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Waspie_Dwarf
Russia Plans "Long-Lived" Venus Probe


The press secretary of the Russian Federal Space Agency, Vyacheslav Davidenko, has said that Russia will design and launch a long-living probe to Venus by 2015. The probe is known as Venera-D.

Davidenko told a news briefing that within the federal Space budget for 2006-2015 was envisaged, “work to develop a principally new spacecraft, Venera D, intended for detailed studies of the atmosphere and surface of Venus”.

“It is expected that the craft with a long, more than one month period of active existence will land on the surface of the planet that is the nearest to the earth. Nobody has done such thing on Venus so far.”

Source: ITAR-TASS
Toma B
smile.gif
Should be good...
Maybe little wheels on that lander... smile.gif smile.gif smile.gif smile.gif smile.gif smile.gif smile.gif
ElkGroveDan
QUOTE (Waspie_Dwarf @ Nov 7 2005, 07:19 PM)
The probe is known as Venera-D.
*

The Russian space program really needs some PR and marketing people.
Waspie_Dwarf
QUOTE (ElkGroveDan @ Nov 7 2005, 08:08 PM)
The Russian space program really needs some PR and marketing people.
*


And NASA and ESA don't? Mars Reconnaissance Orbiter and Venus Express are hardly inspiring names for spacecraft.
JRehling
QUOTE (Waspie_Dwarf @ Nov 7 2005, 12:19 PM)
“It is expected that the craft with a long, more than one month period of active existence will land on the surface
*


No word on the thermal strategy: Build a spacecraft that can withstand the heat. Or, use refrigeration to keep the probe cool. Or some combination of both. A probe that was built to withstand the heat might well last indefinitely, much longer than a month.

Would this be the first Soviet/Russian spacecraft to use an RTG? I think they have been able to rely upon batteries and solar panels thus far.

The next question is what a long-lived probe's long life would be for. Data on wind/temperature/pressure variations would be interesting, but may turn out to be boringly constant. It's possible that wind would blow some dust around, but that's no guarantee. Skyward looking cameras could show variation in cloud structure blowing overhead. One baseline instrument that seems to me to provide a clear need for life beyond an hour would be a seismograph, which is of diminished value without a long life span. Additionally, if there is a sampling/instrument arm, then arbitrarily long mission durations could yield the benefit of more sampling, especially with irradiative spectrometers that require long integration times. Maybe a long, double-jointed arm could scan a grid around the lander, moving a small suite of MER-like instruments carefully around the base. It would then be essential to keep the arm's movements from interfering with the seismometer.
Waspie_Dwarf
Russian spy satellites have employed minature nuclear reactors (although not RTGs I beleive). They have lead to problems. In 1978 Cosmos 954 crashed in Northern Canada spreading radioactive material over a large area.
tty
The Soviet Union certainly developed RTG's which were used for powering e. g. lighthouses in remote locations. Incidentally at least some were insufficiently shielded and so could be dangerous to approach for the unwary.

tty
ljk4-1
QUOTE (tty @ Nov 7 2005, 03:57 PM)
The Soviet Union certainly developed RTG's which were used for powering e. g. lighthouses in remote locations. Incidentally at least some were insufficiently shielded and so could be dangerous to approach for the unwary.

tty
*


Of course anyone on the surface of Venus will have bigger things to concern themselves with than encountering an RTG or two.
tedstryk
I know there were some RTG's that were sent to Peru or thereabouts on Mars'96.
Stephen
QUOTE (Waspie_Dwarf @ Nov 7 2005, 08:15 PM)
And NASA and ESA don't? Mars Reconnaissance Orbiter and Venus Express are hardly inspiring names for spacecraft.

They could always hold a competition. Then they might get to select such inspiring names as "Spirit" and "Opportunity". smile.gif

=====
Stephen
BruceMoomaw
On the way back from the COMPLEX meeting, I attended the afternoon half of the day-long first meeting of VEXAG -- the Venus Exploration Analysis Group, which is the new equivalent of MEPAG and OPAG. There was very little news -- except for the revelation that one of VEXAG's subgroups is currently engaged in a detailed prioritization of the goals of Venusian surface science and the technical difficulty of achieving them, which I hope to get hold of in two weeks or so. But one thing that the Group made clear is that building a long-lived Venusian lander is still going to be bloody hard. You need either a VERY high-powered cooling unit (probably mechanically powered by the waste heat from an RTG), or electronics capable of enduring Venusian temperatures -- or both. (Right now we have experimental electronics capable of enduring 250 deg C. We need 200 degrees above that.) So I think this new Russian news is just more empty whoosh from a nation desperately trying to put up any kind of fake front that it can to say that it's still capable of large-scale space exploration.

What we DON'T need -- as I had suspected earlier -- is wheels (contrary to what the Solar System Strategic Roadmap group had said). As Doug Mackwell said, by precision control of the buoyancy of a Venus lander -- which is more like controlling the buoyancy of a submarine than that of a balloon -- "you can glide along two meters, or 20 meters, above the surface."
Waspie_Dwarf
Whilst you are no doubt correct about how difficult this long-lived goal will be to achieve the Russians have given themselves a decade to achieve this.

