Baku's Foreign Ministry announced that the U.S. astronaut -- a member of the Apollo 16 mission in 1972 -- has been barred from entering the country.
Seems he and Swiss astronaut Claude Nicollier -- who is also now persona non grata in Baku -- attended an international space conference on September 16 in Stepanakert, the capital of Nagorno-Karabakh, the predominately ethnic-Armenian separatist enclave in Azerbaijan.
The conference was dedicated to Neil Armstrong, the first human to set foot on the moon, who died August 25.
Azerbaijani officials said anyone entering the breakaway region without preliminary consultations with Baku automatically becomes persona non grata in Azerbaijan.
In addition to being the 10th man of 12 to walk on the moon, Duke also holds the distinction of being the youngest person to do so. He was 36 years old when he made his moon walk as part of NASA's fifth manned lunar-landing mission.
(Interestingly, he was also the capcom, or capsule communicator, at Mission Control in Houston for Apollo 11 when Armstrong and fellow astronaut Buzz Aldrin first landed on the moon in July 1969. After Armstrong and Aldrin landed safely, and Armstrong announced the historic moment with his famous, "Houston, Tranquility Base here, the 'Eagle' has landed," Duke responded with his almost-equally-famous, "Roger, Tranquility, we copy you on the ground. You've got a bunch of guys about to turn blue. We're breathing again. Thanks a lot.")
As for Nicollier, he flew on four missions on the U.S. space shuttle program from 1992 to 1999 and became the first astronaut from the European Space Agency to participate in a spacewalk aboard the shuttle.
Why hold a space conference in Nagorno-Karabakh, you might ask? Nagorno-Karabakh's acting education and science minister, Vladik Khachatryan, answered that question in a message addressed to the conference:
It may be stretching things a bit, but Nagorno-Karabakh may have been a fitting place for a space conference after all.
Armenia and Azerbaijan have been in conflict for decades over the disputed enclave, with a fragile cease-fire in place since 1994. It's known as one of the post-Soviet "frozen conflicts" still plaguing the region. And the moon holds the distinction of being the coldest place in our solar system.