What if the international space station was empty?

Although the station can be operated remotely, nothing can replace the presence of people on board. Astronauts perform repairs inside and outside the station, replace obsolete equipment, and regularly check survival systems. Flight Controllers can track the condition and health of virtually every element of the station, but astronauts are their eyes and ears. They know a lot more about what's going on, especially in an emergency.

One night in August, while the crew was sleeping, the flight controllers on Earth noticed that the atmospheric pressure on the ISS had slightly decreased – a sign of a leak somewhere on the station. The air did not escape quickly, so the flight controllers decided not to wake the sleeping crew, which at that time consisted of three Americans, two Russians and one German.

When the crew woke up the next morning, he was asked to scour the station to find the source of the leak. The crew found her inside a Soyuz capsule moored to the ISS, in a section that never leaves the orbit – a two-millimeter hole they had never seen before . The crew plugged the hole with mastic and gauze. He took photographs and video footage of the scene and sent them to Earth, where an investigation was opened on the cause.

Russian officials are still working on it. They ruled out any impact with micrometeorides, space rocks that travel thousands of kilometers an hour and can easily cut through the metal. They believe that someone has pierced the hole, but they do not know who, why, or when.

Read: What happened with the International Space Station?

In this emergency situation, mission controllers could talk to the crew and guide them through the mysterious hole correction. But what if the floor could not communicate with the station?

In 2007, Michael López-Alegría, a NASA The astronaut and his teammates woke up one weekend to find that half of the lights were off in the ISS. While floating in the station, they realized that half of everything was out of order, from temperature control systems to gas scrubbers that remove carbon dioxide from the air to make it nontoxic. In addition to that, the communications were down. Mission control did not know what was happening on board, and vice versa.

The crew turned to printed manuals on board, looking for solutions. In the space of two to three hours, the aircraft had restored communication with the ground and the flight controllers were guiding the astronauts into restocking the rest.

"That's the kind of thing that would be a problem if you did not have crew on board," said López-Alegría, retired NASA in 2012, after three flights in the space shuttle and six months in the ISS.

Even without people on board, the ISS is a talkative environment. The station continuously transmits data to the Earth, transmitting thousands of signals about its slice of systems and its state. López-Alegría said that during the communication breakdown, this information was not found on the ground.