It is extremely likely it is the hypergolic fuel used for the on-orbit manoeuvring rockets. Hypergolic fuel is really nasty stuff.

It is likely the same rocket fuel (maybe the same rockets) as used by the space shuttle (OMS).

http://en.wikipedia.org/wiki/Space_Shuttle_Orbital_Maneuveri...

See also:

* http://en.wikipedia.org/wiki/Space_Shuttle_Discovery#Decommi...

* http://en.wikipedia.org/wiki/Hypergolic_propellant#Disadvant...

That's chemical protective gear designed to protect the ground crew against hydrazine or similarly hazardous vapors .

They were first developed in the 1960s for the Titan missiles, which use the chemically nasty (but room temperature) nitrogen tetroxide and Aerozine 50. See http://books.google.com/books?id=MdTZFu1fZ4AC&pg=PA186&lpg=P... for some of the history.

Here you can see the suits in use at the end of the Space Shuttle STS-1 mission: http://www.youtube.com/watch?feature=player_detailpage&v=gYc... along with explanation by both the news and NASA commentators.

http://www.xcor.com/blog/category/thrusters/ and http://www.esa.int/Our_Activities/Space_Engineering/Clean_Sp... are pictures of people in similar suits, in order to fuel spacecraft. I picked those to give commentary about how hazardous hydrazine is, and that there's a push to use alternative fuels.

Months are not a particularly long duration for spacecraft, and solar arrays are not at all unusual as power sources for spacecraft in the inner solar system.

Some data on satellite lifetimes:

* http://www.ospo.noaa.gov/Operations/GOES/status.html

* http://noaasis.noaa.gov/NOAASIS/ml/life_expectancy.html

* http://noaasis.noaa.gov/NOAASIS/pubs/life%20expectancy.pdf (2009)

As for the protective equipment being used in that Yahoo photo, that's probably due to the use of hypergolic fuel:

* http://en.wikipedia.org/wiki/Hypergolic_propellant

Notice nearly-identical protective equipment being used in the Wikipedia entry.

As for protective equipment for radioisotope thermoelectric generators, here's an example from Cassini:

* http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_gen...

This being the Internet, there's far more information on related topics available:

* http://en.wikipedia.org/wiki/Corona_(satellite)

* http://en.wikipedia.org/wiki/File:U.S._RecSat_Big_Picture.jp...

Hmmm. Wonder what other and far more familiar satellite that KH-11 Kennan looks like.

* http://en.wikipedia.org/wiki/File:HST-SM4.jpeg

Clickable url

http://news.yahoo.com/secretive-x-37b-military-space-plane-c...

the guy who took this picture gave a talk 30c3 he takes pictures of military instantiations Seeing The Secret State: Six Landscapes

http://media.ccc.de/browse/congress/2013/30C3_-_5604_-_en_-_...

Thanks, that was really informative. The green X-Files uniform patch for the X-37 program is very ominous.

The protective equipment is probably for fuel or oxidizer leaks.

This page: http://www.airforce-technology.com/projects/boeing-x37/

says that the vehicle uses either hydrazine or nitrogen tetroxide.

Aside from the main engine, reaction thrusters could foul the surrounding fuselage with nasty chemicals.

It states at the end: "The X-37 is powered by a single Rocketdyne AR2-3 rocket engine, manufactured by Pratt & Whitney. Each engine can produce a maximum of 29.341kN thrust and uses solar power and lithium-ion batteries instead of the traditional fuel cell system."

But earlier states: "Fuelled with military fuel JP-8 and hydrogen peroxide, the Rocketdyne engine of the X-37 is designed to run for nine months. The engine installed in the aircraft currently uses hypergolic nitrogen tetroxide or hydrazine."

Odd, no?

What exactly do you consider odd? As others have replied, hydrazine has a long history for RCS systems in spacecraft, and kerosene + oxidizer mixtures have long been used for propulsion engines. The only technology here that isn't entirely orthodox is the lithium battery, but that's just an evolutionary upgrade from NiCads. Apparently the range safety guys finally decided that it was ok for an unmanned craft to fly with lithium.

Says it is powered by a single engine, but states it powered by hydrazine. Later on contradicts, and says it is powered by lithium ion batteries. Which is it?

Both. A more accurate statement would be that it is propelled to stable orbit by a single rocket. The plane's systems are powered by lithium ion batteries, which are recharged by a solar array.

You appear to want something secretive to be uncovered here, but I'm afraid that the use of this protective gear is not the smoking gun you think it is.

Also, it wouldn't be all that strange for there to be a nuclear device on board. Nuclear power is regularly used in satellites. The reactors are not the same as the ones used in terrestrial nuclear power plants though. A satellite typically uses a radioisotope thermoelectric generator.

"You appear to want something secretive to be uncovered here"

Not exactly, just wanted to know more. I know satellites and spacecraft in the past have used nuclear/radioactive energy:

http://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens

The way you're self-educating is very similar to the strategy used by those who wish to imply that there is something being deliberately withheld. You might want to change your form of autodidacticism in order to draw a larger distinction between the two.

For example, consider the two statements "Seems like a radioactive power source with that type of protection." and "Odd, no?" They imply that you know enough to make a reasonably confident statement about 1) the different types of clothing used for different hazmat situations and what's appropriate for space operations, and 2) that you understand enough about space power systems to judge what's odd.

You received many responses pointing out that these are standard chemical hazmat suits for this sort of task, with decades of examples and pointers to multiple space agencies, and not similar to what's used for space-based radionuclear power sources.

That should have been a pointer that you don't have enough knowledge to be able to say if something is "odd", as regards spacecraft. Your default assumption should be that nothing is odd, and that it's your lack of understanding which is the source of confusion. Resolve that first before looking outside for the point of confusion. Eg, "Thanks for the comments. I don't know much about spacecraft. Could you also help me understand why ... ?"

You could even have done so in your original question. There was no need to add "Seems like a radioactive power source with that type of protection."

While on the other hand, those who believe (perhaps correctly, perhaps falsely) that they've uncovered something secret will use that sort of phrasing to imply that something is secret, even though they don't have the ability to outright say that something is secretive without taking the large chance that doing so will reveal their lack of actual knowledge on the topic.

Ok, you should definitely look in to RTGs then:

http://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_g...

I'll reiterate that hazmat suits are essential when working around rocket propellant, because the oxidizers involved will cause any organic material to ignite on contact. Literally, a pair of cotton gloves would turn in to a ball of flames on contact. That is all that is needed to explain their presence.

The government would have no reason to hide the presence of a nuclear power device, so the power systems described as powered by solar cells + LiIon batteries is entirely plausible. Preferred, in fact, because you needn't address the concerns of radioactive material in a tightly confined space. Arguably, it makes the engineering easier (marginally).

This is also why you should stay away from F-16 and other aerospace wrecks. The F-16 has a tank of hydrazine onboard. Very nasty stuff.

I guess the fuel could be poisoning (that was case for some soviet military rockets). Other option is just caution not to introduce dust particles etc...

Exact same suits being worn here...

http://en.wikipedia.org/wiki/Hydrazine#mediaviewer/File:Hype...

It is simply an MMH or UDMH propellant onboard, which is carcinogenic.