Five of history's worst space travel disasters

Following last week's tragic Virgin Galactic crash, we look at how dangerous space travel can really be with the top five space disasters.

Last week we were once again made aware how fraught with danger space travel can be.

Four days ago an unmanned rocket named Antares was scheduled to carry supplies to the six astronauts currently living in the International Space Station. A matter of seconds after take-off the rockets spontaneously combusted for reasons which are currently unknown.

The following day Virgin Galactic's SpaceShipTwo crashed in the Californian desert leaving one pilot dead and the other seriously injured. Virgin said the spacecraft suffered a serious anomaly and investigations into the accident could take more than a year. It has left a serious question mark over Richard Branson's ambition of sending those who can afford it into space.

Here are our top five space travel disasters:

5) Apollo 1

In 1967 Apollo 1 was set to be the first mission of the U.S. Apollo manned lunar landing program, but a disaster in preparation for the flight meant the mission never reached its target launch date.

During rehearsal a fire broke out in the cockpit and 17 seconds after it was reported the fire caused the cabin to combust, killing Lt. Col. Virgil I. Grissom, Lt. Col. Edward H. White and Roger B. Chaffee.

The cause of the fire was never fully determined, but inquiries after the tragedy found that the first Apollo module had some serious design flaws.

4) Soyuz 11

In 1971 Soyuz 11 was a mission to send three men up to the world's first space station, Salyut 1. The Russian spacecraft arrived at the station without issue, and stayed there for 23 days before departing.

During reentry back to earth everything appeared fine to the workers on the ground, but when the recovery team got to the cabin they found the three astronauts named Vladislav Volkov, Georgy Dobrovolsky, and Viktor Patsayev dead.

It was later revealed the trio died from depressurisation caused by the accidental opening of the breathing ventilation valve. The crew remain the only humans to have died outside of earth's atmosphere.

3) Nedelin Catastrophe

The Nedelin catastrophe is a little different from our other disasters as it features an unmanned missile, but it is still more than worthy of a place in our list.

The disaster that occurred happened at a launch pad in Baikonur, where the Soviet Union were testing a prototype missile. It was eventually found that second stage engines ignited accidentally causing the huge explosion, which killed 78 military and engineering personnel.

Despite happening in 1960, the accident was never fully acknowledged by the Soviets until 1989.

2) Space Shuttle Challenger

Approximately 17% of the American population witnessed the Challenger disaster of 1986 when the craft broke apart 73 seconds after take-off.

The cause of the break-up was the failure of a seal on the right solid rocket booster (SRB) which allowed pressurised hot gases to escape. This gas then comprised the structure of the other SRB hardware and fuel tank leading to the eventual separation.

It is understood that the initial accident did not kill all seven astronauts, but rather the crew compartment's crash into the ocean would have been violent enough to kill the remaining passengers.

1) Space Shuttle Columbia

In 2003 Space Shuttle Columbia disintegrated over Texas while reentering the Earth's atmosphere killing all seven onboard astronauts.

It was found that the problem leading to the disaster happened at launch when a suitcase-sized piece of foam peeled off the external tank and crashed through the left wing. This caused a hole in the wing allowed pressurised gasses to destroy the structure of the wing and thus destabilised the shuttle on reentry.

Debris from the shuttle and body parts of some astronauts were found scattered across Texas and Louisiana.