StarDate

The waning Moon will flirt with the star Aldebaran the next couple of mornings. Orange Aldebaran is the brightest star of Taurus, the bull. It will stand to the lower left of the Moon at first light tomorrow, and about the same distance to the upper right of the Moon the next day.

Watching Aldebaran is like taking a trip in a time machine — it shows us what our own star, the Sun, will look like in the distant future.

Aldebaran is a giant — it’s more than 40 times the diameter of the Sun, and hundreds of times brighter. That’s because the star’s “normal” lifetime has come to an end. It’s “fused” the hydrogen in its core to make helium. Now, the core is shrinking and getting hotter. That’s causing Aldebaran’s outer layers to expand and cool.

Before long, the helium will begin to fuse to make oxygen and carbon. That’ll make the core even hotter, so the star will get bigger and brighter. Eventually, though, the helium will be used up. Aldebaran will lose its outer layers, leaving only its hot, small, dead core — a white dwarf — which will slowly fade from sight.

The Sun will continue to fuse its hydrogen for another few billion years. After that, it’ll experience the same process that Aldebaran’s going through now. It’ll get bigger and brighter, and look much like Aldebaran does today. After a billion years in that stage, though, the Sun, too, will die out — leaving only a dead reminder of its once brilliant life.

Script by Damond Benningfield

If at first you don’t succeed, keep looking.

That’s a lesson from planet searches being conducted at the McDonald and Keck observatories. Two decades of observing scores of stars have yielded a special discovery: a planet that takes an especially long time to orbit its star. The discovery will help scientists test theories of how planets form, and help them figure out how unusual planetary systems like our own really are.

The planet orbits HR 5183, a star in Virgo, which is in the southwest at nightfall. The star is a bit bigger and heavier than the Sun, and a few billion years older. It’s about a hundred light-years away.

Astronomers have been watching the star with the Keck Telescope in Hawaii, and the Harlan Smith Telescope at McDonald Observatory, since the late ’90s. They’ve looked for a slight “wobble” in the star’s light as the star is tugged by the gravity of an orbiting planet.

Early last year, they saw such a tug. They calculated that it’s produced by a planet about three times the mass of Jupiter, the giant of our own solar system. It orbits the star every 75 years — longer than any other planet discovered with this technique.

The planet’s orbit is lopsided, so its distance from the star varies by billions of miles. The planet was at its closest last year — which is one reason it was discovered. As the planet moves away, it should be possible to take its picture — showing us a world that took a long time to find.

Script by Damond Benningfield

TODAY'S PROGRAM WAS SUPPORTED BY A GRANT FROM THE NATIONAL SCIENCE FOUNDATION.

Shortly after Apollo 11 splashed down in the Pacific Ocean 50 years ago today, a NASA spokesman was describing the busy scene in Mission Control:

PAO: Across the big board in front is President John F. Kennedy’s message to Congress of May 1961: I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. That has been accomplished.

Mission accomplished — but not complete. Five more sets of astronauts landed on the Moon. They set up instruments to study the Moon, and brought back about 800 additional pounds of samples that scientists are still examining.

A long lunar hiatus followed the last Apollo. But interest in the Moon is increasing. Several nations have sent robotic probes to the Moon in recent years.

NASA is ramping up its plans for the Moon as well. It’s developing a mothership to carry astronauts to the Moon and Mars, for example. It’s also planning a small space station known as “Gateway.” The station would follow a stretched-out orbit around the Moon. Astronauts would live there for weeks at a time, perhaps dispatching and operating lunar robots. And astronauts might land on the Moon themselves — perhaps as early as 2024.

There’s no guarantee that any of these plans will come to pass. Yet it seems certain that the Moon will receive more attention in the years ahead — building on the legacy of Apollo.

Script by Damond Benningfield

Scientists are getting ready to open a treasure chest — three samples of lunar rock and dirt that have never been examined before. They were collected by Apollo astronauts almost half a century ago. But they’ve been stored untouched — waiting for new technology that could reveal more of their secrets.

