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informant
2002-Feb-15, 08:07 AM
Forgive my ignorance, but I wasn't able to find an answer to this. What is the temperature on Venus in the night side?

GrapesOfWrath
2002-Feb-15, 09:42 AM
Good question. Venus (http://www.planetscapes.com/solar/eng/venus.htm) has a mean surface temperature of 482 degrees C, and a "day" of 243 earth days. That's probably make for some great extremes. Plus, a pressure of 92 earth atmospheres, and wind speeds of 350kph (http://www.nineplanets.org/venus.html
).

DStahl
2002-Feb-15, 09:46 AM
I hope that ignorance is easily forgiven, 'cause I've got plenty of it!

Facts on Venus' atmosphere, hot from NASA:

Surface Pressure: 92 bars
Surface Density: ~65. kg/m3
Scale height: 15.9 km
Average temperature: 737 K
Diurnal temperature range: ~0
Wind speeds: 0.3 to 1.0 m/s (surface)
Mean molecular weight: 43.45 g/mole
Atmospheric composition (near surface, by volume):
Major: 96.5% Carbon Dioxide (CO2), 3.5% Nitrogen (N2)
Minor (ppm): Sulfur Dioxide (SO2) - 150; Argon (Ar) - 70; Water (H2O) - 20; Carbon Monoxide (CO) - 17; Helium (He) - 12; Neon (Ne) - 7

I think when they say the diurnal temperature variation is just about zero it means that even in Venus' long night it's darned hot. This stuff comes from the Venus Fact Sheet (http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html).

(Hey, Grapes, you posted whilst I was banging my ten thumbs on the keyboard. Cheers!)

--Don Stahl


<font size=-1>[ This Message was edited by: DStahl on 2002-02-15 05:00 ]</font>

GrapesOfWrath
2002-Feb-15, 10:31 AM
On 2002-02-15 04:46, DStahl wrote:
(Hey, Grapes, you posted whilst I was banging my ten thumbs on the keyboard. Cheers!)
Good morning!

Those NASA webpages don't list anything for Mercury, Jupiter, or Saturn of course, but it lists a diurnal temperature range of 283 K to 293 K for Earth (http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html), ">100 K to <400 K (roughly -250 F to +250 F)" for the moon (http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html), and "184 K to 242 K (Viking 1 Lander site)" for Mars (http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html).

Earth's is reported as +/- 5K. I suppose that's about zero, also, but Venus has a lot longer days. More atmosphere, though.

informant
2002-Feb-15, 01:04 PM
Thank you.
I had this whacky idea of sending probes to Venus's dark side, 'cause it wouldn't be as hot as the bright side. Obviously, I was wrong.
Of course it would be pitch black, and there would still be that bonecrushing pressure...
I suppose we can blame the fast winds for Venus's hot nights.

Kaptain K
2002-Feb-15, 03:17 PM
Just had an interesting idea (ouch, my brain hurts /phpBB/images/smiles/icon_eek.gif ). Seems to me that a good first step toward terraforming Venus would be to nudge one of the major asteroids into an orbit that would result in a tangential impact with Venus. This would have two beneficial results: 1) it would boost the rotational speed and 2) it would (maybe) blow off some of that oppressive atmosphere!
Two caveats: 1) I know that moving major asteroids is WAY beyond our current abilities and 2) I haven't done any calculations, so I don't know if it it would be sufficient to either speed up the rotation or blow off a significant portion of the atmosphere. But it is food for thought.

GrapesOfWrath
2002-Feb-15, 03:28 PM
1) We could use Planet X.
2) I think the instructions are in one of the Velikovsky books.
3) Can we do Mars too, for us guys?

Wiley
2002-Feb-15, 03:50 PM
On 2002-02-15 05:31, GrapesOfWrath wrote:

Those NASA webpages don't list anything for Mercury, Jupiter, or Saturn of course, but it lists a diurnal temperature range of 283 K to 293 K for Earth (http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html), ">100 K to <400 K (roughly -250 F to +250 F)" for the moon (http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html), and "184 K to 242 K (Viking 1 Lander site)" for Mars (http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html).

Earth's is reported as +/- 5K. I suppose that's about zero, also, but Venus has a lot longer days. More atmosphere, though.



It seems to me that Venus, being just lousy with clouds, would have very little temperature variation. A place sans atmosphere, like the Moon, has an enormous temperature delta.

The data supplied by GoW and DStahl seem to verify this.

