We're starting with a report on a US milestone—a measurement, really—known as the first 100 days.

What has the new US leader done and not done in just over three months after inauguration day—April 30th will mark 100 days in office for President Joe Biden.

By day seven, the new leader had signed dozens of executive orders, new directives from the executive branch.

Many of President Biden's orders aimed to unravel the policies of his predecessor, former President Donald Trump—and many of his orders went against the policies of his predecessor, former President Barack Obama—so you can see how these can swing back and forth.

On his 51st day, President Biden signed a new stimulus package, a 1.9-trillion-dollar spending bill intended to ease the financial problems related to coronavirus.

The law had passed in the Democratic-controlled Congress on the Democratic President's 50th day, but it received no support from congressional Republicans.

Another goal the president had was for 100 million Americans to get at least one dose of coronavirus vaccine by his 100th day.

Critics said that goal wasn't ambitious, that the nation was on track to do that anyway.

And it happened on President Biden's 58th day.

But shortly before that, the US Leader announced he'd increase his goal to 200 million doses by his 100th day.

We don't know yet if that will be reached, but this is just a sampling of this particular president's actions.

CNN 10 contributor Rachel Jan Fossa looks at the history of the 100-day Milestone.

Historically, the first 100 days of a new president's administration are significant, Carl.

The term, the first 100 days dates back to President Franklin Delano Roosevelt—you might know him as FDR.

He signed 15 bills into law during his first 100 days in office.

Since then, presidents have been judged—perhaps unfairly—by what they accomplished during the same period

When FDR took office in 1933, he faced the Great Depression, a time of major economic crisis—unemployment had reached an estimated 25%.

During his first 100 days in office, FDR worked with Congress to roll out the "New Deal", an aggressive policy agenda that set out to get the country back on track.

The newly-elected Democratic majority in Congress was eager to help pass the new president's legislation.

FDR signed 15 major bills into law during his 1st 100 days, including the Emergency Banking Relief Act, the Public Works Administration, the Civilian Conservation Corps, the Tennessee Valley Authority, the National Industrial Recovery Act, and the Federal Deposit Insurance Corporation.

Since then, the first few months of a new administration have provided a glimpse into the president's governing style and set the tone for what the Commander-in-Chief hopes to accomplish.

Ronald Reagan, who was shot in the chest on his 69th day in office, signed his first bill into law from the George Washington University Hospital.

And on the eve of his 100th day in office, he delivered an address to a joint session of Congress.

George W. Bush marked the occasion by inviting all 535 members of Congress to the White House for lunch.

And on his 100th day in office, Barack Obama held a prime time news conference in the east room of the White House.

But despite the tradition, Carl, some presidents have said that judging them on their first 100 days is unreasonable, as it doesn't give a new president enough time to accomplish their goals.

John F. Kennedy famously said that even the first 1000 days wouldn't be enough time either.

Another time-related topic.

This Tuesday, an anniversary—yesterday marked exactly 40 years since Nasa's Space Shuttle Program got off the ground.

Before the last flight landed in 2011, Nasa estimated the total cost of the program was $209 billion.

And space history experts say there's been an endless debate over whether it was worth it, but it changed our view of space.

There was a huge acceleration.

Solid rocket propellant burns very rough.

You go from 3Gs to 0G instantaneously, and then it's this overwhelming view of the blackness of space.

Okay, I'm in orbit; I've got a lot of work to do.

Over 30 years, they flew on 135 missions, transporting 355 people and over 3 million pounds of cargo.

Part rocket, part orbiter, and part airplane, Nasa's space shuttle wasn't just the next step after Apollo, it was a giant leap in the way we understood and used space.

The success of the Space Shuttle Program really goes back to that initial foundation, applying what you learn from the Apollo program in the X vehicle world and really taking it to the next level.

The shuttle program began in 1972.

It promised routine access to space and a delivery system capable of building a space station.

Reusability was built into the space shuttle system.

A lot of the key design challenges were making that happen, making this system as light as possible, getting the orbiter just right.

The thermal protection system, all of the propulsion systems that were necessary, really, it was an incredible marvel of human engineering.

The design was perfected by 1981 and, on April 12, the world tuned in to watch Colombia launch.

It had the trademark shuttle look, with two solid rocket boosters and a giant external fuel tank to supply the orbiter's three main engines.

These propelled it to speeds of almost 18,000 miles per hour, fast enough to escape Earth's gravity and begin the shuttle era.

Colombia was joined by Challenger, Discovery, Atlantis, and Endeavor.

Operating at the edge of possibility, it didn't all go to plan.

Challenger, and later Columbia, suffered tragic fatal accidents.

But together, the shuttle fleet redefined our relationship with space.

They served as orbiting science labs, launched, repaired, and upgraded satellites, including groundbreaking instruments like the Hubble Space Telescope.

When the Hubble Space Telescope first launched, it had a mirror problem, but the space shuttle was there to fix that.

It's an incredibly important achievement.

But the shuttle's most important achievement was building the International Space Station.

It's just unbelievable that humans have built this incredible facility 250 miles up above the earth.

Being part of the assembly—it certainly was an incredible highlight for all of us that participated in it.

It took a couple hundred spacewalks, lots of vehicles, lots of robotic activity to put it all together.

We can see the International Space Station—it's a wonderful accomplishment and we'll never forget the role the space shuttle played in its creation.

In 2011, after a decade of work and over 30 shuttle launches, the ISS was complete, and what followed was the final space shuttle re-entry.

We had a nighttime entry, so you can see the plasma—that was pretty intense.

There was just so many thousands of people that had a hand in this vehicle.

One of the greatest honors, certainly in my professional career, if not my entire life.

There's a lot of emotion today, but one thing is indisputable: America is not gonna stop exploring.

It took close to a decade to reestablish astronaut launch capacity from US soil.

But on May 30, 2020, Space X's Crew Dragon Demo II launched to the ISS.

I can't overstate how much work it was to get us back to that point.

It proved that private companies could continue the shuttle's legacy.

For NASA and space exploration, it frees up funding to develop these vehicles that will go beyond low earth orbit.

NASA hopes its Orion spacecraft will make lunar travel routine as part of the Artemis program that will eventually push onto Mars.

Shuttle heritage parts will be used in the Artemis program.

Where we've been and where we're going is so incredibly intertwined.

I would like the space shuttle to be remembered for what it is: an incredibly important piece in this larger evolutionary approach to humans in outer space.

Complex, powerful, and breathtaking.

Three words to describe the shuttle: extremely capable vehicle.

For 10 out of 10, it's a traffic light—for camels!

Green means go, red means don't, but we wouldn't blame you if you were to ask, "Why, Carl? Why?"

Well, this is stopping traffic—camel traffic—in northern China.

There's a camel riding place there that's popular with tourists and that has led to confusion and camel-involved collisions.

So officials have created what they say is the first traffic signal for—you get it—camels.

Now you might be wondering who "camel up" with the idea—were "cam elisions" becoming too dangerous increasing the threat of a "hoof and run"?

Were the animals spitting at others that cut them off, starting trouble right out of the gate?

Of course, it will be the people leading the camels who actually stop and go at the signal—letting the animals do that themselves will be too "dromedary".

I'm "Camel" Azuz for CNN 10

Henderson County High School, we see you watching from Henderson Kentucky, we'll see you all tomorrow.