"Empty whoosh" possibly, but I hope not. Russia has surprised the west many times by achieving things that seemed improbable with the resources they have to hand. I would never rule them out.
Tom Ames
QUOTE (ElkGroveDan @ Nov 7 2005, 03:08 PM)
The Russian space program really needs some PR and marketing people.
*


laugh.gif

"Venera-D" does sound a lot like it belongs up the isle from Preparation-H.
mchan
QUOTE (Waspie_Dwarf @ Nov 7 2005, 01:15 PM)
And NASA and ESA don't? Mars Reconnaissance Orbiter and Venus Express are hardly inspiring names for spacecraft.
*


Er, it may be an American thing, but Venera-D sounds like an abbreviated form of an old term for STD's. ElkGroveDan was polite to not put it so bluntly.
ilbasso
Have the Russians attempted any interplanetary probes since 1996? Do they have any other ones already in development now? I know they are strapped for cash but it's hard to believe it will have been 20 years between their last and next interplanetary attempts.
Myran
The name (that really should need to be something different than 'V.D') suggest its one upgrade of one kind of other of he Venera series of landers.
If so the Russians might have decided to do something they feel they have confidence in pulling off.
ilbasso: You might be right, im not aware of any other since Mars96.
dvandorn
QUOTE (mchan @ Nov 7 2005, 09:59 PM)
Er, it may be an American thing, but Venera-D sounds like an abbreviated form of an old term for STD's.  ElkGroveDan was polite to not put it so bluntly.
*

Reminds me of the big marketing disaster Chevrolet faced when they tried to sell the Nova in Spanish-speaking countries. In Spanish, of course, "va" is a form of the verb of action, roughly translated as "go." And "no" is a rather universal form of negation. So, "no-va" in Spanish is pidgin for "doesn't go."

And, of course, then there's the marketing of Coca-Cola in China, where the sound-alike ideographs first used to represent the brand name translated literally to "bite the wax tadpole."

-the other Doug
Bill Harris
QUOTE
No word on the thermal strategy: Build a spacecraft that can withstand the heat. Or, use refrigeration to keep the probe cool. Or some combination of both


Whew, how would refrigeration (or RTGs) be workable? Those work on temperature differentials, and how would one transfer heat into an 800 degree environment? And under enormous pressure. I'm thinking that some form of evaporative cooling might be the only feasible process.

Don't undersell the Russians. For years, they've been very successful with achieving miracles with old "soviet" technology, in many ways more so that the USA's "space winnebago" misdirection.

--Bill


PS: let's see how this transliterates: Венера-Д is Cyrillic for Venera-D and looks less-threatening.

The Russians can really be a hoot sometimes. I googled this:

Russian marriage agency "Venera" is an international introduction service located in Ufa, Bashkiria.

biggrin.gif
tedstryk
They do have Phobos-Grunt under development for a 2009 Phobos sample return, and also a large Mars lander, although the latter has few specifics released. I doubt Venera-D will actually be its name. I think its a reference to Venera 1-3 (Venera 8) Venera 4-8 (V-cool.gif Venera 9-16 and the Vegas (Venera -C). That sequence may be a little off, in terms of what number goes where, but I do know that it is where the "D" comes from.
Waspie_Dwarf
QUOTE (Bill Harris @ Nov 8 2005, 09:55 AM)
I'm thinking that some form of evaporative cooling might be the only feasible process.
*


Surely an evaporative system would contaminate the local environment, rather negating the point of operating on the surface for a month.

If the name Venera (which is Russian for Venus) is going to cause so much hilarity, heaven help us if NASA anounce they are going to send a probe to Uranus.
Adam
I have already seen this, at the ESA site i believe. I'm serious. I promise. biggrin.gif
ljk4-1
QUOTE (Waspie_Dwarf @ Nov 8 2005, 08:30 AM)
Surely an evaporative system would contaminate the local environment, rather negating the point of operating on the surface for a month.

If the name Venera (which is Russian for Venus) is going to cause so much hilarity, heaven help us if NASA anounce they are going to send a probe to Uranus.
*


Carl Sagan tried to get references to Venus renamed Cytherian, but his Harvard colleagues in the 1960s felt otherwise on the matter. I think Cytheria has a definite romantic sound to it.

For those who recall the Voyager 2 mission to Uranus in 1986, the planet's name kept getting pronounced differently (with a lower case a) by the media as the probe got closer. cool.gif

One hopes that a world will not be ignored by science just because its name may sound funny to the public.
BruceMoomaw
Originally Gordon Chin's Discovery proposal for a "VESPER" Venus orbiter -- which made the finalist list once, and which he's proposing again this time) was named "Venus 2000". I tried to look it up on Google under that name once and was deluged with ads for sex toys. It is probably not coincidence that shortly thereafter it was renamed "VESPER".

As for "Uranus" -- that unfortunate planet whose name sounds obscene no matter how you pronounce it -- Kingsley Amis notes that back in 1961 there was a Swedish movie called "Voyage to the Seventh Planet", in which the actors kept referring to it as "U-rah-nus".
BruceMoomaw
Meanwhile, Uranus don't seem to get no respect at the moment from the planetary science community itself, apparently because they think of it as a Grade-B Neptune, which is unfair. A few years ago, at a meeting of the Decadal Science discussion group, one guy was about to present a talk on Uranus exploration when Reta Beebe (who, by the way, has a spectacularly foul mouth) snapped, "You mean you're actually going to make a case for exploring that boring planet and its scrawny little moons?"
um3k
QUOTE (Adam @ Nov 8 2005, 09:34 AM)
I have already seen this, at the ESA site i believe. I'm serious.  I promise. biggrin.gif
*

I've seen it there, too. It was quite a while ago.
elakdawalla
When I had to teach a fifth grade classroom about Uranus I let them all have a good laugh at me (and them) pronouncing it "Your Anus" and "Urine Us" and then I wrote the following on the board: "You're a Nuss!" and had them all turn to each other and accuse each other of being Nusses. After a brief bit of speculation on what a Nuss could possibly be we moved on and the fifth graders were able to handle talking about Uranus. Unfortunately my husband still can't handle it. Every time I tell him about a new mission to some place he asks "But when are they going to send a mission to Uranus?" and then cracks up. Sigh. I get no respect. Anyway, in the spirit of "any publicity is good publicity" I expect that if a mission ever gets on the books for Uranus its unfortunate name can only help; it will be the best-known space mission among people who listen to shock jocks, watch Jon Stewart for their primary source of news, etc. Howard Stern won't be able to stop talking about it.

