— In a rare example of overlapping space missions, a U.S. space shuttle is set to return to Earth on Saturday just a few hours after a Russian Soyuz arrives at the International Space Station (ISS).

Together the crews of the three craft total 13 people, tying the record for humans in space, first set 14 years ago this month. Thousands more however, are represented aboard the trio of vehicles in the form of mission mementos flown on their behalf.

What goes up...

Launched Thursday from Russia's Baikonur Cosmodrome in Kazakhstan, Soyuz TMA-14 will dock with the ISS at 8:15 a.m. CDT, delivering the commander and first flight engineer for the station's 19th expedition crew, as well as the first spaceflight participant, or space tourist, to return for a second visit aboard the outpost.

The Soyuz has a limited capacity for carrying payload to space, but each crew member is offered a small space to pack some personal items for themselves and for others.

"On Soyuz, we have we are pretty limited on what we can take, up to one kilogram we can take and that's all," said cosmonaut Gennady Padalka in a pre-flight interview with collectSPACE. Padalka is returning to the station for the second time, having led the ninth expedition in 2004. He is the first to command a second expedition, the ISS's 19th.

Padalka, who flew as "Altair", the same call sign he used on his previous flight, hung a small figurine of a snowman inside the Soyuz. The "weightless indicator", which began to float when they reached orbit, was a gift from one of his three daughters.

Padalka and his ISS Expedition 19 flight engineer Michael Barratt involved other children in their flight by holding a contest to design their Soyuz TMA-14 crew's flight patch.

"We got more than 100, maybe 200 pictures," described Padalka of the response to their worldwide art contest. All of the designs were carried to space on the Soyuz, but only one, submitted by Anna Chibiskova, 12, of Moscow, was adapted to be worn by the crew.

"This was one of many ways we used to bring children into our mission," added Barratt. "I would mention that our [ISS Expedition 19 crew] emblem was also designed by a high school student, a very talented artist, who was essentially able to draw what we conceptualized."

Barratt, who has five children, is flying something for each of them. In return, they chose the soundtrack for his flight, reflecting their individual tastes.

"My music mix is essentially my children's contributions, so one of them is a country music freak, so there's a lot of country -- my daughter adopted from India is the country music freak -- and one of them is into heavy metal, one of them is into classical and one of them is into oldies, and it's just this really bizarre, eclectic playlist I am taking with me, but it reminds me of them, too," he explained.

Due to the weight limits on the Soyuz, another of Barratt's items is also traveling digitally: a copy of the book he authored "Principles of Clinical Medicine for Space Flight".

"It is a big, hunkin' heavy book. It's kind of a niche book; you won't find it on The New York Times' Best Seller List. I was fortunate enough to edit that and write a few of the chapters. It is the sum total of clinical medicine knowledge that we have right now so it was an important thing to get," Barratt told collectSPACE, adding that he plans to work on the second edition while aboard the space station.

"One of the things we want to do in this book, aside from just give all the technical information, is to paint a picture of what human space flight is really like, the actual experience of it so that people who are doing science with space medicine or trying to figure out how to make people better, have that understanding of what it is like from the human standpoint," added Barratt, who has an M.D. and a Master's degree in space medicine, and who served as a NASA flight surgeon before being chosen as an astronaut.

Like Barratt, Charles Simonyi also desired to take a book to the station but was limited by the Soyuz. A billionaire who made his fortune developing Microsoft Office and its related applications, Simonyi rode to orbit on TMA-14 as the first privately funded spaceflight participant to make a second trip to outpost. On his first flight in 2007, he took with him two books to start a library for the space station.

"You know, what I really should be taking up is a Kindle," said Simonyi in a telephone interview, referring to a digital book reader developed by Amazon.com. "That's what the future is for any trip, but especially for a trip to space. Unfortunately, I don't have the weight budget for that. But the symbolic value of having books, especially the books I took with me [last time], is tremendous."

As with his first flight, Simonyi also packed his passport to be stamped aboard the ISS, though it is not the same one he flew two years ago.

"It is a new passport," he explained, "so it will have the nicer stamps now that I know where the nicer stamps are."

Between flights, Simonyi was married and so for his wife he packed a stuffed doll from her youth.

"I am taking a seal that was her doll from childhood, her favorite doll," he noted. "That is going to be [my] mascot."

