IPB

Welcome Guest ( Log In | Register )

9 Pages V  « < 3 4 5 6 7 > »   
Reply to this topicStart new topic
Venera Images, VENERA 13 fully calibrated image
tasp
post Jan 10 2006, 06:30 PM
Post #61


Member
***

Group: Members
Posts: 885
Joined: 30-January 05
Member No.: 162



{ I hope I phrase this well enough }

Does any one know the cooling rate for 'earth type' basaltic magma from the time of contact with liquid water to the point it has solidified as compared to the expected cooling rate for the Venusian equivalent of basaltic magma from the time of contact with the Venusian atmosphere to the point of solidification?

Is 1300 psi (or whatever it works out to) CO2 more heat absorbing than H2O at 15 psi ?

Funny if the magma on Venus solidifies faster than the magma on earth in contact with sea water.

Would this effect the forms of the rocks we expect to see?
Go to the top of the page
 
+Quote Post
JRehling
post Jan 10 2006, 06:50 PM
Post #62


Senior Member
****

Group: Members
Posts: 1572
Joined: 20-April 05
Member No.: 321



QUOTE (tasp @ Jan 10 2006, 10:30 AM)
{ I hope I phrase this well enough }

Does any one know the cooling rate for 'earth type' basaltic magma from the time of contact with liquid water to the point it has solidified as compared to the expected cooling rate for the Venusian equivalent of basaltic magma from the time of contact with the Venusian atmosphere to the point of solidification?

Is 1300 psi (or whatever it works out to) CO2 more heat absorbing than H2O at 15 psi ?

Funny if the magma on Venus solidifies faster than the magma on earth in contact with sea water.

Would this effect the forms of the rocks we expect to see?
*


Sea water on Earth is only at 15 psi at the shoreline (eg, on a beach). The pressure is much higher in locations of typical seafloor magma exposure, and would certainly have a much higher thermal inertia than Venus's CO2. It's also much cooler, which is another factor in the speed of heat propagation.

Water, even at 15 psi, is roughly 1000 times as dense as Earth air. Sea water is even denser. Venus's surface atmosphere is very roughly (no time for math now!) 75 times as dense as Earth air.

Anyone who has stood in a 10 km/h breeze and has also been hit by a 10 km/h ocean wave will appreciate the vast difference. Venus's atmosphere is in the middle.
Go to the top of the page
 
+Quote Post
RNeuhaus
post Jan 10 2006, 07:30 PM
Post #63


Senior Member
****

Group: Members
Posts: 1636
Joined: 9-May 05
From: Lima, Peru
Member No.: 385



QUOTE (RNeuhaus @ Jan 10 2006, 11:57 AM)
Why such strange physics laws? 

Venus has very small Tilt of axis (degrees 177.36), so Venus has no typical summer and winter and the temperature in Equatorial line must be warmer all round year and the poles which are not zenith and receive less solar energy and consequently must be cooler but the greenhouse effect might alter these physics laws. 

Why is warmer at its poles than its equator and also of nights versus days?
It would be very good that you find the link about the above odd behavior.

Rodolfo
*

I found an article which mentions about the temperature of day and night and also of polars: The polar temperature is compensated by the thermal regime of Venus in spite of the fact of the temperatures inhomogenitis between equator and poles that arise from the differential insolation. On the other hand, the night-side temperatures exceed day-side temperatures according to the authors. The thermal asymmetry of Venus was confirmed by data from infrarred radiometry on Venera 9 and Venera 10 orbiters, and in particular from the analysis of limb darkening. The variation of temperature between day and night is due mainly to a change in height of the emissivity layer in the vicinity of upper cloud deck (65-68 km).

Interesting smile.gif

More detail, click here

Rodolfo
Go to the top of the page
 
+Quote Post
tedstryk
post Jan 11 2006, 02:49 PM
Post #64


Interplanetary Dumpster Diver
****

Group: Moderator
Posts: 4241
Joined: 17-February 04
From: Powell, TN
Member No.: 33



Here are two more shots. An improved horizon pan:



And an improved version of that cool looking rock formation.



