Let me explain, because I’m sure that the number 2.5 billion is popping into your head right now (see how insidious the narrative is?).

Curiosity had a total cost of 2.5 billion dollars, yes, but it’s not like NASA went over to the Rover Depot, plucked the glamor model off the shelf and whipped out Uncle Sam’s credit card.

No, NASA spread the cost of this mission out over eight years. The money spent went into salaries of highly-skilled engineers, programmers, managers, and independent contractors in over twenty states across the country. Things like the cost of rocket to launch it to Mars are included in that total, too, which accounts for nearly a fifth of the amount.

If you you just divide the total cost by the number of years NASA has saved for it, you come out with about $312 million per year. This works about to approximately 1.8% of NASA’s yearly budget and approximately diddly-squat of the total federal budget. That’s about $1 per year for every American, aka, nothing. Think of it this way: say you lose one dime every month this year. Whoops! You’ve lost more money than you spent on Curiosity.

For this tiny amount of money, we’ve developed some of the most advanced machinery ever created. We advance our scientific understanding of the universe. We encourage the development of highly-educated problem solvers and provide some of them with jobs. We’ll make discoveries and raise new questions that no one could have previously dreamed of.

A larger topic that I’ll discuss in a separate post is our whole Planetary Exploration budget, which is a division inside of NASA responsible for every robotic mission to the planets. And I really mean every mission: New Horizons, Juno, Voyager, Cassini, MER Opportunity, Curiosity, Mars Reconnaissance Orbiter, Mars Odyssey, and the rest. All of those are funded out of the pool of money reserved for planetary exploration, which is filled to the tune of about $1.5 billion a year. That’s really it. Americans spend more on dog toys every year than the cost to run all of these missions. Just think about that the next time someone in the media asks the question, “can we afford this?”

That’s the crux of this sorry joke. Not only can we afford it, we can afford to spend a lot more. Instead, we choose not to explore. We choose not to know what’s out there. We choose to pretend that Curiosity is some budget-busting mission when really it’s one of the best deals we get from our tax dollars.

We need to change the narrative. The next time someone you know comments about the cost of Curiosity or any other NASA mission, respond with, “Yeah, I know! It’s so cheap! It’s amazing how much they can achieve despite their funding.”

Finally, if you are a scientist and you face this type of question, don’t answer defensively! A defensive answer serves only to legitimize the argument. A respectful answer that denies the validity of the question is the most important way to respond.

Slowly, we can change the question from “why so much?” to “why so little?”

See also: this is a good, long letter from the associate director of Science at a NASA center in the 1970's arguing the value of space exploration.