--Emily
Adam
QUOTE (um3k @ Nov 8 2005, 04:44 PM)
I've seen it there, too. It was quite a while ago.
*


I remember seeing other missions as well. What were they?
ljk4-1
QUOTE (elakdawalla @ Nov 8 2005, 10:52 AM)
When I had to teach a fifth grade classroom about Uranus I let them all have a good laugh at me (and them) pronouncing it "Your Anus" and "Urine Us" and then I wrote the following on the board: "You're a Nuss!" and had them all turn to each other and accuse each other of being Nusses.  After a brief bit of speculation on what a Nuss could possibly be we moved on and the fifth graders were able to handle talking about Uranus.  Unfortunately my husband still can't handle it.  Every time I tell him about a new mission to some place he asks "But when are they going to send a mission to Uranus?" and then cracks up.  Sigh.  I get no respect. Anyway, in the spirit of "any publicity is good publicity" I expect that if a mission ever gets on the books for Uranus its unfortunate name can only help; it will be the best-known space mission among people who listen to shock jocks, watch Jon Stewart for their primary source of news, etc.  Howard Stern won't be able to stop talking about it.

--Emily
*


You can also blame the 1982 film E.T. for the unfortunate name association.

Speilberg threw in one of the minor characters making jokes on the planet name in order to get a PG rating; that act seemed to have created an unfortunate awareness among the public.

Perhaps we should have stayed with Herschel's original suggestion of naming it after King George III.
tedstryk
Yes, NASA announcing that it wants to probe Uranus would be great fodder for Leno and Letterman.
ljk4-1
QUOTE (JRehling @ Nov 7 2005, 03:24 PM)
No word on the thermal strategy: Build a spacecraft that can withstand the heat. Or, use refrigeration to keep the probe cool. Or some combination of both. A probe that was built to withstand the heat might well last indefinitely, much longer than a month.

Would this be the first Soviet/Russian spacecraft to use an RTG? I think they have been able to rely upon batteries and solar panels thus far.

The next question is what a long-lived probe's long life would be for. Data on wind/temperature/pressure variations would be interesting, but may turn out to be boringly constant. It's possible that wind would blow some dust around, but that's no guarantee. Skyward looking cameras could show variation in cloud structure blowing overhead. One baseline instrument that seems to me to provide a clear need for life beyond an hour would be a seismograph, which is of diminished value without a long life span. Additionally, if there is a sampling/instrument arm, then arbitrarily long mission durations could yield the benefit of more sampling, especially with irradiative spectrometers that require long integration times. Maybe a long, double-jointed arm could scan a grid around the lander, moving a small suite of MER-like instruments carefully around the base. It would then be essential to keep the arm's movements from interfering with the seismometer.
*


While I have no illusions regarding the complexity this would add to such a mission, perhaps the lander could be attached to a balloon that would periodically rise into the cooler heights, then settle down somewhere else for a while. Perhaps a lack of longevity can be made up for in visiting more places on Venus.
TheChemist
Well, that's the price we pay for using a greek word in its latinized version. The original greek word for this god is pronounced <Uranos> (U like in "put", A like in "cat").
Nothing obscene about that and in modern greek it is translated as <the sky>. smile.gif
elakdawalla
I've always been curious, what domestic uses could there be for the technologies needed to explore Venus's surface -- high temperature and pressure? I don't think scientific needs (like exploring deep-sea volcanoes) count. Is there a need in, say, manufacturing or something for robotics, electronics, and sensors that can operate at Venusian temperatures and pressures? I think that support of the development of the rovers was probably aided by the obvious military uses that you could put smart, autonomous rovers to -- it always helps to be able to demonstrate down-to-earth uses for expensive NASA technologies.

By the way you don't necessarily need to get to the high temperatures that the Venera landers encountered. David Crisp kept pointing out at the VEXAG meeting that you could land in the crater Cleopatra (which is at quite high altitude) and find significantly lower ambient temperature and potentially learn a lot about Venus, namely how the heck a planet that hot can support a topographic feature as high as Maxwell Montes.

--Emily
JRehling
QUOTE (ljk4-1 @ Nov 8 2005, 09:22 AM)
While I have no illusions regarding the complexity this would add to such a mission, perhaps the lander could be attached to a balloon that would periodically rise into the cooler heights, then settle down somewhere else for a while.  Perhaps a lack of longevity can be made up for in visiting more places on Venus.
*


That is a reasonable mission, although a very different one, and it wouldn't help out the seismological goals.

Actually, if a seismometer were the *only* instrument that one cared to preserve, I think it could simplify things a great deal. A seismometer actually involves no parts that aren't easy to make withstand 900F. The trouble would be preserving the electronics that collect and transmit the data, but that has the prospect of being a much smaller unit to refrigerate. One approach could be to drop a lander that has many instruments, with refrigeration available for the central electronics only. Then let all of the instruments but the hardy one die after they've taken initial measurements. The bulk of the science of a surface imager on a static lander comes from the first 360 panorama.

