QUESTION:
Are there any treaties that NASA has entered into with other countries
regarding the exploration of space and landing on other planets.  Does 
the United Nations or any organization in our government handle 
treaties regarding space exploration?

ANSWER from Mark Adler on March 24, 1997. 
Yes, there are treaties about space exploration that the United States 
of America is party to.  NASA by itself has no authority to enter into 
international treaties for the United States.  However, NASA is 
responsible for its own compliance with any relevant treaties that the 
U.S. has entered into.  Other agencies in the U.S. are responsible for 
the compliance of commercial space activities.

The United Nations is a forum from which such treaties can originate,
but in the end treaties are between the countries that sign them.
Most important was the 1967 Outer Space Treaty, following in the 
footsteps of the 1959 Antarctic Treaty, that says for those
governments who signed it (I've heavily paraphrased it): that outer
space belongs to everyone and therefore no one; that no weapons of
mass destruction be stationed in space; that celestial bodies not be
used for military purposes; that if someone else's astronauts have to 
land in your country that you treat them nice and return them; that if 
someone else's astronauts are in trouble that you help them if you can;
that you're responsible for whatever space activities originate from
your country (government-funded or not), including any mess that they
make; that the stuff you send into space or make in space does in
fact belong to you; that you not interfere with anyone else's peaceful 
exploration and use of space; that you not harmfully contaminate other 
bodies with Earth stuff, nor harmfully contaminate Earth with space 
stuff; that you tell everyone what you're doing in space, let them
watch, and share your results; and that you allow visits to your 
facilities on other celestial bodies if practical.
Just about every country signed it including most significantly the 
U.S. and U.S.S.R.  The People's Republic of China eventually signed it
in 1983.  I  believe that Russia, Ukraine, and Kazakhstan, ex-Soviet
states with space facilities, have agreed to "inherit" the treaty as 
signed to by the former Soviet Union.

More treaties followed, expanding on the rescue of astronauts and 
return of space objects (1968), expanding on the liability for 
damage caused by artificial space objects (1972), and some boring 
stuff on the registration of space objects (1975).  Other treaties 
having something to do with space include the 1963 Test Ban treaty 
which prohibits nuclear weapon tests in the atmosphere, outer space, 
and underwater, the 1972 Anti Ballistic Missile Treaty which 
prohibits among other things a space-based ABM system, and the 
treaties creating the international satellite organizations, 
INTELSAT (1971) and INMARSAT (1976).

Perhaps most interesting is the treaty that the U.S. *didn't* sign.  
The U.S.S.R. didn't sign it either.  It is the 1979 Moon Treaty. 
Among other things it stated that any benefits derived from the
natural resources of the Moon or any other celestial body be shared by 
all signatories, especially developing countries, as decided by an
international group to be formed by the signatories.  The L5 Society
convinced the U.S. to not sign on the grounds that the treaty would
effectively prevent the commercial use of celestial body resources and 
therefore prevent the settlement of space.  That makes sense to  me.  
After all, would you invest billions if your profits were to be split 
and scattered by some international committee?

As for the treaties that were signed, it should be kept in mind that
treaties can be broken.  (Ask any Native American.)  They generally
remain in force so long as it's in everyone's interest for them to 
remain in force.  If, for example, a resource were found in space
that was both highly profitable and rather limited, I suspect that
the rules would change fast.