Sending a mixed crew on a long-term mission brings obvious challenges. But if you’re going for a single-sex crew, there’s only one choice that makes sense.

The US has sent 339 astronauts to space, the most of any country. Out of them, only 55 are women. But the US ratio is far better than any other country. The USSR/Russia has 121 astronauts, and only 4 of them were women — and no other country has sent more than two women to space.

But the idea behind an all-female crew is not some moral reparation for this. It’s all out of practicality.

According to a new study, women would be more efficient crewmembers on long-term missions to space. They require less resources, while being able to produce comparable work.

Women in space

In 1959, Brigadier General Donald Flickinger and Dr. W. Randolph Lovelace II suggested that it would be more practical to send women to outer space. Lovelace argued that from an engineering standpoint, it just makes sense, particularly due to womens’ lower body weights and oxygen requirements. However, NASA and the Air Force decided not to follow this recommendation.

In 2000, the argument was picked up again. American aerospace engineer Geoffrey Landis made a “radical” proposal. “It is logical to propose that if a human mission is flown to Mars, it should be composed of an entirely female crew,” Landis explained.

Now, a new study has come back to put numbers behind Landis’ idea. Researchers from the European Space Agency (ESA) calculated that, on average, the female astronaut would require 26% fewer calories, 29% less oxygen, and 18% less water than the average male.

This is pretty much a quarter less required resources — enough to make a big difference. For an estimated mission of just under 3 years (1,080 days), a crew of four women would require around 1,700 fewer kilograms of food compared to an all-male mission — that’s about 10% of a SpaceX Falcon Heavy rocket’s payload to Mars. This would free up valuable cargo space for scientific equipment or other logistical gear.

“These data, combined with the current move towards smaller diameter space habitat modules, point to a number of potential advantages of all-female crews during future human space exploration missions,” the researchers conclude.

The future of space could be female

There’s not much to argue against an all-female crew. When the Air Force didn’t follow through with Lovelace’s recommendation, Lovelace launched a private program to test women and see how they would fare as astronauts. While short-lived, the program suggested that women can outperform male astronauts.

Several researchers have spoken in support of this idea. NASA’s plan to land a woman on the Moon is another positive sign. But whether or not an all-female team can actually happen remains to be seen, and roadbloacks are to be expected. In March 2019, the first all-woman spacewalk was canceled because NASA didn’t have enough medium-sized spacesuits. Astronauts Christina Koch and Jessica Meir subsequently accomplished the feat in October 2019.

NASA administrator Ken Bowersox also offered a bizarre explanation for delaying the all-female spacewalk, saying that men are able to “reach in and do things a little bit more easily”.

In the end, at least for long-term missions, practicality is on women’s side. There are other concerns, but perhaps the other concerns are also on the side of females. Here’s what Landis concluded:

“Statistics show that all-woman groups are far more likely to choose non-confrontational approaches to solve interpersonal problems, and most definitely are more likely to deal with a situation without resorting to violence, which could be a big problem on a Mars journey, where the crew must live in close quarters for 2-3 years,” Landis wrote. “Numerous sociological studies have shown that women, in general, are more cooperative, and less given to hierarchical social structures.”

The study was published in Nature Scientific Reports.