Thought I'd start a new topic for the HiRISE images of the Viking 1 and 2 landers:
QUOTEViking 1's sterilized protective aeroshell (left) gouged out a small crater, half a mile (750 metres) north of the lander site itself (small arrow). The crater (large arrow) was not discovered until orbiter pictures were analysed in 1987.
QUOTEUnfortunately the reference you are looking for as never been published in a peer-reviewed journal. While still at NASA Goddard, Jim Garvin together with Olivier de Goursac from France's Promospace determined what would have been the most likely trajectory for the Viking aeroshell. They then examined photographs of the landing area taken after the spacecraft was on the surface and suggested that a small depression may have been created by the aeroshell. All of this came out in a half-page article in Aviation Week and Space Technology published on June 22, 1987, pages 84-85. The article does not reference an author. I asked Jim as to how the article got published, but that was years ago and I can't remember the story now.
Unfortunately, the book didn't offer any references for the picture; however, four years ago I contacted Bob Craddock at NASM. Years earlier, he had submitted an abstract to the 1994 Mars Environmental Survey workshop entitled "Rationale for a Mars Pathfinder Mission to Chryse Planitia (20 Degrees N, 40 Degrees W) and the Viking 1 Lander." His abstract suggested that MPF could examine the hole gouged out by the VL1 aeroshell, and I thought he might be able to track down the reference I was looking for.