, Luna-9, Venera-4 were both successful probes built by Lavochkin after a long series of similar but failed systems built by OKB-1.

The Soviets had a terrible problem with industrial infrastruction and quality. The four mars probes of 1973 all failed to some degree because of a batch of bad integrated circuits. In other areas, they excelled -- for example liquid-fuel rocket engine technology, where they pretty much schooled everyone else. We buy Russian engines even today for the Atlas rockets, their redesign of the shuttle main engines was very enlightening to NASA's engineers, and the Delta IV engine has a lot of Soviet design tricks in it (the way they do regenerative cooling).

[ljk4-1]

Apparently the plan for the TV was to get entirely closeup photos of Venus, rather than long-distance photos that would have revealed good details about its overall cloud patterns. This seems puzzling at first -- but I actually have a copy of the document in which JPL made its payload recommendations, and it makes it fairly clear that they were hoping for chinks in the clouds through which Mariner 5 just might be able to see Venus' surface directly.

The same thinking they had with Voyager 1 and Titan.

Well, we did discover that the Titanian clouds were really orange, even
up close.

They made an attempt to send a Mars-1 style photo-flyby in 1962, and two attempts to send a Zond-3 style probe in 1965. Two failed to leave parking orbit, Venera-2 lost communication just before it was to relay all of its recorded data, including the photos. It may have actually performed its mission objectives, we will never know.

Crazy Idea of the Day: If a mission could be sent to find Venera 2 and
attempt to recover its recorded data, would it still be readable?

[ljk4-1]

There is a nice little book about the Mariner-2 mission published by JPL (Mariner: Mission to Venus), and lots of scuttlebutt about it. Mariner-2 just barely made it to Venus, and the inside joke then was that JPL stood for "Just Plain Lucky".

I have that book in hardcopy, but I could not find it online. I did find these
relevant documents online, though:

A Summary Review of the Scientific Findings of the Mariner Venus Mission

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1965076650.pdf

Mariner 2

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1965076538.pdf

Mariner-Venus 1962 Final Project Report

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1966005413.pdf

Mariner II - an Example of a Stabilized Interplanetary Space Vehicle

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1965076554.pdf

Mariner R spacecraft for mission P-37/P-38

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1979076756.pdf

Mariner R 1 and 2. Tracking Information Memorandum no. 332-15

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1965072055.pdf

Mariner II Tracking System Final Data Analysis Report

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1965023545.pdf

Tracking and Data Acquisition Support for the Mariner Venus 1962 Mission

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1965023548.pdf

The Mariner R Project, Volume I Progress report, 1 Sep. 1962 - 3 Jan.1963

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1979076621.pdf

The Mariner R Project- Volume 2- Supplementary Documentation. Progress Report, Sep. 1, 1962-Jan. 3, 1963

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1964003267.pdf

Mariner-Venus 1967

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1972013159.pdf

[Guest_DonPMitchell_*]

The same thinking they had with Voyager 1 and Titan.

Well, we did discover that the Titanian clouds were really orange, even
up close.
Crazy Idea of the Day: If a mission could be sent to find Venera 2 and
attempt to recover its recorded data, would it still be readable?

The Mariner-4 camera system was so crude, I can't believe it would have shown anything on Venus, even in UV. Mariner-10 images of Venus are still the best we have. Let's hope Venus Express can do better...that is if we ever get to see them.

Storage tube vidicons were not really such a hot idea. The Russians used them in Vostok, but never in planetary probes. Before real digital image storage (as in Mariner-9), I think the Soviet phototelevision concept of storing images on film was superior. Maybe justt too heavy for our pre-Centaur-stage probes.

I don't imagine the film in the Venera-2 camera is in very good shape by now. Personally, if I had $200 million to blow, I'd send a new mission to Venus, not to Venera-2. :-)

[tedstryk]

Before real digital image storage (as in Mariner-9), I think the Soviet phototelevision concept of storing images on film was superior.

In overal quality, yes, but not per pound. I would add that Soviet phototelevision (or Lunar Orbiter, for that matter), while good quality, would have been a dead end, with the obvious limitation that when you ran out of film, that was the end.

[ugordan]

The same thinking they had with Voyager 1 and Titan.

Well, we did discover that the Titanian clouds were really orange, even
up close.

Correct me if I'm wrong, but the scientists weren't expecting a global cloud/haze cover on Titan. All that was previously known about Titan's atmosphere was it contained methane, even methane's partial pressure was known. The major constituent - nitrogen probably escaped ground detection. I don't know whether complex hidrocarbons were detected via spectroscopy, but the overall expectations were probably of an optically thin atmosphere.

[ljk4-1]

Correct me if I'm wrong, but the scientists weren't expecting a global cloud/haze cover on Titan. All that was previously known about Titan's atmosphere was it contained methane, even methane's partial pressure was known. The major constituent - nitrogen probably escaped ground detection. I don't know whether complex hidrocarbons were detected via spectroscopy, but the overall expectations were probably of an optically thin atmosphere.

Yes, that is the point I was making. They thought there might be some
"breaks" in the clouds that Voyager 1 could peer through to see at least
some of the surface. The probe was even diverted from a possible first
chance at visiting Pluto for this. The results were solid orange clouds.

