The director of Nasa's Mars exploration programme has spoken of hopes that one day the rover Curiosity might be brought back to Earth by astronauts.
Doug McCuistion said it was his personal hope that humans would visit the Red Planet in the 2030s or 2040s.
He said he could imagine astronauts walking up to Curiosity.
McCuistion said the roving laboratory's mission was scheduled to last two years, but it could have enough power for 20 years.
The Nasa chief set out his vision during a satellite link up with Glenelg in the Scottish Highlands at the weekend.
The community of about 280 people has twinned itself with a site on Mars that Nasa has labelled Glenelg.
McCuistion said: "It is my hope that humans will be sent to Mars in the 2030s, or 2040s, and they will be able to walk up to Curiosity and bring it back, as I am sure there is a museum out there that would love to have it."
Plutonium generators that deliver heat and electricity to Curiosity could continue working long after the rover completes its mission.
But McCuistion said wear and tear of working parts were likely to bring an end to Curiosity's life before the generators.
A meteorite strike - the Red Planet is scarred with thousands of such impacts - is another possible threat to the rover.
McCuistion said: "If we put humans on Mars they are going to have to watch for those meteorites."
Retired astronaut Bonnie Dunbar, a veteran of five space shuttle flights, also told the event in Glenelg of her desire to see humans on Mars.
She said: "It is not a question of if, but when and who."
Attending the twinning ceremony in person, Dunbar said it was important future generations took an interest in science and maths. Algebra was key to her career as an engineer working on space shuttles, and later as an astronaut flying in them.
Looking around the marquee where she delivered her talk, she said: "I am counting on some of these young people in here to get us to Mars before I am gone."
Dunbar was also keen to debunk suggestions the 1969 Moon Landing was faked.
She said: "At Nasa I worked with John Young, an astronaut who walked on the Moon."
Dunbar added: "I grew up watching Flash Gordon, which were popular at the time of the landing. In those shows who can see the wires holding up the spaceships."
The former astronaut said wires cannot be seen in the Moon Landing and the special effects were not available 43 years ago to fake the footage.