— The spacesuit that Gemini 4 astronaut Ed White wore 42 years ago this week for the first American spacewalk is on display at the Smithsonian's National Air and Space Museum in Washington, DC.

Within the same building, visitors can see the spacesuits that Apollo 11 crew mates Neil Armstrong and Buzz Aldrin wore during the first moonwalk.

Indeed, all 31 spacesuits used by NASA astronauts while either space- or moon-walking during the Gemini, Apollo and Skylab programs are now owned by the Smithsonian and are on exhibit, on loan or being preserved for study by researchers and historians.

If you wanted, however, to see a flown spacesuit worn on any of the 77 space shuttle extravehicular activities (EVAs, or spacewalks) or any of the 53 EVAs made with American spacesuits outside the International Space Station to date, you'd have to look somewhere else than in a museum.

There aren't any on exhibit today and, if NASA's plans for the shuttle-era spacesuits hold true, there may never be any for museums to preserve, let alone display.

A few sizes fits many

Like the space shuttle orbiter on which they fly, modern NASA spacesuits — or extravehicular mobility units, EMUs — were designed to be reusable. Whereas Gemini, Apollo and Skylab astronauts wore spacesuits that were sized to the individual, shuttle-era spacewalkers wear "off the rack" suits that are available in just a few sizes.

Furthermore, they are mix and match; shuttle astronauts don suits assembled from separate upper and lower parts, in addition to the helmet, boots and gloves, as well as the portable life support system (PLSS, pronounced "pliss") on their back. Each component may have a different history, flown in varied configurations for different astronauts.

So, for example, the EMU worn by Kathy Sullivan on the first American female EVA in 1984 may have later been divided and flown again as components of any number of other astronauts' spacesuits. It doesn't exist any longer as a complete suit and NASA documents only track the parts by the missions on which they flew, rather than by which astronaut wore them.

Even so, museum curators had hoped that when NASA no longer needed all the flown components, that through their own research they could piece together specific suits. That of course, assumed that NASA would retire the spacesuit parts such that the museums could obtain them.

Six of one, half a dozen of another

What if you wanted to assemble as many suits as possible from all the different flight components? How many would there be?

"We have lots of components and a lot of [them] are sized. So the way that we answer that question from our internal bookkeeping is twelve, and that is really twelve life support systems," explained Stephen Doering, who heads NASA's EVA office. "The limiting factor for a functioning suit would be the PLSS backpack."

In fact, throughout the shuttle program there have been a total of 16 backpacks. Two were destroyed in 1986 when Challenger broke apart, but were later replaced. Two more were lost in 2003 on board Columbia.

Beyond the PLSS, the hard upper torso (HUT) is the next component in limited supply, said Doering.

"The limiting factor — from a display perspective ... is the pressure garment, the gloves, the legs, the arms, the hard upper torso, for which it is not really possible to give you a count," said Doering.

According to Doering, there exists a possible 13th PLSS. "We have one qualification unit that is not flight ready, it is called Class II. And that's the only one out there."

Extending the service warranty

The space shuttle fleet is scheduled to be retired in 2010. Every shuttle mission carries at least two EMUs; more, if the flight calls for scheduled spacewalks.

In addition, at any given time, there are three U.S. suits on the International Space Station. After the shuttle is retired, NASA is still planning to support ISS operations through at least 2016.

"Today, the on-orbit life for an EMU is 25 EVAs, or two years, whichever comes first," Doering described. "We're in the middle of upping that, primarily because we have to with the advent of the retirement of the shuttle program. Because we're going to be leaving a number of EMUs on orbit on the station and we now no longer have, without a shuttle, a relatively easy way to get them up there, or any ability to return them."

As a result, NASA has had to look at ways to extend the "lives" of the spacesuits without having to return them for servicing on Earth.

"By the end of July, we should have that two year life limit increased to three years and still 25 EVAs, and our goal by the end of 2010 is to have that three years increase to six," Doering said.

To achieve this, NASA has begun studying the elements of their "fleet leader" spacesuits — those that have had the most use before being refurbished — to identify the parts that are most likely to experience trouble as a result of the longer shelf-life. Of particular interest are the components that interact with consumables, those subject to friction and those with functional electronics. This is a first-of-its-kind study says Doering because "we've never needed to" given the frequency suits were returned home.

"We don't have a lot of actual physical data yet on some of these things to be able to say for sure they can go out for six years," explained Doering.

What goes up can't always come down

In addition to increasing their life on-orbit, the number of EMUs aboard the station is to increase, too.

"We can get away with three right now primarily because we've a shorter interval between flights in which we bring suits up and rotate them up and down. We'll be increasing that to four to provide redundancy for the crew members that are going out, even though you only use two at a time, and we are going to be working to develop the capability and procedures to do change-outs of components that we had previously only done on the ground. We are going to have the ability to have them done by the crew on-orbit," said Doering.

The addition of a fourth spacesuit will also prevent delays that might otherwise have been caused by having to wait for a spare part to be launched on a Soyuz, Progress, ATV or Orion crew exploration vehicle (CEV).

Without the availability of the shuttle after 2010, there will be no capability to bring the EMUs back to Earth. Instead, a fiery fate will await each suit as it is retired.

Like Russia's EMU-equivalent, the Orlan, which was never designed to be reused, the spent EMUs will be stowed in Russian cargo ships with other trash from the station and then allowed to burn up when the spacecraft is purposely sent tumbling into the atmosphere.

NASA's Orion spacecraft, which is intended to replace the shuttle, does not have the weight allowances to permit the return of a single EMU.

The reusable U.S. spacesuits are becoming disposable.