--------------------
Go to the top of the page
 
+Quote Post
paxdan
post Jan 11 2006, 04:02 PM
Post #65


Member
***

Group: Members
Posts: 557
Joined: 29-March 05
Member No.: 221



Looks to me that if you flipped the rock over it matches with the surface immediately above it
Go to the top of the page
 
+Quote Post
tedstryk
post Jan 11 2006, 04:35 PM
Post #66


Interplanetary Dumpster Diver
****

Group: Moderator
Posts: 4241
Joined: 17-February 04
From: Powell, TN
Member No.: 33



QUOTE (paxdan @ Jan 11 2006, 04:02 PM)
Looks to me that if you flipped the rock over it matches with the surface immediately above it
*


The only problem is that in the full pan, there are many spots that look like the area above the formation with no rock sitting next to them.


--------------------
Go to the top of the page
 
+Quote Post
Michael Capobian...
post Jan 11 2006, 05:00 PM
Post #67


Member
***

Group: Members
Posts: 104
Joined: 6-November 05
From: So. Maryland, USA
Member No.: 544



Does anyone else remember the "fact" that refraction in the dense Venusian atmosphere would be so strong that you could see the back of your own head? I remember puzzling over that for hours as a kid, but I never really believed it.

Michael


QUOTE (JRehling @ Jan 10 2006, 01:50 PM)
Sea water on Earth is only at 15 psi at the shoreline (eg, on a beach). The pressure is much higher in locations of typical seafloor magma exposure, and would certainly have a much higher thermal inertia than Venus's CO2. It's also much cooler, which is another factor in the speed of heat propagation.

Water, even at 15 psi, is roughly 1000 times as dense as Earth air. Sea water is even denser. Venus's surface atmosphere is very roughly (no time for math now!) 75 times as dense as Earth air.

Anyone who has stood in a 10 km/h breeze and has also been hit by a 10 km/h ocean wave will appreciate the vast difference. Venus's atmosphere is in the middle.
*
Go to the top of the page
 
+Quote Post
Toma B
post Jan 11 2006, 05:13 PM
Post #68


Member
***

Group: Members
Posts: 619
Joined: 9-May 05
From: Subotica
Member No.: 384



I heard about refraction in Venusian atmosphere...something like "you would have feeling that you are walkin at the bottom of crater with very steep walls even if you are on flat ground...don't remember quite well about that but, seeing the back of your own head????I HAVE NEVER HEARD SOMETHING LIKE THAT...please explain...


--------------------
The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.
Jules H. Poincare

My "Astrophotos" gallery on flickr...
Go to the top of the page
 
+Quote Post
tedstryk
post Jan 11 2006, 05:41 PM
Post #69


Interplanetary Dumpster Diver
****

Group: Moderator
Posts: 4241
Joined: 17-February 04
From: Powell, TN
Member No.: 33



QUOTE (Toma B @ Jan 11 2006, 05:13 PM)
I heard about refraction in Venusian atmosphere...something like "you would have feeling that you are walkin at the bottom of crater with very steep walls even if you are on flat ground...don't remember quite well about that but, seeing the back of your own head????I HAVE NEVER HEARD SOMETHING LIKE THAT...please explain...
*



That was an old theory, but turned out not to be the case. The Veneras showed the horizon just where it should be, when corrected for their odd imaging system.


--------------------
Go to the top of the page
 
+Quote Post
helvick
post Jan 11 2006, 06:43 PM
Post #70


Dublin Correspondent
****

Group: Admin
Posts: 1797
Joined: 28-March 05
From: Celbridge, Ireland
Member No.: 220



QUOTE (Toma B @ Jan 11 2006, 06:13 PM)
I heard about refraction in Venusian atmosphere...something like "you would have feeling that you are walkin at the bottom of crater with very steep walls even if you are on flat ground.
*

I seriously doubt that.

For starters refraction effects happen at interfaces or across density gradients. For the sort of effects described here you would need to have really bizarre density gradients all around you.

Things would probably look a bit different and heat shimmer effects might be more pronounced than on earth but they would be far less extreme than under water on earth for example.

The refractive index of CO2 at STP is 1.000449 (air is 1.000292). The refractive index of a gas changes (very approximately) with density according to (RIx=1+(RIstp-1)*(Dx/Dstp) so the RI of the venusian surface atmosphere is somewhere around 1.04041 (since the Venusian surface atmospheric density is approximately 90x the density of CO2 at STP).

