Earlier this month, Scott Kelly and Mikhail Kornienko returned from the first-ever one-year mission on the International Space Station (ISS). Research from the mission is expected to be invaluable for planning missions to Mars, particularly how astronauts cope with spending a prolonged amount of time in a microgravity environment.

But don’t think this is the end for exciting types of missions like this on the ISS. In fact, it is only the beginning – and NASA has some pretty interesting ideas as to what it will use the station for next, including mock Mars missions on the ground in Kazakhstan after a crew returns from the ISS, in addition to more one-year space missions, IFLScience can reveal.

“Two people is not a full study, it’s more of a case study,” NASA’s chief scientist for the ISS, Julie Robinson, tells IFLScience. “Ideally we would like to have 10 to 12 subjects that have done that long duration, so we can put all that data together and be more confident in our risk assessment.”

The reason for doing these stays is to study the physical effects prolonged spaceflight has on the human body. When astronauts land back on Earth after a stay on the ISS, the time spent in microgravity means they are, at first, almost unable to walk under Earth’s gravity. The loss of bone and muscle mass from their time in space means they even have to be carried out of their spacecraft by helpers on the ground. But scientists want to find ways to overcome this.

“There are a number of ill effects about being in space,” said Robinson. “It’s not about surviving, it’s about being able to perform on the surface [of Mars], and not have the mission fail.”

^{At the moment, astronauts are not really in a fit state to work when they return to Earth. NASA/Flickr}

For missions to Mars, which NASA wants to carry out at some point in the 2030s, this clearly poses a problem. Although Mars has only three-fifths of Earth’s gravity, the time spent in microgravity during transit to the Red Planet – around eight months – means the astronauts will have suffered some debilitating effects of spaceflight, making immediate surface operations on the ground difficult.

To compensate for this on the ISS, astronauts go through a rigorous training and diet regime, performing 2.5 hours of exercise on high-tech equipment every day. This won’t necessarily be possible for Mars missions though.

“The exercise equipment on the ISS is way too big to take to Mars,” explains Robinson. “The space station is like a hotel, and the Mars transit vehicle is going to be more like a minivan, so we’ve got to have something compact that you can fold away.”

Some have suggested that one way to counter the effects of microgravity would be to have a rotating section on the transit habitat to Mars, using the centrifugal force to create an Earth-like gravity environment – something similar to the spacecraft seen in “The Martian.” Robinson, though, says this might not be a solution.

“There are a couple of problems with that,” she said. “The first is that it makes the habitat much larger and heavier than it would otherwise be. The more things weigh, the harder it is to get to Mars. We’re very weight-limited with the Mars mission.

“The other thing is you have to design your engineering systems to deal with all that spinning the entire time, or what if the mechanism breaks, and they have to work in a microgravity environment.

“The preference is for a non-rotating spacecraft.”

^{NASA is apparently not favoring a rotating spacecraft, like this one seen in "The Martian," to get to Mars. 20th Century Fox}

Instead, NASA seems keen to focus on simply providing astronauts the optimal diet and exercise they need to make surface operations on Mars feasible. And one way to prepare for that might be to perform mock Mars missions in Kazakhstan, after a crew has landed, as it does at the moment on Soyuz missions.

“One thing we’ve talked about with Russian colleagues is the possibility you could simulate a full Mars mission [on Earth],” Robinson explains. “You could go to ISS for nine months, or a year, and then you could come back down and do a variety of mission activities. You could even do a re-launch [to the ISS, to simulate launching from Mars].”

It’s not clear what this would be yet – whether they would live isolated in a habitat on Earth for several weeks, for instance – and Robinson readily admits such an idea is very much in its early stages. But it’s something NASA has been testing the water with via their Field Test Study, which involves returning crew performing activities on the ground akin to a Mars mission, including putting together equipment and completing an obstacle course.

When would this be done? Well, Robinson didn’t have a firm estimate on dates. At the moment, the ISS is only funded until 2024, so obviously it would be before then – maybe even in the next couple of years. However, she noted that while the ISS is only funded until 2024, its operational lifetime could be longer.

“The space station extension in the U.S. to 2024 is really just about the budget,” she said. “Really it could go as long as 2030, based on its engineering life, and that’s assuming the engineers weren’t conservative, and you know how conservative engineers can be.”

^{Robinson says the ISS could run until 2030 at least. NASA}

And that’s not the only exciting development for the ISS. Next month, a new module called the Bigelow Expandable Activity Module (BEAM) is being launched to the station on a SpaceX rocket. This module is unlike the others on the station, described as “aluminum tin cans.” Instead, it launches in a compact form and has a soft outer shell, so that it can be inflated on the space station. The actual date for inflation has not been set yet after launch. 

“The BEAM module is like a balloon,” said Robinson. “We’ll put it up there, check it out, then we’ll expand it, keep it sealed, see if it holds pressure, and see what happens if little pieces of space debris hit it by taking measurements on the inside.”

This type of module could be used as part of a Mars mission, but Bigelow itself has its own goals. They want to potentially connect some of these modules together in orbit, away from the ISS, and create some sort of orbiting space laboratory, or space hotel. “They’re very open about it,” said Robinson. “They want some day to operate facilities [in orbit] that normal people can go visit in space.”

Bigelow is not the only private company NASA is partnering with for orbital operations, though. Beginning next year, SpaceX’s Dragon spacecraft and Boeing’s CST-100 Starliner are scheduled to start taking astronauts to the ISS, the first private companies to do so. With each able to seat four astronauts – as opposed to three used on the Soyuz at the moment – this opens up new options for crew configurations on the station.

^{SpaceX's Crew Dragon spacecraft could increase the operational capacity of the ISS to seven. NASA/SpaceX}

“Right now, the reason we have six crew [on the ISS] is because the Soyuz serves as our lifeboat,” explains Robinson. “If the crew needed to abandon ship, those can each only hold three people [and only two are docked at once].

“But the commercial vehicles that the U.S. will be flying hold four crew members, and so that lets us add one permanent crew member to the space station, because they can use the four-person life boat, and we’ll have seven crew in orbit all the time. By having that one extra crew member, essentially they will do nothing but research every day on the ISS, and that will allow us to double our throughput on the U.S. side of the vehicle.”

So, if you thought the conclusion of the year in space meant it was back to business as usual on the ISS, you’d be wrong. There are exciting plans ahead for the space station, and it could all prove vital for missions to Mars.