The Martian High Command was a bit miffed at the fact that Earth had launched a cargo ship so soon. Of course, it was probably a goal of all three powers to have such a capacity, and it wasn't exactly realistic to assume that they had a lead, not in all areas, not in any area. The officers were optimistic about the situation, though, and immediately welcomed any trade, granting the Earthlings permission to send the ship to Mars. It would be watched carefully, of course, at least until it was determined to indeed be unarmed.
As usual, the idealistic diplomats found the chance to interject one of their own ideas into every situation. In this case, they believed, it was time to reveal another treaty they'd come up with sometime ago, but had been wary to propose. They had no idea what the other planets' timetables were, and had not predicted needing to bring up the issue for another year or two, but now that there was a cargo ship known to exist, it was time to start hammering out what the official procedure for claiming worlds would be. While the other two peoples probably didn't know it, the Martians had a real love for Red Tape.
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Greetings Sentients,
We the people of Mars agree to accept free and open trade throughout the system. However, we have another concern that we wish to bring before the interplanetary community. We believe that with the advent of cheap transport, an inevitable race will occur for the planets and moons of our system. To prevent tension for throwing our civilizations back into the horrors of war, we propose the following treaty.
Treaty of Utopia Planitia
The undersigned parties agree that
A) Only individual solid planets or moons may be claimed by a civilization. (Freedom of fuel from gas giants)
B) Only one claim can be made a month of a single body.
C) New claims can only be made if a signatory can exploit the claim within two years.
D) For a new claim made by one signatory, each other power is allowed to make a claim without the previous requirement.
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We are open to any changes suggested by other powers.