Among others exhibiting similar variations, these sentences appear in DWDS:
Um eine echte Atmosphäre aus Partikeln und Gas festzuhalten, ist Merkurs Schwerkraft einfach zu schwach.
"Wir nehmen die gesamte Sonnenscheibe auf, dadurch ist das Signal der Exosphäre Merkurs winzig.
In the first case the genitive of the proper name appears before that which it possesses, and in the second it appears after, both without an article.
Now, I was taught that, if the genitive appears after that which it possesses, it is preceded by an article, usually a definite one, or a properly declined adjective. But these examples suggest that there are actually 4 options. The genitive may be before or after, and with or without an article in either. Are these the options or are there rules of which I am unaware that would restrict the choice of options?