Falling into a Black Hole – This Week in Space

In honor of Black Hole Week, NASA, the United States space agency, has released a simulation illustrating what it would look like if we were to fall into a black hole. The simulation demonstrates two scenarios with a camera approaching a black hole that is four million times the mass of our Sun, similar to the one found at the center of the Milky Way. In one scenario, the camera passes close to the black hole’s event horizon—the point from which nothing can escape its gravity—but does not get trapped inside. In the second scenario, the camera is swallowed by the black hole, allowing viewers to see the stages of being consumed until the inevitable bitter end.

“If you have the choice, you want to fall into a supermassive black hole,” claims astrophysicist Jeremy Schnittman from NASA's Goddard Center, who created the simulation together with his colleague, Brian Powell. “Stellar-mass black holes, which contain up to about 30 solar masses,  possess much smaller event horizons and stronger tidal forces, which can rip apart approaching objects before they get to the horizon.” In contrast, a supermassive black hole has such extreme differences in the gravitational pull acting on the near and far ends of an object found in the vicinity of a black hole, that it causes the former to be drawn in significantly faster than the latter, resulting in a phenomenon known as 'spaghettification’, due to its resemblance to the stretching of noodles.

Black holes are objects with enormous mass compressed into a relatively small volume, with gravity so strong that nothing can escape from them, not even light. The circumference of the black hole’s event horizon in the simulation is about 25 million kilometers, and the camera begins its approach from a distance of 640 million kilometers. Soon, the accretion disk surrounding the black hole fills the field of view. The camera enters an orbit around the black hole, close to the event horizon, completing nearly two orbits before being pulled in. The entire process would unfold over approximately three hours,  culminating in a rapid descent of the camera toward the center of the black hole at the speed of light, completing the process in just 13 seconds. An outside observer would not be able to see this; to observers aboard the mother spacecraft, it would appear that the camera is slowing down and freezing in place.

In the scenario where the camera does not cross the event horizon, it would complete an orbit around it in about six hours. Should an astronaut in the spacecraft undertake this voyage, she would return to the mother spacecraft 36 minutes younger than her colleagues who waited for her, due to the immense speed of the flight and time dilation as the speed approaches that of light.

Schnittman and Powell harnessed NASA's supercomputer to create the simulation, which is based on about 10 terabytes of data.  Running it on the supercomputer took five days, utilizing less than one-third of a percent of its 129,000 processors. According to their estimation, running such a task on a conventional laptop would have taken nearly ten years.

NASA's simulation video - 

Boeing Delayed Again

After many delays, Boeing's much-anticipated launch suffered yet another setback last week. The company's first manned spacecraft voyage to the International Space Station (ISS), slated for liftoff, was postponed again - just two hours before its scheduled departure—due to a malfunction in the ULA's Atlas 5 launch vehicle. The countdown was halted after it was discovered that one of the valves in the liquid oxygen tanks was not functioning properly. The control team decided to remove the rocket from the launch pad for repairs.  This delay means that astronauts Barry Wilmore and Sunita Williams, both veteran and experienced NASA astronauts, will now have to wait another week, until May 17, for the next launch attempt.

Nearly two years ago, Boeing successfully completed an unmanned test flight to the station. However, technical issues with the mission necessitated repairs to the spacecraft, resulting in substantial financial losses for the company due to the ensuing delays. The scheduled launch of the manned spacecraft has faced repeated postponements and is now delayed again due to a rocket malfunction. Boeing's Starliner spacecraft are designed to ferry supplies and astronauts to the station, alongside SpaceX, which is currently the sole American entity performing such missions. Once the spacecraft finally becomes operational, the United States will become the only nation in the world with three entities conducting manned orbital flights - NASA and two commercial companies.

Another delay. Boeing's Starliner spacecraft atop ULA's Atlas 5 rocket on its way to the launch pad approximately a week ago | Photo: NASA/Joel Kowsky

En Route to the Far Side

The Chinese space mission, which aims to bring back soil samples from the far side of the moon for the first time, has successfully entered lunar orbit, ahead of the planned landing attempt, likely in early June. The Chang'e 6 spacecraft was launched from China nearly a week and a half ago, and after a journey of 112 hours, it activated its main engine on Wednesday morning to decelerate in order to be captured by the moon's gravitational pull. It entered a highly elliptical orbit, with its closest point approximately 200 kilometers from the lunar surface. Over the forthcoming weeks, it will gradually make small orbital adjustments to achieve a circular orbit at that altitude. Concurrently, it will deploy a small satellite from Pakistan into lunar orbit, which it is transporting.

Ahead of the landing, the lander is expected to detach from the orbiter—a satellite that will continue to orbit the moon—and land in an area named Apollo Basin, a crater about 500 kilometers in diameter located in the Aitken Basin, an even larger crater over 2,000 kilometers in diameter, situated on the southern far side of the moon, which never faces Earth. The lander is equipped with a scoop for collecting surface samples and a drill capable of extracting samples from depths of up to two meters. In total, the lander is expected to collect about two kilograms of soil and rocks. Subsequently, a segment of the lander is set to lift off from the surface, carrying the sample container, to rendezvous with the orbiter in lunar orbit, and eventually drop the sample container back on Earth by late June. Researchers hope that these samples will provide them with insights into the geological differences between the two sides of the moon.

China is the only country so far to have landed a spacecraft on the far side of the moon, with the Chang'e 4 mission in 2019. At the end of 2020, the Chang'e 5 mission successfully brought back soil samples from the near side of the moon, and the current mission is expected to combine the two accomplishments, propelling China closer to its ambitious plan to land humans on the moon and establish a manned outpost there.

En route to collecting samples from the far side of the moon. The Chang'e 6 spacecraft in lunar orbit | Photo: CNSA

The Mystery of the Vanished Satellite

Twenty-five years after it disappeared from radar, an old American experimental satellite has been located again with the help of data from the United States Space Force. The satellite S73-7, launched 50 years ago in April 1974 as part of a U.S. Air Force experiment entered a circular orbit at an altitude of 800 kilometers, where it was deployed from the larger KH-9 Hexagon parent satellite. It was supposed to inflate a special balloon intended to serve as a target for calibrating the remote sensing equipment of the Hexagon satellite. However, the balloon failed to inflate, and the small satellite remained adrift in its orbit as space debris, disappearing from tracking systems.

Jonathan McDowell, an astrophysicist from Harvard University, managed to locate the small satellite—a ring 66 centimeters in diameter—in Space Force tracking records. He also found that the satellite was briefly detected in the late 1990s before disappearing once more, until its recent discovery. Locating the satellite posed a significant challenge due to the scarcity of data points available for comparison with its radar signature.

The satellite itself holds little significance, but its rediscovery underscores the formidable challenge—and the importance—of tracking space debris. Presently, an estimated twenty thousand sizable fragments of space debris are found in orbit around Earth, measuring tens of centimeters or more, alongside hundreds of thousands of smaller remnants, potentially exceeding one million. This debris poses hazards to operational spacecraft and satellites and has the potential to trigger cascading collisions, creating more fragments and further exacerbating the debris issue. The ability to monitor specific pieces of debris could help prevent such collisions and, in the future, may also form the basis for operations to remove the debris from orbit.

Managing space debris involves the challenging task of its detection. The parent satellite that carried the original tiny satellite into orbit | Source: National Reconnaissance Office, USA