The 73-year-old King Maha Vajiralongkorn – a trained military pilot and long-time aviation enthusiast – and Queen Suthida smiled and waved at the astronauts, who appeared via a large screen from the Tiangong, or “Heavenly Palace”, space station.

The encounter, which took place on Sunday at the Beijing Aerospace Flight Control Centre (BACC), was part of a five-day state visit, the first official trip to the Chinese mainland by a Thai monarch for 800 years. It is also 50 years since the two countries established modern diplomatic ties.

The visit has been widely viewed as a sign that Bangkok is looking to deepen its engagement with Beijing, particularly in hi-tech cooperation, even as it remains a military ally of the United States.

The rare high-level tour of the mission control centre also pointed to fast-growing collaboration between the two countries in the space sector, building on earlier work in satellite data use and technical training.

Thailand has already contributed an instrument to next year’s Chang’e-7 lunar mission. The device, developed by the National Astronomical Research Institute of Thailand, will study cosmic radiation and solar storms while orbiting the moon.

China is collaborating with several countries in space. For example, two Pakistani candidates are currently in training under a bilateral programme, with one expected to become the first foreign astronaut to visit the Tiangong on a short mission.

During their tour on Sunday, the royal couple also visited the China Academy of Space Technology – the main developer of the country’s satellites and spacecraft – and the China Astronaut Research and Training Centre.