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Posted by: ljk4-1 Feb 10 2006, 10:18 PM

Sunspot, NM (Feb. 7, 2006) -- The planet Venus is best known for the thick layers of clouds that veil its surface from view by telescopes on Earth. But the veil has holes, and a New Mexico State University scientist plans on using a solar telescope to peer through them to study the weather on Venus.

"Observations of Venus from a nighttime telescope at a single location are very difficult because Venus is so close to the Sun in the sky," said Dr. Nancy Chanover, a planetary scientist at NMSU in Las Cruces, NM. "You can observe it for about two hours at most." Then the Sun rises and blinds the telescope (or Venus sets, depending on the time of year).

http://www.nso.edu/press/venus06/

Posted by: PhilCo126 Feb 11 2006, 04:02 PM

Well on the subject of ' early ' missions to the planet Venus, I was always amazed that the first unmanned spacecraft didn't carry a camera to make photos of our 'sisterplanet' ... as if the engineers & scientists of the Venera program weren't interested in good photos of the cloud tops ?

Posted by: tedstryk Feb 11 2006, 04:47 PM

Well, as for the first successful mission, Mariner-2, I think it was simply not possible for a mission of its size at the time. But the fact that Mariner-5's camera was removed is stranger. As well as, as you mentioned, the avoidance of using them on the Veneras. My guess is that since Venus was featureless from Earth, they reasoned that, given the crude electronic imaging of the 1960s, the images would be embarassingly blank.

Posted by: Phil Stooke Feb 11 2006, 05:25 PM

Ted said "My guess is that since Venus was featureless from Earth, they reasoned that, given the crude electronic imaging of the 1960s, the images would be embarassingly blank."

I think he's right. Also, there was still in those days a strong bias against imaging from the 'sky scientists' (see Don Wilhelms' great book 'To a Rocky Moon'). Why transmit a million bytes for one fuzzy image when a thousand measurements of the magnetic field, plasma and particles would tell you so much more? People had to fight to fly cameras. That seems strange to us now, but we are talking about a period when the value of images for geological study had not been fully demonstrated - Shoemaker and others at USGS were doing it, but the work was still not fully accepted outside their group.

Phil

Posted by: tedstryk Feb 11 2006, 05:46 PM

On the scientist end, this is definitely a factor. With moon and Mars missions, such as Luna-3 and Mariner-4, the propaganda factor of having images no doubt tilted the tables, but for Venus, the prospect of images that wouldn't be cause for bragging rights allowed the "sky scientist" faction to dominate.

Posted by: BruceMoomaw Feb 12 2006, 06:40 AM

In the case of Mariner 1 & 2, there was never any question of it -- it was necessary to reduce the spacecraft's mass, and therfore its complexity, to an absolute minimum for the Atlas-Agena B to launch it to Venus at all. But even the earlier 500-kg Mariner A -- which carried a tape recorder and was originally planned for launch to Venus in 1962 by Atlas-Centaur, before it became excruciatingly clear in mid-1961 that the extremely troubled Centaur wouldn't be ready by then -- carried a multichannel microwave radiometer and a UV spectrometer, but no camera. It was simply not felt to be justified for Venus precisely because, while we'd known about the existence of the UV cloud patterns since about 1910 (!), they were not adequate justification scientifically for something as complex and data-hungry as a camera. If a third instrument had been added to Mariner A, it would certainly have been an IR spectrometer for more atmospheric composition and temperature data.

The Mariner 5 story is stranger. It was added to NASA's schedule on very short notice in December 1965 (along with the 1969 Centaur-launched Mars Mariners) after it became painfully clear that otherwise there would be no planetary probes at all between 1964 and 1973 (to which the gargantuan "Voyager" Mars landers had been delayed by then). But that very short notice for a mission which consisted of hastily reworking the backup third 1964 Mars Mariner spacecraft meant that they simply did not have time to develop and test many of the new experiments they would otherwise have put on it (UV and IR spectrometers and/or an improved microwave radiometer). Further budget cuts also meant that they had to quickly remove half of the 1964 Mariners' particle and field instruments, and cancel an Earth occultation photometer that could have measured cloud-top altitude. In fact, from the start, its top science goal was listed as determining Venus' surface air pressure (since Mariner 2 was thought to have nailed down its high surface temperature firmly, despite a few scientific dissenters) -- and so its top-priority science experiment was S-band radio occultation, which had been added to the 1964 Mariners as an afterthought!

