I'm Carl Azuz, away from the CNN Center, but happy to be anchoring your news this Wednesday.

The United States passed a milestone yesterday in the number of its Coronavirus cases.

According to John Hopkins University, more than one million cases of the disease have been confirmed in America.

That's about a third of the cases confirmed worldwide, and when we produced this show, about 58,000 Americans had died from COVID-19.

For Perspective, the flu infects roughly 26 million Americans, on average each year, and it kills an average of 36,000 people.

So based on those numbers, the flu infects many more people than Coronavirus has.

But COVID-19 is more dangerous.

Some U.S. states are grappling with decisions on when to allow their businesses to reopen, and some have already started doing that.

Antibody testing factors in here.

This can be done through blood samples, and it can detect if people have had Coronavirus, even if they don't know it.

It's possible that those who've had the disease and then recovered from it, can be protected from getting infected again by the antibodies they develop.

But health officials say there's no proof that will happen.

They don't know how long it will last if it does, and there are concerns about the dependability of the antibody tests themselves.

But they're a step toward knowing who's had COVID-19 and possibly preventing the future spread of it, and contact tracing can help with that, too.

Contact tracing is part detective work, part widely used public health method, and experts believe, a key strategy in fighting the Coronavirus pandemic.

It relies on identifying and interviewing every person who tests positive, isolating them, and then finding anyone else that person could have infected.

These people may then be quarantined before they can spread the infection to others.

A recent study estimates that because one person infected with COVID-19 can infect two to three other people, just one positive case can turn into more than 59,000 cases after ten rounds of infection

Contact tracing can help prevent this potential wave of infections from becoming a tsunami.

It's a tedious approach, but one that is widely credited with stopping SARS in 2004, after that outbreak infected more than 8,000 people around the world and killed nearly 800.

Public health officials say contact tracing is a necessary step before certain businesses can reopen and people can start to return to normal activities.

Some countries, including South Korea, India, and Singapore, are using smartphone technology alongside traditional techniques to ramp up their contact tracing programs.

While the CDC in the U.S. has started a pilot program to ramp up contact tracing in some states, many studies estimate that the U.S. will need hundreds of thousands of additional public health workers before a contact tracing system can really begin nationwide.

10 second trivia.

Which of these stories made headlines in 1947?

"Flying saucers" seen in Washington, Communism declared in China, Barbie Doll Makes debut, or First Corvette introduced.

A civilian pilot named Kenneth Arnold said he saw flying objects that a reporter mistakenly called flying saucers.

For decades, the U.S military has been studying aerial encounters with unknown objects, aka UFOS.

This week, the Pentagon released three videos that were recorded during U.S. Navy training flights, and they apparently show mysterious airborne objects captured by the plane's infrared cameras.

One of the recordings was made in 2004: a pilot who saw that object said it moved rapidly in ways he couldn't explain.

The other two clips were captured in 2015, and in one of those, a pilot can be heard saying the object is a drone.

So, was it?

The Pentagon says whatever was recorded remains unidentified, and it didn't give any hints as to what it thinks the objects might have been.

The reason the military officially released the videos yesterday after they had been published without permission by other organizations was to help clear up public debate over whether the videos were real and if there's anything more to them.

The military also wants to encourage pilots to report anything strange they see because any unauthorized object in the sky could be dangerous to aviators and U.S military operations.

Since humans have crisscrossed the skies, they've made several trips to the moon and mapped it as we showed you earlier this week.

People have also mapped Mars and sent spacecraft to the far reaches of our solar system.

So why is it that more than 80 percent of our oceans are still unmapped and unexplored according to the National Ocean Service?

Like space exploration, deepwater exploration is expensive.

It can be dangerous, it's time consuming, and researchers have trouble getting funding.

But there are some inventors who are finding new ways to go deep.

The latest suit that we're building right now is called an Exosuit, and "exo," very simply, is from exoskeleton, like a crab shell and all your soft meat inside it doing what you want to do.

So it's kind of like Iron Man come to life.

My name is Phil Newton, and I've designed and build things to go under the sea, deep under the sea.

The whole idea of being able to get people down into deep water, that huge part of the planet that were denied access to by birth, is a very exciting one.

We build a lot of devices that haven't been built before.

And, that's what makes the whole thing fun.

We put this into a hydraulic press.

In 1985 we built the first of what were called Newt Suits and named after my last name, Newton and the aquatic salamander.

So we've learned everything that's wrong with them, and over a period of time came up with a brand new, completely upgraded version called the Exosuit.

And that was for a diving suit.

There's nothing more than just a big camera case inside the suit.

You're at the same pressure that we were designed to be at, the pressure that we're at right now, and with this suit, you get onto 1000 feet and even deeper and have no pressure effects whatsoever, because inside it is one atmosphere.

(inaudible)

Submarines work beautifully as submersible deep workers: the subs are terrific for survey work, so they can zip around shipwrecks, wellheads, all the sort of stuff.

The suits are better suited for working.

Your arms are actually in there, your hands are gripping the grippers, and so when you move, it moves.

It's really kind of a paradox, in as much as it has to be absolutely rigid to withstand that high outside pressure at, say, 1000 feet pressure is 500 pounds per square inch.

But it has to be flexible, so you could move the arms and legs and work.

Otherwise, what's the point going down there?

The suit has a tether to the surface, and that tether provides you with power because the suit flies.

It has thrusters on it, and it flies around on the end of this umbilical.

There's optic fiber in the umbilicals so it can take back video.

The option supply system does not come from the surface.

The option supply is built into the suit, and the supply is about two full days.

So why doesn't everybody do it?

Well, first of all, the suits are very hard to build, and they're expensive.

They're very expensive.

So, most difficult thing is getting the price down.

Going down in the Exosuit is almost always going down for a purpose.

I want the pilot to be able to accomplish the task, whatever it is, whether photography, welding, cutting, blasting, burning, and not think about the suit at all - you shouldn't even know it's there.

It has to be unremarkable, the more unremarkable, the better.

I guess what drives me is that there's still so much more to be done.

It's tremendous to be able to go to greater depths than you've been to ever before and to examine them.

And when archaeologists and scientists are able to go down there.

The deeper they go, the more things they find that they didn't even know existed.

[10 out of 10]

NASCAR racer Denny Hamlin recently finished last at Talladega.

Okay, it wasn't a real race.

NASCAR has postponed its events because of Coronavirus, but the online game Hamlin was in came to an abrupt end - for him anyway - when his daughter accidentally disconnected him from the server.

-Hey, my screen just went black. -Uh-oh.

Uh-oh was right!

Daddy Hamlin wasn't too happy when the seven-year-old forced him into last place.

Maybe for punishment, she could just take a lap.

But she might be happy that his talent day got away.

It wasn't all fun and games.

Maybe he seemed too socially distant.

And even if she had to peel out after making his game crash and burn, it's still supposed to be fun when your family comes to the race.

We've got some viewers from across the Pacific today.

Funabashi High School is in Chiba, Japan.

You guys get a perfect CNN 10 of a 10. I'm Carl Azuz!