Judging from how scientists and laypersons alike reacted to our first
real glimpses of Titan's surface in 2004 with Cassini - with a combination
of wonderment and perplexity at the strange patterns - I wonder even if
Voyager could have seen some of the moon's face that it would have done
anything more than add to the mystery levels of Titan?

[Guest_DonPMitchell_*]

In overal quality, yes, but not per pound. I would add that Soviet phototelevision (or Lunar Orbiter, for that matter), while good quality, would have been a dead end, with the obvious limitation that when you ran out of film, that was the end.

Yes, that's very true. The Mars-5 camera held 480 pictures on a roll, but you can never have too many pictures of Mars. I still think the storage vidicons suck. Those early Vostok and Mariner-4 images are "historic" but just aweful quality. The real answer was digital storage of course. And the Russians kept using phototelevision for a couple years after they could have done digital (Mars-3 vs. Mariner-9).

Mariner-9 really seems like the crossing point. The first American planetary probe that was "better" than the Soviet ones. Of course you can't really say something like that objectively. But M-69 was way beyond Mariner-6, and I think Mariner-9 was better than Mars-3. So that's how I make the call.

Yes, I know, M-69 blew up on the pad, but if it had not, it would have been cool. The Russians were so unlucky with Mars.

[ugordan]

I wonder even if Voyager could have seen some of the moon's face that it would have done
anything more than add to the mystery levels of Titan?

Actually, as it later turned out, Titan's surface was just barely detectable through the orange filter, but it was really at the threshold of the signal/noise ratio. This site shows the results of analysis on the imagery and it showed some surface features were clearly detectable. Of course, these results were of little importance having been reached 20+ years after the actual flyby, after Hubble's revealing images and on the verge of Cassini's arrival.
The point I was trying to make is that the scientists weren't just hoping for a break-or-two in the clouds, they were expecting the surface to be largely visible with little/no obstructions.

[gndonald]

The Russians were so unlucky with Mars.

Quite true, I've always found it somewhat poignantly ironic that the only Russian 'Mars' probe that can be classed as a total success (All objectives achieved) was Zond 3, the probe intended to accompany Zond 2 to Mars and which for some reason (Can any one clarify this?) missed the launch window and was later used on a lunar fly-by/engineering test mission.

While hypotheticals have no real force, it is quite possible (based on its performance in that test flight) that had Zond 3 launched on time it might have produced pictures of Mars good enough to steal Mariner IV's thunder

[Guest_BruceMoomaw_*]

I've often wondered about that, too. The only reason I can come up with is that they were unable to devise a technical solution in time for the failure of Zond 2 to unfold one of its two solar panels. Had Zond 3 been launched on time and worked, it would not only have stolen most of Mariner 4's thunder -- it would probably have prevented the Dec. 1965 decision to launch Mariners 6 and 7, at least as flybys. After all, not only would its photos have been higher quality than Mariner 4's, but it would have done some IR and UV spectrometry of Mars as well. (However, the US might then have decided to leapfrog ahead by launching Mariners 6 and 7 as orbiters in 1969, instead.) And what if some of Zond 3's photos had revealed the valley networks and runoff channels that early -- as the Mariner 6 and 7 photos, by remarkably bad luck, failed to do?

I have never been able to gloat about the Soviet planetary and lunar probe failures. Had their Mars probes succeeded -- even given their relatively primitive instrumentation and lack of biological experiments -- we would know much more about surface sites on Mars than we now do, and in fact the knowledge they provided would probably have allowed the US to speed up, and save money on, its own Mars exploration program. As for the 1963-65 Soviet attempts at survivable lunar landings: they would have given us much earlier information on the hardness of the lunar surface that would have been invaluable in designing the LM's landing gear, and might even have allowed us to trim back the expensive Surveyor program and/or focus it more on unmanned science studies of the Moon.

[Guest_DonPMitchell_*]

While hypotheticals have no real force, it is quite possible (based on its performance in that test flight) that had Zond 3 launched on time it might have produced pictures of Mars good enough to steal Mariner IV's thunder

Hypothetically, Mars-1 could have photographed Mars in 1962. It had a camera that was in some respects better than the Zond cameras, but extremely heavy (32 kg). Hypothetically.

There was no reason the Zond-3 probe couldn't have been launched at the same time as Zond-2. 3MV development was finished. Korolev and Keldysh decided to launch one of them to the Moon to get a much-needed success for the papers. It was the second time the farside of the Moon was photographed, and they did get a chance to test various systems -- retransmit photos from great distances, test the ion-engine attitude control jets, etc.

[Guest_DonPMitchell_*]

I have never been able to gloat about the Soviet planetary and lunar probe failures.

I agree. I think the situation in Russia was similar to the situation here, with regard to quality control. You had at Korolev's OBK-1 and JPL doing a lot of new stuff, but without good engineering experience in quality control. Thus a string of failures with 2MV, 3MV, Luna-4, Pioneer/Able, Ranger.

Then there was a hand-off to a different group, NPO Lavochkin and Langley Research Center. Suddenly you had much more sophisticated probes like Surveyor and Lunar Obiter and Luna-13, and a sudden jump in success. To be fair to OKB-1 and JPL, they also generated a lot of knowledge from their failures, and it was tough to be the first ones to make a go at it.

In 1969, playing the hypothetical game some more, M-69 would have eclipsed Mariner-6, even if it had orbited. It was huge, and bristling with interesting experiments and a much better camera, with color capability.