No, not in Mars itself, or the moon itself. The economic effect will occur on earth. We are beyond scarcity. Our automated factories and farms produce all we physically need. But the economic impact of going to Mars, moreso than to the moon, is that we will have to gear up considerably to support such an effort. This means significant jobs in direct government tax-supported positions, but also means support jobs in new communities by whatever ratio these normally occur, 5 to 1 or whatever. The government primes the pump, the citizens build homes, schools, fix cars, rent movies, sell clothes, generally engage in commerce. The exloration of Mars would also draw the bright youth from what used to be called the Third World and is now called the Gap, thereby would promote peace in those regions and add to our considerable wealth and reputation and therefore encourage international trade to our benefit. Mars itself is nothing; Mars as a program is huge.