But JPL neverthless recommended retaining the TV camera, with the red and green color filters replaced by one UV and one visible filter. The reason was that there was still some hope then that there might be gaps in the clouds that might allow the craft to get a glimpse of the surface -- plus the fact that it was fairly easy to retain the already-existing instrument and there was always a chance that it might make some useful observations on cloud patterns. However, NASA HQ overrode JPL and ordered the camera replaced by Stanford's dual-frequency radio occultation experiment (an improved version of the one on Pioneer 6), which was power-hungry enough that it and the camera could not both be flown, and which could both double-check the S-band experiment and obtain some additional data on ionospheric structure.

This is STILL the subject of dispute among scientists -- Bruce Murray, in his 1977 book on Mariner 10, bemoans the fact that the camera wasn't carried, but an article I saw in "Icarus" some time in the 1980s defends the decision. The one thing that puzzles me is that, had the camera been flown, its photos would apparently have been taken at close range like those on Mariner 4 -- although one would think that more distant whole-disk photos of Venus' cloud patterns would have been better. Some engineering reason, I suppose.

And of course we have the Soviets' Venera 2, which (like Venera 3 with its entry probe) came very close to successfully reaching Venus in early 1966, with a scanned-film camera system. I imagine this was an attempt to recycle one of the spacecraft the Soviets had planned to launch to Mars in 1964 along with Zond 2, and cancelled after that craft suffered a failure of one of its solar panels to deploy. (Zond 3, which successfully obtained the second set of lunar farside photos in 1965, was also obviously a recycled 1964 Mars craft -- its other instruments included IR and UV spectrometers which had little use for the Moon, but which were copies of the ones carried along with a camera on the 1962 Mars 1 probe. And it repeatedly replayed the lunar photos from distances up to several tens of millions of km, as an engineering test. There is, however, apparently still dispute as to whether Zond 2 itself was another flyby craft or an actual attempt to land a small parachute-equipped lander on Mars -- which would, of course, have crashed.)

Posted by: edstrick Feb 12 2006, 08:36 AM

I'd have to dig in "the stacks", but I think I have a copy of a brief note from around 1965 or so, discussiong planetary quarentine stuff, maybe in Science, not sure, maybe by Bruce Murray and others, analysing the launch-trajectory info for Mars 2 and concluding it was a probably a landing attempt, given a minimal arrival velocity trajectory or something like that.

Posted by: BruceMoomaw Feb 12 2006, 08:52 AM

I remember that -- it was indeed a letter in "Science", although I don't remember the date. (I think you can find it in the Reader's Guide to Periodical Literature.) There was a longer article on the subject in "Spaceflight" around 1990, but I haven't heard anything more on the subject since then. You'd think the official answer would be available somewhere by now.

Posted by: ljk4-1 Feb 13 2006, 06:43 AM

Andrew Lepage wrote about Zond 2 in the April, 1991 issue of the EJASA.
His conclusion was that the probe did have a landing capsule, but that the Soviets
assumed Mars had a thicker atmosphere than it did, so that even if Zond 2 did
release its lander, the craft would have likely crashed on the Martian surface.

The issue and article can be found here:

ftp://ftp.seds.org/pub/info/newsletters/ejasa/1991/jasa9104.txt

Regarding Mariner 5, Jane's Solar System Log by Andrew Wilson (1987) stated that the
flyby Venus probe was considered for carrying a small landing capsule, but the idea was
rejected.

Any idea what this Mariner 5 Venus lander would have looked like? What instruments it could
have carried? Could they have developed it in time? Would it have been more or less advanced
than the early Venera landers of 1966-1972? Any drawings of it available? Did they expect it
to survive to the surface, or just hope to get atmospheric readings before being crushed?

A Summary Review of the Scientific Findings of the Mariner 2 Venus Mission

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19640016602_1964016602.pdf

Mariner-Venus 1967

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720013159_1972013159.pdf

Posted by: BruceMoomaw Feb 13 2006, 09:16 AM

That I can firmly answer: it would have made temperature and pressure measurements all the way to the surface before crashing -- period -- and, had it been flown, it would have forced elimination of all other science experiments on the mission. NASA nevertheless did briefly but seriously consider it before quickly deciding that it could not be developed in time.


