The shuttle Endeavour is due to blast off to the International Space Station tomorrow – but is it a mission that will see astronauts queuing for the bathroom?

Endeavour’s crew of seven is due to arrive on Monday at the orbiting outpost which already a six spacemen aboard.

It means that there will be a record 13 astronauts on the space station which has only one lavatory, repaired on a recent shuttle mission.

Launch manager Mike Moses, of the Kennedy Space Centre, tells CBS News: “It’s like having your family descend on you for the holidays, right? And they’re going to stay for a very long time.”

If demand for bathroom facilities is too great, they can retreat to a second toilet on the shuttle. And if if they are really desperate, there is another on a Soyuz “lifeboat” attached to the space station.

Endeavour’s 16-day mission will be one of the most challenging yet as construction of the space station continues 220 miles above the Earth.

Astronauts will make five lengthy spacewalks to attach a Japanese platform and replace massive batteries for the solar panels.

Shuttle commander Mark Polansky has already begun using Twitter to keep space fans updated on the mission’s progress – his username is Astro_127.

Endeavour was already prepared for launch last month in case it was needed to rescue astronauts on a daring mission aboard sister ship Atlantis to repair the Hubble space telescope.

Picture: Endeavour’s crew gather at launch pad 39a. (Photo: NASA)

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