I think space is governed by international maritime law, and several treaties between the US and RU, namely you can't test nuclear weapons in space, and they are supposed to assist each other in event of alien invasion. Gambling is legal.
Madness string 21898
Until something is explicitly made illegal, it's legal and it can take a while for the law to catch up to reality, especially with how fast technology is changing. There have been lots of times when something happened where people agreed it was morally wrong, but technically legal.