CAPE CANAVERAL, Fla. - The international space station needs space shuttle Atlantis and its repair crew more than ever as more parts break and it slips lower and lower in orbit.
Atlantis is scheduled to lift off shortly before sunrise Friday with new batteries and other replacement parts for the space station.
It will be NASA's fourth attempt to send the shuttle to the rescue. Gusty wind wiped out all three launch attempts in late April. Perfect weather was forecast this time.
Four of the six electricity-generating batteries on the space station have failed or are failing. Replacing them is NASA's No. 1 priority.
During the past three weeks, yet another electrical component began faltering: a Russian battery-charging device, which will have to be replaced.
NASA's No. 2 priority is boosting the space station.
For months, the station has been dropping about 1´ miles each week because of increased solar activity, which causes the atmosphere to expand and spacecraft to sink.
The station is nearly 210 miles high. Atlantis will give it a 26-mile lift during the six days that the spacecraft are docked.
That will put it on par with Russia's Mir, which is flying high again with cosmonauts after being abandoned for months and experiencing a fire, a collision and numerous breakdowns.
The first piece of the international space station was placed in orbit in November 1998, and the second piece a month later. But because of delays by the Russians, no major parts have been added since then, and a permanent crew will not move in until November at the earliest - 2´ years behind schedule.
"There's been a lot of talk about the space station's up there with problems and people are on board Mir and we're second-string, if you want to say it that way. But we're not," space station deputy manager Robert Cabana said Thursday.
"The truth be known, Mir is noisier and noisier than the international space station and when we're done, the international space station is going to be extremely quiet and nice."
Still, the seven shuttle astronauts will have to wear ear plugs while working inside the Russian half of the space station, because of the racket from whirring equipment.
They will also carry their own fans. The air circulation is so poor in the Russian module that the last astronauts who visited, one year ago, became ill.
The pace in orbit will pick up greatly once the Russians launch their service module, supposedly in July.
On the Net:
NASA's human space flight program: http://spaceflight.nasa.gov/index-m.html