I wonder if another instrument that might be easy to design for thermo-durability would be an alpha-particle spectrometer, if the durable radioactive sources and detectors could be placed in the head, and the sensitive electronics stashed far away inside the safe cooled space within the lander. If so, an arm that swung one of those around, holding it over various loci in the vicinity of the lander could take a few days intregrating data at the slow pace it needs and generating a coarse elemental composition "map" that could be registered with the visual panorama.

I think one approach to the difficulties of Venus is going to be to begin from basics and use "analog" approaches when it turns out that our fancy microelectronics won't work. Of course, that ends up being a lot of R&D, running up mission cost. But R&D in Russia ought to be cheaper than basic R&D in US/W. Europe.
mcaplinger
QUOTE (elakdawalla @ Nov 8 2005, 08:40 AM)
I've always been curious, what domestic uses could there be for the technologies needed to explore Venus's surface -- high temperature and pressure?
*


The pressure isn't as much a problem as the temperature. There are probably a lot of industrial uses for high-temp electronics -- jet-engine controllers, for example. When we were writing our Venus probe proposal (which I like to call "Tom Swift and His Nuclear Refrigerator" -- see http://www.msss.com/venus/vgnp/vgnp.txt.html ) there was a lot of work being done on silicon carbide (SiC) electronics for engine control. Haven't looked lately; it wasn't really viable in the mid-90s.
The Messenger
QUOTE (elakdawalla @ Nov 8 2005, 09:40 AM)
I've always been curious, what domestic uses could there be for the technologies needed to explore Venus's surface -- high temperature and pressure? 
--Emily
*

Once smart sensor technology is well developed and robust enough for exploring Venus, there will be (there already is) a hungry market. Start with oil exploration: If cheap, reliable, lightweight, small, integrated sensors tracked tooling and shaft temperatures, shear, loads, spectrographic profiles and strain, engineers could develop more profitable and safer drilling profiles. Now look at mining, automobile and diesel engines, HVAC systems and smart, integrate home energy management systems.

Chemical industrial environments, petroleum cracking columns, jet engine fatigue sensors. Pottery, metal fabrication, waste reclaimation - the list of hostile manufacturing environments is extensive.

The real question is not what, but why haven't these advanced technologies already emerged? I guess the best answer is that they are emerging, but a better-funded space technology research program could have, and still should accelerate advances in energy and resource mangement.
elakdawalla
QUOTE (JRehling @ Nov 8 2005, 09:54 AM)
That is a reasonable mission, although a very different one, and it wouldn't help out the seismological goals.

Actually, if a seismometer were the *only* instrument that one cared to preserve, I think it could simplify things a great deal. A seismometer actually involves no parts that aren't easy to make withstand 900F. The trouble would be preserving the electronics that collect and transmit the data, but that has the prospect of being a much smaller unit to refrigerate.
*

Another problem with a seismometer that they discussed a lot at VEXAG was that it needs to be "intimately connected" with the surface -- essentially it needs to be bolted to bedrock. It's not quite as simple as landing the device on the surface. Also, nobody really knows how long you would need one seismometer to operate in order to pick up anything useful -- a day? a week? a month? a year? -- there were also discussions at VEXAG that it may be possible to get a handle on that question by doing seismometry of the atmosphere.

I sure hope I see a seismic network on both Mars and Venus in my lifetime. We are so blind to what is going on underneath the skins of those two planets.

--Emily
BruceMoomaw
I remember Malin's "nuclear refrigerator" very well -- fully 97% of its RTG's electrical power would have been utilized just to keep itself cool! As one guy at COMPLEX pointed out, though, seismometry is likely to be one of the hardest things to do at Venus even with a long-lived lander -- because of the racket from the cooling unit that such a lander will need.

As for John Rehling's suggestion for an alpha-scatter spectrometer, even the sensors for it can't stand up to such temperatures -- and in any case the air density at Venus is so high that it interferes disastrously with the ability of alpha particles to reach the sample, so it's always been considered hopelessly impractical unless you take the sample inside. There was a suggestion back in 1978 that it might be possible to develop in-situ sensors for a Venusian X-ray spectrometer, but I haven't heard anything about it since. But I think the element analysis problem has been solved in any case -- you just use a LIBS (Laser-Induced Breakdown Spectrometer), which is scheduled to fly on MSL and which has enormous advantages even on an airless world. It can analyze a sample in a fraction of a second, at a range of a dozen meters or more, with even more sensitivity than an hours-long measurement by an alpha-scatter or X-ray spectrometer -- and a test reported at the 2004 LPSC has already shown that it will work perfectly well on Venus, eliminating the need to take the sample inside the craft through an airlock.

The big problem is how you do mineralogy. An X-ray diffractometer or a Mossbauer spectrometer require ingesting the sample, and the latter at least also requires hours-long measurements. But -- besides near-IR spectroscopy -- a Raman spectrometer may solve a lot of the problem; it too can make a long-distance analysis in a fraction of a second using a laser, and in fact an instrument has already been tested that can combine it with the LIBS. Since a Raman must detect a very faint scattered-light signal, it's possible that Venus' thick air might interfere with it at long range, but you could still do it on the immediate surface using a fiber-optics head on an arm.

However, the one thing a Raman can't do well is iron mineralogy -- that requires a Mossbauer, unless near-IR spectrometry can do it well enough (which might be the case).