Snells law gives us something to calculate what this would mean for a human in a spacesuit on the surface of Venus. Assuming we have an optically neutral window and we simplify the calculation down to an air (at stp) CO2 (at Venus surface) boundary.
Snell's law : RIi*Sin(Thetai)=RIr*Sin(Thetar)
Thetai = Incident beam angle and Thetar= Refracted beam angle
So Sin(Thetar)=1.000292*(sin(45deg)/1.04041
The refracted beam would be at 42.8deg. Noticable but not significant.
As a comparison for a water:air interface on earth the equivalent refracted beam would be at 32.9deg.

All in all it might be hard to play pool well on the surface of Venus but it certainly wouldn't create any bizarre visual effects.
Go to the top of the page
 
+Quote Post
JRehling
post Jan 11 2006, 07:06 PM
Post #71


Senior Member
****

Group: Members
Posts: 1572
Joined: 20-April 05
Member No.: 321



QUOTE (helvick @ Jan 11 2006, 10:43 AM)
All in all it might be hard to play pool well on the surface of Venus but it certainly wouldn't create any bizarre visual effects.
*


Unless you count two scorched and imploded skeletons slumped over an incinerated pool table as a bizarre visual effect.
Go to the top of the page
 
+Quote Post
ljk4-1
post Jan 11 2006, 07:20 PM
Post #72


Senior Member
****

Group: Members
Posts: 2454
Joined: 8-July 05
From: NGC 5907
Member No.: 430



Don Dixon made some paintings of the alleged super refraction of Venus' atmosphere from the surface here:

http://www.cosmographica.com/gallery/portf...fraction%20.htm

http://www.cosmographica.com/gallery/portf...097-Inferno.htm

As a bonus, here is Dixon's rendition of what the Pioneer Venus Day Probe probably looked like as it sat on the planet's surface and radioed back to Earth for 67 minutes in 1978:

http://www.cosmographica.com/gallery/portf...enusLanding.htm


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

Go to the top of the page
 
+Quote Post
Toma B
post Jan 11 2006, 07:27 PM
Post #73


Member
***

Group: Members
Posts: 619
Joined: 9-May 05
From: Subotica
Member No.: 384



QUOTE (ljk4-1 @ Jan 11 2006, 10:20 PM)
Don Dixon made some paintings of the alleged super refraction of Venus' atmosphere from the surface here:
*

...but now we know that's not true don't we? sad.gif
ljk thank you for that links....those images really rock!!!


--------------------
The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.
Jules H. Poincare

My "Astrophotos" gallery on flickr...
Go to the top of the page
 
+Quote Post
ljk4-1
post Jan 11 2006, 07:29 PM
Post #74


Senior Member
****

Group: Members
Posts: 2454
Joined: 8-July 05
From: NGC 5907
Member No.: 430



QUOTE (Toma B @ Jan 11 2006, 02:27 PM)
...but now we know that's not true don't we? sad.gif
*


Yes, if you will note from his headers, the paintings were made in the 1968 to 1974 period, and Dixon even labels one as outdated.

I just thought since super refraction was being talked about here, some folks might enjoy seeing a Venus that never was. smile.gif


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post Jan 12 2006, 01:47 AM
Post #75





Guests






Yes, the first shots of Venus from Venera 9 and 10 turned out to be remarkable for their sheer ordinariness. Not only was there no super-refractive "swimming pool effect" (which had recently become a staple of SF stories about the planet; John Varley's first published story used it and was called "In the Bowl"), but even in those grainy photos it was clear that the horizon was fairly sharp and that the shadows even of small pebbles, despite the dense atmosphere, were quite sharp. In fact, the Soviets had equipped the two landers with floodlights on the assumption that the solar illumination might be too dim to see the surface otherwise! The much better photos from Venera 13 and 14, of course, confirmed all this even more dramatically (and also revealed that fiery orange sky, although I don't know whether that color was predicted in advance).

Scientists have, really, a pretty bad track record when it comes to predicting the optical qualities of surface photos. Remember how astonished everyone was when Viking 1's first black-and-white photos showed a light-colored sky (which later turned out to be pink) instead of the deep violet sky everyone had expected? They even predicted that deep violet sky again for Pathfinder, since there was less dust in the air at the time of its landing.
Go to the top of the page
 
+Quote Post

9 Pages V  « < 3 4 5 6 7 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 26th October 2014 - 04:24 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.