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Update: Newly published paper in Nature Geoscience Atmospheric mountain wave generation on Venus and its influence on the solid planet’s rotation rate has open-access links in Science News, Motherboard, and Science.

There is a stationary gravity wave in Venus's very dense atmosphere. It is intermittent, but has been detected several times. See the NYTimes article Venus Smiled, With a Mysterious Wave Across Its Atmosphere for a discussion of recent observations by JAXA. See Akatsuki and Happy Birthday, Akatsuki!, celebrating it's first Venusian year at Venus.

Considering the extremely high density of the atmosphere near the surface, would it be possible for a suitably shaped spacecraft to "surf" or somehow remain aloft in this wave without propulsion, or even use it to rise high in the atmosphere, taking vertical data (e.g. composition, temperature, radar surface imagery and doppler profiling) and then gently return to the surface?

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above: "A sequence of images showing the stationary nature of the bow-shape wave above Venus when it was observed in December 2015. Planet-C" from NYTimes. credit: Planet-C/JAXA

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above: "An illustration of how gravity waves travel up mountains and into Venus’s atmosphere. Credit ESA" From How Mountains Obscured by Venus’s Clouds Reveal Themselves.

uhoh
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    You could use a balloon if you could make it out of a material that could withstand the heat and the chemical reactions (e.g., I recall Venus having sulfuric acid in its atmosphere). – honeste_vivere Jan 30 '17 at 14:25
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    @honeste_vivere I'm asking about a craft using this articular atmospheric phenomenon to rise to high altitude without using propulsion. e.g. a glider. A balloon can generate lift on its own \on Venus anytime, anywhere, and so wouldn't be related to this question, would it? – uhoh Jan 30 '17 at 17:28
  • Oh, I apologize. I saw the question title and thought you meant lateral displacement, not vertical. However, would the physics not be the same? Technically, the buoyancy force is the same thing as what air planes use to generate lift, i.e., they "push" down enough air to generate a counter force that lifts them up. If the object displaces more air mass than its own mass, it should "float," should it not? – honeste_vivere Jan 30 '17 at 17:31
  • @honeste_vivere I rode in gliders as a passenger when I was young, on Earth :) I remember the glider pilot always explaining to me that he was looking for "thermals" - vertically rising columns of air, that would physically lift the glider up to higher and higher altitudes. Birds of prey do it as well. Gliders and birds are not buoyant, but they use - let's call it a vertical wind - to gain altitude. See "Most exploit meteorological phenomena to maintain or even gain height." in https://en.wikipedia.org/wiki/Glider_(aircraft). – uhoh Jan 30 '17 at 17:52
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    Ah yes, that is slightly different. In that case, they are still relying upon a pressure gradient but instead of "pushing air down" there is an unbalanced dynamic pressure due to the rising air. Okay, I think I am starting to see what your are thinking about... – honeste_vivere Jan 30 '17 at 18:48
  • If I've read some articles well, the "wave" is not moving as to the surface of Venus because it's caused by a high mountain plateau, so at one side you could gain altitude and maybe get above the plateau and leave it on the other side but then your wave is over, i think. – Cornelis Oct 04 '18 at 18:03
  • @Conelisinspace right. That's why I've asked "would it be possible for a suitably shaped spacecraft to "surf" or somehow remain aloft in this wave without propulsion, or even use it to rise high in the atmosphere, taking vertical data (e.g. composition, temperature, radar surface imagery and doppler profiling) and then gently return to the surface?" I think if you can get a density and a velocity, you can probably come up with a good answer here. You remain stationary by balancing all of the forces involved. https://www.youtube.com/watch?v=lhkhqkBC2EU – uhoh Oct 04 '18 at 18:06
  • So should not the question be, "how can we get the density and the vertical velocity in those gravity waves ? – Cornelis Oct 05 '18 at 08:32
  • @Conelisinspace some question could be that certainly, but my question is the one posted. – uhoh Oct 05 '18 at 10:35
  • I've learned from you that it is not good practice to start a question with "Would it be possible…..?" I don't understand what the problem is, if gliders do well here on Earth, why should they not in this wave ? – Cornelis Oct 05 '18 at 10:45
  • But this question looks beautiful and is worthwhile reading, so can't you create some more attention for it ? :) – Cornelis Oct 05 '18 at 12:17
  • @Conelisinspace yes, "Would it be possible to X" questions are often poorly received but apparently not always. When X is implausible or vague or outlandish, or when it would take an astronomical amount of time and/or resources, then the question is often poorly received. However for this question, these are not the case. I've asked about a highly plausible scenario (dense atmosphere, high wind velocity with documented vertical component) and included several references as well. – uhoh Oct 05 '18 at 12:33
  • Have you ever ride a wave ? There's still a strong horizontal component from the zonal winds ! Could a glider beat up against that wind ? – Cornelis Oct 13 '18 at 11:41
  • @Conelisinspace check the video again in my previous comment and consider ways that shifting your weight on the board allows you to vary the balance between horizontal and vertical forces. – uhoh Oct 13 '18 at 11:47
  • Interesting comparison, but the glider will never get on the horizontal winds like the surfer does on the water. I think the illustration of the gravity waves is too simple, the horiziontal winds will push that waves from the side. – Cornelis Oct 13 '18 at 12:14
  • @Conelisinspace consider adding this to your answer? Comments should be for clarification of the question, not an ongoing discussion or exploration. – uhoh Oct 13 '18 at 12:24
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    O.k. , i'll think about it. Gliders could be very succesful within the polar vortices of Venus. https://en.wikipedia.org/wiki/Polar_vortex – Cornelis Oct 13 '18 at 12:53
  • Science news says the planet's spin is speeded up, but i've read on Wiki Venus rotation has slowed down in 16 years. And Nature geoscience says a change in rotation rate of 2 minutes by the gravity waves could explain the difference in rotation rates measured by spacecraft. So isn't Science news wrong ? – Cornelis Nov 20 '19 at 16:29
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    @Cornelisinspace If you think you've found a contradiction, why not ask about it in a new question? That will allow other users to look into it as well. This is a specific question and will have a clear answer, so I think you can ask it in a way that's both on-topic and not too broad. – uhoh Nov 20 '19 at 22:37
  • I was not sure enough that it was indeed a contradiction, and i don't like to be embarrassed ! Thank you for your support. – Cornelis Nov 20 '19 at 23:29