Valiant Dancer
2002-Feb-15, 06:48 PM
On 2002-02-15 08:04, informant wrote:
Thank you.
I had this whacky idea of sending probes to Venus's dark side, 'cause it wouldn't be as hot as the bright side. Obviously, I was wrong.
Of course it would be pitch black, and there would still be that bonecrushing pressure...
I suppose we can blame the fast winds for Venus's hot nights.

That's up to debate. During the Magellan project, the data from the mapping portion indicated a geologically dead surface relatively new in origin. Several theories came up. One was that Venus had a thick lithosphere and the heat was due primarily to the cloud cover. One was that Venus had a thin lithosphere and could radiate the heat through the surface directly. The reason for the young but dead lithosphere was that periodically, the internal temperature of Venus got so great as to completely melt the crust. After the planet cooled again, the crust would re-solidify. (Thick lithosphere proponents suggested this.)

There is no doubt that Venus is hellishly hot, but the main cause of failure of probes was pressure coupled with the highly acidic atmosphere. So far, top duration for a Venus surface lander is 1 hour. (set by a Russian probe.)

Good idea, just the atmospheric factors worked against it this time.

link Nova program transcript 17 October, 1995. "Venus Unveiled"

http://www.pbs.org/wgbh/nova/transcripts/2210venus.html

edited to correct errors and add link
_________________
Valiant Dancer



<font size=-1>[ This Message was edited by: Valiant Dancer on 2002-02-15 13:56 ]</font>

Espritch
2002-Feb-15, 09:44 PM
That brings up some questions. How many Venura type probes did the Russians send to Venus? Has anyone else ever landed a probe on Venus? And are there any current plans to do so in the future?

Chip
2002-Feb-15, 10:05 PM
On 2002-02-15 16:44, Espritch wrote:
That brings up some questions. How many Venura type probes did the Russians send to Venus? Has anyone else ever landed a probe on Venus? And are there any current plans to do so in the future?


Here's the Venura history (http://nssdc.gsfc.nasa.gov/planetary/venera.html). 16 Venuras were sent to Venus. Many failures before success.

Venera 7 (Russia)
First to return data from Venus or any other planet* in the solar system. (1970) (*Planets not moons.)

Venera 9 (Russia)
First spacecraft to send back pictures from the surface of Venus. (1975)

Pioneer Venus (USA)
First acurate mapping of the surface of Venus. (1978)

I know of no short term future plans, but it would be great if we had a long lasting orbiting platform around Venus.

<font size=-1>[ This Message was edited by: Chip on 2002-02-15 17:06 ]</font>

Espritch
2002-Feb-15, 10:30 PM
Thanks for the link. I didn't realize they had sent so many landers. It listed 8 that actually touched down. Didn't they try to put a lander on Mars 14 times without success? You would think, given the hellish surface conditions, that Venus would be a lot harder to land on.

I guess all their best people were on the Venera project. /phpBB/images/smiles/icon_smile.gif

<font size=-1>[ This Message was edited by: Espritch on 2002-02-15 17:31 ]</font>

Simon
2002-Feb-16, 01:11 PM
On 2002-02-15 13:48, Valiant Dancer wrote:
There is no doubt that Venus is hellishly hot, but the main cause of failure of probes was pressure coupled with the highly acidic atmosphere. So far, top duration for a Venus surface lander is 1 hour. (set by a Russian probe.)


I was wondering, just how harsh would conditions be on Venus's surface? I mean, I know most of the numbers, but I don't know what kind of impact they would have on equipment. Robotic submarines take pressure far greater than 80-90 atmospheres, and it seems that it should be possible to shield against a corrosive atmosphere... I suppose those things would make a spacecraft heavier and more expensive, but still...

Thargoid
2002-Feb-18, 06:12 AM
http://web.utk.edu/~rhatcher/terraform.swf

Note: I did this in one day for a seminar class on Flash 5, and there was little to no proof-reading. Also, that "newly liberated oxygen" comes from disassociated CO2, which is processed from the condensed atmosphere. Yeah, I should have read over it more than once... Nonetheless, arbitrarily advanced tech. civilizations are fun, aren't they? /phpBB/images/smiles/icon_smile.gif

<font size=-1>[ This Message was edited by: Thargoid on 2002-02-18 01:14 ]</font>

<font size=-1>[ This Message was edited by: Thargoid on 2002-02-18 01:14 ]</font>

m1omg
2007-Aug-21, 04:51 PM
I was wondering, just how harsh would conditions be on Venus's surface? I mean, I know most of the numbers, but I don't know what kind of impact they would have on equipment. Robotic submarines take pressure far greater than 80-90 atmospheres, and it seems that it should be possible to shield against a corrosive atmosphere... I suppose those things would make a spacecraft heavier and more expensive, but still...

