Christie's hopes the bottle, now up for grabs in a private sale, will fetch $1 million, which would make it the most expensive wine ever sold.

The bottle is one of a batch of 12 that European startup Space Cargo Unlimited sent into orbit as part of research into how food and drink matures in space.

The wine spent almost 440 days in space, or the equivalent of 300 trips to the Moon, Space Cargo Unlimited Nicolas Gaume said in a press release.

It left for the ISS on November 2, 2019 in a spacecraft known as a Cygnus capsule and returned on January 14, 2021 aboard a Dragon capsule manufactured by Elon Musk's SpaceX.

Tests carried out in March by a wine science institute in Bordeaux found that the bottles "positively endured all the constraints of preparation, travel, and storage on the ISS," Christie's said in its press release.

At the end of a blind tasting, the researchers noted "remarkable differences in the colour, aroma and taste components," between the celestial bottles and equivalents which had remained on earth.

"The wines sampled were commended for their complexity and considered to be great wines," Christie's added.

The sale is expected to smash the record price for a standard 750 ml bottle of wine.

The most expensive was a 1945 Romanee-Conti Burgundy which sold at Sotheby's in New York for $558,000 in 2018.

The private sale means the buyer and price will remain confidential unless the buyer chooses to identify themselves publicly.

Proceeds will go towards funding future space missions focused on agricultural research.

Petrus, from the Pomerol region near Bordeaux, is considered one of the world's finest wines. A classic bottle of Petrus 2000, considered a great vintage, currently sells for around 4,500 euros ($5,400).