I struggle with these bandwidth/cost of storage type questions but I will go ahead and take a shot because why not?
I am going to calculate bandwidth requirement with the following formula:
Gmail users in Mars * Average bandwidth allowed by Gmail (upload and download) per day
Gmail users in Mars:
Google just announced that it now has more than 1 billion active users on Gmail. That’s not super useful because it does not tell us a relative %. Well maybe we can say that the world has 8 Billion people and if 1 billion of them are active on Gmail, then Gmail has a 12.5% share of the world’s population.
Lets assume that the people who build a community on Mars will be millenials, Gen z folks and they will have a higher Gmail penetration – lets say closer to US’s penetration = 30%.
How many people will live on Mars? Mars is half the size of Earth but Earth is 70% covered with water. And Mars has no water. So, lets say that Mars can roughly accommodate all of earth’s population because people can live all over the place. But due to it being a newly inhabited planet, lets say we ultimately end up with 1/4th of the population = 8/4 = 2 Billion people
Out of this 30% will use Gmail (based on our earlier adoption assumption) = 0.6B = 600M
As per Gmail documentation each person is allowed
Download: 1250 MB
Upload: 500 MB
If Gmail plans for this size to be available to each user per day, then total size per user per day = 1750 MB per day = 1.75 GB per person per day
Total bandwidth required per day = 0.6 GB people * 1.75 GB storage