After meeting the archaeologist and diplomat, Ephraim George Squier, Heine was invited to accompany him, as an artist, on his consular duties to Central America.
Proceeding ahead of Squier, he collected and recorded indigenous plants and animals and compiled notes for future publications.
Until Squier arrived, Heine stood in as consul, negotiating a commercial agreement between the Central American countries and the United States, which he delivered to Washington.
Nominally attached to Perry's expedition as an Acting Master's Mate; he served on the flagship USS Mississippi under Sydney Smith Lee.
The sketches he produced of the places he visited and the people he encountered there, together with the daguerreotypes taken by his colleague Eliphalet Brown Jr., formed the basis of an official iconography of the American expedition to Japan which remains an important record of the country as it was before the foreigners arrived in force.
This was taken up and while in Berlin he received an invitation to join the Eulenberg Expedition as official artist once again, and was simultaneously given a premium to send back reports for a Köln newspaper.
[2] Eventually, in 1864, he published his major work, a voluminous book on travel in the Orient, Eine Weltreise um die nördliche Hemisphäre in Verbindung mit der Ostasiatischen Expedition in den Jahren 1860 und 1861 (Leipzig, two volumes).