The final preparations for the final launch of NASA's space shuttle programme have created a mood nearly as heavy as the 80 per cent humidity here at the Kennedy Space Centre on Florida's east coast.
This is my fourth trip here in 10 months and the vibe is distinctly different.
There are more TV satellite trucks parked in front of the press centre just off from the famous launch countdown clock, and some of the NASA staff are clearly overwhelmed.
But I imagine their less-than-jovial mood is not solely based on the fact that 2,500 journalists are here to cover the last launch, but because this is "it".
After Shuttle Atlantis blasts off on a pillar of flame, no more shuttle launches, no more steady and regular media attention on NASA and the splendour of its regular rocket launches into space.
And there is a huge question mark hanging over the future of US spaceflight. For the foreseeable future, US astronauts will be riding as $50m/ seat ticketed passengers on Russian Soyuz spacecraft as work continues on the International Space Station (ISS).
The US space agency is looking to private companies that are working on programmes for manned-space flight to be their less-expensive option, but that is still years from becoming reality.
I spoke with former 30-year NASA project manager and astronaut Story Musgrave, and he put it plainly while sitting on the edge of his palm tree grove in Florida.
NASA does not have vision. Bureaucracy and the games of Washington politics have distracted them from keeping on track of the grander goal; space exploration.
The shuttle was supposed to be a "bus" that would assist further exploration, but design issues caused spending to skyrocket and that came at the cost of other programmes being killed.
So when Atlantis clears the tower on launch pad 39A in the coming days (it's scheduled for Friday but the weather is looking to be an issue), the books close on the programme that became the face of US spaceflight for a generation.
I saw my first launch at age 12 and like millions of other US children, dreamt of being a shuttle astronaut.
Atlantis and her already retired siblings deserve the grand send off they will get when she blasts off, but once the smoke and steam clears, Americans will be looking for the next NASA icon.