by Terry Virts
The really scary effects of this are unseen. Those particles, originating at our sun or other stars in our galaxy or even in other galaxies, some moving at nearly the speed of light, some massive atoms or molecules, sped through the walls of the ISS unimpeded and impacted the cells in my body. Sometimes they would kill a cell, and sometimes they would zip right through my body. But sometimes they would impact the DNA in a cell, altering it at the molecular level. Hence the term ionizing radiation. And when that happens, one of the possible outcomes is that the cell would start to mutate, becoming cancerous.
Unfortunately, we have data points from the effects of acute radiation, from the survivors of Hiroshima and Nagasaki. Many of those survivors were stricken with cancer, and one of the most common was basal cell carcinoma, a less-serious type of skin cancer. After both of my spaceflights my dermatologists found this in my skin—quite a bit, unfortunately, after my long-duration flight. Thankfully, it wasn’t a serious threat, but it was nonetheless a sobering reminder of this risk. What’s worse, the seeds of serious cancer could also be sown during a spaceflight, taking years to ultimately grow into a deadly disease.
There are really two ways to protect yourself from radiation. First, minimize your time in space, which reduces risk. Astronauts have to be on the ISS 365 days per year, so there’s little we can do there other than limit career doses for individuals. NASA’s rules limit astronauts to between one and two years of cumulative time in space, depending on the dose of radiation each individual receives. The second way is to have shielding. Our sleep stations on the ISS have some foam bricks that they say reduce radiation, and I’m sure they do. Some. But I can’t imagine they help that much. The best shielding is actually water, though our living areas on the ISS don’t have water surrounding them. So for now we just roll the dice.
Throughout my time at NASA, I would occasionally ask our doctors about what we knew about radiation and cancer. A few themes were common. First, astronauts die from cancer at a higher rate than the general population, which is surprising given the fact that they tend to be a healthy lot. Second, it’s impossible to say whether this is statistically significant because so few astronauts have flown in space; there have been only a few hundred to date. To put that number in perspective, getting a drug approved by the Food and Drug Administration often requires tens of thousands of test subjects. The standard answer from NASA was, “We can’t prove that your cancer was from space; it may just be genetic, or from other environmental factors on Earth.” And they’re right, you can’t say with scientific rigor that astronaut cancer is caused by spaceflight. But you sure can make an anecdotal case that, if a number of otherwise healthy people—who just spent a significant amount of time in a heavily irradiated environment, full of high-energy particles that can’t exist on Earth—get cancer, maybe there’s some correlation.
Although we measure radiation dosage on the station with great precision, we don’t measure its effects on the human body. And for me, that is the most important question when it comes to future space exploration plans.
The most surprising medical experiment for me was one that never happened. After I returned from my second mission, having been diagnosed with carcinoma for the second time, I began to ask: Have radiation and weightlessness affected my DNA? I was just a fighter pilot and definitely not a qualified geneticist. But I figured that surely, given all the blood samples and medical tests that I had undergone, someone had checked my DNA before and after my mission. After all, a 23andMe test costs less than a hundred bucks. Nope. Nothing. Nobody checked my DNA at any point, pre-, during, or postflight, as best I can tell. I’ve spoken with some academic researchers at various medical schools, as well as the National Institutes of Health and the Centers for Disease Control and Prevention, who were shocked at this lack of basic genetic research, but there just hasn’t been an effort to study the effects of radiation on astronaut DNA.
Again, I’m just a fighter pilot and certainly don’t understand the nuances of DNA, and I know it’s not as easy as a simple “before and after” test, but I do know that we have been sending astronauts and cosmonauts into space for decades, at a cost of billions of dollars, and we have lost valuable scientific data because of a lack of research in this area. Although we measure radiation dosage on the station with great precision, we don’t measure its effects on the human body. And for me, that is the most important question when it comes to future space exploration plans. Not to mention my own pink body!
There was another surprise after I left the astronaut office, after Congress passed and the president signed into law the Treat Astronauts Act, in 2017. The bill’s sponsor declared that it “makes sure that our brave men and women who venture into space receive support for medical issues associated with their service.”
However, after leaving NASA, when I went to get follow-up treatment for my skin cancer, I was told that NASA didn’t cover the cost. My doctors couldn’t prove that the cancer was associated with spaceflight, and there was no coverage for medical care unless you were in line for another mission. Which was both funny and disheartening. First, providing astronauts with health care is much more than a benefit for them; it is necessary to fully understand the effects of spaceflight. The US government spends an awful lot of money to send us to space, and without gathering comprehensive medical data for the rest of an astronaut’s life, any medical conclusions about those effects are based on incomplete data, and therefore invalid. The only medical contact NASA currently has with retired astronauts is through an annual physical, when we are asked if we saw any doctors during the prior year and what were the results. Of course, whatever “data” are gathered through this method are highly suspect to say the least and would never pass muster in a peer-reviewed scientific journal. To properly study the effects of space travel on the human body, you would need all medical data from all space travelers over the rest of their lifetimes.