As for that balloon that repeatedly lands briefly and then takes off for the clouds again to cool off, JPL has been working on the design for just such a mission for years (the "Venus Geoscience Aerobot"), and Martha Gilmore has a long article on it in an issue of "Acta Astronautica" early this year. It would use a so-called "variable-buoyancy aerobot" -- using a mixture of helium and some substance like water that condenses from vapor into liquid at high altitudes -- to carry out such repeated dives without using up either gas or power, kind of like those "drinking ducks". (Such dives can be done in a controlled way if the plumbing on the liquid tank has controlled valves.) The main problem seems to be finding a plastic for the thin balloon envelope that can stand up properly to Venus' savage surface heat; polybenzoxasole is the one usually mentioned, but Victor Kerzhanovich expressed doubts in an LPSC abstract this year that it can be properly seamed. However, he's recently told me in an E-mail that he thinks this may be possible after all.
Richard Trigaux
THE TECHNOLOGICAL CHALLENGE OF A LONG LIVED VENUSIAN LANDER

First of all, as many already pointed in this thread, a baloon is much better than an lander on Venus: with much higher pressure, the air is very dense and the same baloon can wear maybe 20 times more weight. The overal thing may look something between a submarine and a zeppelin, with a rigid skin and balast compartments. The easiest way to inflate it is with water steam, it is one of the lightest gaz (except helium or hydrogen) and it would be relatively easy to get in Venus air. Neon would work too, while being less corrosive.

Refrigeration or heat withstanding? I think refrigeration would be feasible for only a very small volume, or for a short time, thus offering little possibilities (or frustrating results like with Huygens). The reason is that the efficiency of refrigeration decreases very fast with the difference of tempereature. In a home regrigerator, the difference is 20-30K over 300K (10%) on Venus it would be 450K over 750K (60%) thus requiring much more energy. So I think that WE MUST THINK FROM HE BEGINNING TO 100% 450°C withstanding probe. This is the problem.

Corrosive air. Venus air is not only very hot, but it contains gasses which, at this temperature, react very vigorously to produce oxygen, sulphur and sulphuric acid, perhaps other acids. This is a problem, and every sensitive parts of a probe (electronic boxes, instruments, motors) will need tight seals.

Structural Materials They will have to withstand heat, but also corrosive air (acid, oxydizing, sulphurizing). Common materials like steel and aluminium alloys are ruled out at once, and even titanium (a steel sructure would burn in only several hours). We must from the very start think at precious metals, special alloys used in aeronautics turbines or nuclear plants, or even ceramics, composite ceramics, etc. Possible but need some development (including a "venusian test chamber").

semiconductors for computers, power control and radio emitters are perhaps the domain where a solution seems the less possible. But there are perhaps hundreds of couples of semiconductor materials, and many common materials become semiconductor at higher temperature, so it would be a really bad luck if we do not find one working at 460°C (perhaps diamond do this). This is a matter of research and development, which can go astray with bad solution for years, or we can be lucky to find a good material quickly. Few researches were done in this domain, as, on Earth, there is alway a mean to offset the electronic in a protected environment. But we do not need the highest performances in a venusian lander.
If really we find no semiconductors living at 460°C, we could go back to... vacuum tubes. Micro-sized, simplified technology with flat electrodes triodes, built with the technologies used for integrated circuits, may have electrical properties undiscernible from a N channel MOSFET transistor, which with we could make computers, power "transistors", etc. And, at 460°, it would need no heater... Here, the question is not to find some elusive material, but to test once if it works or not. The only serious problem I see with those triodes would be that, the anode being as hot as the cathode, it should be made from a much less electropositive metal than the cathode.
Another alternative would be static-electricity actuated micro-relays, which, at sub-micronic size, would be fast enough to build computers. And work with a very wide range of temperature... We could probe lava lakes with this electronics.


Electricity conducting materials pose a problem, as their quality much lowers with temperature. Of the three best metals, aluminium is ruled out, remain silver and copper. Silver is better on Earth, on Venus I do not know, but it may be used exclusivelly for wiring. This arises special problems with power transformers.

For insulators plastics are widely used, as they have two magical properties: when we bend an electrical wire, plastic does not break, and it does not change thickness as a soft material would do. On Venus kapton and even Teflon are out. Remains things such as fiber glass guipures impregnated with some soft mixt. (In ancient times silk guipures were used as insulator in power transformers and turbomachines, while paper ribbons were the rule in telephone cables).

Magnetic materials used in power transformers and motors arise a special cconcern, as at 460° most magnetic materials have degraded quality, if they do not have reached their Curie point (where magnetic properties disappear completelly). Things are still worsened if we consider that all these machines work at at temperature which can be 100°C more than their environment, and this is worsened by degraded electrical and magnetic properties. May be some special alloys or rare earths may still have some interesting efficiency, I do not know. Anyway transformers windings and motor windings would need special techniques, working at higher frequency, or at resonnance (which would require a very precise winding of thin ribbons), and cooling from inside (at least a circulation of fluid to bring it back at ambient temperature).
The alternatives to electromachines are piezoelectric crystals or pneumatic actuators. Piezo crystals can work at high temperature, and a design with a U-shaped crystal oscillating around a shaft may replace an electrical motor.

