SpaceShipTwo and the Dangers of Space Travel

"Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace." These are the words President Richard Nixon was prepared to say if Apollo 11 had sizzled in the stratosphere rather than soaring through space. The words we would have remembered had we not heard, "That's one small step for man, one giant leap for mankind."

"In Event of Moon Disaster" was written by William Safire, who was a presidential speechwriter before he was a columnist. It speaks to human frailty as much as it does to human ambition. "In ancient days, men looked at stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood," it reads.

While Apollo 11's journey was a success, space travel's inherent dangers have not been conquered. We saw that firsthand just last week when Virgin Galactic SpaceShipTwo crashed to the Earth, killing test pilot Michael Alsbury.

Whether space exploration is a private endeavor as it was with Virgin Galactic or a hybrid government/private mission as it was with the Antares disaster just days before, the past week has shown that the risks of space travel are still as great as the rewards.

Virgin Galactic intends to take average space enthusiasts to the stars (for a price). Speaking to the press on Saturday, Sir Richard Branson said he would offer refunds to those who wanted them, but he doubted many would take him up on it.

"We would love to finish what we started some years ago, and I think pretty well all our astronauts would love us to finish and would love to go into space," he said. If Twitter comments are any indication, he seems to be right.

The words that were meant to be a comfort to us 45 years ago provide some today: "Others will follow, and surely find their way home. Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts." See the slideshow for those who came before.

1. Virgin Galactic SpaceShipTwo

The National Transportation Safety Board is still investigating the reasons behind the crash. What is known so far is that a feature where the tail section "feathers" during its descent deployed too early and caused an atmospheric drag that led to disintegration. Pilot Michael Alsbury was killed and pilot Pete Siebold, who managed to parachute out, was injured.

2. Antares

While widely reported as a NASA rocket crash, Antares was a rocket owned by the private company Orbital Sciences. NASA paid for the unmanned rocket to carry a payload to the International Space Station. Fifteen seconds after launch it erupted into a fireball. The cause is still being investigated.

Another firm doing ISS re-supply missions is SpaceX, which is headed up by Elon Musk. In an interview with Wired a couple of years ago, Musk took issue with his rival's materials. "One of our competitors, Orbital Sciences, has a contract to resupply the International Space Station, and their rocket honestly sounds like the punch line to a joke. It uses Russian rocket engines that were made in the ’60s. I don’t mean their design is from the ’60s—I mean they start with engines that were literally made in the ’60s and, like, packed away in Siberia somewhere."

3. Columbia

When it sailed off on its 28th mission in 2003, Space Shuttle Columbia lost a piece of foam insulation from a tank that flew off and hit one of its wings. The damage was too great for the wing to withstand the pressures of re-entry into earth's atmosphere and it broke apart. The seven astronauts on board were killed.

4. Challenger

Space Shuttle Challenger took off on its 10th mission on January, 28, 1986, but within two minutes it disintegrated. At fault was an O-ring seal. The seven astronauts on board all died, including teacher Christa McAuliffe, whose students were watching the event during the school day.

5. Soyuz 11

The first space station was Russia's Salyut 1, which launched in 1971. That same year Russia launched the Soyuz 11 with three cosmonauts so that they could dock with and board Salyut 1. After a successful 23-day mission where they became the first people on a space station, the men headed home. Everything looked fine, with no explosions to spark suspicion. The crew cabin hit the water as planned and was taken to land. But when it was opened, three bodies lay inside. An air vent had opened during re-entry and depressurization in the cabin killed all those onboard.

6. X-15

The X-15 was a rocket-powered aircraft. On a NASA-run test flight in 1967, it entered a Mach 5 spin from which the pilot immediately recovered but then headed into a crash. An investigation found the cause to be a combination of the pilot's distraction, misinterpretation of instrument controls, and possible vertigo resulting from the spin. The pilot Michael J. Adams was awarded astronaut wings posthumously and is considered by NASA to be its first space fatality.