One additional note: until the Soviets pulled off the Venera 4 landing, NASA was leaning toward flying a single April 1972 Mariner Venus mission that would have flown by and released an entry probe, which would have carried a mass spectrometer and some of the other basic weather sensors. The flyby craft had a number of alternative instruments considered for it, including a camera and a high-resolution microwave radiometer to do some altitude mapping of the surface (although, oddly, radar altimetry doesn't seem to have been considered in the preliminary design). After Venera 4, this mission was dumped as too redundant -- although, even given a mass spectrometer cruder and less sensitive than the one on Pioneer 13, it seems to me that it would have gotten a lot of important new data. Maybe the assumption was that, by then, the Soviets would already have flown an entry probe with a mass spec. If so, NASA overestimated them.

Posted by: edstrick Feb 13 2006, 10:15 AM

Something in my infinitely long list of "would love to do" is create a version of the "image" of Venus that Mariner 2 took.

Yes. I know Mariner 2 didn't carry an imaging system.

Not entirely true.

Both the microwave radiometer and infrared radiometers were mounted on a scan platform. Each had 2 channels: 2 different wavelengths.

(going from memory) The design was for the platform to scan back and forth at a high slew rate till the brighness temperature sensed by the microwave radiometer got above a threshold, then scan back and forth in a zig-zag slow scan pattern, reversing direction every time the signal dropped below a threshold. This would have generated a 4 crude zig-zag raster scanned images of Venus' disk: 2 microwave, 2 IR.

During launch, the microwave radiometer was probably damaged -- some of it's thermal shielding may have been disturbed. Output signal was lower than designed and the second channel's data was actually reversed! When scanning past a calibration "warm plate" on the edge of the scan range it put out a LOWER signal than when pointed at black space! As a result, the instrument couldn't do the fast "search" scans it was designed to do.

During the encounter, which was at about twice the nominal pre-launch distance (they didn't take the risk of a second midcourse just to get closer than the acceptable result of the first), they got 3 slow rate scans across the planet's disk, one by accident when the scan got confused by the reversed signal, sped up, hit the end of the stop and reversed direction. There were about 15 total microwave measurements (and IR) on the limb and disk of the planet and they could be turned into very crude "sparse" images.

The microwave channels basically showed limb darkening caused by the atmosphere attenuating the heat from the surface. The IR (one in a CO2 window) both showed cloud top temperatures with no breaks in the cloud, one measurement apparently hit the cold polar collar and was lower than expected for it's emission angle.

Posted by: Gsnorgathon Feb 13 2006, 05:38 PM

Oh dear - this is off-topic for this thread, but I can't help but note that the EJASA article makes an interesting assertion I've never heard before:

Posted by: Bob Shaw Feb 13 2006, 06:50 PM

Wrong planet, same spacecraft family, so not *too* off-topic - and an interesting article. The assertion that it was an orbiter failure that did in Mars 3 is entirely fresh so far as I can see...

Bob Shaw

Posted by: ljk4-1 Feb 13 2006, 07:38 PM

It was also mentioned in the October, 1989 EJASA from a Soviet source:

http://www.seds.org/pub/info/newsletters/ejasa/1989/jasa8910.txt

And in a revised version of the same article in Spaceflight magazine in the
August, 1990 issue (does the BIS have any articles online?).

The Soviets always preferred to blame nature as the cause for space probe
failures, rather than the Glorious Socialist Technology of the Workers Party.
They did the same for Mars 1 and Venera 1, both of which stopped transmitting
before reaching their target worlds (and they were hardly isolated events),
because they were apparently struck by those darn meteoroids zipping
around the Cosmos, rather than failures of their communications technology.

Posted by: Bob Shaw Feb 13 2006, 09:00 PM

I don't suppose you know who wrote the article to which you refer?

And the article actually refers to the matter of the supposed telemetry failure being a conclusion reached by western analysts...

Oh, go on. Go on, go on, go on.

Bob Shaw

Posted by: BruceMoomaw Feb 13 2006, 10:37 PM

I knew some (but not all) of what Ed Strick says about the partial foulup of Mariner 2's radiometry; thanks for the new details, Ed. I gather there was also some electronic "cross-talk" in its circuitry that had to be sorted out, with the result that the conclusions weren't announced until three months after the flyby. The conclusions turned out to be pretty accurate, though. (The National Geographic did an article at the time with a picture showing the locations on the Venusian disk of those 22 measurements the radiometers did make. Calling it a "crude" image is the understatement of the year.)

As for the Mars 3 failure, V.S. Perminov, in his history of the Mars program (with which he was intimately associated), doesn't mention an orbiter failure, and instead suggests that an electrostatic discharge from the powerful dust storm in which the lander touched down may have knocked it out. And a set of articles in "Spaceflight" from a St. Petersburg-located correspondent suggest that the failures of some earlier planetary craft were due to:

(1) Immediate failure of a cooling unit on Venera 1, so that its electronics quickly overheated.

