Pablo Martinez Monsivais / AP

Almost two years ago, with no regard for safety precautions or protocol, President Donald Trump faced the sun head-on. As the rest of us watched the solar eclipse through specially purchased glasses or cereal boxes outfitted with X-acto-knifed slots, President Trump squinted unblinkingly into the bright, unfiltered sunlight and emerged unscathed. Then, on Friday, he came for the moon.

Less than three months ago, Vice President Mike Pence announced that the Trump administration’s goal of sending a crew to the moon by 2028 would be accelerated by four years; in the past month, the president has said that he wants an additional $1.6 billion dedicated to that aim. But in a tweet sent Friday afternoon, the president chastised NASA for doing exactly the job he’d instructed it to do. “NASA should NOT be talking about going to the Moon,” he wrote. “They should be focused on the much bigger things we are doing.”

The moon, Trump’s tweet seems to imply, is a boring destination. Too old-school, too small potatoes, too … reachable. Trump isn’t the first president to suggest a return to the moon, and he’s also not the first to suggest skipping that costly, time-consuming, already-made trip in favor of putting a foot on Mars. But he’s the first to muddle both plans in quite this way. (When he noted that the moon is a part of Mars—it’s not—he may have meant that many see a moon base as a stepping-stone to a Mars mission.)

The backtracking implied by Trump’s tweet carries enormous weight for a government agency that’s all too familiar with the bait and switch of being redirected halfway through a project. NASA has a long legacy of being hampered by presidential turnovers, which can hinder any worthwhile, groundbreaking project from making it to fruition. NASA’s most important accomplishments have spanned presidencies and required agreement across administrations. Barack Obama spent his time in office pushing for a decades-away Mars mission—exactly what it appears Trump, who cut Obama’s plans off at the pass with his moon-and-militia fixation, now wants.

Since it was established by President Dwight Eisenhower in 1958, NASA has had to weather the blows of presidential whims time and time again: Trump’s swing from Mars to the moon and back again is only the latest iteration of an ongoing pattern.

John F. Kennedy: Mars—No, Wait, the Moon

Before John F. Kennedy wanted to go to the moon, he wanted to land on Mars. But NASA’s associate administrator, Robert Seamans Jr., insisted that the moon was a more achievable goal, and warned Kennedy against laying out a plan destined to fail. It was during the Kennedy administration that the idea of the moon as a necessary step to human arrival on Mars first emerged, but ultimately the moon was promoted to the more realistic destination of choice.

Kennedy’s famous call for lunar ascendancy drove NASA’s feverish agenda in its early years. In 1961, when work on the Apollo program began, NASA’s budget was increased by 89 percent. Getting to the moon was of unwavering political importance.

Lyndon B. Johnson: The Moon

During his years as Senate majority leader, Johnson had helped spur the creation of NASA by putting pressure on President Eisenhower to respond to Russian space activity. He continued to nurture the Apollo program throughout his presidency, but the attention and money diverted toward the Vietnam War meant that little planning was done for any continued space exploration. The moon landing, scheduled for the end of the decade, was still the goal.

Richard Nixon: The Moon (We Made It!)

Nixon presided over the celebrated 1969 moon landing, but his attitude toward the rest of the cosmos remained reserved and flatly unambitious. NASA wanted to launch a 20-year Mars mission; the president refused to discuss the possibility.

Gerald Ford: Earth Orbit Only

During Ford’s three-year tenure, a U.S. Apollo module docked with a Soviet Soyuz spacecraft during the 1975 “handshake in space”—part of the Russian-American Apollo-Soyuz Test Project. Ford, a longtime NASA supporter, continued to develop the Space Shuttle program, which aimed only to reach Earth orbit. He made no public plans for a return trip to the moon or anywhere beyond. One lunar landing was enough.

Jimmy Carter: Earth Orbit

In 1979, when the Space Shuttle program ran into technical challenges, President Carter considered shutting it down, though he ultimately decided not to. Human spaceflight fell by the wayside during Carter’s administration. Privately, though, Jimmy was a dreamer: According to multiple accounts, he expressed abstractly a belief that human civilization would one day extend beyond Earth.

Ronald Reagan: Earth Orbit

President Reagan energetically supported human spaceflight and enjoyed the grandiosity of Space Shuttle launches. He wanted commercial interests involved in spacefaring, with satellite placements and other innovations. But even reaching Earth orbit started to seem fraught after the Challenger disaster in 1986, which left the administration shaken and hesitant to push other planned launches forward.

George H. W. Bush: The Moon and Mars

Bush took office ready to champion NASA into a new era of human spaceflight. On the 20th anniversary of the Apollo 11 landing, he announced an ambitious Space Exploration Initiative with two clear goals: Put a man back on the moon, and put a man on Mars. Bush talked a big game, but his far-reaching plans were dead on arrival: NASA’s resources were already stretched thin by the Space Shuttle program and the creation of a space station.

Bill Clinton: Earth Orbit, Again

Clinton had none of his predecessor’s starry-eyed ambitions for space exploration. Though he kept the space-station program alive, against the advice of his budget director, Clinton said that a crewed mission to Mars was too expensive to even consider. He was keen to search for evidence of life there—but only if robots were doing the work.

George W. Bush: The Moon and Mars

Once again, a new president meant a pivot for the executive branch’s aspirations beyond Earth. In 2004, Bush laid out his Vision for Space Exploration, which, much like his father’s preferred plan, imagined a moon landing—this time for 2020—as a stepping-stone for a future Mars mission. Work was to begin after the completion of the space station and the subsequent retirement of the Space Shuttle fleet in 2010—after Bush’s term.

Barack Obama: Mars

Less than a year after being sworn in, President Obama canceled the plans Bush had set in motion for a crewed moon mission. Instead, the president began to push the idea of skipping the moon altogether and instead allocating funds to begin construction on landers for a 2030s trip to Mars.

Donald Trump: The Moon—Or, Maybe, Mars?

When he first came into office, Donald Trump knew he wanted to send astronauts to some other spot in the solar system—he didn’t seem too hung up on the exact destination. But, perhaps because he wants to witness a NASA milestone before leaving office, soon he was talking about reaching the moon before 2024. Putting together a crewed lunar mission in the next few years was always going to be hard; perhaps the president now understands that NASA might as well be dreaming bigger and on longer timelines.
