———————

As an incubator of life, our Earth has a lot going for it, something we often fail to appreciate fully from within its nurturing bounds.

But we are seekers, our quest for answers, insatiable. We have sent rovers to the moon and Mars and probes to all the other planets in our solar system and the Sun too.

Launched in 2018, the Parker Solar Probe is right now zipping through the Sun’s corona, an extremely hot 4000000ºC environment. Its carbon fibre heat shield withstands that heat because the corona has a very low density and therefore the few ionized particles that hit the probe cause the heat shield’s temperature to rise only to around 2500ºC, something it is designed to withstand easily.

We (the Parker probe, that is) are now, in cosmic terms, within touching distance of the Sun’s surface, just 4 million miles, the closest we have ever gotten and we will come out unscathed. The gravitational sling-shot has made the probe the fastest man-made object, reaching speeds in the excess of 430000 mph or 120 miles every second.

However, simply sending unmanned spacecrafts won’t satisfy us. For various reasons, be it adventure, anticipation of an apocalypse or simply commerce/greed, we insist upon taking ourselves to those places where survival is uncertain, worlds so distant that a simple transmission to a mission in orbit around Neptune will take four hours to receive and another four to respond to. 

———————

Multiple private companies have announced plans to put up hotels in space soon, correctly surmising that space travel will be mundane, inexpensive even for the common Joe at some future date. NASA wants to 3D print neighborhoods within a couple of decades. And while it will probably take longer than that to build and populate an outpost on even the closest planet, Mars, preparations are being made. 

This July, four NASA crew members ended a 378-day stay inside a 1700 sq.ft, 3D printed habitat called Mars Dune Alpha at NASA’s Johnson Space Center at Houston, Texas. The objective was to test the psychological effects of prolonged life in a Mars-like environment, the effects of isolation and confinement on the crew.

Every day, the crew suited up and went on simulated ‘Mars-walks’. They exercised rigorously for the same reason that astronauts on the ISS do. (The Mars gravity is only 38% of Earth gravity). To supplement their diet, they harvested veggies they grew inside the controlled environment of the habitat and recorded their own health data. They made sure that all the habitat and the equipment were well maintained. 

The isolation and the transmission lag of up to 22 minutes with the outside world were challenging but they learned to get along with each other.

They learned to be a family. They played board games and table tennis, threw each other birthday parties, gave each other haircuts, celebrated holidays together and sat down every day to share meals. At the same time they also learned to give each other space for some ‘me’ time during which they did stuff like paint, read, etc. Since the habitat was earth-bound the health challenges due to zero gravity could not be replicated.

---

Off-world dwellings look pretty cozy on NASA’s drawing boards, but it is easy to lose sight of just how hostile space is to human health.

Consider what will happen if you find yourself in low Earth orbit or on Mars or the Moon without a spacesuit on. You will pass out from a lack of oxygen within a matter of seconds, a condition known as hypoxia. You will die soon after. In the brief interval, all the gases inside your body, including any air still in your lungs, will expand in the absence of external pressure. Depressurization will also cause your internal fluids to bubble and boil, not because they’re heating up, but because they are transmogrifying into their gaseous state.

The temperature will not be much of a problem, even though thermometers in low Earth orbit produce readings from minus -160º to plus 125º Celsius, depending on whether you are in shadow or in sunlight. As in the case of the Parker probe, space as a near vacuum, has very little matter to conduct heat to or away from you, so you are not likely to feel instantly hot or cold.

While hypoxia is a real threat should your space vessel or extraterrestrial habitat leak, it is a manageable one. I am assuming you haven’t leapt naked out of your space capsule or off-world dwelling. But two other major challenges confront our fragile bodies when we leave our planet, neither of which has been entirely solved yet, even indoors……

Gravity and Radiation.

Gravity is determined by the mass of objects and their distance from one another. Because Earth is so big, it is impossible, while on it, to escape its gravity for any serious length of time. As a result, we don’t know very much about what our lives would be like without — or under some diminished influence of — this omnipresent attraction. On the moon and on Mars, which are smaller than our world, the gravitational tug will be much less: a sixth and a third, respectively, of what it is here on earth.

Conversely, radiation exposure intensifies with elevation, because there’s less atmosphere above you to block it. And you get a much larger dose if you get beyond the protective bubble of Earth’s ozone layer and the much larger magnetosphere, which is a magnetic field that stretches roughly 40,000 miles from the earth at its most compressed point.

