When it comes to taking an outdoor stroll in this solar system, options are limited. Here we'll quickly compare the experience of taking a daytime hike on the Moon, Mars, and Saturn's moon Titan.
Outermost Jovian moon Callisto is possible, but comparable to Earth's Moon. We've also left out Mercury (roasting), Venus (boiling acid bath), asteroids (gravity too low), the inner Jovian moons (too much radiation), and the gas planets themselves (no proper surface).
Titan has a thick nitrogen atmosphere, slightly more dense than our own. No pressure suit is required. The Moon and Mars have effectively no atmosphere. Without a pressure suit your blood would boil. These suits are unavoidably bulky and resist your every movement, creating the Michelin Man effect. For the pressure suit standard, we use NASA's xEVA / Artemis suit baseline. [1][2]
| Component | Earth | Moon | Mars | Titan | |
|---|---|---|---|---|---|
| ============== | ===== | ===== | ===== | ===== | |
| Pressure suit | – | 110 | 110 | – | kg |
| Insulation/gear | 5 | 15 | 15 | 15 | kg |
| CO2 Rebreather | – | 25 | 25 | 25 | kg |
| Cooling system | – | 25 | 25 | – | kg |
| Heating system | – | – | 5 | 5 | kg |
| Hydration | ½ | 1 | 1 | ½ | kg/h |
| Coms system | – | ½ | ½ | – | kg |
| Total suit mass | 9 | 178 | 182 | 48 | kg |
| Local gravity | 1.00 | .165 | .378 | .135 | g |
| Local weight | 9 | 29 | 69 | 6 | kg |
| hiker body weight (assumed 75 kg person) | |||||
| Hiker body mass | 75 | 75 | 75 | 75 | kg |
| Hiker local weight | 75 | 12 | 28 | 10 | kg-eq |
| total load on hiker | |||||
| Total carried weight | 84 | 41 | 97 | 16 | kg-eq |
| Earth baseline (84 kg-eq) | 100% | 49% | 116% | 19% | |
| Max comfortable hike | 8+ | 2 | ½ | 6+ | hours |
Shaded rows are additions. kg-eq = kilograms-equivalent force at Earth gravity.
Earth baseline = hiker (75 kg) + gear (9 kg) = 84 kg-eq.
With proper gear, we can expect Titan to be downright comfortable. A heated dry suit, helmet, and closed-loop breathing system suffice for at least 6 hours, and you can talk normally with your companions during the hike. By comparison, the Moon and Mars are more like going for a walk in a personal submarine with appendages.
[1] NASA, EVA-EXP-0042, Rev. B, Oct 19, 2020.
[2] NASA, et al. "Space Suit Portable Life Support...", 52nd International Conference on Environmental Systems, 2023.