The International Space Station cost more than $100 billion. A ham radio set can be had for a few hundred bucks.

Perhaps that explains, in part, the appeal of having one of humankind's greatest scientific inventions communicate with Earth via technology that's more than 100 years old. But perhaps there's a simpler explanation for why astronauts and ham radio operators have been talking, and talking, for years.

NASA astronaut Doug Wheelock was just a few weeks into his six-month mission at the space station when feelings of isolation began to set in.

Wheelock would be separated from loved ones, save for communication via an internet phone, email or social media. At times, the stress and tension of serving as the station's commander could be intense.

One night, as he looked out a window at the Earth below, he remembered the space station's ham radio. He figured he'd turn it on—see if anyone was listening.

"Any station, any station, this is the International Space Station," Wheelock said.

A flood of voices jumbled out of the airwaves.

Astronauts aboard the space station often speak to students via ham radio, which can also be used in emergencies, but those are scheduled appearances.

A team of researchers affiliated with several institutions in China, one from Italy and one from Iceland has used a machine-learning artificial intelligence application to count and note the location of over 100,000 craters on the moon. In their paper published in the journal Nature Communications, the group describes programming their system to recognize craters by training it with data collected by Chinese lunar orbiters.

Prior work identifying and mapping craters on the moon has tended to be a slow process—it has generally been done by hand, with researchers studying photographs and transferring those observations to maps or moon globes. In this new effort, the researchers have found a way to dramatically speed up the process by teaching a computer to identify craters and then to count them.

Teaching a computer to recognize craters on the moon has been a difficult process due to the many forms craters can take. Not all are round, and they are of different ages, which means defining characteristics have eroded over long periods of time.

Deck the halls with space-based bubbles!

Here is a festive bauble you will not see on Earth: a bubble produced by the Multiscale Boiling experiment, known affectionately as Rubi.

In this image, electrostatic forces are pulling the bubble upwards and making it spherical, producing not only a cool image but also cool insights into the boiling process.

Understanding how boiling behaves in weightlessness is imperative because gravity plays an important role. Without gravity, boiling takes place in slow motion and produces larger bubbles. This has allowed scientists to observe and measure effects that are too fast and too small on Earth.

The experiment is also installed with an electrode to observe the effect of an electric field on the bubbles, enabling scientists to observe and quantify the effect of external forces.

"Boiling is an extremely efficient way of getting rid of excess heat. This research could therefore provide very valuable information for improving the thermal management systems in space as well as in terrestrial applications," says ESA project scientist Daniele Mangini.

With this insight and more accurate calculations of the boiling process, products such as laptops can be improved and made more compact.