The solar and galactic radiation that washes over Mars and will potentially be 700 times more than what passes through the earth’s magnetic defenses. Space travelers beyond low Earth orbit will also be bombarded with high-energy atomic nuclei from exploding stars throughout the galaxy. (There is at least one star exploding into a supernova at any given time inside our Milky Way Galaxy). 

Those high-energy particles are normally deflected by the magnetosphere and prevented from reaching the surface of our planet. However, they are so heavy and moving so fast that they penetrate spaceships, spacesuits and the skin underneath, smashing into and mutating cells in ways researchers are only beginning to understand. A single gamma ray burst from a nearby supernova can pass through six inches of lead easily.

So far, most of what we know about the effects on the human body of these threats comes from astronauts in low Earth orbit, and because safety of paramount concern, we don’t send many of them up there, and we don’t let them stay for long when we do. Six months is the average length of a visit to the International Space Station, and fewer than 300 people have made the 250-mile voyage.

The magnetosphere still shields the I.S.S. from most of the radiation. Only 24 humans who flew in the Apollo program have gone beyond it. As the moon orbits at an average distance of 238,000 miles, which is way outside the shelter of the magnetosphere, these 24 souls were constantly at peril, even while sitting inside their spacecrafts.

Those two dozen Apollo astronauts who spent little more than a week at a time without the magnetosphere’s protection, they have died of cardiovascular disease at a rate four to five times higher than that of their counterparts who stayed in low Earth orbit or never entered orbit at all. This suggests that exposure to cosmic radiationmight have damaged their arteries, veins and capillaries.

How then do we plan to survive a 21-month round trip to Mars?

—————————

It would be foolhardy to send people to Mars, or to live on the moon, until we can be reasonably confident that they’ll survive getting and residing there. But the space-based medical science needed to make that possible has been hindered by a small sample size that isn’t representative of the general population.

All of the Apollo astronauts were very carefully selected, super-healthy white men born between 1928 and 1936. That is a limited demographic. In order to ensure long-term off-world survival, it is necessary to find out how ordinary, not so healthy people will react to that environment. You don’t learn to treat illnesses from healthy people. It is when people get sick that you understand how people get sick and how to prevent that sickness.

It’s like pandemics. Before epidemiologists can figure out how to protect the population, they must wait for harm to come to enough people to expose the causes. If space travellers are less-rigorously screened medically, the chances that someone will have a health emergency up there will increase and turn the unwell traveller into a sort of guinea pig for space medicine research. Yeah, there will be horrible, painful deaths, our cells will mutate, our babies will be disfigured, stunted, etc, etc.

A question no one can presently answer is whether over years of living and reproducing in deep space, we will learn to cope and protect ourselves, whether we will even mutate into very different human beings who might then, on a trip back to Earth, find it unsurvivable. Remember those smart but obese folks who could move around only on wheel chairs inside that spacecraft in the 2008 cartoon film “WALL-E”? Perhaps humans will also learn to exist in deep space in a similar condition and still find fulfilment in their lives, believing that to be the normal.

Fortunately our own thirst for answers ensures there will never be a lack of guinea pigs among us. Hey, for the first Mars mission, if NASA wants a 70-yr old guinea pig riddled with pre-existing conditions, I’ll go, no question about it.

—————————-

Let’s trip back to the 1950s. Scientists then thought that we wouldn’t survive in the absence of Earth’s gravity. Without this still barely understood force pulling us downward, how would we swallow? Wouldn’t our tongues slide back into our throats? Wouldn’t we choke on our own saliva? And if we survived those perils, wouldn’t escalating pressure in our skulls kill us after a week or so?

All those questions got answered when, in 1961, Yuri Gagarin returned from his single 108-minute orbit, in humanity’s first trip beyond the mesosphere, he proved that our internal musculature could maintain our vital functions in conditions of weightlessness. He ate and drank up there without difficulty. Technically, he hadn’t escaped Earth’s influence. To orbit is to free-fall toward the ground without ever hitting it, and he was inside a condition known as microgravity. This felt, he reported, like being in a suspended state, a condition familiar to anyone who has been on a roller coaster or jumped off a diving board. Gagarin said he got used to it easily.

I suspect, given the then ongoing intense east-west rivalry, Gagarin may have been bullshitting a bit. Either that or he had a strong stomach. On a first flight, many astronauts feel intense motion-sickness which can lead to nausea, headache and vomiting. But you acclimatize eventually.

