The Royal Mail recently sought NASA’s help to answer a question from five-year-old British boy Oliver Geddings. How much, he wanted to know, would it cost to send a Christmas card to Mars? Geddings, who wants to be an astronaut when he grows up, was worried the cost of the postage might be more than he could afford. And indeed, it was.

NASA calculates cost of sending Christmas card to Mars.

NASA calculates cost of sending Christmas card to Mars. Image by Monica Arellano-Ongpin / CC BY 2.0

With the help of the NASA Kennedy Space Centre in Florida, USA, the Royal Mail estimated Geddings would need some 18,416 first class stamps at a cost of £11,602.25 to send a card to Mars.

Andrew Smout, senior customer advisor at Royal Mail, said his team spoke to NASA’s Mars outreach unit to come up with a total. To calculate the cost they factored in the distance to Mars (567 million km), the average weight of a Christmas card (100g), the amount of fuel needed and, in spectacular display of attention to detail, the £2.25 it would cost the Royal Mail’s international team to send the envelope to NASA’s launch site.

European Southern Observatory.

European Southern Observatory. Image by European Southern Observatory / CC BY 2.0

Geddings’ response? “Wow! That’s a lot of money. Thank you Royal Mail for working out the answer, I enjoyed reading it. It’s very expensive to send a letter to Mars. You would need so many stamps!”