(2) First-day loss of all of Mars 1's attitude-control nitrogen due to a leak. The Soviets knew on the first day that it couldn't make it to Mars, so they put it into a slow spin-stabilized roll to see how long they could maintain contact with it -- and thus briefly held the distance record for long-range radio communication.

(3) Quick loss of the internal pressurization of Zond 1's electronics compartment, presumably leading to the electronics being knocked out by the resultant internal temperature extremes.

Posted by: edstrick Feb 14 2006, 09:52 AM

The soviets immediately <speculatively> blamed the Mars 3 failure on the great 1971 global dust storm. Unfortunately, that blame game has a bit of a hole in it. While I'm sure there are pretty impressive turbulent horizontal velocities during the expansion phase of a dust storm, by the time of the Mard 3 landing, the storm had entered the essentially quiescent phase.

The storm started in ?late August? 71 ?or early September? and became the only truely global dust storm so far recorded. Not just "globe-encircling" but global! (usually one or both polar regions remain fairly clear). But by late October or so, the atmosphere was relatively uniformly filled with dust and the strong thermal gradients between sun-heated dusty atmosphere and dominately surface-of-Mars-heated less-dusty atmosphere was gone and both models and observation indicate winds had died down.

I don't recall whether Vikings saw less wind during high opacity periods or not.... I think during the second storm, it shut down some thermally driven tidal mode of atmosphere "sloshing" or shut down cold fronts out of the winter northern plains.

Regardless.... when Mars 3 landed, there was a global dust storm, but "Raging" it was not.

The Mariner 2 microwave radiometer results were published in (I think) Journal of Geophysical Research. They took the measurement points, convolved them with the instruments in-flight calibrations and known "time response function" (there was lag in it's response to reduce random noise) and calculated the actual observation brightness temperatures.

You could take the data, calculate an interpolated series of brightnesses, and plot it in sky coordinates to actually get a quasi image. I've seen worse. I've MADE worse and found them useful.

Posted by: ljk4-1 Feb 14 2006, 04:35 PM

VENUSIAN HEAT

- Filter Problems Hamper Venus Observations

http://www.spacedaily.com/reports/Filter_Problems_Hamper_Venus_Observations.html

Sunspot, NM (SPX) Feb 13, 2006 - Instrument problems have kept the team at the
Dunn Solar Telescope from observing the planet Venus as they had hoped.

"The filter on our infrared camera is leaking thermal radiation and keeping us from
observing the planet," said Nancy Chanover, principal investigator from New
Mexico State University.

Posted by: ljk4-1 Feb 22 2006, 04:09 PM

Science/Astronomy:

* Planetary Protection Study Group Mulls Life On Venus

http://www.space.com/scienceastronomy/060221_venus_life.html

A special study group has advised NASA that Venus is far too hellish of a world
for life to exist on or below the planet's surface. Furthermore, while the
potential for life in the clouds of Venus can't be ruled out, the expert panel
gauged this possibility as extremely low.

Posted by: JRehling Feb 22 2006, 04:21 PM

Well, the lava-drinkers who have built glorious cities all over Venus will be surprised to hear this.

Aside from the acid problem, and the finite nutrition in a droplet, the problem with cloud-life, on Venus or elsewhere is that turnover will lead individual droplets to undergo harsh temperature changes.

The usual issue with life and extreme conditions is that it's one thing for life to originate in an accomodating niche and spread/adapt to a harsher one, but another for it to originate in a place with narrow margins. The best hope for life in the Venusian clouds would be if it once existed on the surface, before Venus lost its H2O and gained its CO2 and heat (if there was a time before that), spread to the clouds, and adapted to the massive changes that took place in the meantime. This seems less likely than fossilized life on Mars, but any attempt to prove that mathematically would require some assumptions with little basis in fact.

Posted by: ljk4-1 Mar 23 2006, 03:32 PM

I also get a small thrill out of looking at a planet in the night sky
and knowing that one of humanity's probes is there exploring it
at that very moment.

I particularly recall when Mars Pathfinder landed on Mars on
July 4, 1997. I was outdoors watching a fireworks display when
between the artificial explosions I could see the Red Planet
shining fairly bright in the dark sky. And I knew right at that
moment that the first machine in 21 years was just getting
down to business on that world.

