The last launch of a US space shuttle will take place on Friday 8 July.

美国将于7月8日，星期五最后一次发射航天飞机。

The final Atlantis mission will have a crew of four, led by Chris Ferguson (far left)
The Atlantis ship has the honour of closing out the 30-year orbiter programme and will lift off at 1126 Florida time (1526 GMT).

Up to 750,000 people are expected to line the roads and beaches around the Kennedy Space Center, all eager to witness a piece of history.

The launch date was fixed¹ by US space agency managers on Tuesday following a review of mission preparations.

They passed as fit to fly a new fuel valve（燃料阀） on one of the vehicle's main engines. The old valve was suspected to have a leak and was changed.

And inspections² ordered on support beams on the ship's big orange external fuel tank found no issues of concern. Cracks in these structures were the cause of a major delay on a previous shuttle mission.

Four astronauts will ride Atlantis to orbit - Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandy Magnus and Rex Walheim.

Their 12-day sortie（出击，突围） will take them to the International Space Station (ISS), where they will deliver more than 3.5 tonnes (8,000lb) of supplies - including a year's worth of food. It will give the US space agency some room to play with as it looks to introduce a commercial cargo³ re-supply service over the next 12 months.

"This flight is incredibly important to space station; the cargo that is coming up is really mandatory⁴（强制的） ," said Nasa's Associate Administrator⁵ for Space Operations, Bill Gerstenmaier.

A shuttle would normally fly with six or seven crew members onboard, but the number has been reduced for this final flight because there is no orbiter left on standby to go and rescue them should they to get into trouble.

In the event of Atlantis sustaining serious damage on lift-off, similar to the ill-fated Columbia ship in 2003, the astronauts would take refuge on the ISS until they could all return to Earth in Russian Soyuz capsules over a 10-month period.