Two original Tintin comic strips are expected to break records on Saturday when they go under the hammer in Paris.
The first from "Explorers on the Moon", widely regarded as one of the two best Tintin adventures, could fetch up to up to $1 million.
The page, entitled "We walk on the moon", has the boy reporter, his dog Snowy and blundering sidekick Captain Haddock making their first moon walk from their red and white rocket.
With the 1954 book viewed as one of the artist Herge's masterpieces, the Paris auction house Artcurial values it at least 900,000 Euros ($950,000).
The late Belgian artist already holds the world record for the sale of a comic strip.
A double-page ink drawing that served as the inside cover for all the Tintin adventures published between 1937 and 1958, sold for $3.7 million to an American fan two years ago.
Saturday's sales are expected to break records for single strips.
Rival auction house Christie's is putting drawings from another rare Herge strip up for sale later in the day in Paris.
It said the page from the unfinished story "Tintin and the Thermozero" -- estimated at 250,000 Euros -- was the first ever to come to market.
Why the artist never finished the tale of espionage and a terrifying secret weapon set against the backdrop of the Cold War, is one of the great mysteries for Tintin-ologists.
Herge wrestled with it for years, "starting it at the end of the 1950s", said Christie's, but never got further than eight pages.
Drunk Captain Haddock
Artcurial's comics expert Eric Leroy described the "Explorers on the Moon" as "a key moment in the history of comic book art... it has become mythic for many lovers and collectors of comic strips.
"It is one of the most important from Herge's postwar period, on the same level as 'Tintin in Tibet' and 'The Castafiore Emerald'," he added.
The story completes the lunar adventure started in "Destination Moon" (1953) and features several hilarious episodes including Haddock getting drunk on whisky and floating off into space to briefly become a satellite of the asteroid Adonis.
It turns on Tintin foiling a plot by a mysterious foreign power to hijack the rocket by the evil stowaway spy Colonel Jorgen.
The moon drawings are being sold alongside 20 ink sketches Herge created for a series of New Year's greeting cards known as his "snow cards".
The cards are expected to go for between 60,000 and 120,000 euros each, Artcurial estimate.
Prices for cartoon art have multiplied tenfold in the last decade, according to gallery owner Daniel Maghen, who also works with comic art.
The sales comes as Tintinmania again grips the French capital, with Herge currently the subject of a huge retrospective exhibition at the Grand Palais.