The last (planned) flight of space shuttle Atlantis
So, we get down to the "first of the lasts". Friday's launch of the space shuttle Atlantis is expected to be the final outing for this particular orbiter before retirement.
It won't go to a museum straightaway on its return from the space station, however. It will go back into the processing flow, as they say, and made ready as the "launch on need" rescue shuttle should November's Endeavour flight get into trouble.
As I've already discussed in this blog, there is some talk in the US as to whether having gone to the trouble of prepping Atlantis in this way, Nasa should just fly it out anyway.
The extra spares and supplies would be gratefully received at the station and were the ship to sustain damage itself - a holed wing on lift-off, for example - the small crew (just four individuals) could return to Earth in Soyuz capsules.
That's a decision for later in the year. President Obama still has to convince Congress that his new strategy for space exploration is the correct one and that the shuttle fleet should be stood down as planned.
Some politicians persist in trying to get orbiter operations extended, so nothing can yet be said to be a done deal
But the assumption of many is that this mission (STS-132) will be the last for Atlantis.
The commander on the flight, Kenneth "Hock" Ham, speaking for his crew put it thus:
"The six of us are calling this the 'first last flight of Atlantis' and I think that's appropriate because we really don't know what she's going to do next."
One man who would certainly like to see Atlantis make one further "last hurrah" is Jerry Ross.
During his astronaut career, he flew seven shuttle missions, five of them on Atlantis - more than anyone else. Naturally enough, he calls the ship his "favourite".
In a media conference last week, he listed some of the orbiter's key achievements and numbers, and it's worth repeating them here:
And the notable missions:
Jerry Ross recalls a great story about his very first Atlantis flight on 26 November, 1985. It was a mission to put three satellites in orbit and to test some of the construction techniques needed to assemble large structures in space.
This was back when the astronauts climbed aboard the orbiter in light clothing, not the orange pressure suits we're familiar with today:
"My first shuttle flight on Atlantis was the 23rd overall shuttle flight. So, I had listened to 22 crews come back and give us very excruciating details of what they saw, what they felt and what they learnt on each of those missions.
"I put all that information in my think-tank and every time I'd go out running I'd day-dream about what it was going to be like to strap that puppy on and go for a ride. And I can frankly tell you that about 20 seconds after lift-off, I was thinking to myself, 'Ross, what in the world are you doing here?'.
"That was back when we were still launching in a cloth flight suit and a motorcycle helmet. We didn't have our launch and entry suits [used on later flights]; we weren't in a pressurised environment inside that little cocoon that gives us.
"Those suits really do muffle out a lot of the sounds and a lot of the vibrations that the vehicle generates during first stage. And so for me that first ride was a pretty exciting ride. A lot of rumbling and shaking."
A launch is always special, including for those just watching. The crowds on all the approach roads and along the beach near the Kennedy Space Center have reportedly increased in size for the last few shuttle lift-offs.
Quite where Atlantis will live out her retirement is not entirely clear - whenever that happens. Nasa will make all the orbiters safe for display and then ship them to their final homes. Museums interested in taking an orbiter were told this process would cost about $30m.
Space shuttle Discovery has already been promised to the National Air and Space Museum which also has possession of Enterprise, the test shuttle that never actually went into space.
Atlantis is the vehicle I've got closest to, having inspected it in the Orbiter Processing Facility at Kennedy shortly after its return from servicing Hubble last year.
"Magnificent" is the word that springs to mind as you walk under its belly. The patchwork of heat-resistant tiles immediately catches the eye, as does the immense nozzles of the main engines at the rear.
I agree with the "Nasa Brit" on this flight - Piers Sellers - who thinks the orbiters are among the most remarkable machines ever built:
"It's tough because we're right in the middle of it, but we're aware that there is a sense of history here. These three surviving shuttles are a piece of history. We've been to the USS Constitution and HMS Victory, for myself - these old ships which marked the state of technology. Well, these three ships will go down in history, too."