Days after NASA's Curiosity landed safely on the surface of Mars, it's still a breathtaking accomplishment. That humans can drop an SUV-sized machine onto another planet with such precision is a bewildering achievement.

Today, scientists are tediously testing Curiosity’s cameras and systems, making sure nothing was damaged during the nearly nine-month voyage from Earth to Mars. After 352 million miles and a landing that saw the rover slow from 13,000 mph to stop in seven minutes, a tire-­kicking is in order.

But while millions of earthlings are wowed by new photos from the Red Planet, many others ask: “Why?”

It’s a reasonable question. At a time when the United States is cutting food stamps for the poor and tens of millions are out of work, how can we justify $2.6 billion to launch robots into space?

Practically speaking, it’s a step toward manned Mars missions. NASA’s goal is to get there by 2035. These robot missions are a toe in the water, teaching scientists how to get astronauts safely there and back.

Beyond that, Mars exploration is a study of our friendliest neighbor. Mars has water. It’s closest to Earth in size and gravity. It has four seasons and a 24-hour day. Did it ever sustain life? Does it? Could it? The answers are clues to Earth’s past and future.

But, mostly, the exploration of Mars carries out the inherently human impulse to explore and discover. How many asked: Why explore the depths of Earth’s oceans or jungles? Why set sail for new worlds, or fly? Humans have been launching spaceships at Mars for decades — 40 since 1960. NASA’s Viking missions in the 1970s cost $1 billion.

Some will say it’s too expensive, there are other priorities. They’ll ask: Why now? We haven’t even finished exploring the oceans. The answer: Mankind relishes the challenge, striving always to know what’s around the next corner.

Since announcing in 2010 the retirement of the space shuttles, NASA has been eager for this landing. Now and for the next two years, the rover will send back an encyclopedia of pictures and data. With Curiosity, we return to the forefront of human exploration. If not us, someone else surely will.

In 2010, President Obama said, “Space exploration is not a luxury, not an afterthought in America’s brighter future. … It is an essential part of that quest.”

Still, economic realities back home on Earth led Obama’s administration to call for cuts to the 2013 Mars exploration budget of more than $200 million — close to 40 percent — effectively freezing the program at the height of its success. A TechCrunch report, however, shows Curiosity’s $2.6 billion price tag comes to about $8 per American. That’s less than 1 percent of the U.S. defense budget. That’s a fraction of London’s $14.5 billion budget for the 2012 Olympics.

More and more, private dollars are being spent on space exploration. Private firms, such as SpaceX, promise that industry and innovators will have a hand in the competition for celestial knowledge.

One discovery leads to the next. Maybe the Curiosity mission leads to new commercial products — the Next Big Thing in communication or technology. Maybe photos from Mars will inspire a new generation of scientists — and who knows what they’ll discover? Or, maybe, we simply learn something about our universe we didn’t know before.

Every dollar that does that has been spent well. If we stop now, what might we never learn?