Do astronauts tend to get Alzheimer’s, or the flu, or broken bones, or schizophrenia, or whatever, more or less than the general population? Do astronauts get fewer colds than others, or do they suffer less vision and hearing loss? I don’t know. And neither does anybody else. Because the only way to know that would be to provide comprehensive health care for life, ensuring that NASA got every seemingly innocuous piece of medical data. Only then could you begin to develop a set of data over time that would be statistically significant. And taxpayers would get true medical data return on their investment, rather than what they get today, which is nada. One final irony in this situation—the Russian space agency provides all of their flyers with health care for life, as do the other international partners, and they invited me to go back to Russia for health care should I need it.
Hopefully in the future, more serious “before and after” medical investigations will take place, especially as they relate to DNA and cancer, and legitimate, comprehensive, longitudinal health studies will take place to help us understand the long-term effects of space travel. Until then, I count myself blessed that I was able to spend seven months in space, contributing in a very small way to humanity’s exploration of space.
Time Travel
Einstein and the Whole Relativity Thing
When I returned from my 200-day spaceflight, I spoke with a NASA physicist about the effects of the radiation exposure I had experienced. While we were talking about why I glowed in the dark (just kidding), I asked him about relativity and the impact that my space mission had on my body’s clock. He told me that I had aged seven milliseconds less than the poor humans who were stuck on Earth during those 200 days, which was both amusing and a source of pride. A few months later, I was talking with a prominent Hollywood actress about this bonus time, and when I told her that I aged less during my space travels, she was amazed. She wanted to know how quickly she could go into space to slow time and the aging process.
The origins of the concept of relative time date back to the beginning of the twentieth century and a rather obscure Ge
rman scientist by the name of Albert Einstein. As a young boy, he had struggled in school with middling grades. It turned out that the problem was not his intellect, but a lack of being challenged. The insights that he would eventually uncover completely reshaped our understanding of the physical universe. He audaciously claimed that many properties such as length, mass, and even time were relative, depending on your frame of reference. This was a radical idea, one that probably had Sir Isaac Newton turning over in his grave. Relativity is a concept that doesn’t affect us in our day-to-day lives but is tremendously important in understanding the cosmos on an interstellar scale. And it would eventually affect me in a very personal, if small, way.
At the core of Einstein’s general and special relativity theories is the concept that everything is in its own inertial reference frame, which defines how fast it is moving. For example, if you are standing still, you have a different reference frame than someone moving on a train. Also, the Earth isn’t stationary, and because of its twenty-four-hour rotation period you are moving eastbound at roughly 1,700 kph at the equator, but 0 kph at the North or South Pole, with respect to the center of the Earth. Not only is the Earth rotating, but it revolves around the sun once per year, and it flies along at 106,900 kph with respect to the sun. But wait, there’s more! The sun isn’t standing still but is orbiting our galaxy at a comfortable 800,000 kph, taking more than 200 million Earth years to travel once around the galaxy.
You get the point—everything is in motion relative to something else. And because of that relative motion, mass, time, and size will all change relative to other inertial reference frames. Yes, this is really true. Let’s assume for a minute that you’re a fighter pilot, because the universe clearly revolves around you. From your point of view, you appear to be perfectly normal and your watch ticks off the seconds at a normal rate, but from your friend’s point of view your time has slowed down and you’ve also gotten shorter and fatter. For the purpose of this chapter, let’s focus on that change in time.
One of Mr. Einstein’s most profound insights was that the speed of light is always constant, no matter how fast you’re moving, everywhere in the universe (black holes are problematic for some laws of physics, but that’s a topic for another book, one written by a proper physicist and not a fighter pilot). To illustrate this concept, consider two trains moving toward each other, each traveling 50 kph. If you are riding on one, it appears that the other train is moving at 100 kph toward you. However, if you shine a light beam at someone on the other train, you will measure its speed as it leaves your flashlight as 300,000 kilometers per second, and when that light beam hits him, he will also measure it as 300,000 kilometers per second. He won’t perceive the light as traveling that extra 100 kph. No matter where you are or what speed you are traveling, light always appears to travel at the exact same speed. Even if both trains were traveling at 99 percent of the speed of light, a passenger on the other train would still measure your light beam as hitting them at the normal speed of light. Bizarre, but true.
The constant speed of light is one of the foundations of physics because it has a lot of implications for how the universe works. One of them is the fact that the speed of light is an absolute speed limit—nothing can travel faster than light. Another is the fluid nature of time. Let’s say you are on Earth with your buddy, and you both synchronize your wristwatches. He goes off and flies around the galaxy at near the speed of light. When he comes back and you compare watches, yours will be much later than his. His watch will have counted off much less time than yours. He not only appears to be, but in fact is much younger than you, thanks to his high-speed galactic travels. There is a scene in the movie Interstellar where the crew goes down to a planet near a black hole in a very strong gravity field, which is the physics equivalent to acceleration. They feel that they are only there for a few hours, but when they return to their crewmate orbiting far from the black hole, they find that he has aged several decades, due to relativity.
