IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Venus landing sites
Guest_PhilCo126_*
post Dec 29 2007, 10:59 AM
Post #1





Guests






Didn't notice any topic on the landing sites on the sister-planet of our Earth, so I started a topic on landing sites on Venus unsure.gif
Looks like the Soviet-Russian Venera 14 (landed March 1982) and American Pioneer Venus 2 day probe (landed December 1978) came 'close' together:
Go to the top of the page
 
+Quote Post
JRehling
post Dec 29 2007, 10:15 PM
Post #2


Senior Member
****

Group: Members
Posts: 2530
Joined: 20-April 05
Member No.: 321



I never worked out the details, but I assume that the narrow longitudinal range among most landing sites is an artifact of the near-synchrony between Venus's rotation and the synodic period between Earth and Venus. What this means is that for the minimal-energy trajectory, Venus is always oriented about the same way (WRT the Sun and the Earth) every time. The only desirable landing sites are in the longitudes that face the Earth and are also in daylight (to enable surface imaging). Venus was about half-full when VEx arrived, so that should have been the same situation when all previous landers have arrived, effectively limiting the landing sites to about 1/4 of the planet, with further constraints on latitude, and still further longitudinal constraints owing to entry mechanics.

By expending a bit more energy for the cruise phase, or by taking a more roundabout path, a craft could meet the daylight+Earth contact constraints and land elsewhere. A relay satellite could also provide that flexibility. Or, as was done with one of the Pioneer probes, dropping it into the night side.
Go to the top of the page
 
+Quote Post
edstrick
post Dec 30 2007, 10:35 AM
Post #3


Senior Member
****

Group: Members
Posts: 1870
Joined: 20-February 05
Member No.: 174



The early venera landers, #'s 3 through 8, were "lob it at the planet" designs, went in on high inclination cannonball trajectories. The later Veneras, I suspect but haven't checked, probably came in at shallower angles, though they still used spherical entry shells.
Go to the top of the page
 
+Quote Post
Phil Stooke
post Dec 31 2007, 01:04 AM
Post #4


Solar System Cartographer
****

Group: Members
Posts: 10127
Joined: 5-April 05
From: Canada
Member No.: 227



My version of the map. The sites aren't really so clustered.

Phil

Attached Image


--------------------
... because the Solar System ain't gonna map itself.

Also to be found posting similar content on https://mastodon.social/@PhilStooke
NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain)
Go to the top of the page
 
+Quote Post
JRehling
post Dec 31 2007, 05:20 AM
Post #5


Senior Member
****

Group: Members
Posts: 2530
Joined: 20-April 05
Member No.: 321



All told, they're pretty well distributed, but the four Veneras that returned surface imagery are within a mere 19 degrees of longitude of one another. It's this slice of the planet where I think most craft that have the same goal would end up landing unless a specific effort is made to diversify.
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 28th March 2024 - 07:45 PM
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 funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.