Residents of Perth in Western Australia are planning to turn on their lights, just as they did 36 years ago when he flew over on his way to becoming the first American to orbit the earth.

The BBC's Sue Nelson: John Glenn enjoys being the oldest man in space

On that occasion he reported that the lights were clearly visible. This time his flight path will take him further north and the city will be harder to see.

However the director of Perth's observatory, Dr James Biggs, says the senator will have a perfect opportunity to see the city clearly.

He said US Shuttle Discovery would pass over at roughly midnight and the light of Perth would be contrasted with the darkness of the surrounding desert.

Wonderful trip

The 77-year-old senator has said he is having a wonderful time on his trip.

John Glenn: "This is beautiful!"

"This is beautiful. The best part of it is, to do a trite old statement, zero-G and I feel fine," he said.

His commander said the senator had been grinning from ear to ear and "we haven't been able to remove it yet."

John Glenn (centre) during takeoff

As he took off Senator Glenn gave the thumbs up sign to the onboard video camera and shook hands with some of his six fellow astronauts.

On Friday he was due to start medical tests - during his nine-day voyage, he is to be the subject of numerous experiments to find out about the ageing process and to see how older people fare in space.

Lost panel

Space Shuttle Discovery blasted off successfully on Thursday, but lost an aluminium panel two seconds into the flight.

The heat of blast off may have damaged Discovery's drag parachute

However, mission control said the mishap should not affect the voyage or its landing.

The panel protects the shuttle's drag parachute, sometimes used during landing. Mission control said the craft could be landed without the chute if necessary.

The launch was delayed slightly by an aeroplane entering airspace above the craft.

President Bill Clinton and a host of Hollywood stars were among the 250,000 spectators who watched the takeoff.

Discovery is a luxurious ship compared to the cramped rocket Glenn used in 1962.

The crew of seven will perform more than 80 experiments and release a satellite for two days of solar studies.