One of the technologies that had to be developed in order to return to the Moon, and possibly go on to Mars, is spacesuits. It may seem like we already have developed adequate spacesuit technology, since we used them on the Moon during the Apollo missions, but this is not true. The Apollo suits were only designed to survive for days on the Moon, not for the much longer missions the Artemis program plans. They were also very clumsy, as you can tell from watching any Apollo footage of the astronauts.

Developing the next generation of spacesuits has proven more challenging than initially thought. Recently NASA announced delays in completing their Artemis spacesuits, which will be available no sooner than 2025, at a development cost of over $1 billion. If we managed to develop spacesuits usable on the Moon in the 1960s, why is this proving so challenging six decades later? Essentially it’s because our goals are more ambitious, but let’s review the challenges.

The Moon is a harsh environment, most obviously because it is a near vacuum. At a minimum spacesuits need to maintain sufficient pressure to keep astronauts alive and comfortable. Current suits use a pressure of 4.3 psi (pounds per sq inch). One atmosphere of pressure is 14.7 psi, which means the suits are pressurized to the equivalent of 30,000 feet altitude. You can compensate for the lower pressure by increasing the percentage of oxygen in the air mix. Why use such low pressure? Because this pressure causes the suit to be tight. At one full atmosphere of pressure the suit would be so tight the astronauts couldn’t move.

Another option is to use a skin-tight suit, with direct pressure on the skin. This would be a much skinnier suit and allow for greater movement, but such suits would be very expensive to build, and would have to be minutely customized to each individual wearer. They would also be challenging to get in and out of. This might require some new fabric technology that can “shrink wrap” around the wearer after being put on. But there are no plans to develop this technology, so for now we are stuck with pressurized suits.

Suits will also have to deal with extremes of temperature. Without an atmosphere for heat conduction and convection the temperature you experience in space depends entirely on whether or not the sun is shining on you. In direct sunlight you can experience temperatures of about 270 degrees F, while in shadow you will experience -270 degrees F. Without robust temperature control, astronauts would either be burning or freezing at any moment.

Outside the protection of Earth’s atmosphere and magnetic field, astronauts also are vulnerable to radiation. Spacesuits provide shielding from UV rays from the sun, but not from particle radiation from either solar wind or cosmic rays. The only protection from this radiation is time – limiting the amount of time astronauts spend outside the protection of a shielded base or ship. They can also measure radiation exposure directly using radiation-sensitive badges and other technology.  On the Moon, being underground is really the only effective long term protection from cosmic rays.

Astronauts who do EVAs from the ISS have usable pressurized spacesuits with temperature control, so this basic technology exists. But these suits have a few problems. First, they do not fully accommodate the more diverse range of astronauts that make up the modern space program. Second, they are still fairly primitive in terms of their heads-up-display and information technology. Astronauts still use a spiral book clipped to their sleeve to go over checklists. Dexterity inside these suits is still limited. And finally, these suits are not designed for the lunar surface.

The primary challenge of the lunar surface compared to EVAs in orbit is the regolith (I hate regolith, it’s sharp, it gets everywhere). The surface of the Moon is covered in a fine powder of what is essentially tiny razor blades (there is no erosion from wind or water to smooth out sharp edges). The regolith tore up the Apollo suits, which were unusable even after a single mission. They can get into joints and equipment and cause a lot of damage. The new Artemis suits are designed to be more resilient to the regolith, protecting potential points of entry. In addition to spacesuit and lunar station design, future lunar stations (if they are on the surface) will probably need to clear the regolith from landing sites and around the base. You could theoretically use the regolith to make a solid concrete-like substance for a firm surface, or even in base construction.

The new spacesuits will also have more integrated technology to improve communication and provide astronauts better control over tools. For example, they will have “integrated information technology and information subsystem (IT IS).” This is an in-helmet display that can provide them with information about their current mission (such as those checklists), as well as the condition of their suit and communication with their station or base. It can also give them the ability to control external tools, by integrating controls in their gloves that are remotely connected to robots, arms, computers, or other tools. This can be essential, as the pressurized gloves seriously limit dexterity.

Recently field tests of the Artemis spacesuits were conducted in the High Desert region of Oregon. This is the same location where the Apollo astronauts trained in their suits in the 1960s. The suits are designed to give a much greater range of motion and mobility over the Apollo era suits. But this is still a challenging technology, and the sleek suits we see in science-fiction movies are likely a long way off.