...also comes down

Simonyi will return to Earth in less than two weeks on a Soyuz with Fincke and his Expedition 18 crew mate Yuri Lonchakov, leaving the station to be tended by Padalka, Barratt and Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, who arrived with space shuttle Discovery on March 17.

Wakata's STS-119 crew mates, including Sandy Magnus who he replaced aboard the station, are expected to land on Saturday at NASA's Kennedy Space Center in Florida, with their first chance for a touchdown at 12:39 p.m. CDT.

Unlike the Soyuz, the space shuttle is considerably larger. Large enough in fact, to deliver the 30,000 pound, 45-foot long truss and 240 foot solar array wings that were used to complete the station's backbone during the time Discovery was docked with the complex, and yet still leave room for a duffle bag-size container of mementos referred to as the Official Flight Kit (OFK) and smaller pouches for the seven astronauts known as the Personal Preference Kits (PPK).

NASA and the astronauts pack the OFK with souvenirs for organizations that have supported the mission. The PPKs are used to store small trinkets for their family and friends. Both the OFK and PPKs are stowed aboard the orbiter for the entire time they are in space, only to be retrieved after landing back on Earth.

The most numerous items flown in the OFK are small U.S. flags to be awarded to those who worked the mission and replicas of the crew's patch, with about 700 of each flying.

Traditionally, the patches are designed by the astronauts as a team building exercise. In STS-119's case, that honor fell to the daughter of the flight's lead spacewalker.

"She's in school now working on a graphics design degree, that's why I thought she might like to do it," shared Steve Swanson, who took part in two of three spacewalks during the 13-day flight.

Swanson's inflight outfits included a shirt embroidered with the mission insignia and the inscription "Thanks Caroline" in reference to his daughter's design work.

Other items carried in the Flight Kit represent the group for which they are flying, rather than the mission they are on.

"I'm flying a couple of things for organizations who've done a lot to support our wounded veterans coming home from Iraq and Afghanistan," shared Discovery's commander and U.S Air Force Colonel Lee Archambault. The kit's manifest (see below) includes several flags and medals for military organizations.

Another common theme within the OFK are items flown for the crew's educational institutions. Pilot Tony Antonelli is one of at least three crewmembers carrying photos of their affiliated schools.

"Everybody stood outside the school and took a picture of the whole thing," said Antonelli of the elementary school where his aunt is a teacher. "Of course, it's packed away, so I don't get to float it around and take a picture of it, but I'll get it back to them."

Joe Acaba and Ricky Arnold, who like Swanson made two spacewalks each, are themselves former educators.

"For my middle school in Dunnellon [Florida] they took a photograph of the school from the sheriff's helicopter, so all the students were outside and they had a sign on the roof saying 'Mr. Acaba's Lab' over the building that I used to teach in," Acaba told collectSPACE.

"From Melbourne High School [Florida], I'm flying one of their school banners," he added. "They cut a hole in the banner and inserted a coin that was designed by one of the former teachers that has a special meaning to the staff and students."

For Arnold, who taught in Saudi Arabia, Indonesia, and in Romania, those types of items were not available.

"The schools are very transient communities, and people come and go pretty quickly at these international schools where I worked," he explained. "What I hope I am taking is that I will be able to go back and talk to some of these communities [about my experience]."

Like his crew mates, mission specialist John Phillips took items for his children and their schools.

"I have two children in universities, and I'm taking a hat for one of their universities and a shirt for another that we're allowed to wear because they in fact represent educational institutions," he said, adding that he was also taking a pair of eyeglasses he wore when he lived for six months on the station in 2005.

Other mementos returning with STS-119 include a National Guard flag flown for Dale Earnhardt Jr.'s NASCAR racing team; a flag for Danica Patrick's IndyCar racing team; and a child-size spacesuit for the Maryland Science Center in Baltimore.

A purple stuffed duck is also aboard Discovery, at Koichi Wakata's request, along with other items for organizations in Japan. They will await his return from space on the next shuttle mission to the ISS, scheduled to launch in June.

The STS-119 Official Flight Kit Manifest

The following is the STS-119 Official Flight Kit manifest, as provided by NASA. Inventory numbers that are missing indicate items that were removed prior to launch.