Thanks to Brilliant for supporting this SciShow video!
As a SciShow viewer, you can keep building your STEM skills with a 30 day free trial
and 20% off an annual premium subscription at Brilliant.org/SciShow.
When you’re on a flight to Florida, you’re probably thinking about which book you should read
on the beach…not about the chances your plane will collide
with a rocket launching from Cape Canaveral!
You might assume that the professionals tracking your plane
also know when and where rockets are in the air.
But you’d be wrong.
And we’re living in the age of commercial space flight.
In 2022 alone, there were a record-setting 180 successful rocket launches around the world!
The off chance that something goes wrong between a plane and a rocket is higher than ever.
So to keep us safe in this rocket-filled world,
engineers and air traffic controllers have to reinvent the way we keep track of rockets.
[♪ INTRO]
Let’s start with why rockets are effectively invisible to air traffic controllers.
It’s all because of space history.
When humans started going to space,
each launch was a massive undertaking run by federal agencies like NASA.
And to keep commercial airplanes from hitting those rockets, air traffic controllers
borrowed the technique that the military used to clear airspace for practice exercises.
They declared a temporary no-fly zone known as a Special Activities Airspace.
For several hours, airplanes had to detour around these areas,
which could range anywhere from 90 to 4400 square kilometers surrounding the launch pad.
With such large empty swaths of airspace around a rocket, the Federal Aviation Administration,
or FAA, didn’t need to know where that rocket was at all times.
Strategically speaking, having to clear out such a large airspace wasn’t that big of a deal
when NASA was launching one or two rockets a year.
But now that there are nearly 200 launches a year worldwide,
including ones run by private companies, the technique is pretty inefficient.
It’s wasteful, too.
Planes fly longer routes around rocket launches and use a lot more fuel.
For just one rocket launch in 2018, 563 flights were delayed,
and those planes flew an extra 64,500 kilometers in total.
But the system also needs a revamp because of safety.
Now, even if there weren’t any airspace restrictions to separate planes and rockets,
there’s still not a huge chance a rocket would actually hit a plane, or vice versa.
Rockets have to be pretty zippy to get up into space,
so they leave the airspace that commercial planes fly through pretty quickly.
The real concern is damage from the debris that rockets drop.
Two types of rocket debris exist: pieces that are intentionally ejected,
and pieces that fall back to Earth due to any number of accidents.
The stuff that engineers plan to eject is made from materials with low melting temperatures.
So, after it’s ejected, it burns up in the atmosphere at way higher altitudes
than commercial planes fly.
Meanwhile, debris from accidents can fall through commercial airspace.
And what’s worse, it often ends up spreading out over a pretty wide area.
For example, when the space shuttle Columbia disaster happened,
it generated 38,000 kilograms of debris
that ended up covering an area 1000 kilometers long by 40 kilometers wide.
But NASA had only planned to close airspace in a 48 kilometer circle
around an emergency shuttle landing.
It’s incredibly fortunate that no commercial aircraft was struck by anything.
Nine planes flew through the debris zone during the 40 minute period when pieces were falling,
and no system was in place to warn them.
And if you’re wondering if a plane ever has had the misfortune of getting struck,
the answer is yes.
In 1996, space debris hit a Chinese plane, cracking its windshield and forcing it to land,
although no one knows exactly what the debris was.
And an emergency landing is the best case scenario in accidents like these.
So air traffic controllers want to avoid collisions
while keeping no-fly zones as small as possible.
Currently, if anything goes wrong, someone at NASA or the rocket company
has to email or call the FAA to let another person know.
It’s a time-consuming process that needs double checking to avoid introducing any human error.
All in all, it would take around 13 minutes for a plane to maneuver away from an accident.
Which is not nearly fast enough,
because large debris could fall through commercial space in as little as four minutes.
So the FAA is developing a new system that should allow planes to adjust their route
within the first minute and a half of an accident occurring.
It’s called the Space Data Integration system, or SDI for short,
and it will finally let the FAA track rocket launches in real time.
Knowing a rocket’s actual location will let air
traffic controllers treat them more like airplanes.
Currently, the FAA gives each commercial plane its own personal bubble of space
that’s about 16.7 kilometers wide.
With the SDI, rockets…or at least the ones that can prove they’re reliable…
could be upgraded and assigned bubbles of their own.
The exact size of these bubbles would vary on a case-by-case basis,
but they’d be a much smaller, no-fly zone compared to what we’re working with, now.
But if we’re actually going to feel comfortable
transitioning to these bubbles of restricted rocket airspace,
the SDI will need to do more than track where rockets are at any given moment.
It’ll also need to help the FAA protect planes from flying through debris fields…
predicting where high-risk debris areas will be as soon as an accident happens,
and suggesting the fastest detours.
Computer scientists are hard at work developing algorithms
that are up to such a complicated task.
One group uses a famous statistical method called a Markov Decision Process.
This model estimates the outcome of a particular decision at a point in time…
say to reroute a plane to the left…based on the current position of the plane.
For example, 90% of the time the decision to bank left at a specific moment
will result in a safe flight and 10% of the time it will result in collision.
Then the algorithm estimates other rerouting choices, say to banking right instead of left.
Once the safest choice is identified for one point in time,
the model estimates all the safe rerouting choices for the next chunk of time.
Another group of researchers updated this decision-making tool
using a related statistical method called the Monte Carlo Simulation.
This method randomly samples the possible movements of both airplanes
and debris to calculate the best, most efficient route to fly to safety.
Random sampling works better when addressing the uncertainty of where debris pieces will be,
but Monte Carlo simulations are slow and require a lot of computational power.
Fine tuning these algorithms and connecting them to all the data they need for their calculations
is a big process, so the FAA doesn’t have the Space Data Integrator up and running just yet.
Once they do, maybe we’ll all get to see some rocket launches
pass our plane as we fly into Florida!
Or you can just go back to second-guessing your beach read.
Thank you for watching this SciShow video and thanks to Brilliant for supporting it!
If you could use a little more background and explanation for all of that
Markov and Monte Carlo talk just now, Brilliant’s got your back.
There could be entire courses about that stuff.
And in fact, Brilliant has made them!
Brilliant is an online learning platform with thousands of lessons in science,
computer science, and math, including statistics and probability.
To learn way more about Markov chains and other probability fundamentals,
immerse yourself in Brilliant’s 23 lesson Applied Probability course.
You can understand Markov with a 30 day free trial
and 20% off an annual premium Brilliant subscription.
And you get that special deal because you’re watching SciShow!
Find those savings at the link in the description down below or at Brilliant.org/SciShow.
[♪ OUTRO]