Ambitious plans for colonizing Mars have hit a serious technical dead end. As NASA engineers have discovered, modern lunar spacesuits, representing the pinnacle of modern engineering, are physically unsuitable for working on the surface of the Red Planet. This was revealed in a report presented at the 55th International Conference on Environmental Systems (ICES).
The main problem lies in gravity. The lunar xEMU spacesuit weighs 170 kg. On the Moon, where gravity is one-sixth of Earth's, an astronaut feels this load as only 28 kg. However, conditions on Mars are radically different: gravity there is three-eighths of Earth's. Under such conditions, the same suit would press on the astronaut's shoulders with a force equivalent to 64 kg.
Critical Load on the Body
The situation is exacerbated by the physiological state of the crew. After a long flight in weightlessness, the human body loses between 15 and 25 percent of its aerobic capacity (VO2 max indicator). The combination of reduced endurance and the colossal weight of the suit creates a critical load.
According to standards set by the U.S. National Institute for Occupational Safety and Health, the maximum lifting load for a person should not exceed 23 kg. Considering that the internal pressure of the spacesuit (working on the principle of a balloon) relieves about 22 kg from the shoulders, engineers calculated the maximum allowable mass of a Martian suit (MxEMU). It should not exceed 104 kg. This means that the current xEMU prototype must be lightened by 40 percent.
Survival Scenario and Safety Radius
Strict limitations are dictated by the scenario of an emergency walking return. If a rover breaks down far from the base, the crew will have to walk back to the habitat module. Due to the excessive weight of the spacesuit, oxygen consumption increases sharply, reducing the radius of safe excursions to just 1.8 km from the base (assuming a walking speed of 3.5 km/h).
To achieve target indicators, developers will have to rethink weight distribution: about 62 kg will have to be allocated to the portable life support system (PLSS backpack), and 42 kg to the airtight suit itself.
Compromise for Safety
To achieve such indicators, engineers propose abandoning the modern modular architecture and returning to the integrated design of the Apollo program era. Back then, life support components simultaneously served as elements of the physical frame of the spacesuit.
However, this step carries serious risks. Apollo-era spacesuits were protected against only a single failure (single fault tolerant), whereas modern xEMU suits have double redundancy (double fault tolerant). Engineers will have to make a conscious compromise on safety to remove excess weight from the shoulders of Mars' first visitors.