Now we can do the same for Venus and Venus Express:

NOW IS THE BEST TIME TO SEE VENUS THIS YEAR

Astronomy Magazine Press Release

WAUKESHA, WI — The “morning star” Venus lights the sky before dawn,
heralding spring’s arrival. On March 25, the brilliant planet reaches
its greatest western elongation — when the planet is as far west of
the Sun as possible. Then, it sits just above the horizon in the
east-southeast sky 2 hours before sunrise. Look for the waning
crescent Moon passing to the right of the “morning star.” Venus will
be the bright object just to the upper left of the Moon.

Each day thereafter, Venus’ sky position sinks closer to the horizon.
Venus shone at its brightest, magnitude –4.6, in February, but the
planet will dominate the morning sky throughout summer.

Take a Look

To the naked eye, Venus’ light rivals only moonshine in the early
morning sky. But you can use a telescope to watch as the planet
changes phases, like the Moon’s, during the year. By March 25, its
globe measures 25" through a telescope and has fattened to half-lit.
It’s at its brightest for the year now; even though the phase
increases, its angular size decreases as the Earth-Venus distance
increases.

Venus’ Orbit

Our “sister planet” lies an average of 67 million miles (108 million
kilometers) from the Sun. Because Venus lies closer to the Sun than
Earth, it always appears close to our star in the sky.

On March 26, Venus and the Moon help you spot a rarely seen planet:
Neptune. At about 5 a.m. local time, Venus appears slightly north of
(above) Neptune. The Moon lies just below and to the left of the
planets.

Quick Facts

- Venus orbits the Sun in 225 days.

- The planet is about 7,521 miles (12,104 km) in diameter, or 95
percent the size of Earth.

- Venus spins on its axis once every 243 days, but it spins in the
opposite direction of Earth — on Venus, the Sun rises in the west
and sets in the east.

- Venus’ atmosphere is thick sulfuric-acid clouds, which reflect
sunlight extremely well.

- The surface temperature on Venus can approach 900º Fahrenheit (482º
Celsius); it’s the hottest place in the solar system after the Sun.

- In Roman mythology, Venus was identified with the goddess of love
and beauty, Aphrodite. To the ancient Mayans, Venus was the patron
planet of warfare called Kukulcan (the feathered serpent).

Also in the Sky

- Throughout March — Saturn lies high in the southeast. An hour after
sunset, the ringed planet shines at magnitude 0 and stands among the
faint stars of Cancer the Crab.

- Through the end of March — Jupiter can be spotted in the southwest
sky in the predawn sky.

- Wednesday, March 29 — A total solar eclipse darkens the sky over
northern Africa and Asia. Astronomy magazine is leading two tour
groups through the eclipse path. Visit Astronomy.com for special
coverage.

Posted by: angel1801 Mar 25 2006, 06:47 PM

Off course, we (depending on location) got a chance to see Venus transit the sun on June 8, 2004. We will (again, depending on location) will get to see another one on June 5-6, 2012.

Posted by: ljk4-1 Apr 10 2006, 03:48 PM

"VENUS' CLIMATE IS TELLING US THAT WE REALLY DON'T UNDERSTAND THE EARTH"

The Observer, 9 April 2006

Venus: the hot spot

This week a European spacecraft will arrive for a date with Venus, our closest
planetary neighbour. Scientists hope the mission, made on a shoestring budget,
will reveal vital lessons on how unchecked greenhouse gases can turn a world
into a blistering Hades. Robin McKie reports on a journey to the Forgotten
Planet

On Tuesday morning, mission controllers in the European Space Agency's
operations centre in Darmstadt will put the finishing touches to an
international bid to study the ultimate neighbour from hell.

They will transmit a series of radio commands to a robot spacecraft currently
hurtling towards the Sun. Its rocket engine will fire for 50 minutes as it
passes Venus, slowing the craft down so that it can be captured by the planet's
gravitational field. Once in orbit, the wardrobe-sized probe - Venus Express -
will then study the planet's acid clouds, searing heat, crushingly dense
atmosphere and hurricanes to find out why Earth's nearest neighbour has become a
place of insufferable heat and poison.

'Venus is very like Earth in that it is the same size and has an orbit round the
Sun close to ours,' said David Southwood, head of science at the ESA. 'Yet Venus
went wrong. We did not. We want to find out why Venus became our evil twin.'

Venus and Earth are almost identical in size. In addition, both orbit the Sun in
'the Goldilocks zone', a swath of space in which conditions are considered by
astronomers as being not too hot and not too cold to prevent the evolution of
life. Venus should make ideal planetary real estate, in other words. Yet it is
the solar system's most inhospitable planet.

