Writing out the suggested solution a bit more neatly, and highlighting the crucial bits, we get:
Code:
8LONG:-RRU145GTW12.61.32
BU06JF538.0 615 LYBODY 3
F663I574+5 6435TY-TR3544
G7.- 64.W RT-4.H 4JT4D5
T-47E3.6E-T.2.4E75-41ST
YR546-9-SRHW12 46TY3- Y
4T:P72 DTT8R G24G.762-
PYGH-1EE G-4+RD..4 .743
The above text is simply the result of applying a cylinder cipher with stride 8. This fits very nicely for a few reasons:
- The key is provided: the highlighted digit 8 is the first character of the message
- Little waste: the secret message is spread through the entire length of the LP ciphertext
- It fits the typical pattern of Listening Post puzzles.
By that last point I mean, that typically LP puzzles followed a set pattern. By visiting multiple listening posts, you would get different but linked messages that would all indicate a rough distance (allowing triangulation), would typically put the target latitude and longitude in different messages, and would put different parts of the body identification in each message. In the case of the Adamastor puzzle, the one distance (615 LY) is here and rather precise, while a second less-precise distance (300 LY from a nebula) is given at the Sidewinder. Similarly, we have the longitude of Geo Survey 23B here, and the latitude in the Adamastor ship log. Finally, we have the body number here (BODY 3), and the star class and body type (M class ... metal) in the Adamastor log.
The only real oddity is the line break between LONG:- and 38.0. One wonders if there is perhaps a typo that adds an extra character in the LP message, because otherwise the decoded message would fit neatly on the first rank of descrambled text. Or perhaps it was intentional, to make the solution a little harder to spot.