Lubricants also are a problem. When we think at a lubricant, it is nearby alway to oil, understand an hydrocarbon. No hope for anything such on Venus, the only stable hydrocarbon is methane, and it is not really oily... But basically a lubricant is a liquid which 1) sticks on the parts to lubricate 2) has relatively low fluidity 3)is stable enough (not an emulsion, not solidificate or evaporate) so that it forms a layer between the parts, preventing them from the devastative metal-to-metal contact. Many fluids can do, liquid metals or minerals, eventually mixtures to ensure the right properties. Solid lubricants like graphite or molybdene sulphide can also do, but I do not believe very much o such solution for a long lived mechanism. Once the solid lubricant is gone, it is gone, while a liquid lubricant is alway pumped back to the right place.

Etancheity must be achieved thoroughly, not only from dust, but also from corrosive gasses. Tightness around rotating shafts or parts is usually achieved with elastic materials, but nothing such may exist at 460°. Tight tolerance and wetting the joint with a liquid metal would do the trick, together with a chemical control of the inner atmosphere of the probe.



Energy is perhaps the biggest problem. There is little solar energy on Venus, and no wind, rivers etc. (perhaps some thermics could be used for navigation). A RTG would not be at ease: the thermocouple semiconductors are limited to 300°C. Only thermoionic generators could work.
It exist on Earth generators made of a source of heat (fire) and infrared-sensitive photovoltaic cells. Could some photovoltaic cells be able to harness the abundant infrared emitted by venusian rocks, while being themselves at the same temperature? Why not, you will say. Except that this would violate the second principe of thermodynamics: a one source thermal engine... I wait for explanations of this... or for experiment.



Where to go??? Once visited the basic lava flows of Venus, we shall have many overal explanations of the hystory, structure and compsition of Venus. But after?
My idea is as follows: Venus may have experienced a stage with an Earth-like climate, with water, ocean and plate techtonics. Until the greenhouse effect increases itself and trips out to reach the today conditions. If this is true, the mountain ranges of Venus would be in fact continents (which would maintain their alitude by isostasis, floating on the unerlying basalt mantle, this explaining why they do not collapse witht he high temperature softening the rocks). Maybe the oceans and continents of Venus evolved for two billion years (infered from the increase of Earth continents).
But if so, LIFE HAD GOOD CONDITIONS AND PLENTY OF TIME TO APPEAR ON VENUS. Of course it hopelessly disappeared since, witht the increase of temperature. This increase also destroyed limestone rocks and any trace of coal or oil near the surface. So only very few would remain today.
So the idea is of an aerobot exploring the mountains (cooler places) for years, hovering along the many cliffs and examinating them closely mith a microscopic imager in search of... fossils. Microscopic fossils, but fossils anyway. Large animals? civilization? I don't hope so much, but who knows. At least with what we know of Mars now, we have more chances on Venus.

Sorry for the long post, but it was worth writing it I think.
David
QUOTE (ljk4-1 @ Nov 8 2005, 02:41 PM)
Carl Sagan tried to get references to Venus renamed Cytherian, but his Harvard colleagues in the 1960s felt otherwise on the matter.  I think Cytheria has a definite romantic sound to it.


Before the word became exclusively associated with STDs (as a euphemism), "venereal" would also have had "romantic" associations. Hopefully we won't hear about "cytherean diseases" any time soon.

It should be Cytherea (sith-uh-REE-uh) and Cytherean (sith-uh-REE-un), not Cytheria (sith-EE-ree-uh).

QUOTE
For those who recall the Voyager 2 mission to Uranus in 1986, the planet's name kept getting pronounced differently (with a lower case a) by the media as the probe got closer.  cool.gif
One hopes that a world will not be ignored by science just because its name may sound funny to the public.
*


As a matter of fact, the pronunciation "yoo-RAY-nuss" is erroneous, as in Latin the stress is on the first syllable: "YOO-ruh-nuss". The adjectival form is, however, still Uranian (yoo-RAY-nee-un), which may be in part the source of the confusion.

On the question of how worthwhile it would be to explore the Uranian system -- If I were entitled to have any opinion on the matter at all, I'd think it was remarkably silly to downgrade any of the major planets as "boring". Certainly a planet that's tipped all the way over relative to its orbit is intrinsically interesting. And if Voyager II found nothing particularly fascinating about Uranus' system of icy moons, that is more likely a reflection of the very brief and cursory opportunities it had to examine them. Pretty much every place in the Solar System reveals some strange and unexpected qualities on closer examination. Places as previously dull-seeming as Enceladus and Dione reveal themselves to have remarkable characteristics. I have no doubt but that Miranda, Ariel, Umbriel, Titania and Oberon would be discovered to have be no less wonderful, if we only had a chance to view them over a longer period and up close.
RNeuhaus
QUOTE (ljk4-1 @ Nov 8 2005, 11:22 AM)
While I have no illusions regarding the complexity this would add to such a mission, perhaps the lander could be attached to a balloon that would periodically rise into the cooler heights, then settle down somewhere else for a while.
*

As we know that Venus' atmosphere is very heavy, about 90 times of Earth's ones and it is like that we are about 900 meters under the sea.

Then it is true that when "we" or the robot are on the Venus' surface, then we are going to walk very slow and alike as to swiming under the water, isn't ?

If it is true, so the spacecraft won't need a parachute to land on the Venus' surface when it is above, as an example 1000 meters of surface since the spacecraft, without a parachute will go down like a shipwreck?