'It's very disturbing that we do not understand the climate on a planet that is
so much like the Earth,' said Professor Fred Taylor, a planetary scientist based
at Oxford University and one of the ESA's chief advisers for the Venus Express
mission. 'It is telling us that we really don't understand the Earth. We have
ended up with a lot of mysteries.'

Full article here:

http://observer.guardian.co.uk/uk_news/story/0,,1750001,00.html

Posted by: Julius Apr 13 2006, 09:28 PM

Unnecessary quote removed - moderator

My biggest query about Venus is that despite the lack of magnetic field and hence complete exposure to atmospheric erosion by the solar wind,Venus has managed to retain a thick atmosphere.Could this be indirect evidence for continued volcanic activity on the planet??!!

Posted by: edstrick Apr 14 2006, 09:30 AM

I don't know the exact modelling based on Venera 9 and 10 and Pioneer Venus Orbiter solar wind interaction data, supplemented by Galileo/Cassini flyby data, but I think it boils down to there being significant erosion has occured, but it's still quite a small fraction of the total atmosphereric mass.

Posted by: BruceMoomaw Apr 14 2006, 07:01 PM

Venus has both a much greater mass than Mars (about 8 times more), and much more volcanic activity over its total history than Mars. Thus the ability of the solar wind -- even though it's much stronger at Venus than at Mars -- to strip away atmospheres has done far less to reduce Venus' total atmospheric mass than it did for Mars.

Posted by: RNeuhaus Apr 14 2006, 07:55 PM

And also the Venus' greater gravity than Mars might influence in some degree to the clouds formation? Mars has lost much of its atmosphere due to low planet gravity as one of the factors?

Rodolfo

Posted by: ljk4-1 Apr 14 2006, 11:43 PM

Not long after Pioneer 12 (aka, Pioneer Venus Orbiter) arrived at the
Cloudy Planet in late 1978, it detected a recent drop in the amount of
sulfur dioxide in the planet's thick atmosphere, which was interpreted
as the result of volcanic activity.

Examining various radar images, especially from Magellan, has anyone
ever seen any flow patterns or other changes that might have indicted an
active volcano or two?

Posted by: DonPMitchell May 5 2006, 02:37 AM

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 fatel 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.

Posted by: DonPMitchell May 5 2006, 02:52 AM

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 undestand 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.

Posted by: BruceMoomaw May 5 2006, 06:37 AM

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

Posted by: BruceMoomaw May 5 2006, 06:56 AM

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...

Posted by: DonPMitchell May 5 2006, 02:30 PM

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).

Posted by: ljk4-1 May 5 2006, 02:57 PM

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?

Posted by: ljk4-1 May 5 2006, 03:14 PM

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.ntrs.nasa.gov/19650076650_1965076650.pdf

Mariner 2

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650076538_1965076538.pdf

Mariner-Venus 1962 Final Project Report

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660005413_1966005413.pdf

Mariner II - an Example of a Stabilized Interplanetary Space Vehicle

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650076554_1965076554.pdf

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

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790076756_1979076756.pdf

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

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650072055_1965072055.pdf

Mariner II Tracking System Final Data Analysis Report

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650023545_1965023545.pdf

Tracking and Data Acquisition Support for the Mariner Venus 1962 Mission

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650023548_1965023548.pdf

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

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790076621_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.ntrs.nasa.gov/19640003267_1964003267.pdf

Mariner-Venus 1967

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720013159_1972013159.pdf

Posted by: DonPMitchell May 5 2006, 04:58 PM

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. :-)

Posted by: tedstryk May 5 2006, 06:31 PM

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.

Posted by: ugordan May 5 2006, 07:02 PM

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.

Posted by: ljk4-1 May 5 2006, 07:17 PM

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?

Posted by: DonPMitchell May 5 2006, 07:25 PM

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.

Posted by: ugordan May 5 2006, 07:27 PM

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. http://www.lpl.arizona.edu/~jrich/vgertitan.html 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.

Posted by: gndonald May 6 2006, 01:34 AM

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 http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1965-056A, 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

Posted by: BruceMoomaw May 6 2006, 03:34 AM

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.

Posted by: DonPMitchell May 6 2006, 03:36 AM

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.

Posted by: DonPMitchell May 6 2006, 03:55 AM

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.

Posted by: gndonald May 6 2006, 04:14 AM

Now that is interesting and I would love to know the source for that. I am also going to add that in going for the 'quick success' at the Moon with Zond 3, in hindsight the Russians lost out on the chance to get some good Mars photos.