Astronauts brought 842 pounds of rocks, pebbles, and other materials back to Earth. Most of those samples are stored in a vault at Johnson Space Center in Houston, including the untouched samples.

Researchers have conducted thousands of studies on the Apollo samples, gleaning many secrets about the Moon and about Earth. And the pace of discoveries has quickened in recent years.

About a decade ago, for example, scientists discovered water molecules inside tiny grains of volcanic glass. That suggests that there’s water all across the lunar surface. More recently, they’ve found evidence that the Moon once had a fairly dense atmosphere.

Earlier studies suggested that the Moon was born when another planet hit the embryonic Earth. Debris from the collision came together to make the Moon.

But recent studies have suggested that the picture is more complicated. The size of the other planet, the angle and force of the impact, and other details are still being debated.

Scientists expect to continue studying the Apollo samples for decades to come — learning more secrets about the Moon.

More about lunar exploration tomorrow.

Script by Damond Benningfield

Apollo 11 was coasting toward the Moon 50 years ago this month when Mission Control passed along a request.

CAPCOM: Roger, Apollo 11. We got a laser. It’s a blue-green laser that we’re going to flash on and off. It’s coming out of McDonald Observatory. Would you please take a look through the telescope and see if you can see it? Over. ... APOLLO 11: Okay, Houston, neither Neil nor Mike could see it.

Although the astronauts didn’t see the laser, a special reflector they set up on the Moon did. The McDonald Observatory laser first found it a few weeks after the astronauts left the Moon. And the observatory continued to ping the reflector for more than four decades.

Today, other observatories are carrying on with that work. They’re using five reflectors, left by American and Soviet missions. Scientists time how long it takes a laser beam to hit a reflector and bounce back to Earth. That reveals the Earth-Moon distance to within about a millimeter.

From those observations, scientists have found that the Moon is moving away from Earth at about an inch and a half per year. By measuring “wobbles” in the Moon’s motion, they’ve discovered that the Moon has a molten outer core. And by measuring how Earth and the Moon “fall” toward the Sun, they’ve confirmed Albert Einstein’s theory of gravity to a high degree of precision.

The laser experiment continues today — the last working experiment from Apollo.

More about Apollo science tomorrow.

Script by Damond Benningfield

On the night of July 20th, 1969, Neil Armstrong was ready to make history:

ARMSTRONG: That’s one small leap for man, one giant leap for mankind. [:08]

The commander of Apollo 11 became the first person to set foot on another world: the Moon. Crewmate Buzz Aldrin joined him on the Sea of Tranquility a few minutes later.

During their two-hour moonwalk, they gathered about 50 pounds of rock and dirt. They set up a seismometer that recorded “moonquakes” for days after their departure. And they set up a laser reflector that’s still being used; more about that tomorrow.

While 600 million people watched on TV, the astronauts took a phone call from President Richard Nixon:

NIXON: For one priceless moment, in the whole history of man, all the people on this earth are truly one, one in their pride in what you have done. And one in our prayers, that you will return safely to Earth.

And Armstrong read a plaque attached to their lander, Eagle, which stayed on the Moon when they left:

ARMSTRONG: First there’s two hemispheres, one showing each of the two hemispheres of the Earth. Underneath it says, “Here Men from the planet Earth first set foot upon the Moon, July 1969 A.D. We came in peace for all mankind.”

Armstrong and Aldrin left the Moon on the morning of the 21st — starting the long journey home.

Script by Damond Benningfield

Earthlings first touched another world 50 years ago today. Apollo 11 astronauts Neil Armstrong and Buzz Aldrin guided their lunar module, Eagle, to a landing on the Sea of Tranquility, a volcanic plain on the Moon. It was the culmination of an eight-year effort launched by President John F. Kennedy.

The final moments of their descent to the Moon were anything but easy, though.

For a while, the astronauts had a hard time communicating with Mission Control. Their computer was overloaded, so it gave them error messages. And their radar was guiding them into a field of boulders. Armstrong had to fly past that area, burning extra fuel.

