Astronauts on the space shuttle Discovery have made a rare night-time landing on a floodlit runway after completing their mission to the International Space Station.

Discovery swooped through a mostly clear sky and touched down at Kennedy Space Center just after 0200 local time (0700BST).

It was only the 11th time that a space shuttle had landed in darkness.

Discovery astronauts spent six of their 10 days in orbit preparing the International Space Station (ISS) for its first long-term occupants next year.

They left nearly two tonnes of tools, water, clothes and other supplies for the first permanent crew, due to arrive next spring, and fixed a broken radio.

The crew also launched Starshine, a 48cm spinning ball covered with 900 highly-polished mirrors which will reflect the suns rays for observers on Earth.

Light reflected from the satellite will be visible as far north as Scotland and Canada, and as far south as the New Zealand and the southern tip of South America.

Higher orbit

The space shuttle undocked from the ISS on Thursday.

Orbiting 400km above earth

Astronaut Tamara Jernigan said the embryonic outpost "was a tremendously pleasant working environment".

Just before undocking commander Kent Rominger and pilot Rick Husband fired the shuttle's thrusters to boost the ISS nearly 10km (six miles) higher.

The new orbit will allow the connection of the next component, a Russian service module, in November.

That piece will serve as the living quarters for the station's first residents, who are scheduled to move in next March. The next temporary guests are expected in December when space shuttle Atlantis delivers more supplies.

Once undocked, Discovery did two slow laps around the space station so the crew could take photographs, before firing its engines for home.

Improved comfort

"You all certainly left the International Space Station in much better shape than you found it," Mission Control told the astronauts as they left.

They had unloaded 1,600kg (3,600 pounds) of equipment, including tools, computers, water, clothes and even refuse bags.

Most were placed in the Russian-built Zarya module, stuffed behind panels and strapped to the walls.

"We spent a lot of this mission stowing supplies ... so it should be pretty comfortable," said Ellen Ochoa, the astronaut in charge of the moving.

The astronauts also reduced the noise level in Zarya by placing mufflers over clattering fans, ducts and outlets, though the reduction was only about three decibels.

The first day in the ISS was taken up with repairs that successfully resurrected an Earth-ISS communication system and a solar-power storage system.

The mission began with a marathon space walk which attached cranes, tool bags and hand-rails to the outside of the outpost to aid future construction.