Rodolfo
David
QUOTE (RNeuhaus @ Nov 8 2005, 07:20 PM)
If it is true, so the spacecraft won't need a parachute to land on the Venus' surface when it is above, as an example 1000 meters of surface since the spacecraft, without a parachute will go down like a shipwreck?
*


It seems to me you'd still need a parachute to slow your descent through the upper layers of atmosphere. But according to what Bruce is saying, if your craft has enough buoyancy, you don't ever actually need to land; the craft could float in the atmosphere without ever touching down.
RNeuhaus
QUOTE (David @ Nov 8 2005, 02:44 PM)
It seems to me you'd still need a parachute to slow your descent through the upper layers of atmosphere.  But according to what Bruce is saying, if your craft has enough buoyancy, you don't ever actually need to land; the craft could float in the atmosphere without ever touching down.
*

Thanks David.

Now it understand perfectly.

It is very funny to think this strange experience: walk in the air like under the water...

Of course, the buoyance depends upon the relative of density of the body-weight of spacecraft versus the Venusian air. So to land to Venus is by far simpler than to Mars since there is no worry of final thrust before landing the surface.

Rodolfo
tty
QUOTE (David @ Nov 8 2005, 09:44 PM)
It seems to me you'd still need a parachute to slow your descent through the upper layers of atmosphere. 


I don't see why. Normally You use a parachute to do the final braking after a probe has more or less slowed to terminal velocity. In the Cytherean(?) atmosphere terminal velocity would probably be low enough for a "soft" landing (or even zero at some point i. e. floating).

There is another problem though, I seem to remember that more or less all landers have experienced problems or damage in some particular altitude band in the atmosphere, so there may be bad things we know little about there. huh.gif

tty
JRehling
QUOTE (RNeuhaus @ Nov 8 2005, 12:20 PM)
As we know that Venus' atmosphere is very heavy, about 90 times of Earth's ones and it is like that we are about 900 meters under the sea.

Then it is true that when "we" or the robot are on the Venus' surface, then we are going to walk very slow and alike as to swiming under the water, isn't ?

If it is true, so the spacecraft won't need a parachute to land on the Venus' surface when it is above, as an example 1000 meters of surface since the spacecraft, without a parachute will go down like a shipwreck?

Rodolfo
*


Venus's air exerts the same pressure as water 900 m under the sea, but it is by no means as HEAVY as that water, or as viscous. It is possible for a craft to land without a parachute -- modest design factors should still maximize surface area: a needle-shaped craft would smash very hard.

But don't mistake pressure with density and viscosity. These are three separate things. Oil can be lighter than water and at the same time more viscous. Water is not much denser at 90 atmospheres than at 2 atmospheres. Perfect gas laws don't apply to gases, and they certainly don't apply to water! The fact that wood is lighter than water doesn't mean you can swim through wood.
ljk4-1
QUOTE (JRehling @ Nov 8 2005, 04:29 PM)
Venus's air exerts the same pressure as water 900 m under the sea, but it is by no means as HEAVY as that water, or as viscous. It is possible for a craft to land without a parachute -- modest design factors should still maximize surface area: a needle-shaped craft would smash very hard.

But don't mistake pressure with density and viscosity. These are three separate things. Oil can be lighter than water and at the same time more viscous. Water is not much denser at 90 atmospheres than at 2 atmospheres. Perfect gas laws don't apply to gases, and they certainly don't apply to water! The fact that wood is lighter than water doesn't mean you can swim through wood.
*


The later Veneras (9-15) only had to use their aerobreak disk to land safely on Venus once released from the entry shell, the atmosphere is that thick. Imagine something like a coin drifting down to the bottom of a pond, only more stable.

Regarding the protection of the lander from the harsh environment, would it be possible to put some kind of shelter around the lander and its immediate area? I am envisioning a tent made of special materials that would unfold in an area around the lander. Would an inflatable type shelter work? If it could at least reduce the temperature around the lander to make it possible for the machine to last longer and conduct its data gathering, I would consider it worth it.

How about using the surface itself as protection? Could the lander have a way to dig down enough to cover itself with regolith? Would a Deep Space 2 type penetrator work?

These may be seen as "radical" ideas, but for a probe to last on Venus longer than a few hours, the scenario demands radical ideas.
helvick
QUOTE (ljk4-1 @ Nov 8 2005, 10:37 PM)
These may be seen as "radical" ideas, but for a probe to last on Venus longer than a few hours, the scenario demands radical ideas.
*


The problem is that the heat on the venusian surface is just high ambient temperature, diffuse and scorching. Think something like a high pressure kiln that has been burning for millenia so the heat is probably extreme all the way down, or at least down to depths of kilometers so digging in won't help, the heat is constant and everywhere. There is no precipitation to shelter from at low altitudes at any rate so there's no reason to do that.

A high altitude landing on top of Maxwell would be quite a bit cooler with lower temperature and pressure. Still insanely hot and pressurised though.
BruceMoomaw
God, what a flock of questions! Let me answer at least a few of them:

(1) Venus' atmosphere isn't nearly as dense as water -- but it IS dense enough that, as LJK said, the Soviet landers carried out all the final part of their deceleration just using a circular disk (not very wide) fastened to their upper end as a drag brake. (They touched down on a ring fastened to their by a bunch of shock-absorbing struts.)

(2) Venus penetrators are simply not worthwhile -- the surface, after all, is as hot as the atmosphere, and the slim shape of a penetrator makes it much harder to properly thermally insulate its contents.

