At this time of the year, most kids just want to send letters to Santa at the North Pole. And although that's still a daunting task for the postal service, one five-year-old boy from the U.K. decided he'd rather send a letter farther than that: he wants to send a letter to Mars.

So the boy in question, Oliver Giddings, asked the Royal Mail (the British postal service) about how much a stamp might cost to get his letter to the red planet. Of course, that organization had no idea, but officials consulted with the experts at NASA to come up with a figure.

To begin with, even sending something as small as a normal-sized letter to Mars isn't a very easy task. The letter would need to find transportation, as Mars is well outside of the territories of any Earth-based postal agency. And that transportation isn't easy to come by because it's not like there's a shuttle to Mars every day.

So to get a letter to Mars, the letter would have to get launched into space aboard a rocket headed to the red planet. And that's where things get expensive. NASA told Giddings that the last visit to Mars cost around $700 million.

"Based on how much the spaceship weighed compared to how much it costs to get to Mars, they said that something weighing up to 100 grams [about 3.5 ounces] would cost them approximately $18,000 to fly to Mars," said a representative for the space agency.

That's about the cost of 36,000 U.S. postage stamps.

Of course, cost isn't just a factor in sending Giddings' letter to Mars. There's also the issue of time. Again, rockets just don't launch with missions to the red planet that often, and no space-based organization yet has an official launch date for the next mission there. So Giddings will likely grow up and become an adult before his letter ever leaves Earth.

Of course, there are private organizations gunning to beat NASA to Mars. Companies like SpaceX already have plans for building rockets and capsules that can carry humans to the red planet, as well as developing technology for human settlement once they get there. But even considering that, the next trip to Mars is still probably not in the near future.

However, maybe this will encourage young Giddings to become an astronaut and be one of the first to set foot on Mars. In that case, he could deliver his letter himself.