The world’s largest aircraft, developed by Microsoft co-founder Paul Allen’s aerospace firm, emerged from its hangar in California desert for the first time on Wednesday. “This is a first-of-its-kind aircraft, so we are going to be diligent throughout testing,” Jean Flyod, chief executive at Allen’s firm Stratolaunch Systems Corporation, said in a blog.

The Stratolaunch aircraft, which has the largest plane wingspan measuring 385 feet, is powered by six 747 aircraft engines and is designed to launch rockets into space from the air. The aircraft is 238 feet long from nose to tail and is 50 feet high from the ground. It has 28 wheels and can carry more than 500,000 pounds of payload.

The Stratolaunch was announced in 2011 and is expected to be demonstrated in 2019, reported AFP. The aerospace firm will soon test its fuel systems and engines before the demonstration.

In the past, Allen had said that the project would be a more cost-effective option for cargo and human missions sent to space. “We could deploy more satellites that would enable better understanding of why our weather patterns are changing and help increase agricultural productivity,” he had said last year according to Telegraph.