Space Questions for the Everyday - Volume I
Corinne Moore, Technical Business Development Associate
5 minute read
This Space Questions series is here to answer the everyday questions about space! Big or small, KMI would love to take a shot at answering your queries about space travel, astronauts, life in space, and more!
Do you have a burning question you’d like to see answered in future publications? Contact us at questions@kallmorris.com and you just might see your question featured in our next issue.
For today, we’ll be diving into a variety of topics, including microgravity, the impact of the space environment on the human body, why going outside a spacecraft without a helmet is such a bad idea, and more!
Are astronauts in zero G, microgravity, free fall, or what?
Contrary to popular belief, astronauts orbiting around the Earth are not in zero gravity, but merely in a state of free fall. The gravitational field on Earth’s surface is quite strong, which helps keep our feet on the ground even if our attention is far overhead. This field doesn’t have a distinct line of demarcation and instead is weaker the further away you are, similar to a magnetic field. As astronauts orbit the Earth, the field of gravity is constantly trying to pull them in, so the floating effect we see is actually a steady free fall (or gravitational pull) back to Earth. With the International Space Station moving around the Earth at ~17,000 mph to stay in orbit, the crew, equipment, and fun props are in relative speed to each other and are together in low gravity, approximately 0.89 g, also known as microgravity. While there are areas in space less impacted by the gravitational field of the nearest planet or star, true zero G is non-existent, as it’s the force that holds everything together, from celestial bodies to the human body. The answers of space are almost as challenging as the effort to get there!
(NASA 2019)
What is a light-year? And why is it a measurement of distance and not time?
Light moves incredibly fast, so much so that when you flip a lightswitch in your home, the light appears to instantly fill the room, but that isn’t exactly the case. A light-year is the distance light travels in one Earth year, defined as an astounding 5.88 trillion miles. That kind of distance can be difficult to imagine, so let’s break it down. A light-minute, the distance light travels in 60 seconds, is ~11.2 million miles, and a single light-second is ~186,000 miles, able to reach the moon from Earth in just over a second. If we go even smaller than that, a light-millisecond is ~186 miles and a light-nanosecond is a single foot. This is why, if the Sun were to suddenly blink out of existence we wouldn’t know for about 8 minutes. The light we see when we look to the stars, including our own Sun, has us gazing into the past over vast distances, even as we are steadily traveling into the future.
Do astronauts really get taller in space? Why?
Gravity is constantly holding us down, but what happens when we expose the human body to an environment where gravity is far weaker? Many things, but one of which is we get a little bit taller! The human spine is composed not only of bones, but soft discs that cushion each bone of the spine, allowing for flexibility of movement. When a human goes to space, the downward force of gravity on the spine dramatically decreases. Think of a compressed spring you hold between your hands: as you reduce pressure, the spring relaxes and expands. The same thing happens to an astronaut’s spine and they typically gain between 1-2 inches in height while in-orbit. For those of you wishing to be just a bit taller, don’t go hopping on the nearest rocket just yet! On return to earth, your spine will eventually compress back down and you’ll return to your original height. Astronauts who have spent significant time in space even require assistance on their return, as the whole body readjusts to the gravity forces here on Earth.
Did anyone actually used to think the moon was made of cheese?
This common saying was never a real belief, but stems from the medieval folk story called The Fox and The Wolf. As was common with oral storytelling of the time, there are many versions, but the essential plot is that a hungry wolf is chasing a fox. The fox, being clever, brings the wolf to a well and convinces the wolf that the moon’s reflection in the water is actually cheese and will make for a far easier meal. The wolf believes it, and the fox escapes. As with all fables, it comes with a lesson that we see today as the dangers of believing that which is untrue, but easier to digest. This still heavily applies today, as much social discord arises from the science one chooses (or chooses not to) believe. Thankfully, truth is what it is, and sometimes it’s best to leave the wolf to its chase for cosmic dairy.
What is a parsec?
"It's the ship that made the Kessel run in less than twelve parsecs!" - Han Solo
Much like the light-year, the parsec is often misunderstood as being a unit of speed, but a parsec is also a unit of distance, specifically 3.26 light-years. If you remember your high school trigonometry, it all boils down to calculating the leg lengths of a right triangle. One leg length is always set to 1 AU, or astronomical unit, which is the approximated distance between the Earth and the Sun at any given point. The opposite angle measures arcseconds between the Earth, Sun, and a distant star. Given that we are using a right triangle, we also know that we have an angle of 90 degrees.
(Swinburne University of Technology)
Parsec calculations in astronomy are quite handy, as they allow one to determine the distance of a star in spite of the inevitable shift of our position in our orbit around the Sun. The use of this unit of distance in astronomy comes down to preference and ease of calculation, much like one may prefer to use kilometers over miles, some may prefer parsecs to light-years.
What would happen if you went into space without a helmet?
Unlike most science fiction films set in the space environment, the 1968 feature 2001: A Space Odyssey is relatively accurate when it comes to Bowman surviving 14 seconds without a helmet. While that’s a surefire way to die quickly, it certainly isn’t an instant death. The cold of space would eventually freeze you solid, but it’s suffocation that does the job. Humans don’t do well in the cold, but we can survive freezing temperatures far longer if we have oxygen to breath. What exactly would happen? First, due to a lack of atmospheric pressure, the air would rush out of your lungs and the nitrogen in your blood would bubble to the surface of your skin, causing mass swelling. Depending on physical fitness, you may stay conscious for about 45 seconds, but you’d suffocate completely within 2 minutes. Holding your breath here is not an option either, your lungs don’t stand a chance against the pressure differential between your body and the vacuum of space. The best advice to surviving in space without a helmet: put it back on!
If the ISS orbits the Earth so many times a day, when does their day start and end without a regular sunrise/sunset?
The ISS orbits the earth a whopping 16 times over a 24-hour period, with 45 minutes of daylight and 45 minutes of darkness in repeating 90-minute cycles. The best way an astronaut keeps time is with a wristwatch set to GMT, or Greenwich Mean Time. They can also view their schedule on their laptops, which gives them a minute-by-minute view of planned activities. Both the astronauts and ground command centers operate off of GMT and this keeps everything from scheduled lab work, sleep time, and even lunch running smoothly. As you can see from Alan Gerst’s day schedule in 2014, this can mean those operating on the ground follow vastly different schedules to keep the ISS flying “on time.” While we only have one shot a day to catch a gorgeous sunrise, astronauts aboard the ISS need only wait 45 minutes.
Thanks for tuning in to the first issue of Space Questions for the Everyday! We would love to hear from our readers and answer your questions next time, which can be submitted at questions@kallmorris.com.
Recommended column to read next: Space Terms 5: Some Jargon, Some Relativity