Traveling through the area of today's northern South Africa and central and southern Namibia he founded the mission stations at Bethanie and Steinkopf and discovered the natural harbour at Walvis Bay.

Schmelen was born into a middle-class family on 7 January 1776 in Kassebruch, today a suburb of Hagen im Bremischen in the German state of Lower Saxony.

He accompanied Christian Albrecht to Pella in the Northern Cape from where he traveled the Oranje to serve a number of small nomadic pastoral tribes.

He then traveled further north until approximately 22 degrees latitude but returned and founded a missionary station for Amraal Lambert's clan of the Kaiǀkhauan (Khauas Nama) people.

After a drought and a locust plague befell Bethanie, which was blamed on his anger towards the community, he closed the missionary station[3] in 1822[2] and returned to the shore of the Oranje.

[3] Schmelen set off to a second northwards journey in 1824 or 1825, again with the aim to find a hospitable place at the coast to improve logistics for the support of the missionaries in the hinterland.

They followed the ephemeral Kuiseb River and made contact with the Topnaar Nama at Rooibank (Scheppmannsdorf during Imperial Germany's colonial rule of South-West Africa).

[10] After several years of criss-crossing the vast area of Namaland, Schmelen owned neither shoes nor clothes and dressed himself with hides until in 1818 he got the opportunity to travel to Cape Town to procure new essentials.

[4] Four children emerged from this marriage, one son who died early, and three daughters, Hanna, who married Franz Heinrich Kleinschmidt,[12] Johanna, and Friederike.