In 1752, he was invited to assist professor Knud Leem in his efforts to create a Sámi dictionary, all the while pursuing his studies at the Trondheim Cathedral School.
In 1764, Porsanger returned to Trondheim to provide further support to Knud Leem while concurrently serving as a hospital priest.
In 1769, the College of Mission in Copenhagen summoned him to address a proposal from the Hungarian Jesuit scientist-priest János Sajnovics.
Sajnovics and astronomer Maximilian Hell's visit to Vadsø in order to observe the Venus transit in 1769 revealed that Sámi and Hungarian shared linguistic roots.
While on a journey to Copenhagen to seek a new ecclesiastical position, he, along with his family, perished in a shipwreck near the town of Risør.