It's the start of a tough week for the North American Space Agency (NASA) after hearing about the loss of their longest-serving astronaut.
John Young passed away on the night of January 5th in Houston, Texas following complications from pneumonia at the age of 87.
He retired in 2004 after 42 years with the U.S. space agency, and became famous around the world for being one of the few men to have walked on the moon and the first to fly a space shuttle.
Young was in the same astronaut class as other space legends like Neil Armstrong, Pete Conrad, and James Lovell in 1962.
He received more than 80 major honors and awards, including four honorary doctorate degrees.
Young walked on the moon in 1972, and even managed to smuggle a corned beef sandwich into orbit.
The former U.S. Navy test pilot went to space six times and was the ninth person to set foot on the moon. He flew into space twice during NASA's Gemini program in the '60s, twice on the Apollo lunar missions and twice on space shuttles in the 80s.
"Astronaut John Young's storied career spanned three generations of spaceflight. We will stand on his shoulders as we look toward the next human frontier," NASA Administrator Robert Lightfoot said in a statement.
His fellow space travelers and fans gave their condolences on Twitter.
"John was more than a good friend," former President George H. W. Bush said in a statement. "He was a fearless patriot whose courage and commitment to duty helped our nation push back the horizon of discovery at a critical time."
"John Young is one of my heroes, an astronaut's astronaut, a fearless individual and a good friend. Godspeed," wrote Canadian astronaut Chris Hadfield.
"To Commander John Young, thank you for your amazing service not only to Americans but to the world with your extraordinary insight of the exploration or space. We honor you & are indebted for opening our eyes to endless possibilities. To your family, we mourn your deep loss," wrote one Twitter user.
Young leaves behind his wife Susy Feldman and his two children, Sandra and John.
"We will stand on his shoulders as we look toward the next human frontier," Lightfoot said.