My first design features a red flag (as Mars is the Red Planet this seemed appropriate). Towards the hoist is a pair of hands which symbolise humanity. The hands are open, and holding the astrological symbol for mars (which is coincidentally the male symbol, which I think represents the shield and spear of the Roman God which the planet gets its name from). Inside this is the Astrological symbol for Earth the home planet of the colonists.
Let me know what you think of these designs. If you are brave (or mad) enough to sign up as a one-way astronaut or are just curious their website is here.