I would say that nothing we do in space is economic! That word implies that you are getting some physical return for your money, as if it's a product that you have bought. Instead, I think our investigations into space travel are an investment. There may be little or no immediate return on them, but that's okay. We're still learning how to do this stuff, and it's fantastically difficult. Remember, the first satellite was launched into space less than 50 years ago, and it took a few decades before that sort of technology could be turned into hard economic results (look at the just the cell phone industry, for example). Nowadays we're talking about fundamentally more complicated procedures. Landing a probe on Mars is hard. The people that try to do this stuff are very, very smart, and they work very, very hard on it.

Is it effective? Well, yes and no. I can't imagine a day when we won't be learning new ways of traveling in space, but right now just about everything we learn is new. So as long as we can learn from our mistakes as well as our successes, we're doing an effective job. As of the time I write this, the cause of the failure of the Polar Lander is unknown. People are trying to figure out why contact was lost. As long as this is unknown, then we cannot learn anything from the failure.

Another important thing to remember is that the recent Mars probes have been "technology-testers," designed and built to try out new things. When the "faster better cheaper" policy was unveiled, we knew it would result in some failures. The philosophy is better to lose a cheaper mission and learn from it than a very expensive one! So far, we're actually doing pretty well. I'd rather have intact, working probes, of course, but it's too early to start doomcrying.