Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
9
days
How to estimate it
Fermi’s official “Napkin math”
The space station is closer than it sounds. It sits about 250 miles up, roughly the drive from New York to Washington, just pointed straight up. How fast is the escalator? A bit over 1 mph, so call it 1.
- Height of the ISS
- ~250 mi
- Escalator speed
- ÷ 1 mph
- 250 ÷ 1
- ≈ 250 hours
- ÷ 24
- ≈ 10 days
The space station is closer than it sounds. It sits about 400 kilometers up, roughly the distance from London to Paris, just pointed straight up. How fast is the escalator? Not quite 2 km/h, so call it 2.
- Height of the ISS
- ~400 km
- Escalator speed
- ÷ 2 km/h
- 400 ÷ 2
- ≈ 200 hours
- ÷ 24
- ≈ 8 days
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- ISS average orbital altitude (NASA)
- ≈ 400 km (250 miles)
- Assumed straight-up speed
- 0.5 m/s
- 400,000 m ÷ 0.5 m/s
- ≈ 800,000 seconds
- ≈
- 9 days
Reference cited by Fermi: NASA ISS altitude; ASME A17.1 escalator speed (assuming straight-up travel)
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