The problem is nothing huge. Engineers found a foot-long dent in a fuel line that circulates hydrogen to the three engines. Apparently somebody had stepped on it. But they should have it mended quickly and officials are tentatively planning to blast the orbiter into the heavens at 9.18pm next Thursday. Among the crew of seven will be the British-born astronaut, Michael Foale.
None of this is ideal. First, it means that the agency will have people in space over Christmas for the first time since 1983. All holiday time has been cancelled. More worryingly, it brings the nine-day mission perilously close to the last day of the year. There is no certainty that the computer software on the Discovery shuttle can handle the potential pitfalls of Y2K. It has to be back home by 27 December.
But the pressure on Nasa to perform a successful launch as soon as possible is intense. And it has little to do with Hubble itself, even though the telescope has been completely disabled for the past month. There is such urgency because this has been the year when Nasa has fumbled almost everything.
Both politicians in Washington and the public are starting to ask what is going on. Even President Clinton felt compelled during a press conference this week to offer Nasa his support. "We all use the slogan, `Well, it isn't rocket science'. Well, this is rocket science," Mr Clinton remarked. "We have to keep doing this if we ever hope to know what's beyond our galaxy".
Nasa's worst calamities have been in the Mars programme. In September, the Mars Climate Orbiter was incinerated when it dipped into the Red Planet's atmosphere - somebody forgot to convert imperial measurements to metric. Then, last weekend, all contact was lost with the Mars Polar Lander after it was supposed to touch down. It is now presumed dead and nobody yet knows what went wrong.
In the meantime, Russia's inability to continue funding its contribution to the construction of the International Space Station means that the project has been put on ice. Until Russia is able to complete a crucial part of the orbiting complex, no further work on it can proceed.
The picture with the shuttle programme here on Cape Canaveral is hardly better. There have only been two missions so far this year - the slowest pace since the aftermath of the Challenger explosion in 1986. What is more, the last flight in July - the first to be commanded by a woman - almost ended disaster when a short circuit disabled two computers that control the shuttle's engines. It was that near miss that led to the slowdown in the launch schedule. The wiring problem was deemed so severe that Nasa responded by grounding its entire fleet of four orbiters for wiring inspections, which took several weeks. Thus, the Hubble mission that was originally meant to launch in October, is still here on the ground. The latest delay was the sixth.
The agency is naturally defensive about all the problems. "Obviously everyone at the Space Center would like to see the shuttles fly more often," Joel Wells, a Nasa spokesman, agreed. "But our primary concern must be that the shuttle is safe to fly and if that means we have to sacrifice a little bit of the frequency of flights then that is what we'll do".
Apparently the pressure and all the delays are even getting to some of the astronauts, including Foale, who completed a highly perilous mission on the Russian Mir station in 1997. "I am paying more attention to the readiness of this flight than I have on my previous flights," he admitted. "If you get off the curve, you get off your edge, you lose a little bit, and I think we've been too long from flying."
Nasa knows that its troubles may only really begin when Congress reconvenes in Washington after the Christmas break. Already, members have warned that hearings will be convened to assess whether or not the agency is doing its job properly. For many representatives, the loss of the Polar Lander was the last straw and evidence that taxpayers were wasting money on Nasa.
"This week's failings of the Mars Polar Lander as well as difficulties Nasa has had with the International Space Station, shuttle launches and the Chandra X-ray telescope, among others, have made it clear that we need a total reassessment of Nasa's approach to interplanetary exploration," warned Representative Bill Frist, who heads a sub-committee that oversees the agency.
The man in the hot seat will be Daniel Goldin, who is in charge of Nasa. Because of pressure to cut costs from Congress, he has pushed through a new "cheaper, better, faster" policy at the agency. Under Goldin's leadership, the agency has switched from concentrating on a few grand - and grandly expensive - mission programmes to juggling a great number of less expensive ventures, like the Mars landers. And it has all been done on what some believe is a shoestring.
"There is still this misunderstanding in some circles that Nasa is getting all this money," Wells insisted. "When in fact our piece of the pie could not even stand up on its own - we get less than 1 per cent of the federal budget".
Some contend that it is precisely the tightening of the federal purse that has caused an overstretched Nasa to commit avoidable errors, including here at Canaveral. "The thing is, the shuttle workforce has been reduced. They are sorely tried to do all they're supposed to do with the staff they've got," remarked Seymour Himmel, a retired Nasa official now on the Aerospace Safety Advisory Panel.
There was a time, of course, when Nasa could do no wrong. It put the first man on the moon. It rescued its crew from the crippled Apollo 13 craft against all reasonable odds. Now, this is a place that feels under siege.
Michael Foale, like everybody else, knows how important getting Discovery off the pad and into space has suddenly become. "I think after this flight, Nasa will breathe a collective sigh of `Ahh, we're back in the business again'," he said.