What exactly causes this strange time dilation? Einstein proposed two distinct theories—special and general relativity. This is an oversimplification, but the special theory of relativity claims that time is relative based on velocity. However, general relativity says that time is relative based on acceleration, which can also be measured by the presence of a gravity field. These theories lead to the conclusion that the speed of light is constant—which may not be intuitive, but trust me, it’s true.
There are several contradictory implications of Mr. Einstein’s theories to my time in orbit. In my case, traveling 28,000 kph relative to the surface of the Earth, time slowed down a little bit for me compared to earthlings, thanks to the special theory of relativity. However, I was at a higher altitude (approximately 400 km), where Earth’s gravity (aka acceleration) is slightly less than it is on the surface. This reduced gravity field sped time up for me relative to folks on the surface of Earth. However, during launch and landing I was under significantly increased acceleration, which slowed time down.
So, adding up all of these effects—time slowing down because of my higher velocity, speeding up because of slightly less gravity in orbit, and slowing down very briefly under launch and landing accelerations, between November 23, 2014, and June 11, 2015, I actually aged a little less than everyone reading this book (unless your name is Anton or Samantha). It was only 0.007 second according to my NASA physicist friend, but hey, I’ll take it!
Re-Entry
Back on Earth, landing in the Kazakh Steppe. Not exactly a soft landing, but a safe one.
Riding the Roller Coaster
Re-entry Is Not for Sissies
There are several key things that every spaceship has to do if it wants to leave orbit and come back to Earth. The most obvious is changing its flight path to bend down toward the atmosphere, where the air drag will capture it and bring it relentlessly down to the surface. Next is withstanding the tremendous temperatures of re-entry. Changing your flight path angle in an airplane is a relatively easy thing; you push forward on the stick and the air pressure on the elevator moves the nose of the airplane down and the trees get bigger. Pull back on the stick and the trees get smaller.
However, in space we have Sir Isaac Newton to thank for a very useful trick that allows astronauts to come home. Orbital mechanics are what determine a spacecraft’s motion once in space, and one of their implications is that to change your course to the left or right you need a tremendous amount of delta-v, or change in speed. Because of this, it’s very inefficient to change your inclination, or heading. Most human spacecraft carry only enough rocket fuel to change their heading by a few tenths of a degree to the left or right. The good news is that we don’t have to move left or right to come back to Earth, we just need to go down. Here’s where the useful trick comes in handy—if you slow down, your orbit will descend. Conversely, speeding up makes your orbit climb. The amount of delta-v required for this trick is much less than for changing your inclination.
So, when it was time to come back to Earth in both the shuttle and Soyuz, we turned the rocket around backward, fired the engine for a few minutes, slowed down by a few hundred mph, and our orbital flight path trajectory was bent downward toward the planet. This put us on an inevitable collision course with the atmosphere and our eventual landing site, which was still on the other side of the planet. While the rocket is firing it is a gentle ride, only a few tenths of a g, nothing at all like dramatic Hollywood movies with astronauts screaming and being smashed into their seats. That was launch. After the burn finished, we had some time to relax and enjoy our last few minutes of weightlessness. Because once we contacted the atmosphere, about twenty minutes later, at what we call EI (entry interface), there was no more relaxing.
It was at EI that the shuttle and Soyuz experience diverged. Dramatically. The space shuttle was a magnificent flying machine, roughly the size of an airliner, and once it was back in the atmosphere it could bank and turn and maneuver like a normal plane. Except it was trave
ling at 17,500 mph and was surrounded by a cocoon of plasma that was as hot as the sun, created by the indescribable friction of the massive shuttle smashing into unsuspecting O2 and N2 molecules of the vanishingly thin upper atmosphere.
Because we were still supersonic until a few minutes before landing, people in Florida below us heard a very distinctive, double sonic boom from the shock wave the shuttle created as it smashed into air molecules faster than they were able to get out of the way.
The view from the pilot’s seat was spectacular. At first there was a gentle pink glow outside my window, then it began to glow a brighter orange and then red, accompanied by a flashing white light above the overhead window, reminding me of the scene in Alien when the strobe light was flashing while the ship was getting ready to self-destruct. Thankfully, this final phase of my mission took place in darkness, so I was able to see every nuance of the colorful plasma. It finally turned gray, and I raised the visor on my helmet and leaned over to the window. The plasma was slowly swirling around, like eddies and currents on a pond. I reached up, pulled my hand out of my glove, and felt the window, which surprisingly wasn’t at all hot. The most bizarre thing was a very distinct yet faint sound, like tapping your fingertips gently on a counter.
Ironically, as Endeavour continued to slow from the mounting air pressure, things began to speed up in my brain. The airspeed felt by the shuttle’s wings steadily increased, and the g loading built up to roughly one and a half g’s. Because our orbital track did not take us exactly to the runway at the Kennedy Space Center, we had to make several S-turns to fly toward our destination, taking advantage of the orbiter’s big wings. Our first roll reversal took place over Central America as I peeked out the window, trying to get a glimpse of the ground speeding by below, but I couldn’t see anything other than a few city lights in the darkness.