1 Answers1

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The density of carbon dioxide on Venus varies from about 67 kg/m3 at the surface to about 52 kg/m3 at a height of about 5 km, calculated with this software tool

Average wind speed Venus

Image from Solar Powered Flight on Venus

According to the graph above and Appendix A from the article the wind speed on Venus varies from 0.6 m/sec at the surface to 1.2 m/sec at a height of 5 km.

The dynamic force at the surface on 1 square meter would be: 1/2 x 67 kg/m$^3$ x (0.6$)^2$ m$^2$/sec$^2$ x 1 m$^2$ = 12.06 kgm/sec$^2$.

The dynamic force at a height of 5 km on 1 m$^2$ would be: 1/2 x 52 kg/m$^3$ x (1.2)$^2$ m$^2$/sec$^2$ x 1 m$^2$ = 37.44 kgm/sec$^2$.

Aphrodite Terra is the highland region near the equator that causes the wave in the atmosphere and looking at the image of its topography its height will be 5-7 km.
So we could assume that at a height of 5 km near the border of the highland the horizontal wind of 1.2 km/sec would be forced to go vertical, so the vertical dynamic force there would be about 37 kgm/sec$^2$.

So with a surface gravity of Venus being 8.87 m/sec$^2$ and a horizontal surface area of 1 m$^2$ for the spacecraft it probably could have a mass of a few kg to stay above the highland region !

Cornelis
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  • Thanks for the excellent analysis! I can't find a suitable humorous image to go along with "Surf's up!" right now nor 1950's movie clip in YouTube, but I'll keep an eye out for one. – uhoh Oct 12 '18 at 11:07
  • @uhoh It could be that my analysis is much to simple. – Cornelis Oct 12 '18 at 11:36
  • It is simple because the angle of the wind above horizontal is not taken into account yet, but it seems there's plenty of room for reduction and still some kind of surfing air vehicle would at least stay aloft. I think a more in depth analysis is certainly possible but not necessary. – uhoh Oct 12 '18 at 13:57
  • @uhoh Is an in depth analysis possible if we don't have the necessary measurements ? – Cornelis Oct 12 '18 at 14:13
  • it depends on the analysis but like I said, "not necessary." You called your own analysis "much to simple." – uhoh Oct 12 '18 at 16:55
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    @uhoh O.K, thank you for being informed about this interesting " wave ". – Cornelis Oct 12 '18 at 17:49
  • @uhoh Made an edit, the wind speed at 5 km height seems to be considerably lower than assumed before. So it would have to be a very slim surfer to ride the wave ! – Cornelis Apr 03 '20 at 17:19
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    Oh, I see what you mean, thanks for the update. Well if a suitable suit could be manufactured then one of these surfing dogs might be able to give it a try :-) – uhoh Apr 03 '20 at 22:30
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    @uhoh Great video, and nothing against dogs, but concerning the exploration of Venus i think even today's robots would be better in balancing the board. :-) – Cornelis Apr 04 '20 at 09:01
  • The CO2 density looks very small for me. Its pressure is 93 bar, van der waals equation gives about 400 kg/m3 for that. – peterh May 15 '21 at 13:16
  • @peterh I got 92.1 atm and 462⁰ C at the surface from wiki. Did you take into account the high temperature ? – Cornelis May 15 '21 at 13:47
  • @Cornelis Yes. Probably there are some gas law calculators on the net. – peterh May 15 '21 at 14:40
  • I checked here: http://calistry.org/calculate/vanDerWaalsCalculator the post seems okay. – peterh May 15 '21 at 14:49
  • @peterh Don't you trust the peace software link in the answer ? Seems a lot easier to use. :) – Cornelis May 15 '21 at 14:56