By Mike Wall, Space.com Senior Writer | February 18, 2013 07:00am ET

Credit: NASA

Kennedy's speech, which came just six weeks after cosmonaut Yuri Gagarin became the first person to reach outer space, had a huge impact on NASA and space exploration. It jump-started the agency's Apollo program, a full-bore race to the moon that succeeded on July 20, 1969, when Neil Armstrong's boot crunched down into the gray lunar dirt.

Kennedy, of course, isn't the only leader who had a vision for the nation's space program. Since NASA's founding in 1958, every president from Eisenhower to Obama has left his mark. Take a look at how each U.S. commander-in-chief helped shape and steer American activities in space.

Credit: NASA

However, Eisenhower didn't get too swept up the short-term goals of the space race. He valued the measured development of unmanned, scientific missions that could have big commercial or military payoffs down the road.

For example, even before Sputnik, Eisenhower had authorized a ballistic missile and scientific satellite program to be developed as part of the International Geophysical Year project of 1957-58. The United States' first successful satellite, Explorer I, blasted off Jan. 31, 1958. By 1960, the nation had launched and retrieved film from a spy satellite called Discoverer 14.

Credit: NASA

The Soviets had launched Sputnik I in 1957, and cosmonaut Yuri Gagarin had become the first person in space on April 12, 1961, just six weeks before the speech. On top of those space race defeats, the U.S. plan to topple the Soviet-backed regime of Cuban leader Fidel Castro the so-called Bay of Pigs invasion had failed miserably in April 1961.

Kennedy and his advisers figured they needed a way to beat the Soviets, to re-establish American prestige and demonstrate the country's international leadership. So they came up with an ambitious plan to land an astronaut on the moon by the end of the 1960s, which Kennedy laid out in his speech.

The Apollo program roared to life as a result, and NASA embarked on a crash mission to put a man on the moon. The agency succeeded, of course, in 1969. By the end of Apollo in 1972, the United States had spent about $25 billion on the program well over $100 billion in today's dollars.

Credit: NASA

As Senate majority leader in the late 1950s, he had helped raise the alarm regarding Sputnik, stressing that the satellite launch had intiated a race for "control of space." Later, Kennedy put Johnson, his vice president, in personal charge of the nation's space program. When Johnson became commander-in-chief after Kennedy's assassination, he continued to support the goals of the Apollo program.

However, the high costs of Johnson's Great Society programs and the Vietnam War forced the president to cut NASA's budget. To avoid ceding control of space to the Soviets (as some historians have argued), his administration proposed a treaty that would outlaw nuclear weapons in space and bar national sovereignty over celestial objects.

The result was 1967's Outer Space Treaty (OST), which forms the basis of international space law to this day. The OST has been ratified by all of the major space-faring nations, including Russia and its forerunner, the Soviet Union.

Credit: NASA.

By the late 1960s, NASA managers had begun drawing up ambitious plans to set up a manned moon base by 1980 and to send astronauts to Mars by 1983. Nixon nixed these ideas, however. In 1972, he approved the development of the space shuttle, which would be NASA's workhorse space vehicle for three decades, starting in 1981.

Also in 1972, Nixon signed off on a five-year cooperative program between NASA and the Soviet space agency. This deal resulted in 1975's Apollo-Soyuz Test Project, a joint space mission between the two superpowers.

Credit: NASA

Ford also signed off on the creation of the Office of Science and Technology Policy (OSTP) in 1976. The OSTP advises the president about how science and technology may affect domestic and international affairs.

Credit: NASA

While Carter wanted to restrict the use of space weapons, he signed a 1978 directive that stressed the importance of space systems to national survival, as well as the administration's willingness to keep developing an antisatellite capability.

The 1978 document helped establish a key plank of American space policy: the right of self-defense in space. And it helped the United States military view space as an arena in which wars could be fought, not just a place to put hardware that could coordinate and enhance actions on the ground.

Credit: NASA

Consistent with his belief in the power of the free market, Reagan wanted to increase and streamline private-sector involvement in space. He issued a policy statement to that effect in 1982. And two years later, his administration set up the Office of Commercial Space Transportation, which to this day regulates commercial launch and re-entry operations.

Reagan also believed strongly in ramping up the nation's space-defense capabilities. In 1983, he proposed the ambitious Strategic Defense Initiative (SDI), which would have used a network of missiles and lasers in space and on the ground to protect the United States against nuclear ballistic missile attacks.

Many observers at the time viewed SDI as unrealistic, famously branding the program "Star Wars" to emphasize its supposed sci-fi nature. SDI was never fully developed or deployed, though pieces of it have helped pave the way for some current missile-defense technology and strategies.

Credit: NASA

Bush had big dreams for the American space program. On July 20, 1989 the 20th anniversary of the first manned moon landing he announced a bold plan called the Space Exploration Initiative. SEI called for the construction of a space station called Freedom, an eventual permanent presence on the moon and, by 2019, a manned mission to Mars.

These ambitious goals were estimated to cost at least $500 billion over the ensuing 20 to 30 years. Many in Congress balked at the high price tag, and the initiative was never implemented.

Credit: NASA

According to the policy, the United States' chief space goals going forward were to "enhance knowledge of the Earth, the solar system and the universe through human and robotic exploration" and to "strengthen and maintain the national security of the United States."

This latter sentiment was consistent with other space policy statements from previous administrations. However, some scholars argue that the 1996 document opened the door to the development of space weapons by the United States, though the policy states that any potential "control" actions would be "consistent with treaty obligations."

Credit: NASA

Bush also dramatically shaped NASA's direction and future, laying out a new Vision for Space Exploration in 2004. The Vision was a bold plan, calling for a manned return to the moon by 2020 to help prepare for future human trips to Mars and beyond. It also instructed NASA to complete the International Space Station and retire the space shuttle fleet by 2010.

To help achieve these goals, NASA embarked upon the Constellation program, which sought to develop a new crewed spacecraft called Orion, a lunar lander named Altair and two new rockets: the Ares I for manned missions and the Ares V for cargo. But it was not to be; Bush's successor, President Barack Obama, axed Constellation in 2010.

Credit: NASA/Bill Ingalls

A year later, Obama announced his administration's space policy, which represented a radical departure from the path NASA had been on. The new policy canceled George W. Bush's Constellation program, which the Augustine Commission had found to be significantly behind schedule and over budget. (Obama did support continued development of the Orion spacecraft for use as a possible escape vehicle at the space station, however.)

In place of Constellation, Obama's policy directed NASA to focus on getting humans to an asteroid by 2025 and then on to Mars by the mid-2030s. This entails, in part, developing a new heavy-lift rocket, with design completion desired by 2015.

The new policy also seeks to jump-start commercial spaceflight capabilitites. Obama's plan relies on Russian Soyuz vehicles to ferry NASA astronauts to the space station in the short term after the space shuttles retire in 2011.

But over the long haul, Obama wants this burden shouldered by private American spaceships that have yet to be built. So Obama promised NASA an extra $6 billion over five years, which the agency would use to help companies develop these new craft.

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Michael was a science writer for the Idaho National Laboratory and has been an intern at Wired.com, The Salinas Californian newspaper, and the SLAC National Accelerator Laboratory. He has also worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Mike on Google+.

The rest is here:

50 Years of Presidential Visions for Space Exploration