re: Your image failed.
That Sputnik has a double rim. This isn't seen with impact craters, but it is seen with volcanic vents and craters.
The Sputnik image and the images mentioned from the "Pyroclastic Landforms and Pyroclasts" online lecture are available on the bautforum.com bbs. You'll have to register with the site if you're not already a member to view them:
Sputnik crater as a volcanic vent.
http://bautforum.com/showpost.php?p=1020731&postcount=436
Bob Clark