"Quite frankly, I'm not sure that the community has gotten their minds wrapped around the idea that EMUs are going to be turned into disposable units. Our community that has been working on EMUs for the past 30 years are having a hard time with that as well, as you can imagine," Doering admitted.

As if it never happened...

"We are going to put four suits on orbit by the last shuttle flight. Those will last, depending on what our life extension capability is, three to six years. They'll have to be replaced either on an attrition or failure basis. So I suspect for real live functional suits, we are probably going to end up with one or two that never made it to orbit post-shuttle," said Doering.

That assumes of course that NASA's planned exit from the space station is not extended past 2016 and, as Doering alluded, that the spacesuits' change-out schedule can be supported.

The chance that there could be no complete flown EMUs available for preservation has the concern of at least one museum curator.

"I would think for the sake of history one would want at least one preserved. At our museum we have the whole evolution of spacesuit technology. It would be a terrible void to have no evidence at all of a complete shuttle flown EMU. It would be as if EVA never happened during the shuttle era," said Valerie Neal, the curator of post-Apollo human spaceflight at the National Air and Space Museum, after learning for the first time about NASA's EMU plans during an interview with collectSPACE.

"This is something we had better get busy working on — making the case with NASA that at least one suit should be held out to be preserved in the national collection," she stressed.

More than just for display, Neal said that the importance of preserving an intact EMU is its value for future research and study. As an example, she referred to recent visits by NASA and contractor teams studying the Apollo suits and spacecraft as they work to design the Orion CEV.

"There is still a great value to having the real thing," Neal said.

It's with that in mind that Neal has been reminding NASA of the museum's interest in an EMU for many years.

"It's been on the top of our wishlist throughout the shuttle era," shared Neal. "I have tried on occasion to see if there was any set of components or any spacesuit that could be decommissioned to come into the collection and always have been told that not so as long as it has useful life in it remaining."

"We do have in the collection some excess parts of arms, parts of legs, but they don't all fit together and they don't all necessarily have all their pieces and all their layers, but we have them just to have something that's representative of shuttle EMU technology. So a full suit has been on the top of our wishlist and every time that we meet with NASA about artifact related issues, we remind them that it is the number one item."

The current waiting list

According to Doering, NASA has received three formal requests for EMUs, for which he doesn't a have a single real spacesuit yet to fulfill. "There are a lot of display suits that are out there however, almost all of them come from this company in California that builds replica stuff for the movies. In fact, the one on display in the lobby of NASA's headquarters is one of those," Doering explained.

"There is not much historical value in a replica because it is not going to have all the correct materials and correct manufacturing techniques and the fine details of an actual flown suit," said Neal, who added that her second choice to a flown EMU would be a training unit.

"There are only two display suits that currently exist that use real NASA hardware. One is in the lobby of my office, the EVA office suite, and one is in Building 7 here at the Johnson Space Center in our engineering directorate for the crew and thermal systems division. Those were both built up with hardware that was either used as Class III, which is training, and has outlived its useful life, in other words, it's no longer available for training, or was originally Class I at one point, but for one reason or another, either through failures, blemishes or things associated with that, we couldn't use them any more. We have been keeping those and piling them up in bond and when we get enough of them, we put them together as a display suit," Doering said.

"My office has been waiting eight years for the suit that we have. We just got it last summer."

Assuming Doering can pull together more display suits, he has already ranked the three requests.

"In order of priority — at least my priority — the top of the list is from the Smithsonian," said Doering. The other two requests are from the neutral buoyancy lab (NBL) and the U.S. Naval Academy.

"[The NBL] gets a lot of folks coming through; it and the mission control center are the two highest visited places here and since it is an EVA training facility, we have been wanting to get a suit out there for display. The delay on it, primarily, is due to cost, and that we are not very inventory rich on hardware. We use this stuff until it's threadbare."

"Of course it costs money, and resources being what they are, it's kind of, as our administrator likes to say, a 'go as you pay' kind of thing. When we have them, we put them aside and we'll build it up someday when we have enough stuff," said Doering.

Been there, worn that

"It would be sad if they did not get one back, or several for display. It's a sign of the desperate budget constraints that NASA is in that they have to consider throwing the suits away," said Thomas Jones, a former astronaut, veteran of three spacewalks and the recent author of "Sky Walking: An Astronaut's Memoirs."

"I know the philosophy is to stockpile spares on the station once the space shuttle is grounded. I hadn't thought of the implications of what was to become of those suits."

For Jones, who got the keep the insignia off his EMU but had to leave the rest of the suit on the station, the rightful place for his or any other flown suit would be paired with the vehicle that took it to Earth orbit.

"I think it would be nice to have it front and center, right with a real space shuttle orbiter on display somewhere. I think that is what people expect to see when they go to a museum: the vehicle, and what they brought back or the work they did in some fashion, like a lunar sample or some piece of experimental gear or some images they brought back. Then it's what you wear people want to see," Jones said.

Doering agrees that the shuttle spacesuits have become a central figure to NASA's image.

"Almost any time you look at a NASA publication of one sort or another, regardless of what it is, nine times out of ten you're going to find a picture of a spacesuit. So it is the visible face of NASA's human spaceflight program as well. It's almost as visible as a shuttle launch is," said Doering. "It is a large part of the United States' space heritage."

"I think one of the most attractive things to me, even as a space traveler, is going to the Smithsonian's National Air and Space Museum, either in Chantilly or in downtown DC and seeing one of the Apollo moon suits and the real lunar dirt on it," said Jones. "I think that's outstanding and while the EMUs aren't going to be as dirty, having a real EMU with an indication of how many hours it has been worn in vacuum and how many people wore it would make for a very impressive display."