But the astronauts and flight controllers overcame the problems. And on July 20th, 1969, Eagle landed on the Moon:

EAGLE: Contact light. Okay, engine stop. ACA out of descent. Mode control both auto, descent engine command override off, engine arm off, 413 is in. CAPCOM: We copy you down, Eagle. ARMSTRONG: Houston, Tranquility Base here. The Eagle has landed. CAPCOM: Roger, Tranquility, we copy you on the ground. You’ve got a bunch of guys about to turn blue here. We’re breathing again. Thanks a lot.

We’ll talk about the next step tomorrow.

Script by Damond Benningfield

One of the things that amazes many about the Apollo Moon landings is how primitive their computers seem. A smartphone is millions of times more powerful than the computer on Eagle, the lunar module that carried Neil Armstrong and Buzz Aldrin to the Moon 50 years ago tomorrow.

But that’s a bit deceptive. Armstrong and Aldrin didn’t use the computer to play video games, book dinner reservations, or post on Instagram. Instead, they used it for a single job: landing them safely on the surface of the Moon.

The Apollo computers were developed by MIT — a process that took eight years. The computers stored information in tiny metal “doughnuts” interlaced by wires.

As Eagle descended toward the Moon, though, its computer began fussing at the astronauts. Through a series of unforseen circumstances, it was getting overloaded. So it set off alarms.

But the computer was designed to not freeze or crash when things went wrong. Instead, it dropped the least-important programs and kept running the crucial ones. In that way, the computer successfully guided astronauts to the Moon — a task no smartphone has ever done.

Script by Damond Benningfield

Flying to the Moon is dangerous. Radiation, for example, can threaten both spacecraft and their human cargoes.

The first threat is the Van Allen radiation belts. Earth’s magnetic field traps charged particles from the Sun in these doughnut-shaped zones. They extend from a few hundred miles above the surface out to about 35 thousand miles.

A long stay inside the belts could cause radiation sickness. But when Apollo 11 headed to the Moon 50 years ago, the crew faced little danger from the belts. Their trajectory avoided the belts’ most dangerous regions, and they zipped through the belts in a few hours.

After they cleared the belts, the astronauts still faced threats from the Sun. An especially big solar storm could have caused serious radiation sickness in astronauts who were on the Moon, requiring an immediate return to Earth.

To keep the astronauts safe, NASA kept a close eye on the Sun. And the Apollo mothership’s aluminum hull blocked most radiation. So Apollo astronauts received doses that were equal to no more than a few dozen chest X-rays. The doses were spread out over several days, though, and they covered the astronauts’ entire bodies. So the radiation wasn’t strong enough to cause damage.

Future missions may spend a lot more time on or around the Moon than Apollo did. So planners will need to spend more time thinking about how to keep astronauts safe from the dangers of spaceflight.

We’ll have more about Apollo 11 tomorrow.

Script by Damond Benningfield

By late May of 1961, the United States had launched one man into space — on a 15-minute hop into the Atlantic Ocean. And American spacecraft hadn’t been able to even hit the Moon, much less study it. Even so, on May 25th, President John F. Kennedy set a new goal for the space program:

KENNEDY: I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth.

Kennedy didn’t establish that goal for science. In fact, he wasn’t interested in the science at all. Instead, he was trying to improve American standing in the Cold War.

Space was playing a key propaganda role in that war. The Soviet Union had scored several big “firsts” in space exploration. It sent the first man into orbit, and took the first pictures of the far side of the Moon. That earned it bragging rights about Soviet technology and its way of doing things — boosting Soviet standing among other nations.

So Kennedy sought a major new goal for the American space program. He wasn’t looking for something immediate, though. Instead, he wanted a goal that would be difficult, take years to accomplish, and be spectacular — all in full view of the world.

That goal was achieved 50 years ago this week, with the flight of Apollo 11. We’ll have more about that tomorrow.

Script by Damond Benningfield