I'd also like to propose that any further discussion of Zond 3 be moved to the Lunar Missions forum, as that is where the probe ultimately went.

Posted by: DonPMitchell May 6 2006, 04:34 AM

Boris Chertok's books (in Russian, unfortunately).

Posted by: BruceMoomaw May 6 2006, 05:11 AM

First, JPL was in charge of Surveyor, and NOT in charge of Atlas-Able (whose failures were entirely with the booster rather than the spacecraft anyway).

Second, I've seen the experiment list for the 1969 Soviet orbiters: exactly the same as the Mars 2 and 3 orbiters two years later -- and V.G. Perminov, in "The Difficult Road to Mars", says that there was great pessimism about whether they'd work given the crash development schedule the Kremlin had insisted on. They would have gotten only a handful of photos compared to the thousands that even a single successful 1969 US Mars orbiter would have obtained, and -- like those of Mars 5 -- they would have been no better in quality than those provided by the US orbiter's vidicon camera (since the cameras on the 1969 Mariners were tremendously better than that on Mariner 4). I'll also have to reread that JBIS article -- in the Sept. 2000 issue -- to check when the Luna handoff to Lavochkin actually happened.

Posted by: Phil Stooke Jun 14 2006, 04:11 PM

I thought I'd post this here for want of anywhere better. A map of Venus in two hemispheres, 0 and 180 longitude, made of a composite of radar and altimetry datasets from Magellan. Public domain. The map projections are azimuthal equidistant.

Phil

Posted by: DonPMitchell Jun 14 2006, 05:08 PM

Very good. Did you use Venera data at the north pole? Someone needs to map the south pole one of these days. Even the Earth-based radar imaging seems to concentrate on the northern hemisphere for some reason.

Posted by: DonPMitchell Jun 14 2006, 05:37 PM

Here's a Venus map I put together for my solar system simulator. It needs work, to match the different sources better. This is constructed from Magellan (left, right and stereo passes), Venera and the two published Arecibo maps.

[attachment=6245:attachment]

The projections are stereographic and mercator. I do spherical image processing in this representation, because it allows pretty conventional operations with just isotropic scaling of the filters for different regions.

Posted by: Phil Stooke Jun 14 2006, 06:07 PM

Nice, Don. My map is a composite of two datasets - the Magellan altimetry, patched with Pioneer Venus, which is used in USGS's Pigwad system, and the Magellan global mosaic (composite of all three cycles, I think) which is patched in the north with Venera. That was originally off the Photojournal but I have reprojected it. So at the pole there is a bit of Venera imagery, very subdued. I just add the SAR images to give a bit of extra information over the rather bland altimetry image.

Phil

Posted by: DonPMitchell Jun 14 2006, 08:10 PM

I reprocessed the Magellan altimetry data with the corrected spacecraft ephemeris produced in the 1990s. If you've noticed radial grooves in the data, this will fix that for you. If you're using the raw altimeter samples, that is.

Posted by: Phil Stooke Jun 14 2006, 08:51 PM

The relief I used, from Pigwad, does have those streaks along orbit tracks. I did a bit of editing - to the image, not the DEM - to remove them. Could still be better though!

Phil

Posted by: JRehling Jun 15 2006, 02:47 PM

I'm likely reposting this every six months as amnesia overcomes me, but here's a link to a map I put together based on a DEM bump map and SAR for albedo, set to Venera 13/14 colors.

Additionally, I reprojected it onto an ellipse to mimic the great National Geographic map of Mars that had a similar feel.

http://www.cogsci.indiana.edu/farg/rehling/astro/venus-oval.jpg

Posted by: Phil Stooke Jun 15 2006, 06:12 PM

Very nice map, JRehling

Phil

Posted by: DonPMitchell Jun 15 2006, 06:39 PM

Yes, that's a nice projection.

Posted by: ljk4-1 Jun 19 2006, 07:33 PM

Part V: Astrobiology

Sympathy for the Devil: The Case for Life on Venus

David Grinspoon, Southwest Research Institute, Boulder

33 min.

"Venus favors the bold."

-- Ovid (43 BC - 17 AD)

The next four lectures will ask the question: "Why did things go so right for
life on Earth?" To answer that question, we ask, "Why did things go so badly on
Earth's nearest neighbors, Venus and Mars?"

