1QUESTION 1 OF 3
Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
48,400
person-days
How to estimate it
Fermi’s official “Napkin math”
People have lived up there nonstop since late 2000, so about 26 years. How many are aboard at once? Three in the early days and seven now, so call it five.
- Years with a crew aboard
- ~26
- Days a year
- × 365
- People aboard at once
- × 5
- 26 × 365 × 5
- ≈ 47,000
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Continuously crewed since Expedition 1 docked
- 2 Nov 2000
- 253 long stays, Expeditions 1 to 75, launch to landing
- 46,462 person-days
- Minus travel to and from the station
- − 444
- Shuttle crews on 32 visits
- + 1,594
- Soyuz taxi crews, tourists, Axiom missions
- + 550
- Soyuz MS-29 crew, aboard since July
- + 235
- Total to 1 October 2026
- ≈ 48,400 person-days
Reference cited by Fermi: ISS expedition crew dates (Wikipedia, from NASA records), totalled by us to 1 October 2026
How close was your guess?
Your comparison will appear here.
Compare by ratio: divide the larger number by the smaller one. The closer to 1×, the better.