Credit:
NASA
NASA is working on countermeasures to mitigate the risk that these hazards pose to astronauts, as the agency explained in a recent five-part series on “Houston, We Have A Podcast.” Read on to learn more about the dangers that astronauts face, and what NASA is doing about them.
1. Radiation can lead to cancer and other serious health problems
As crews escape the protective envelope of Earth’s magnetic environment, they run across forms of radiation in space that are bad for human health. Just three months working aboard the International Space Station would subject an astronaut to more than triple the maximum recommended dosage of radiation for one year.
Long-term radiation exposure is associated with an increased cancer risk in the long term. In the short term, extreme radiation doses can lead to sickness, hair loss, and even death. So NASA has a vested interest in protecting its crews and making sure that they are going to be exposed to as little radiation as possible.
NASA has lifetime guidelines for how much radiation it allows individual astronauts to receive. Astronauts are not allowed to receive any more radiation than what would increase their risk of cancer mortality by 3 percent. The space agency uses a formula that depends on an astronaut’s gender and age at the time of the radiation exposure. This standard is a little hard to understand, given that individual astronauts are so distinct. Perhaps an easier metric is one from the European Space Agency, which limits astronauts to 1 Sievert (a unit of radiation exposure) over their careers. The Curiosity rover found that that’s about the same level of radiation that a crew would receive during a single 860-day trip to Mars.
Credit:
NASA/Scott Kelly
“If you can get there faster, that’s probably the biggest thing... because that minimizes the time you have to spend in space,” says NASA scientist Zarana Patel in the podcast. So more efficient propulsion might be one way to reduce exposure. Future spacecraft could also make use of magnetic shielding to protect the crews. Or perhaps there’s another technology out there that hasn’t been invented yet.
2. Isolation is really tough on your psychological health
Seniors, people with disabilities, and people living in harsh environments all face a similar issue — isolation. If there are few options to leave your house and see other people and participate in what many consider “normal” life, it’s difficult for humans to function psychologically. In space, that isolation is also extreme. Astronauts must remain inside of a small space station for six to 12 months at a time, only going “outside” during a spacewalk — and that’s if they’re lucky and have one scheduled.
“We’re very resistant and adaptable to different changes in our environment,” says NASA scientist Tom Williams. “And what isolation does is sort of remove that context of adaption, because when we’re isolated, we’re not being able to engage our environment in as many different ways as we are when we’re not isolated. And so, therefore, some of the things that we depend on to help us adapt to the different challenges that we may encounter are now removed from that.”
Credit:
NASA
One sign of crew stress shows up in how they sleep. One research study cited in the podcast showed that in a sample size of 21 people, crews on the space station aren’t sleeping well roughly 29% of the time. (To put that in time perspective, that’s roughly two months out of a six-month mission.) NASA is still trying to figure out how to help astronauts adapt to isolation and a strange environment.
3. Time delays when calling home increase emergency problems
Say there’s a huge emergency on the way to Mars — maybe an Apollo 13-style explosion that cripples one of the spacecraft. In such a situation, astronauts may only have a few seconds or minutes to react in order to save their lives. The instinct of all crews today is to call home for more help, because NASA’s Mission Control is filled with experts on human health and spacecraft operations. But on the way to Mars, calling Earth — and waiting for a response — could take 40 minutes.
NASA already has its crews trained in basic medical procedures in space, so they can deal with many common issues by themselves. This not only cuts down on superfluous calls to the ground, but the astronauts can also report symptoms precisely instead of giving a vague description, says NASA astronaut and former flight surgeon Mike Barratt.
“Instead of getting a panic call to the ground, asking immediately to talk to the surgeon, what we may get is a report saying, ‘Crew member so and so was clutching their abdomen in very bad pain. We pulled out the ultrasound, we found a stone. We think it’s passing. We’ve given pain meds, and they’re resting comfortably,” he explains.
Credit:
NASA
The podcast focused more on medical issues than engineering issues, although one can assume NASA is of course working on ways to make its spaceflight as safe as possible from an engineering perspective, too. The agency is already implementing new virtual reality systems on the International Space Station to have astronauts learn procedures for fixing things that break down, for example. These systems will also be useful on the way to Mars.
4. Microgravity eats away our bones and muscles
On the ISS, astronauts constantly “fall” around the Earth as they orbit, so they don’t feel the effects of gravity. While floating around for six months or a year in space sounds like a lot of fun, there’s a serious side effect; once you get back to Earth, you’re basically a cripple. At worst, an astronaut walking out of their spacecraft for the first time could slip and break a bone the moment they get back to Earth, because their bones and muscles have weakened over time.
NASA has made a lot of strides in this regard. It mandates that its astronauts spend about 90 minutes per day exercising in space, using a resistance machine as well as either a treadmill or an exercise bike. Although astronauts are oversubscribed with things to do in space, that exercise time is sacred — everyone makes sure the astronauts are not pressured to abandon their time exercising to complete some experiment.
The doctors say that this time sweating it out is extremely important.
“On muscle and bone, you have de-loading effects which can be mitigated by extensive exercise,” says NASA’s Peter Norsk.
Credit:
National Museum of the U.S. Navy
Norsk said that doctors still don’t understand how radiation can affect astronaut bone and muscle. It’s hard to simulate deep-space radiation on Earth, and we only sent a handful of astronauts to the moon back in the 1960s and 1970s.
5. Space attacks our immune system
One of the things that hurts astronauts in space is the loss of a regular “day” in space. The sun rises and sets 16 times in 24 hours aboard the ISS, because astronauts hurtle around the Earth once every 90 minutes. While crews do as much as possible to keep their bodies to a schedule – like eating at regular times and having firm sleep periods – it’s pretty difficult to fool the brain when light and dark keeps changing outside the window.
Right now, doctors are trying to better firm up the circadian cycle by improving sleep for astronauts, which means reducing noise, making their schedules less stressful in the evening so that they can wind down, and taking other measures.
“In-flight sleep is important,” says NASA immunologist Brian Crucian. “It can affect the immune system.”
The doctors also look closely at studies of crews working in isolated, confined environments such as Antarctica to get more ideas about how to improve human immune systems in space. Doctors have been looking at circadian disruptions for years using the saliva of crews that are staying over winter. In more recent years, as technology improved, they’ve been having the crews analyze their samples on site to deliver the science more quickly.
Doctors are still characterizing exactly how circadian problems affect Antarctic explorers, but the hope is in future years they’ll be able to implement countermeasures to help both the crews on Earth and the crews in space.