Tim Peake leaves the ISS for his journey back to Earth after six months in space

British astronaut Tim Peake has said goodbye to the orbiting laboratory that has been his home for the past six months.

At 6.52am, UK time, the spacecraft carrying Peake and his two crew mates back to Earth undocked from the International Space Station (ISS).

Sprung hooks attaching the Soyuz TMA-19M to the space station were released to free the craft which took the three men into orbit on December 15.

An outside camera showed the spacecraft backing away from the space station with the Earth turning slowly below.

Soyuz TMA.
Tim Peake tweeted this photo of the Soyuz TMA-19M hours earlier (Tim Peake/ESA)

Some four hours earlier Peake, American Colonel Tim Kopra, and Russian cosmonaut Yuri Malenchenko had scrambled from the space station into the Soyuz.

Closing the hatch marked the official end of Peake's historic mission, which earned him an honour from the Queen for "extraordinary service beyond our planet".

Peake was the first British astronaut to be sent to the ISS by the European Space Agency (Esa).

The father-of-two took part in more than 250 experiments, performed a space walk, ran the London Marathon on a treadmill, and inspired more than a million schoolchildren.

The Soyuz capsule carrying Major Tim Peake and his two crewmates.
The Soyuz capsule carrying Major Tim Peake and his two crewmates (ESA screengrab)

The trip home involves a hair-raising plunge through the atmosphere in the tiny middle section of the Soyuz, the descent module.

Friction on the spacecraft's heat shield will slow its speed from 17,398 mph (28,000 kph) to 514 mph (827 kph) and raise the outside temperature to 1,600C.

The rapid deceleration will push the crew back into their shock-absorbing seats with a force of around five gee - five times normal Earth gravity.

One Nasa astronaut, Doug Wheelock, has described the experience of a Soyuz descent as "like going over Niagara falls in a barrel, but the barrel is on fire".

Peake with cosmonaut Yuri Malenchenko and fellow astronaut Tim Kopra.
Peake with cosmonaut Yuri Malenchenko and fellow astronaut Tim Kopra (ESA)

In preparation for undocking, the crew donned their Sokul space suits, took their positions in the module, and carried out final air leak and communication tests. Peake was strapped in the right seat.

After separation, two burns from the Soyuz rocket engine moved the craft to a safe place from which to begin the no-turning-back descent into the Earth's atmosphere.

If all goes according to plan, the return to Earth will be controlled automatically by the craft's on-board computer. In an emergency, the crew, led by commander Malenchenko, can alter their trajectory manually using a hand controller.

A critical moment will come at about 9.20am UK time, when the rocket motor fires for four minutes and 45 seconds to put the Soyuz on a trajectory that will take it out of orbit.

The Soyuz capsule undocking from the ISS.
The Soyuz capsule undocking from the ISS (Esa)

If the "deorbit burn" is too short the astronauts could skip across the atmosphere like a stone skimming a lake and fly out into space. If too long, they could come in at too steep an angle too fast, and risk being incinerated.

Next, half an hour before landing and at an altitude of 87 miles, explosive bolts will fire, splitting the Soyuz into three parts.

The descent module containing the crew will turn so that its heat shield is pointing in the direction of re-entry. The other two sections, the service module containing propellant and control systems, and the spherical orbital module that housed the crew during their launch, are allowed to plunge into the atmosphere and burn up.

The capsule is expected to land in a remote location on flat steppe scrubland more than 200 miles from the major Kazakhstan city of Karaganda.

SNAPPA Peake Soyuz

Fifteen minutes before landing, four parachutes will be deployed in succession. One second before touchdown, retro rockets will fire and the spacecraft will hit the ground at 3mph.

Recovery crews will rapidly arrive at the site to help the space travellers out of their capsule and take them for medical checks.

They will be helicoptered to Karaganda airport, where according to tradition they will be offered bread and salt and a traditional Kazak hat.

Peake will then be flown to the European Astronaut Centre in Cologne, Germany, while his American and Russian colleagues go their separate ways to Houston and Star City, near Moscow.

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