A team of NASA and industry engineers has concluded that the agency’s most advanced spacesuit — the Exploration Extravehicular Mobility Unit, or xEMU — is unsuited for Mars missions. The finding was presented at the 55th International Conference on Environmental Systems (ICES), according to reporting by Universe Today.
A Lunar Suit, Not a Martian One
The xEMU, built for the Artemis missions to the Moon, weighs 170 kilograms on Earth. It is a showcase of modern engineering: it withstands large pressure differentials, offers unprecedented mobility, and features a modular design that allows components to be swapped out as needed.
But those same attributes become liabilities on Mars. With Martian gravity at roughly three-eighths of Earth’s, the suit would still impose an effective burden of 64 kilograms on an astronaut’s body. By comparison, on the Moon — where gravity is one-sixth of Earth’s — the same suit feels like just 28 kilograms.
Why 64 Kilograms Is a Real Hazard
The engineers anchored their analysis in occupational safety standards. The U.S. National Institute for Occupational Safety and Health (NIOSH) sets a maximum recommended load of 23 kilograms for human lifting and carrying. Spacesuits have one mitigating factor: their internal pressure acts like a balloon, buoying the wearer and offsetting about 22 kilograms of the suit’s weight on the shoulders.
Using a conservative reference case — a female astronaut at the 5th percentile of body mass, approximately 50 kilograms — the team calculated that the absolute maximum allowable suit mass for Mars would be 104 kilograms. That represents a 40 percent reduction from the current xEMU’s mass.
To reflect this new target, the team has proposed a conceptual redesign dubbed the Mars Exploration Extravehicular Mobility Unit — the MxEMU.
The Walkback Nightmare
A key driver behind the analysis is the so-called “walkback” scenario. If an unpressurized rover breaks down kilometers from the habitat, astronauts would be forced to return on foot inside their suits. With the current xEMU, carrying the equivalent of 64 kilograms across rough Martian terrain would make such an emergency trek extremely risky — potentially impossible.
Even with a 40 percent mass reduction, the engineers recommend imposing a strict limit: no more than 30 minutes of walking from the habitat. That translates to rover excursions confined within a radius of roughly 1.8 kilometers.
Shedding 40 Percent: How It Could Be Done
Historically, about 60 percent of a spacesuit’s mass comes from the Portable Life Support System (PLSS) — the backpack that provides oxygen, temperature control, and other vital functions. The remaining 40 percent is the suit itself. Applying that ratio to the MxEMU target yields approximately 62 kilograms for the PLSS and 42 kilograms for the suit structure.
One proposed path to weight savings is counterintuitive: abandon the xEMU’s modular architecture and return to the integrated design of Apollo-era suits, where components served multiple structural functions to save mass. The drawback is reliability. Apollo suits were designed to tolerate only a single simultaneous failure, whereas the xEMU can withstand two. The trade-off between weight and resilience is exactly the kind of engineering decision NASA will have to confront before humans set foot on Mars.
As the agency charts a course toward the Red Planet, the message from the ICES presentation is clear: the suit that will serve astronauts on the Moon cannot be the same one that carries them across Martian landscapes — and redesigning it will force hard choices between safety, capability, and survivability.
Source: Olhar Digital
