When the Apollo astronauts journeyed to the Moon, they had a hard time sticking to schedule. Virtually all of their excursions fell behind their pre-set timelines, new research finds, and that could have big implications for how NASA handles human missions to Mars in the future.

The astronauts’ tardiness was uncovered by researchers at the Georgia Institute of Technology, who analyzed all of the Apollo Moon walks in a new study presented to NASA. Specifically, they pored over the logs of each trip the astronauts took outside their spacecraft to collect lunar samples, called an “extravehicular activity,” or EVA. They found that all the EVAs were slightly late for a variety of reasons, including malfunctioning technology and dealing with new hardware. As a result, the astronauts would sometimes have to drop some assigned tasks altogether.

NASA will need to be flexible when it sends astronauts to Mars

Lags on the lunar surface weren’t that detrimental, because the Moon is relatively close to the Earth. There’s only a half a second of communications delay, so NASA’s Mission Control could tell the astronauts in real time which tasks they needed to drop. But Mars is much farther away, and radio communications will take between five to 20 minutes to reach Earth. So if astronauts fall behind, they’ll need to figure out what tasks to abandon on their own. That means NASA will probably need to be flexible when it sends astronauts to Mars and have tools that crews can use if they stray from their schedule.

One critical tool is software that can do the thinking for the astronauts, rapidly calculating the best tasks to drop so that the astronauts can get back on track and still do the best science. “If you’re sending someone all the way to Mars, you want to get every last ounce of science and understanding out of it as you possibly can,” study co-author Karen Feigh, an associate professor at Georgia Institute of Technology, tells The Verge. “You do want to pack the mission, but also send up tools that allow you to be robust when things happen and still accomplish as much as you can.”

To develop this software, it’s important to know how past EVAs worked. NASA already has a bunch of data on how astronauts conduct spacewalks outside the International Space Station, but those trips are a lot different than what astronauts will have to do on Mars. Astronauts on the space station usually only suit up when some piece of hardware needs to be installed or fixed on the outside of the ISS. “They really try not to go outside to do science if they can avoid it, because there are just too many risks involved,” says Feigh.

But excursions on Mars will revolve around doing science, much like the Apollo missions. Astronauts will be tasked with collecting lots of samples, to help determine what the Red Planet’s environment is like, and whether or not it once hosted life. Plus, they will likely have some sort of rover, just as the astronauts on the later Apollo missions had. That’s why Feigh and her team wanted to know how the Apollo EVAs fared. “But there was no report that would give us the answer,” says Feigh. “Well that means we have to go figure this out.”

“It was all over the map.”

So the researchers compared the time a task was expected to be completed during Apollo to the time it took to actually complete the task. And practically none went according to plan. “It was all over the map,” says Feigh. In fact, three of the EVAs were “so off the rails,” the researchers couldn’t even do a comparison. “We could only partially analyze them because they did some extensive timeline deviations, and we couldn’t match it up after a certain point,” says Feigh. “It’s so off.”

The problems usually revolved around tech that didn’t function properly. During one Apollo 14 EVA, an astronaut’s communications system didn’t work, so he couldn’t hear Mission Control. As a result, the astronaut’s crew mate had to constantly relay all of the information he was getting from the ground. Tasks also got thrown off when NASA introduced a rover on Apollo 15, and the astronauts had some issues getting the equipment working for the first time.

Astronauts also ended up using way more precious supplies, like oxygen and water, than they had expected. Each time astronauts suit up, they need a few crucial elements to keep them alive, such as air, a way to remove the carbon dioxide they breathe out, water to drink and keep cool, and power for their communication systems. These are known as consumables, and based on Feigh’s research, the Apollo astronauts wound up using about 20 percent more consumables than they had planned to.

Since Apollo, NASA has gotten a lot better at figuring out how much consumables an astronaut needs during a spacewalk, so that may not be as much of a problem on Mars. But a lot of things could still go wrong: if a Mars EVA lasts longer than expected for whatever reason, that could eat into the limited resources. Technology could still malfunction, and it’s possible that astronauts will get thrown off track simply by being in a place that we know very little about. We can get detailed imagery of Mars from NASA’s satellites orbiting the planet, but it still doesn’t prepare astronauts for what it will be like to live on the surface.

“There are things you can’t plan for.”

“The Apollo astronauts spent a ton of time training with geologists to try and prepare themselves for what they were going to need,” says Allison Paige Anderson, a space suit expert and associate professor at the University of Colorado at Boulder, who was not involved in the study. “But just the fact that there were so many unknowns that could not be accounted for, that led to the deviations from the timelines.” In some cases, the Apollo astronauts were too well-trained. During one EVA, for instance, the crew decided to go off course to collect a rock they found interesting, adding extra tasks to their timeline. “There are things you can’t plan for,” Anderson tells The Verge. “They didn’t know they were going to see this rock that was going to lead to these geologic findings.”

That’s why software could be really valuable on Mars. Feigh and her colleagues at Georgia Tech are developing a timeline-tracking tool, while NASA researchers are working on their own software that can update timelines when astronauts fall behind. Meanwhile, researchers are also working on heads-up displays that can show astronauts on their helmets how many resources they have left. That way, astronauts have as many tools at their disposal to do the best EVAs they can.

“The astronauts themselves are going to need to have more flexibility and control of their own timelines in order to accomplish all of these different goals,” says Anderson. “Getting behind in a timeline, even now, adds stress and operational pressure. Giving more cushion and planning gets rid of some of those potential issues.”