Mars is half the size of Earth, but Venus is nearly Earth's identical twin. All
three planets likely had substantial oceans, but Venus and Mars lost their
oceans some time ago. Mars' oceans apparently evaporated almost immediately,
but Venus may have kept its oceans for 600 million years, as estimated by Jim
Kasting of Penn State in 1988, or for as long as two billion years, as
suggested by David Grinspoon in this week's lecture.

The Evolutionary Biology Lecture of the Week for June 19, 2006 is now available
at:

http://aics-research.com/lotw/

Posted by: Sunspot Nov 2 2006, 10:00 AM

http://www.newscientistspace.com/article/dn10427-venuss-surface-may-be-much-older-than-thought.html

The colossal outpouring of lava thought to have almost totally resurfaced Venus 500 million years ago never happened, a new study says. If correct, it means that a much longer record of Venus's history is preserved on the planet's surface.

Posted by: cndwrld Mar 27 2007, 09:43 AM

Excellent Ground-Based Venus Images

At http://www.astrode.de/venus07.htm, one can see some excellent 'amatuer' ground-based images of Venus. Text in German.

My understanding is these are taken from a 10th floor location in the center of Munich, using a web cam that takes data over a period of time and then uses an algorithmic selection of the most crisp images, which are then overlayed.

Most excellent.

-don

Posted by: JRehling Mar 27 2007, 03:41 PM

That is really great stuff -- the best ground-based Venus images I've seen. And Munich seems like an exceptionally poor location to work from compared to the Andes or Arizona.

By comparison, the one Mercury image, while impressive in its own right, is far from the best I've seen, with amateurs like the late Erwin van der Velden having resolved crater ray systems. I wonder if the best practices for imaging Mercury could be adapted to Venus and produce even better work? Of course, there are many factors making the two tasks different -- Venus is intrinsically brighter but only shows this detail in UV or IR. Mercury is less luminous per unit surface area, shows details in visible spectra, but offers very low contrast. And offers much less favorable separation from the Sun.

These Venus images make me wish for a systematic ground-based survery showing "video" of its global weather. Easily done for a tiny fraction the cost of a space-based mission.

Posted by: J.J. Mar 27 2007, 06:55 PM

WOW!!!



Those are far and away the best ground-based Venus images I've seen; that kind of quality would have been unthinkable even from large observatory telescopes a generation ago.

Ditto for JRehling's movie concept...

Posted by: tedstryk Apr 9 2007, 07:58 PM

Check out these images I came across. Looks almost like a spacecraft image.

Posted by: JRehling Apr 10 2007, 08:41 PM

http://www.msnbc.msn.com/id/18040861/

New pictures!

I can't find any mention on the ESA mission page. MSNBC may have raided their data and released it for them.

Posted by: elakdawalla Apr 10 2007, 08:45 PM

Those are the four that were released a couple weeks ago:
http://www.esa.int/esaSC/SEM9N77DWZE_index_0.html

I've gotten a (very) little more info on these and have been planning to post but haven't managed to get to it yet...

--Emily

Posted by: AlexBlackwell Apr 10 2007, 08:53 PM

Speaking of Venus science, the first of several papers of http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=EXVENUS1, has been published online.

Posted by: cndwrld May 7 2007, 12:39 PM

Venus Ground-Based Images

At ESA's pages for the Venus Amateur Observing Project, more excellent photos of Venus taken from her sister planet are now posted at:

http://tinyurl.com/2xxb2d

These video frame overlays are just fantastic.

Posted by: cndwrld May 7 2007, 03:03 PM

Movies of Venus' South Pole Vortex

The ESA science pages have been updated to include an article on the south pole vortex on Venus. Venus Express has imaged the pole over a period of days, and used special downlink arrangements to take much more data than previously allowed. The resulting movies taken by the VIRTIS imaging spectrometer are quite amazing.

The page, entitled "Venus Express’ infrared camera goes filming", is available at:
http://www.esa.int/SPECIALS/Venus_Express/SEMQKVU681F_0.html

More science results can be viewed at:
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39432

Posted by: cndwrld Jun 20 2007, 03:20 PM

Another set of ground-based images of Venus has now been posted at:
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=41107


And some cute pictures of the recent occultaion of Venus by the Moon can be found at:

http://foto.star-shine.ch/details.php?image_id=630
http://forum.astronomie.de/phpapps/ubbthreads/showflat.php/Cat/0/Number/525968/an/0/page/0#525968
http://www.flickr.com/photos/peter_heinzen/567875780/

http://forum.astronomie.de/phpapps/ubbthreads/showflat.php/Cat/0/Number/525967/an/0/page/0#525967