15 Important Moments in Space Exploration

Back on May 25, 1961, President John F. Kennedy announced before the world that America would put a man on the moon by the decade's end. By the middle of 1969, the Americans had completed their mission. Since then, America, and a series of other countries, have pushed space exploration's bar farther and farther, helping expand our understanding of the universe. There have been many triumphs—and tragedies—along the way. Here are 15 of the most important moments in space exploration history. As you read them, remember these words:

“Not only do we live among the stars, the stars live within us.” 

― Neil deGrasse Tyson

America has been known as the leader in space exploration for decades, but it was Russia who first pulled the trigger way back when. When the Sputnik I satellite was launched into space on October 4, 1957, everything changed. Sputnik was about the size of a beach ball, but the tiny space craft prompted the entire world to begin looking at the sky as a new frontier to explore, and it single-handedly started the space age.

Back in the states, American public was in fear that Russia's technology would mean they would be able to launch nukes toward any target on the planet. Of course, under this supposed threat, Americans responded by placing money in their own satellite program, and NASA was formed a year later. Then, three years later, President Kennedy delivered his famous speech which set America's sights on the moon within a decade. Nothin' better than competition to get the juices (and money) flowing in the right direction.

Apollo 8 was the second manned space mission of NASA's Apollo program, launched on December 21, 1968. It became the first manned spacecraft to leave Earth's orbit, orbit the moon, and return safely home. The three astronauts aboard, Frank Borman, James Lovell and William Anders, became the first humans to see Earth as a whole planet, and see the far side of the moon that isn't visible from our planet's surface. The crew orbited the moon 10 times in 20 hours, and made a Christmas Eve television broadcast where they recited the first 10 verses of the Book of Genesis—which, at the time, was the most watched TV program ever.

During the mission, Anders took this now famous photograph of Earth, known as Earthrise:

Their successful mission paved the way for Apollo 11 the following year.

Getting out of sticky situations is something humans are good at, and this is ever apparent in NASA's aborted Apollo 13 mission in 1970. Apollo 13 was meant to be the third manned trip to the moon, but was quickly canceled when an oxygen tank exploded two days into the mission, and the astronauts alerted NASA with the words, "Houston, we've had a problem." Astronauts James Lovell (of Apollo 8), John Swigert and Fred Haise, overcame a loss of power, loss of cabin heat, and a shortage of water, using their ingenuity and knowledge of physics to get their spacecraft back into trajectory toward Earth.

The mission was made into a film featuring Tom Hanks and directed by Ron Howard in 1995.

The Voyager probes were launched into orbit in 1977 to study Jupiter and Saturn (the outer planets were lined up that year, making it a perfect time to send probes their way). The probes both carried plates called "The Golden Record," which contained inscribed messages detailing our civilization, in case they were ever intercepted by aliens, or perhaps humans in the distant future (imagine that moment). "This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings," President Jimmy Carter said in a message placed in the record. "We are attempting to survive our time so we may live into yours."

Voyager I and Voyager II completed their missions by sending back information about Jupiter and Saturn, like the active volcanoes on Jupiter's moons, and the intricacies of Saturn's rings. As Voyager II drifted off into space, it expanded its mission by exploring Uranus and Neptune; and now, both space probes are the farthest traveling manmade objects ever, and are on the verge of being the first manmade objects to leave our solar system and reach interstellar space. 

Voyager I is more than 11 billion miles away from the sun.

On January 28, 1986, Space Shuttle Challenger broke apart just 73 seconds after its launch, killing all seven of its members. The O-ring seal on a rocket booster had failed, which sent hot gas from a rocket motor to the surface, and subsequently broke apart the spacecraft. Some of the crew members are known to have survived the shuttles disintegration, but they died upon impacting the ocean. An investigation revealed that the accident was likely preventable: NASA organizational and decision-making processes were flawed, which led to the shuttle being labeled as certified to fly on a morning that was deemed too cold for it to handle by some engineers. The disaster started a three year hiatus in the shuttle program.

Space Shuttle Columbia exploded upon re-entry into Earth's atmosphere on February 1, 2003, killing seven crew members. When debris from a suitcase-sized piece of foam insulation broke off from the shuttle's external tank, it slammed into the left wing, which damaged the shuttle's thermal protection system (the system that protects th shuttle from heat during re-entry). Sadly, an investigation concluded that NASA engineers had suspected damage, but NASA managers limited the investigation after they decided the astronauts aboard couldn't fix the problem. Later, investigators concluded that a rescue mission may have been possible. The shuttle program was suspended for two years after the disaster.

During the biggest space mission in the social media era, the Mars rover, Curiosity, survived the "Seven Minutes of Terror" as it descended into the Martian atmosphere. NASA's control room broadcasted a live-feed of the event, which was watched by millions on tablets, computers, smartphones and televisions. In its first year, Curiousity has sent back the most detailed photographs of the martian landscape ever, and concluded what scientists long suspected: Mars likely had an environment suitable for life, long ago.

Check out Curiosity's Twitter feed at @MarsCuriosity.