Conversation so far:
What happened in 1903?
As the first significant person to return from the Antarctic, he found that he was in demand.
In demand for what?
the Admiralty wished to consult him about its further proposals for the rescue of Discovery.
What are some other interesting aspects about this article?
In search of more permanent employment, Shackleton applied for a regular commission in the Royal Navy, via the back-door route of the Supplementary List.
Why was he applying for employment?
he was not successful.
Instead, he became a journalist, working for the Royal Magazine, but he found this unsatisfactory.
Why was it unsatisfactory?
CANNOTANSWER.

Question: What else did he do in his career?
Self-contained rewrite: Aside from his Antarctic return and journalism, what else did Ernest Shackleton do in his career