Forty years after the first manned moon landing on July 20, 1969, SPACE.com asked Apollo astronauts and leaders of the space community to ponder the past, present and future. Steve Squyres, lead scientist for the Mars Exploration Rover Project and a professor at Cornell University, is an avid fan of human spaceflight though he works on one of the most successful robotic missions to space, and is optimistic about humanity's chances of getting back to the moon - and even to Mars - in the coming decades:

SPACE.com: Did the Apollo mission have a big impact on you?

Squyres: Oh, yeah, of course it did. I mean, it was one of the key historic events of my formative years. And there are several missions I particularly remember. I remember John Glenn's flight very well, though I was only 6 years old at the time. I remember Apollo 11 vividly. I remember Apollo 8; Apollo 8, that was the first time that humans went to the moon, and I remember being at my grandparent's place on Christmas Eve, and then listening to the astronauts read from the book of Genesis. It was a very stirring, very moving sort of thing. So, yeah, I would say that all of those things captured my imagination, got me very interested in space exploration.

S: What do think of the direction that space exploration took between Apollo and now?

Sqyures: Well, there has been a period that we've gone through since Apollo, where we've focused on doing things in low-Earth orbit. I think that makes a certain amount of sense, because the next leap beyond going to the moon is a very big one.

I am very excited at the prospect of astronauts not just going back to the moon, but in the near future I hope, going on to explore near-Earth asteroids, going on to explore Mars and so forth. And so what I'm looking to is the future and hopefully, I want to see during my lifetime, astronauts not just back at the moon, but at asteroids. I'm hoping to see that.

S: Do you think that that might actually happen?

Squyres: Yeah, yeah, absolutely, absolutely. It's going to require a substantial commitment of resources - these things are difficult to do and they are expensive to do, but they're certainly technically within our grasp. And I think the reasons for sending humans out into deep space, out to explore these distant targets are sufficiently compelling, and the benefits are sufficiently great that it's worth doing.

S: So how do you think this effort affects the manned vs. unmanned mission balance?

Squyres: You know, I'm a robot guy, that's what I have spent most of my career doing, but I'm actually a very strong supporter of human spaceflight. I believe that the most successful exploration is going to be carried out by humans, not by robots.

What Spirit and Opportunity have done in 5 1/2 years on Mars, you and I could have done in a good week. Humans have a way to deal with surprises, to improvise, to change their plans on the spot. All you've got to do is look at the latest Hubble mission to see that.

And one of the most important points I think: humans have a key ability to inspire, that robots do not. Somebody once famously said, ' Nobody's ever going to give a robot a ticker tape parade,' and there's something to that.

Just drawing from my own experience, many of the other people who worked on building the MER rovers, and who work on operating them today, are people who grew up during the '60s, like me, watching Mercury and Gemini and Apollo on TV as kids and dreaming of sending spaceships to Mars someday. And now we do it.

And there's going to be another generation of kids that are going to watch astronauts go back to the moon, go to asteroids, go to Mars, and be inspired to do incredible things that we can't even dream of right now.

S: What do you think will be the necessary impetus to get us back to the moon and beyond?

Squyres: Well, I think we have the impetus. I think the desire to explore, the imperative to continue to do what NASA is doing in space, I think that impetus exists. It's a matter of ensuring that we have the necessary resources, because it's expensive stuff, and having a viable plan for getting the job done. And that's going to be the kind of thing that the next NASA administrator, the Obama administration, the Senate and the House of Representatives is going to have to work out.

S: Do you think it can be done by NASA alone, or will it take other countries' programs or private spaceflight to do it this time around?

Squyres: For one, I think that NASA can do it alone. NASA certainly has the technical competence to go it alone. Whether they should go it alone or not is another question. There can be some benefit to doing things internationally — I think the space station vividly shows that.

Now as far as commercial stuff is concerned, boy, I would love to see more commercial activities, more commercial development of space. I think there's enormous potential there. Now you have to exercise that potential very, very carefully. When you send humans into space, mission success and crew safety are paramount — those cannot be compromised. And so using the COTS [Commercial Orbital Transportation Services] program as its being used right now initially to start by launching cargo, and let the commercial entities develop a solid track record of launch vehicle success launching cargo into space first, before you move on to talking about humans, I think is an appropriate way to go.

S: One of the big questions seems to be whether or not we as a country, or a planet, want to go back to the moon and beyond.

Squyres: I sense when I talk to people - I go out and give talks a lot - that there's still a lot of excitement about space, about the places we can go. I'm an unashamed enthusiast for space exploration - always have been since I was a little boy watching John Glenn on TV when I was six, and always will be - and that's the way I look at it.

• New Video - Leap to Lunar Orbit
• Image Gallery - Project Apollo: "Before This Decade is Out"
• SPACE.com Special Report - THE MOON: Then, Now, Next

Forty years after astronauts first set foot on the moon, SPACE.com examines what we¹ve done since and whether America has the right stuff to get back to the moon by 2020 and reach beyond. For exclusive interviews and analysis, visit SPACE.com daily through July 20, the anniversary of the historic landing.