The two hand-written notes from Apollo 13 crew that show how astronauts saved stricken space mission

These two bits of paper with notes hastily scrawled across them are actually part of the emergency checklist that helped save the crew of the doomed Apollo 13 space mission.

Astronauts marked the cards with critically important instructions after an explosion crippled their craft, prompting the famous 'Houston, we have a problem' line.

The record is a real time step-by-step account of how the crew set about powering down the craft in order to conserve enough power for them to get back to Earth.
Apollo 13 notes

Critical: Two notes written by astronauts on board the stricken Apollo 13 space mission recount the dramatic steps they took to safely return to Earth

Jim Lovell, Fred Haise and Jack Swigert all survived the 1970 mission, which was later made into Hollywood blockbuster Apollo 13 starring Tom Hanks.

The emergency power down checklist was kept by Fred Haise for years afterwards and has now come to light for the first time after being made available for sale.

Described as an 'amazing part of space history', it comes with a letter of provenance from Mr Haise and is expect to sell for up to £50,000.

Apollo 13 was Nasa's third space mission to the moon, but two days after the launch it suffered an oxygen tank explosion which lead to a loss of power, oxygen and heat.

Checklist: The notes detail in step-by-step detail how the crew powered down their craft to conserve enough power to get home

The crew had to abandon the main command module and use the moon-landing Lunar module as a lifeboat to coast back to Earth.

Nasa experts had to very quickly recalculate the emergency procedures which they later radioed through to the crew.

Haise and Lovell marked the checklist accordingly in black and red pen while in space.

They opened and closed various circuit breakers in order to shut down and conserve battery power and marked on the list 'close' or 'open' on the appropriate circuit.

Haise made the first changes 79 hours into the mission and Lovell updated the list as he implemented further changes 82 hours in.

Safe: The relieved astronauts are rescued after their command module lands in the Pacific Ocean and, right, mission commander Jim Lovell who wrote some of the notes

Blockbuster: The Apollo 13 mission was turned to a 1995 Hollywood film starring Tom Hanks as Jim Lovell

Lovell, who commanded the mission, had written a reminder of what antennas should be used when they saw the Earth or the moon in a certain window.

There was also a note reminding him how much time it should take mission control to make a link to the antenna.

In his letter, Haise wrote: 'This sheet played an important part during the emergency conditions of the Apollo 13 flight.

'It is a record of the real time steps the Nasa and industry team developed for us to perform ensuring our safe return to Earth.'

The document was signed by both astronauts when they returned to Earth. It is being sold by a private space collector, who acquired it from Haise.

Matthew Haley, of Bonhams auctioneers, said: 'The auction features items that hark back to the first golden age of space exploration.

'It serves as a poignant reminder of the precarious state the three astronauts' lives were in.

'Their survival and safe return to Earth is one of the most celebrated triumphs of 20th century space flight.

'We expect the lot to entice international interest.'

Andrew Currie, a spokesman for the auctioneers, added: 'These are fascinating documents that were right at the heart of the crew's battle against time to get safely back to Earth.

'In these notes you see the real life drama unfolding line by line.'

It follows the sale of the flight plan for the first moon landing on which astronaut Neil Armstrong wrote his famous phrase 'one small step for A man, one giant leap for mankind'.

The document, believed to be the only time he ever wrote the phrase, is set to sell at auction for £55,000.

The phrase - one of the most memorable of the 20th Century - has been subject to years of debate over what Armstrong actually meant.

It was inscribed and signed by the Apollo 11 mission leader whilst he was in quarantine and handed to Nasa press officer John McLeaish. Mr McLeaish later authenticated it and wrote a declaration on the back.

The auction for the Apollo 11 flight plan takes place on April 13 at Bonhams in New York and for the Apollo 13 notes on the following day.