In the next 10 years the ISS can play a critical role in overcoming hurdles on the road to human exploration of Mars, not only as a laboratory for key research topics, but as the starting point for simulated Mars missions that take humans from a zero-G environment to Mars analog sites on Earth. Areas of research include environmental and life support systems, habitation module development, human factors, space nutrition, space suit testing, long duration human physiology, surface adaptation and rehabilitation, and much more. The ISS is a unique facility for solving scientific mysteries, and if we leverage everything it has to offer, it will accelerate our efforts to explore the solar system.
Integrated Mars mission analogs
One unanswered question is how long it will take for astronauts to recover from their zero-gravity transit to Mars when they reach the martian surface. Currently, astronauts returning from the ISS are scooped up by support staff moments after they reach the Earth; however, astronauts will not have the same luxury on Mars. They will need to self-recover on a dangerous alien planet after six to nine months in a zero-g environment and begin work as soon as possible. Given this reality, it is necessary to understand how long astronaut recovery, both physical and mental, will take in order to design the architecture of future Mars missions to meet their needs. We can start to answer these questions with astronauts returning from the ISS now.
Mars missions will also require updates to the operations concepts, tools and processes astronauts need to enable their ground activities as quickly and safely as possible. Expeditions that simulate astronaut operations with time-delayed support teams will demonstrate where knowledge is lacking. These activities should be incorporated into upcoming ISS expeditions to maximize the benefits of the ISS while it is in orbit. Addressing these unknowns will allow us to buy down significant risk for the crews on their way to Mars.
To take full advantage of any of these tests, we need to start now. If humans are going to go to the martian system in the 2030s, it requires an understanding of what the crew will experience. Integrated analog missions, in harsh environments such as the dry valleys of Antarctica or the Arctic, which combine the above research areas, could potentially revolutionize our understanding of Mars mission operations.
Long duration spaceflight studies laboratory
The ISS is also useful for testing how humans will perform during deep space missions. Early Mars missions may be as long as 1,100 days from launch to Earth return for both orbital and surface missions. Whether by design or as a contingency plan, the crew could end up spending the entire duration in a zero-G environment. It is currently unknown how missions of this duration will affect astronaut health and performance. In fact, there are zero data points for long term human spaceflight beyond 438 days (Valeri Polyakov's Mir mission in 1994), not even half the duration of the shortest Mars missions.
Missions such as The Year in Space, with Scott Kelly and Mikhail Korniyenko's time aboard the ISS, have been key to understanding how long-duration space flight affects the human body and psyche. That being said, we need more data points to generate a statistically meaningful dataset from a diverse population if we are going to generalize the findings.
The two-and-a-half hour exercise regimen currently employed on the ISS largely remediates the effects of bone loss and muscle deterioration on 6-month to 1-year missions. But, even if these problems prove manageable, there are still other challenges that we need to examine. For example, astronauts on the ISS can also experience vision blurring, renal stone formation, bone fractures and limited access to medical care, to name a few. How astronauts will overcome these and other unknown challenges that may arise as they extend their stay in space is currently unknown. But we can pursue more long duration missions on the ISS to find out.