About that nausea thing, researchers only learned about the prevalence of those symptoms in the 1970s, well past the Mercury and Gemini and into the Apollo programs and it was only when they heard Skylab astronauts talking about it with one another over a hot mic. Competition was (and still is) so intense that astronauts were notoriously stoic and unforthcoming about any symptom that might have grounded them.

——————————-

On Earth, your body maintains your blood pressure such that enough oxygen reaches your organs and waste is ferried away. One of the biggest oxygen users — your brain — is positioned above your heart for much of the time you are awake. But microgravity suddenly stops pulling blood downward into your legs, just as lying down or getting into a pool does, except more so. That lets blood collect in the upper body, triggering pressure sensors in your heart and the carotid vessels of your neck, which then send hormonal instructions to urinate more and decrease blood production. This is why you often feel the need to pee shortly after climbing into bed or sinking into a swimming pool. On our planet, that’s usually enough to reduce your blood pressure and rebalance the system.

In microgravity, however, the blood volume above your neck will most likely still be too high, at least for a while. This can affect the eyes and optic nerves, sometimes causing permanent vision problems for astronauts who stay in space for months, a condition called spaceflight-associated neuro-ocular syndrome. It also causes fluid to accumulate in nearby tissues, giving you a puffy face and congested sinuses. As with a bad cold, the process inhibits nerve endings in the nasal passages, meaning you can’t smell or taste very well. The nose plays an important role in taste. The ISS galley is often stocked with wasabi and hot sauce, to help enhance taste.

These sensory deficits can be a blessing, though, because the ISS tends to smell of body odor and farts. You can’t shower, and microgravity prevents digestive gases from rising out of the stew of other juices in your stomach and intestines, making it hard to belch without barfing. Because the gas must exit somehow, the frequency and volume of flatulence increases.

Other metabolic processes are similarly disturbed. Urine adheres to the bladder wall rather than collecting at the base, where the growing pressure of liquid above the urethra usually alerts us when the organ is two-thirds full. “Thus, the bladder may reach maximum capacity before an urge is felt, at which point urination may happen suddenly and spontaneously,” according to A Review of Challenges & Opportunities: Variable and Partial Gravity for Human Habitats in L.E.O (Low Earth Orbit).

---

The longer astronauts stay in microgravity, the more they change. Here are some of the stuff that happen to them up there…..

– Because they don’t need to support any weight, bones and muscles begin to atrophy….much faster than they do in advanced age on Earth.

– Bone density in the hips and spine decrease by 1 to 2 percent per month, compared with 0.5 to 1 percent per year in elderly Earthlings. The calcium that leaches from the bones is expelled in urine, increasing the risk of kidney stones.

– Muscle mass decreases. That is why astronauts must exercise vigorously for more than two hours a day to keep in decent shape. They also must constantly dab their skin with a towel while exercising, to prevent their sweat from beading and floating into colleagues or equipment.

– The spinal discs between spinal vertebrae spread farther apart. Astronauts grow taller, but the stretch causes the lower back to hurt.

– On earth our body’s sensors raise our blood pressure when we rise up from lying down, so that we don’t faint. These sensors atrophy with disuse. This degeneration, along with reduced muscle mass, is why astronauts must be carried from their capsules when they return to terra firma after a long mission.

---

Once back on earth, the body recalibrates to normal, but protracted stays in microgravity (the current record, 437 days, was set by the Russian astronaut Valeri Polyakov in 1995) make for painful recoveries. After 340 days in space, Scott Kelly, a NASA veteran of three previous shorter missions, described the period immediately following his return as “much, much worse” than those of earlier trips: “All of my joints and all of my muscles are protesting the crushing pressure of gravity,” he wrote in his 2017 memoir, “Endurance.”

Legend has it that Polyakov, unlike Kelly, strolled out of his capsule unfazed, bummed a cigarette from a friend and started smoking, no kidding. So, I guess the reaction to gravity varies, person to person.

——————————

Of course, physiological recalibration and recovery is relevant only when an astronaut plans to return to earth.

But what if you never came back and instead, planned to stay in orbit or on the moon or Mars or any other off-world for the rest of your life? What if you were one of the travellers on a future cosmic ‘Mayflower’?

If you are one of those with a one-way ticket, relax, that cloud may have a silver lining. The question of the ways that the negative effects of a zero-gravity environment can be beaten is being researched at this very moment. All that we need to do is find a way to create artificial gravity in space.

And all that we humans ever needed to get ahead was a challenge.