The journey up to space is like no other to be found on Earth. It’s one that so many of us dream of, yet only a select few of highly trained astronauts get to embark on this unique endeavor. Who knows? Maybe with the developments in recreational space travel, we all might get a chance to fly up to be amongst the stars one day. For now, we’ll leave it to the astronauts…and the super-rich. But is space travel a one-way ticket? Well, it might be if you were traveling to Mars, but astronauts aren’t doing that just yet. Astronauts fly up to live and work on space stations that orbit our world relatively closely. Then once they’re finished, they are able to return to us. But how exactly do astronauts get back to Earth? It’s time to find out.
So, how do astronauts get back to Earth? Astronauts get back to Earth via what’s known as a reentry capsule. A reentry capsule is a portion of the original spacecraft that is detachable from the main section. With a special aerodynamic shape and blunt bottom to protect it from the heat inside the atmosphere, the reentry capsule safely transports astronauts back down through Earth’s atmosphere all the way to its surface.
Sounds complex, right?
Well, interestingly, all astronauts have to do is buckle up and enjoy the trip back down.
Which is perhaps a good thing by the time it comes around.
Besides, they will have been in space for many months by that point and are most likely exhausted.
So how do these reentry capsules work, exactly? What about landing, and how long does the journey take?
Let’s find out, shall we?
How Do Reentry Capsules Work?
Reentry capsules detach from the main spacecraft, position themselves toward Earth, and are then drawn into the atmosphere by an increasing gravitational pull. They then descend through the atmosphere, using their design to ensure the hostile speed and environment they travel through. Once through, reentry capsules safely land at a specified set of coordinates.
Let’s pin some basic facts about reentry capsules to the board.
Reentry capsules are about 5 meters in diameter, which allow for a pro-aerodynamic nature.
They are designed for one use, although technology is evolving, and we are starting to see space organizations, such as SpaceX, design reusable reentry capsules.
How do they actually work? Let’s talk through the process.
When it’s time for the astronauts to say goodbye to space, they board the reentry capsule. The reentry capsule will then propel itself toward Earth.
The closer the capsule gets to Earth, the stronger the gravitational pull becomes, meaning it will be drawn toward home.
When it enters the Earth’s atmosphere, it’s safe to say that the temperature whacks up a notch!
Luckily for the astronauts onboard, the capsule has a blunt bottom which helps it endure these hostile temperatures in the Earth’s atmosphere.
This blunt bottom and the capsule’s aerodynamic shape are integral to the safety of any return landing to space. It’s what makes them so enduring of high energy reentries.
When the reentry capsule impacts the Earth’s atmosphere, the blunt bottom creates a shock wave that keeps the heat at bay…but only for so long.
The heat is so intense that a reentry capsule’s surface temperature can reach 1,480 °C while it travels through the Earth’s atmosphere.
The reentry capsule ensures that this heat doesn’t go any further, reaching interior structures, or perhaps even the astronauts, by using what’s called an Ablative Heat Shield. This shield absorbs the heat, then it vaporizes, taking the heat with it.
Heat isn’t the only issue. Reentry capsules also have to be incredibly strong so that they can endure powerful forces faced when reentering the atmosphere.
Where are the astronauts in all of this? Well, astronauts lie down in the reentry capsule because this is the optimum position for a human body to withstand the g-forces faced when the capsule races through the Earth’s atmosphere. But don’t assume that astronauts can enjoy a nap on the way down; it’s not exactly going to be comfortable.
Now, what happens once a reentry capsule is through the Earth’s atmosphere?
Fortunately, the atmosphere acts as a natural braking system, slowing the reentry capsules’ descent down.
Reentry capsules are designed so that they assume an angled attitude which provides them with a lift that is used for directional control.
Reaction control system thrusters are then used to steer the capsule simply by using a rotating lift vector.
Of course, astronauts aren’t expected to pilot their capsule to a specific location on Earth. Mission control will use a Propulsion System to send the capsule on a trajectory toward a specified set of coordinates. (The common locations of these coordinates will be discussed soon.)