The problem is that complex microelectronics are fryed by such temperatures.
Corrosive atmosphere is not a problem, it is corrosive only when you are in clouds and it is H2SO4 that will not corrode many common metals and glass.
One proposal is sending a rover without complex microelectronics and a solar powered aircraft carrying these sensitive components flying high above the surface where the conditions are relatively mild that will be radio connected to the "dumb rover"; http://en.wikipedia.org/wiki/Observations_and_explorations_of_Venus#Proposals .

Materials are absolutely no problem because even a candle flame is much hotter than the surface of Venus.
Just do it pressure resistant and you have a functional probe.

novaderrik
2007-Aug-21, 06:18 PM
.

Materials are absolutely no problem because even a candle flame is much hotter than the surface of Venus.
Just do it pressure resistant and you have a functional probe.
wow. .gotta be about the oldest thread ever brought back from the dead.
at what temp does the solder that holds the "dumb" rover's electronics together melt? you'd need some high temp wire insulation, as well.
i think thepressure is the easy thing to deal with- it's the heat and corrosive effects that are the show stopper.

Swift
2007-Aug-21, 07:09 PM
<snip>
Materials are absolutely no problem because even a candle flame is much hotter than the surface of Venus.
Just do it pressure resistant and you have a functional probe.
Having worked with various high temperature and high pressure equipment in corrosive environments (though they were designed to keep the nasty stuff in, not out), I would say it is a little bit of a stretch to say "no problem". Solvable, but not no problem.

By the way, this website (http://www.mentallandscape.com/V_Venus.htm) has some great stuff about the Soviet's explorations of Venus. From that website:

Conditions on Venus are extraordinarily harsh: ~100 atmospheres of pressure, temperatures of 475 C (890 F) and the chemical actions of sulphuric acid. Under these conditions, common materials like aluminum and glass soften or melt, titanium and magnesium can combust, and organic compounds can pyrolyze or dissolve in the supercritical carbon dioxide. Later American probes would be partially disabled by chemical corrosion, short circuits caused by condensation of unknown conductive substances and mysterious mid-air electrical shocks. There is still much that is not known about this environment.

The core of the descent vehicle was a spherical titanium hull about 80 cm in diameter. It was formed in several sections, bolted and sealed with gold-wire gaskets. That was covered in a 12 cm layer of thermal insulation (a composite honeycomb material) and a thin outer skin of titanium. The pressure hull was lined inside with insulation, possibly layers of fiberglass and metal foil. A large thermal accumulator of lithium nitrate trihydrate and a circulating fan distributed and absorbed excess heat. This lithium salt has a high specific heat of fusion, like ice, but melting at 30 C.

AK
2007-Aug-22, 07:13 AM
American probes?

Tim Thompson
2007-Aug-22, 07:39 AM
On a historical note, the fact that Venus is as warm on the nightside as on the dayside was first revealed by thermocouple infrared observations made at Mt. Wilson Observatory (http://www.mtwilson.edu/), and the 100-inch Hooker Telescope (http://www.mtwilson.edu/vir/100/), by Edison Pettit (http://en.wikipedia.org/wiki/Edison_Pettit) & Seth Nicholson (http://www.phys-astro.sonoma.edu/BruceMedalists/Nicholson/index.html), in the early 1920's (Pettit & Nicholson, 1924a (http://adsabs.harvard.edu/abs/1924PA.....32Q.614P), Pettit & Nicholson, 1924b (http://adsabs.harvard.edu/abs/1924PASP...36..227P), Pettit & Nicholson, 1955 (http://adsabs.harvard.edu/abs/1955PASP...67..293P)). So this is not a discovery made by spacecraft, but rather by old fashioned, ground based astronomy, over 80 years ago.

Radrook
2007-Aug-24, 04:38 PM
Here is what I found on the temerature question:

Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of Venus' surface does not vary significantly between the night and day sides, despite the planet's extremely slow rotation....


The surface of Venus is effectively isothermal; it retains a constant temperature between day and night and between the equator and the poles.[20][21] The planet's minute axial tilt (less than three degrees, compared with 23 degrees for Earth), also minimises seasonal temperature variation.[22] The only appreciable variation in temperature occurs with altitude

http://en.wikipedia.org/wiki/Venus_planet)