The James Webb Space Telescope has arrived in space at its destination 1.5 million kilometers from Earth.
The telescope threw on its engines for five minutes on Monday and reached the so-called second Lagrange point (L2), as the US space agency Nasa announced.
"Webb, welcome home," said NASA CEO Bill Nelson.
“We are one step closer to discovering the mysteries of the universe.
I can't wait to see Webb's first new take on the universe this summer."
The James Webb Telescope is designed to explore the early days of the universe 13 billion years ago, just a few hundred million years after the Big Bang.
Astronomers hope to draw conclusions about the formation of the first stars and galaxies.
The most powerful telescope to date far exceeds its predecessor Hubble in size and complexity.
It looks further into space than Hubble and therefore further back into the past.
Webb focuses on infrared radiation.
An Ariane 5 rocket launched the Webb telescope on Christmas Day from the Kourou Cosmodrome in French Guiana.
Named after a former director of the US Space Agency, the telescope was jointly developed by NASA, the European Space Agency ESA and the Canadian Space Agency CSA.
The Max Planck Institute for Astronomy, the University of Cologne and several German companies also took part.