CAPE CANAVERAL, Fla. — For most people, the final launch of the space shuttle Endeavour is a love story, a gripping tale about the astronaut married to the congresswoman who was critically injured in a mass shooting some months ago.

But for Massachusetts Institute of Technology professor Samuel C.C. Ting, Endeavour’s Friday take-off is about finding the secrets to the universe. The Nobel prize-winning physicist spent the past 17 years figuring out how to build — and fund — a magnet big enough to shoot into space and study the cosmos.

His $2 billion particle detector — the Alpha Magnetic Spectrometer — leaves Friday for the international space station, and will never come back. For the first time, a device will study the particles in space that would otherwise be lost in the atmosphere.

“”Why we want to do it is to find what is the origin of the universe,”” Ting explained. “”What is the universe made out of?””

The AMS, as it’s known, is the principal payload (that’s “”cargo”” in space lingo) for the Endeavour’s final mission. It’s launch is scheduled for 3:47 p.m. EDT, weather permitting. It will be a bittersweet moment for the National Aeronautics and Space Administration, which is preparing for its final shuttle launch in June.

So while the Space Coast community prepares for a viewing crowd expected to reach 700,000, NASA scrambles for visits from President Barack Obama and his family.

Arizona Rep. Gabrielle Giffords, shot in the head by a would-be assassin’s bullet in January, is also expected. Her husband Mark Kelly is the flight captain and he wrestled with the difficult choice of whether to leave for a two-week mission while his wife struggled to regain speech and mobility.

Both she and the first family are expected to be out of sight Friday, away from the more than 2,000 journalists who registered to chronicle the historic mission.

“”I feel quite sad that this happened to him,”” Ting said in an interview. “”I admire Capt. Kelly’s ability to carry it on.””

He and other experts interviewed insist that Kelly is ready for the mission.

“”It’s primarily a family medical matter, and I haven’t seen or heard him discuss it — and I sit about 30 feet away from him,”” said Stanley Love, an astronaut who is not participating in the mission. “”We all know and love Gabby and don’t doubt for a moment that she wants him to do this. It is a rare case of a difficult decision where both answers are right.””

Love is the rare astronaut who has a PhD in astrophysics, so he’s one of the few here who actually understands the payload and its purpose.

“”Why is the universe made of matter and not equal amounts of matter and anti-matter?”” he asked, like it was something everyone was thinking about. “”There’s very little anti-matter in the universe. It’s a big question: where did we come from?””

He pointed out that 1920s era “”esoteric lab experiments”” involving quantum mechanics (“”a bunch of math””) were ultimately the basis for today’s computer.

“”The mission of this is to search what was happening in the beginning of the universe,”” said AMS project manager Trent Martin. “”Why? Because we can. Why? Because we have a thirst for knowledge.””

The universe, he said, is expanding further than we can see. “”We call that dark matter, but we don’t know what it is,”” he said. “”Hopefully, with an extremely precise detector, which can only take measurements in space, we can identify dark matter, anti-matter, strange matter and all kinds of phenomenon theorists think about but we have no knowledge of.””

Some experts dismiss AMS as an astronomic boondoggle, and have called it an “”outrage.”” Ting said the 16 countries that built and funded the project clearly thought otherwise. As for the University of Michigan professor who called his project a space station “”hood ornament,”” Ting said: “”I went to the University of Michigan; they used to have a very good football team.””

NASA Payload Manager Joe Delai called it the “”most challenging and exciting”” payload he has ever dealt with.

“”The objective of the AMS is to probe the unknown, that’s what’s exciting about it,”” Delai said. “”To probe what’s known is not exciting. We don’t know what it’s going to do; that’s how you do science.””

The magnet will study the matter swerving toward it by measuring how far it veered right or left. That helps assess its size, speed and charge. The device is controlled by 650 microprocessors and can take measurements to the accuracy of 1/10 of a human hair.

Built around the world and assembled in Switzerland, it has a life span of about 20 years. It was transported to the Kennedy Space Center in a C-5 cargo carrier borrowed from the U.S. Air Force.

Ting acknowledges that it will be hard to see it go, not be able to touch it again or make modifications.

“”For me, as a physicist, it’s curiosity,”” he said. “”Curiosity is what is driving us to do science.””