Multiple parachutes can be deployed to slow the speed of the capsule’s descent.
Once safely landed, astronauts sit tight until they are picked up by a recovery ship. And the reentry capsule will be salvaged, yet not used again.
Where Do Astronauts Land When They Come Back To Earth?
Astronauts land on a pre-selected set of coordinates located in the ocean.
Astronauts can’t just land anywhere. They’ve got to land somewhere where it is safe, not only to land but also to wait until they are picked up by their colleagues.
This means that landing on top of a volcano or in the middle of a warzone probably isn’t the wisest idea.
The landing destination will also be pre-selected. It’s not like astronauts drive the reentry capsule around, looking for a free parking bay as if they were out shopping at Walmart.
Astronauts just sit tight and wait for it to all be over.
So where do they actually end up landing? The coordinates chosen will vary between different missions as well as different space organizations.
But one thing you can be sure of is that astronauts and their reentry capsules land in an ocean somewhere.
It’s the safest place to land as the water can cushion the fall, allowing astronauts to float around until they are picked up.
What ocean that will be will depend on what organization the astronauts are working for. If an astronaut is working for NASA, then the chances are they’ll land somewhere off the coast of the USA, in the Pacific Ocean.
How Do Astronauts Land When Coming Back From Space?
Astronauts land by undocking the reentry capsule, propelling it at the right speed and angle toward Earth, then bracing for impact…then waiting.
Luckily, returning to Earth is part of an astronaut’s training program. So they will be prepared for this final stage of their wonderful journey.
They have to start by undocking the reentry capsule from the main spacecraft and propelling it towards Earth. Astronauts have to ensure that it is traveling at the right speed and at the right angle without any margin for error.
While this happens, mission control uploads the data required by the reentry capsule’s computer to steer you to the pre-selected coordinates.
A lot of the training astronauts do for this involves studying and understanding how air resistance and gravity work.
If astronauts don’t get their calculations correct, then the intense levels of heat in the Earth’s atmosphere could melt the capsule.
Then, at about 8.5 km above ground level, the parachutes are deployed.
Astronauts then brace for impact when the reentry capsule lands on the water.
And then the most exciting bit of all…they wait!
A boat will come and lift them out of the water and take them home.
Sometimes a helicopter takes the reentry capsule of the boat’s hands, flying it back to base, wherever that may be.
How Long Does It Take For Astronauts To Get Back To Earth?
From start to finish, an astronaut’s journey back home on a reentry capsule can be over in less than 3 hours.
That might seem like a long time, but this isn’t exactly a quick flight to the next state.
These astronauts are flying from the space station, up in space, funnily enough, all the way back down to the Earth’s surface. There is a lot of ground to cover in that time.
I mean, the distance between the Earth and the moon is about 386,400 km. Quite a distance, right?
But astronauts do this pretty fast in a reentry capsule, traveling at speeds we Earthlings couldn’t comprehend.
Some journeys will take longer than others, depending on the trajectory of the Reentry capsule’s descent, though it never typically exceeds 6 hours.
Finally
What goes up must come down. And that’s certainly still the case for an astronaut.
It doesn’t matter how much fun they’re having up there; astronauts have to return at some point.
One day, I’m sure humans will be able to pack up and just leave Earth for good.
In fact, one-day, humans will need to do this if they are to survive!
But that’s a long way away from now.
Until then, astronauts will have to pack up their bags and enter the reentry capsule.
The fun certainly isn’t over. I mean, the best part of riding up a hill on your bike is always the way down. So I suspect it’s the same in space!
Other related astronaut guides you may want to check out:
- Can Astronauts Walk After Returning From Space?
- What Do Astronauts Do When Not In Space?
- How Do Astronauts Train For Zero Gravity?
Hey, my name is Jeremy. I’m a passionate and seasoned astronomer who loves nothing more than observing the night sky. I also love researching, learning, and writing all things Space and the Universe. I created Astronomy Scope to share my knowledge, experience, suggestions, and recommendations of what I have learned along the way while helping anyone to get into and maximize their enjoyment of the hobby.