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>.

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

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.

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.

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.

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

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.

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.

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).



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.

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

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

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.

tty

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.