Name: SpaceX-PLOSIONS: Why It Matters - Smarter Every Day 138
Uploaded: 2020-03-26T02:26:11.000Z
Duration: 7 min 19 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

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.

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.

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.

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

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

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

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

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

as well as an international docking adaptor,

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,

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

When it comes time to eat on the space station

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.

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.

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,

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

There are billions of wifi connections all over the world

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

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,

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.

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.

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SpaceX-PLOSIONS: Why It Matters - Smarter Every Day 138

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