USSR Probes on Venus

[Cham]

Here's a small addon placing all the USSR probes on Venus (all Venera and Vega missions) :

Corrected flipped coordinates :

USSR_Venus_Probes.zip

Please, report any comment and error here.

[rthorvald]

Here's a small addon placing all the USSR probes on Venus (all Venera and Vega missions) :

Hey, very nice!
I?ll provide some feedback after i have completed the Vega XYZ.

- rthorvald

[BobHegwood]

Thanks once again, Martin...

Damn, you spend more time with Celestia-related activity than I do, and that's hard for me to believe.
As always though, much appreciated at this end.

[Cham]

Please guys, I want to cross check all the positions (even if I'm pretty sure the locations are all right). Could you find a map of Venus with the landing sites indicated ?

[BobHegwood]

Please guys, I want to cross check all the positions (even if I'm pretty sure the locations are all right). Could you find a map of Venus with the landing sites indicated ?

Best I could find was HERE, Martin. Hope that helps.

[Cham]

Thanks a lot Bob.

The texture on this pict is very hard to recognise, but I was able to use it and ... well, the match isn't right. Apparently, there's a 180 degrees flip.

EDIT : Okay, I changed the sign of all the coordinates I used, and now the match appears to be very good. I'll have to update the linked file in my first post above.

[chris]

Thanks a lot Bob.

The texture on this pict is very hard to recognise, but I was able to use it and ... well, the match isn't right. Apparently, there's a 180 degrees flip.

Probably the usual confusion between the IAU's planetographic coordinate convention and the one that is mathematically sensible. There's a disagreement when between the two systems when the planet in question is a retrograde rotator. Invert the latitude and longitude and you should be ok.

--Chris

[chris]

Thanks a lot Bob.

The texture on this pict is very hard to recognise, but I was able to use it and ... well, the match isn't right. Apparently, there's a 180 degrees flip.

Probably the usual confusion between the IAU's planetographic coordinate convention and the one that is mathematically sensible. There's a disagreement when between the two systems when the planet in question is a retrograde rotator. Invert the latitude and longitude and you should be ok.

This issue has been discussed before:

viewtopic.php?f=2&t=12343&p=102906&hilit=iau+retrograde#p102904

--Chris

[Cham]

Chris,

when you say "invert", do you mean a simple change of sign of BOTH coordinates ? Or something like 180 - old, or something else ? Sorry if I'm dense.

[chris]

Chris,

when you say "invert", do you mean a simple change of sign of BOTH cordinates ? Or something like 360 - old, or something else ? Sorry if I'm dense.

Right: a simple sign change of both coordinates will do the trick. Calculating the longitude as 360-old longitude will also work--it's equivalent to flipping the sign, but harder to calculate

--Chris

[Cham]

Thanks. I'm doing the changes.

All these coordinates orientations sucks ! I was suspecting something like this inversion, in the case of Venus.

I want to see another map, to doublecheck the positions...

[BobHegwood]

Right: a simple sign change of both coordinates will do the trick. Calculating the longitude as 360-old longitude will also work--it's equivalent to flipping the sign, but harder to calculate

If you don't mind a quick aside here...
Is this the reason that Venus is approached - in a CEL script for example - and then arrived at with the planet in an upside down position?

[chris]

Right: a simple sign change of both coordinates will do the trick. Calculating the longitude as 360-old longitude will also work--it's equivalent to flipping the sign, but harder to calculate

If you don't mind a quick aside here...
Is this the reason that Venus is approached - in a CEL script for example - and then arrived at with the planet in an upside down position?

Probably . . . But whether you think it's upside down depends on your definition of what right side up is

--Chris

[Cham]

I just updated the file linked to the first message.

[chris]

Right: a simple sign change of both coordinates will do the trick. Calculating the longitude as 360-old longitude will also work--it's equivalent to flipping the sign, but harder to calculate

If you don't mind a quick aside here...
Is this the reason that Venus is approached - in a CEL script for example - and then arrived at with the planet in an upside down position?

Probably . . . But whether you think it's upside down depends on your definition of what right side up is I regard the IAU's decision to use 'ecliptic north' instead of 'rotational north' as a poor choice. Rotational north (i.e. the north pole is the one at which a observer would see the planet rotating counterclockwise) is mathematically well-defined. Ecliptic north is a poor choice for three reasons:
- The north pole is undefined when the axis of rotation is parallel to the ecliptic plane
- The north direction could even change periodically for a precessing object--there are undoubtedly a few small bodies in the solar system with a pole that precesses through the ecliptic plane.
- By definition, ecliptic north makes no sense outside our own solar system; while we won't be mapping the surfaces of extrasolar planets in the foreseeable future, it is conceivable that we might be able to observe features on large stars.

--Chris

[BobHegwood]

I know that Venus is upside-down because it is rotating in the same direction as all of the other non-retrograde bodies in the Solar System. That's all I meant by "upside-down" but thanks very much for this useful explanation. As always much appreciated by the Brain-Dead.

[BobHegwood]

I just updated the file linked to the first message.

Thanks again, Martin. I tried to find other maps for the surface locations of the spacecraft, but apparently, they are hard to come by.
Have downloaded the updated file, and thanks once again.

[BobHegwood]

Martin,

I did manage to find a PDF document which contains another map of the landing sites, but I seem to have lost the URL. Would you like me to e-mail you a copy of the PDF file?

Thanks, Bob

[Cham]

Sure Bob. Send it to me right away !

[Cham]

Bob,

thanks a lot for the PDF document !

Landing on Venus: Past and future
A.T. Basilevsky, M.A. Ivanov, J.W. Head, M. Aittola, J. Raitala

This PDF document is very precise, and the match is perfect with the coordinates I used. It confirms the locations of most probes in my SSC file