First steps: What would first human on Mars say?
Neil Armstrong is a very hard act to follow.
The words he used after stepping off the lunar lander are arguably the most famous ever uttered and perhaps an impossible act to follow should we ever go to Mars.
But what would the first human on the Red Planet try to say, to encapsulate the thoughts of a watching globe as they watch our first visit to another planet?
The BBC has asked readers for their suggestions via the Twitter hashtag #BBCMARS as part of the BBC News special How to put a human on Mars, which describes a concept mission to the planet designed by scientists at Imperial College London.
"Sending a man or a woman where they've never been before would be a massive achievement and it would excite the whole world," says Martin Archer, a space plasma physicist who worked on the Imperial College design team.
"If I were to be the first to set foot on Mars, I think I'd have to go back to the Roman mythology and Mars was the god of war and I'd say 'We as a race step foot on this planet in peace not war'."
Mystery still surrounds when and where Armstrong's first words were crafted. The late astronaut maintained they came to him only after landing on the Moon.
But in a 2012 BBC film, Neil Armstrong - First man on the Moon, his brother Dean gives another account in which he and his brother were playing the board game Risk before the Apollo 11 mission.
"During the game, he slipped me a piece of paper and said, 'Read that'. I did," he told the documentary makers.
"On that piece of paper there was, 'That's one small step for man, one giant leap for mankind'. He says, 'What do you think about that?' I said, 'Fabulous'. He said, 'I thought you might like that, but I wanted you to read it'."
The circumstances of a Mars landing would be different to 1969. The crew would have been in space not for four days before landing, as with Apollo 11, but at least nine months and would emerge into a butterscotch atmosphere where winds or sand storms might be blowing.
Unless we create some form of artificial gravity, as the Imperial team propose, they may also have experienced substantial muscle and bone loss en route due to weightlessness, which could leave them struggling even to make those first steps once in Martian gravity.
The radio signals back to Earth would take not a second or so as with Armstrong, but 3-20 minutes depending on the alignment of Earth and Mars, which means the first human on Mars would utter those first words in total isolation.
There would be no conversation with Houston, just a human talking alone.
"I suspect the first words would be written for them in all honesty," says Dr Simon Foster, a space physicist and another member of the Imperial design team.
"Just like Neil Armstrong's word, they're going to echo for the rest of time for human kind. They are going to be words that every human being will know and that kind of responsibility is huge."
Ideas for first words from BBC readers included a satirical suggestion from astronomer Nick Howes: "Why has it taken so long to take the next giant leap for humanity?"
Paul Phillips tweeted "Here Rover... come on boy!"
Shakespeare Today, an account which finds a quote from the Bard for modern times, tweeted from Henry VI part 2: "Well, for this night we will repose us here: /To-morrow toward London back again."
David Spencer wrote: "I've made a huge mistake."
While Sunil Gogna suggested we just repeat a proven formula: "The same as the great Neil Armstrong's on the moon."
But perhaps the most poignant comment came not from a human, but "a robot".
In a message to BBC News, the social media team behind Nasa's Curiosity Rover account tweeted: "I look forward to footprints next to my rover tracks. Data I collect will help future human explorers."