All Fermi answers
Fermi #13 · Question 3

How many people have ever been to space?

Explore the official answer and the simple reasoning behind this Fermi estimate.

3QUESTION 3 OF 3

Answer & explanation

Anyone who has crossed the Kármán line

The official answer, with Fermi’s reasoning step by step.

Answer & explanation

Official answer

690

people

How to estimate it

Fermi’s official “Napkin math”

No population to lean on, so use the calendar. People have been going to space since about 1961, roughly 65 years. How many new people get up there in a year? Not many, maybe a dozen.

Years since 1961
~65
New people per year
~11
65 × 11
≈ 700

Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.

Source calculation & reference
FAI threshold (Kármán line)
100 km
Of whom Blue Origin suborbital fliers
92
Same tally on the lower US 80 km line
≈ 780
Unique humans above 100 km, 1961 to 2026
≈ 690

Reference cited by Fermi: FAI / Space Foundation

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