The sun rises over the space shuttle Discovery Friday at the Kennedy Space Center in Cape Canaveral, Fla. Discovery and her crew of seven astronauts are preparing for today's planned liftoff and 13-day mission to the international space station.

Cape Canaveral, Fla. ? With good weather in the offing and no bumps in the countdown, NASA pushed ahead with today’s planned launch of space shuttle Discovery on a delivery trip to the international space station.

The mission has taken on new urgency – the seven shuttle astronauts will take up a new pump for the space station’s malfunctioning toilet.

They’re also ferrying a $1 billion Japanese space lab that has been more than 20 years in the making.

Dozens of Japanese journalists and space program officials jammed NASA’s launch site Friday, their excitement growing with every passing hour of the countdown. As many as 400 Japanese were expected for the late afternoon launch today.

Their enthusiasm was catchy.

“We are on the verge of a very historic event, the launch of this amazing spacecraft, the first major manned element for the Japanese Space Agency,” said NASA payload manager Scott Higginbotham.

The Japanese lab – named Kibo, which means hope – will be the biggest room at the space station once it’s installed. It’s 37 feet long and more than 32,000 pounds.

The first part of the lab flew up in March, and the third and final section will be launched next year.

The Russian toilet pump, on the other hand, is a mere 1 1/2 feet long and tucked into the crew cabin. It was flown to Florida from Moscow on Wednesday, a rush job precipitated by last week’s toilet breakdown at the space station.

Three spacewalks are planned during Discovery’s 14-day flight, to install Kibo, replace an empty nitrogen-gas tank and try out various cleaning methods on a clogged solar-wing rotating joint.