In proposing a mission to Mars, George Bush is joining a long line of American presidents who have sought immortal fame with a "big idea".
Bush is not the first president to have sought a 'big idea'
The ideas are often the results of a crisis. Some touch the deepest emotions of the nation and the world; some are worthy but unworkable and some are the product of public relations. History tends to be the judge as to which is which.
I have chosen five examples from the last 100 years. I could have gone back further, of course, to the vision, for example, of Thomas Jefferson who sent Lewis and Clark to explore the American continent in 1804.
Then there was the greatest big idea perhaps of all, that of Abraham Lincoln, who declared on the civil war battlefield at Gettysburg that "government of the people, by the people, for the people shall not perish from this earth".
'Safe for democracy'
But nearer our time, one could start with President Woodrow Wilson, who declared in 1917 that the world must be made "safe for democracy".
Wilson was in fact asking Congress to declare war on Germany following Germany's decision to engage in unrestricted submarine warfare.
But he wanted to elevate war into something noble.
He stated: "The world must be made safe for democracy. Its peace must be planted upon the tested foundations of political liberty. We have no selfish ends to serve.
"We desire no conquest, no dominion. We seek no indemnities for ourselves, no material compensation for the sacrifices we shall freely make.
"We are but one of the champions of the rights of mankind."
The world, as we know, was not made safe for democracy by that war.
'Only thing we have to fear is fear itself'
Another idea which emerged from a deep crisis, in this case an economic one, was the New Deal proposed by Franklin Delano Roosevelt.
In his inaugural speech to Congress in 1933, in the depth of the depression, he produced the phrase which summed up his aim of tackling the depression head on:
"Let me assert my firm belief that the only thing we have to fear is fear itself - nameless, unreasoning, unjustified terror which paralyses needed efforts to convert retreat into advance."
Historians argue about whether the New Deal actually worked for America. It certainly worked for President Roosevelt.
Man on the moon
The closest precedent for Mr Bush is of course the pledge by President John Kennedy to send a man to the moon.
This nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon
He stated his ambition in a "special message to the Congress on urgent national needs" in May, 1961.
Kennedy was in trouble at the time. His presidency had started badly with the failed attack on Cuba. In his speech he referred to the Soviet advances in space and said that space was part of "the battle that is now going on around the world between freedom and tyranny".
And he declared: "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth."
The goal was achieved. Neil Armstrong stepped onto the moon on 20 July 1969. Kennedy did not live to see it.
Kennedy's successor Lyndon Johnson promoted the Great Society, a proclamation of civil rights from a southern president. He proposed it in a speech to the University of Michigan in 1964.
"We have the opportunity to move not only toward the rich society and the powerful society, but upward to the Great Society.
"The Great Society rests on abundance and liberty for all. It demands an end to poverty and racial injustice, to which we are totally committed in our time."
Johnson made progress towards his Great Society but in the end his presidency was destroyed by the Vietnam war.
'Curing this dread disease'
Then there was Richard Nixon and his war on cancer. This is a largely forgotten big idea. At the time it was made, in his State of the Union message in 1971, it seemed a good idea. The hope was that a cure could be found by the end of the century or even earlier.
"The time has come in America when the same kind of concentrated effort that split the atom and took man to the moon should be turned toward curing this dread disease. Let us make a total national commitment to achieve this goal.
"America has long been the wealthiest nation in the world. Now it is time we became the healthiest nation in the world."
Nixon hoped this would be what he was remembered for.
"I hope that in the years ahead that we look back on this as being the most significant action taken during this administration," he said.
He was remembered for something else. And the war on cancer is not over.