welcome back to Smarter Every Day.

Depending on where you get your media

you're probably aware that we just failed for the third time

in eight months to get cargo vehicles up to the International Space Station,

which means that cargo didn't make it up there.

Now the media's really negative about this and I understand that.

It's never good to blow up rockets.

However, as a rocket tester, that's my day job,

I think I'm a little bit more positive about this.

And the reason is because I've always learned more from rocket failures than from successes.

Before I show the explosions let's talk about one thing.

It's called staging.

So imagine you've got this rocket and you've got really big propellant tanks and you've got engines on it right?

At some point along the way you're gonna have really big empty tanks and that's just a lot of extra weight.

Rocket engineers figured out a long time ago that if they drop off all that extra weight

and they switch over to another rocket engine and smaller tanks

that they can get to orbit more efficiently.

This is a beautiful thing and it works because of something called the rocket equation.

OK time to look at the failures.

The first failure was an Orbital Sciences Antares vehicle carrying the Cygnus spacecraft.

Now this vehicle was interesting because it used Russian engines that were literally 40 years old.

Now that sounds crazy at first but rocket engines are super expensive

and these were actually really efficient engines.

Anyway, they were refurbished but still there was a catastrophic failure.

Unfortunately a lot of stuff didn't make it to the space station.

The second failure was a Russian vehicle called Progress 59.

It launched like normal from Baikonur and it even made it to space

but somewhere up there there was a failure on the third stage and everything went cattywampus.

The engineers couldn't regain control and the vehicle eventually burned up in the earth's atmosphere.

Among other things there were a lot of toilet repair parts on that progress vehicle

which is a pretty big deal.

You gotta poop somewhere.

The most recent failure was of a Falcon 9 rocket made by SpaceX.

Again the launch seemed to be normal,

everything seemed to be going well

and then it seemed to vent something out the side that looked like liquid oxygen

and then all of a sudden it exploded.

I'm not gonna speculate on why it exploded because I'm not a system expert.

Those exist and I'm not one of them.

In terms of hardware loss there was a lot of normal supplies and scientific gear

as well as an international docking adaptor,

a HoloLens and a space suit.

Space suits don't really grow on trees.

OK let's talk about what this means for the space station

because there's a lot of chow that didn't make it up there.

There's a person in the front of the control room called the ISO,

the inventory and stowage officer,

and their job is to know exactly what is where on the International Space Station.

For example, food.

When it comes time to eat on the space station

astronauts have large bags of food.

They'll scan it with a scanner. Boop.

That tells the ISO that that bag is now open.

They'll open the bag up and they'll start eating food out of that bag and that bag will last them about a week.

They try to plan at least 60 days ahead of the next cargo vehicle.

It's called a skip cycle.

So when Cygnus blew up they took that 60 day window and they compressed it down to about 45 days.

This is an internal discussion that these guys have to manage their assets.

The good news is there's no longer 3 astronauts on the American side of the space station

eating up all the food. There's only one. Scott Kelly.

And trust me, Scott Kelly can't eat three astronauts worth of food.

The fact that we've lost three vehicles pretty much in a row

and we still have plenty of supplies on the space station

speaks to how awesome these engineers and mission planners are.

ISOs are pretty awesome.

Is it OK to keep blowing up rockets?

No. But I would submit to you that this might be the perfect time for it to happen if it has to.

The cargo vehicle program has been incredibly reliable,

almost routine in fact.

I mean look at these numbers.

These reliability rates are right on par for the non-human-rated rocket business.

You know why this is impressive to me.

There are billions of wifi connections all over the world

and there are absolutely no moving parts

yet we still don't have it figured out.

That's crazy.

Now think about rockets.

If you had a million moveable parts on this wifi connection would you expect it to work?

I wouldn't, but somehow rockets work.

That's amazing.

Space is hard, but we're doing it.

Think about staging again.

You compute your guidance and control algorithm based on a huge rocket to hit the right course.

When you get to altitude you've got to stop one set of rocket engines,

break the rocket in half,

safely separate the two parts,

recalibrate your entire guidance and control scheme,

start another rocket engine and make sure that one's on the same track.

Oh by the way your center of gravity just moved half way down your vehicle,

you're doing this while you're on a collision course with the ground

and you're going several times the speed of sound

using materials that were the lightest you had available

and you shaved every single gram you could so you could get more payload to orbit.

That's really hard.

So what do these failures mean for human space flight.

Well for one thing cargo vehicles are not human rated vehicles.

Once you put a human on top of that rocket the rules change.

For example a cargo vehicle might have two guidance computers

but a human rated vehicle might have six.

Human rated vehicles might have extra valves so you can isolate a problem with propellant.

Another thing, the very top of a human rated system is often a launch abort system.

If something goes squirrely with the big rocket you can just punch the launch abort system

and it'll pull the capsule away, saving the humans.

OK my words might not be right but I'm a little excited that these failures happened exactly when they did.

And this is why.

If you think about it, we are stressing the system in a way we did not anticipate.

Three cargo vessels did not make it, that's a big deal.

But everything's still working, so we have great mission planning .

We stressed the system in a way we didn't expect and it's working flawlessly.

Number two, we're gonna uncover something right?

We did something wrong.

I don't know what it is but there might have been a weld that was wrong,

we might have done something wrong procedurally,

something is wrong.

And we're gonna take a really stinking hard look at it

right now, just before we transition to human flight

and we're probably gonna be safer because of it

because if these rockets had kept working every single time

that flaw in the system or in that part would still be there

but it would remain uncovered.

So it's a really good thing that it happened right now

before we put humans on these rockets.

So my grandfather worked on Apollo and my mom found something really cool this week in the basement.

It is a coin made from materials that flew with Apollo 8 around the moon.

Really cool.

It comes with this letter from Frank Borman who was one of the astronauts

thanking the people that made his rocket for their dedication to safety.

Really really cool.

Also there's this.

It's a lunar landing celebration invitation from Dr Werner von Braun

and if you zoom in here you can see what he says in closing.

He says 'My greatest hope is that together we can work on ever greater ventures in the future'.

That's exactly what the International Space Station is.

It's a greater thing.

It transcends politics, it transcends language, it's just amazing.

And so you've gotta ask yourself,

in this situation, resupply vehicles fail,

what would von Braun do?

And I think he would double down.

I think he would realize that he could learn from mistakes in these resupply vehicles

and roll that knowledge into the human space flight effort.

And I'm really excited about that.

I hope you enjoyed this episode of Smarter Every Day.

It was sponsored by audible.com where you can get a free audio book by going to audible.com/smarter.

I recommend Endurance by Alfred Lansing.

I read this book because I saw a space station astronaut reading this book on one of the tours I watched online.

Incredible parallels.

They were stuck trying to cross Antarctica by land,

they tried to resupply by boat, didn't work,

they had to survive on what they had.

There's penguins that they would kill and eat.

I'm not gonna telly you if they eat the dogs but it's an incredible book.

Anyway check it out.

It's about Shackleton's incredible voyage.

audible.com/smarter, Endurance by Alfred Lansing.

I am Destin, you're getting Smarter Every Day.

Have a good one.