(3) As for the corrosive atmosphere, there are some worries about that -- but the sulfuric acid in Venus' air is found only in the upper levels at the cloud layer (where its droplet density is actually quite sparse; as with Titan's smog, it's opaque from the outside only because the layer is so spatially thick). There clearly IS something chemically reactive in the trace gases in Venus' hot lower atmosphere, which caused the mysterious set of reactions that caused a large number of the sensors on all four of the Pioneer 13 probes to malfunction at (I believe) 8 km above the surface -- but what that something is we still don't know, despite an entire workshop devoted to the mystery two decades ago. Apparently some substance on the sensors -- probably their insulation -- actually reacted with some trace gas and caught on fire at that height, but we still have no idea just what the reaction actually was, or why the Soviets had no such problem.

(4) The idea of using tiny vacuum tubes on Venus electronics has actually been floated since the late 1970s. But the whole problem of temperature is still huge. On pg. 25-26 of the Solar System Strategic Roadmap report ( http://www.hq.nasa.gov/office/apio/pdf/sol...lar_roadmap.pdf ) -- which was described at the COMPLEX meeting as still mostly valid -- it's noted that we have electronics that can operate at 300 deg C (not 250, as I stated earlier), but we still need 200 degrees higher. Also: "Not all electronic components can or should be implemented in high temperature components. Communications and power electronics have the most payoff. Digital electronics, which have low power dissipation, are best implemented in conventional electronics by using active thermal control." The idea of running the active cooler with a mechanical drive that utilizes the large amount of waste heat from an RTG is mentioned (as a necessity) on pg. 22. For this reason by itself, an RTG seems to be a necessity on any long-lived Venus lander. (A Venus rover that would use just such a system is described at http://www.agu.org/cgi-bin/SFgate/SFgate?&...t;P54A-06" -- although, once again, wheels seem less practical for Venus exploration than an active buoyancy system, utilizing a small steel bellows balloon as described by Victor Kerzhanovich, which allows the rover to glide along just a few meters above the surface and touch down periodicially for sampling.)

(5) As for electric power, I've seen both RTGs and temperature-resistant solar cells mentioned as possibilities (the latter for the bobbing Venus Geoscience Aerobot). There is actually quite a lot of sunlight on Venus' surface -- even given the blocking of sunlight by the cloud layer, it's about half as bright on the Venusian surface as it is on Earth. But another possibility for the VGA is a simple vertical windmill fastened to the gondola, utilizing the flow of dense air past the gondola during descent and ascent to run a generator recharging onboard batteries.

(6) As for the scientific goals of long-lived Venus landers, the Strategic Roadmap places great emphasis on the search for granite or sedimentary rocks that might indicate the presence of oceans on ancient Venus. It's a bit hard to see where we go from there, though. Just finding any sedimentary deposits on Venus that might be able to preserve fossils will be atrociously hard, let alone examining them for microbial or biochemical fossil evidence using in-situ instruments. (Especially since, I imagine, the heat alone will have been likely to break down complex organics even in the interiors of sedimentary rocks.) A sample-return mission would be mindbogglingly difficult and expensive -- the figure of $10 billion has been mentioned in the past, which means that there's an excellent chance that we won't have seen it by mid-century. And indeed the National Research Council, in its review of the Strategic Roadmaps ( http://www.nap.edu/books/0309099439/html/ ), indicates on pg. 18 that the Roadmap errs in describing such an astrobiological goal as the only important goal for Venus exploration -- which will be especially true if it turns out that the massive crustal recycling processes that seem to have occurred on Venus have totally destroyed any ancient crustal rocks. The only workable way to explore Venus would seem to be very incrementally -- checking cautiously with early missions to see if there's anything geologically interesting enough down there to be worth any near-future follow-ups with more technologically sophisticated and much more expensive later landers.
Waspie_Dwarf
QUOTE (ljk4-1 @ Nov 8 2005, 09:37 PM)
The later Veneras (9-15) only had to use their aerobreak disk to land safely on Venus once released from the entry shell, the atmosphere is that thick.  Imagine something like a coin drifting down to the bottom of a pond, only more stable.
*


I can see the sense in this system. With these Venera craft having such a short life span it would be imperative to get them onto the surface as quickly as possible. The last thing you would want is for the spacecraft to die whilst it is still dangling from a parachute.

Does anyone know at what altitude the craft seperated from the aero-sheild / parachute?

QUOTE
But another possibility for the VGA is a simple vertical windmill fastened to the gondola, utilizing the flow of dense air past the gondola during descent and ascent to run a generator recharging onboard batteries.


Does this system actually make sense? For a short lived vehicle the battery life isn't the major consideration. The craft itself is likely to die before the batteries. For a long lived craft then the amount of battery time conserved is negligable compared to the life of the probe.

Even on a short lived lander this system would only make any sense to me if the windmill / battery recharging system were to offer a weight reduction over the additional batteries required for the re-entry landing phase of the mission. Even then the added complexity of the system makes it more likely to fail, actually reducing the lifetime of the lander.
Jeff7
I'm not quite sure of something here, probably due to my limited knowledge of the subject smile.gif :
As I understand it, an RTG relies on a difference in temperature to cause a thermocouple to produce current flow. If both the RTG and the environment are hot, how's it going to produce power?
Rakhir
QUOTE (Waspie_Dwarf @ Nov 9 2005, 02:23 AM)
I can see the sense in this system. With these Venera craft having such a short life span it would be imperative to get them onto the surface as quickly as possible. The last thing you would want is for the spacecraft to die whilst it is still dangling from a parachute.

Does anyone know at what altitude the craft seperated from the aero-sheild / parachute?
*


For Venera-9 and -10, main parachutes were jettisoned at the altitude of 50 kilometers above the surface.

http://www.russianspaceweb.com/venera75.html

Rakhir
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