Updated on March 20 at 5:53 p.m. ET
Humanity will come crashing down earlier than expected.
The Humanity Star, a satellite launched into space in January, will reenter Earth’s atmosphere and disintegrate sometime this week, according to websites that track the movement of objects in orbit around the planet. The satellite was always going to come back down. But it was supposed to remain in orbit for nine months, according to Rocket Lab, the U.S. spaceflight company, based in New Zealand, that built the satellite.
SatView and Space-Track, databases that track all artificial satellites and space probes around Earth, forecast that the Humanity star will reenter the atmosphere sometime on Thursday, March 22. (See SatView’s page here, and Space-Track’s page here.) Rocket Lab’s own tracker shows that the satellite’s altitude is already steadily dropping.
The Humanity Star is a 3-foot-tall, 23-pound spherical satellite made of carbon fiber. It’s covered 76 highly reflective panels that direct sunlight back to Earth as it spins rapidly. It looks like a disco ball, a fitting description for its sole purpose: Rocket Lab just wanted to put a shiny object in space to draw people’s attention. Rocket Lab launched the satellite, along with three other small commercial satellites, on the company’s Electron rocket, on January 21. It was the first time the rocket successfully reached orbit.
Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, shared with me a chart to illustrate what’s happening. Some of the objects Rocket Lab launched into space in January remain in their original orbits. They include, shown in blue, the Lemurs, two satellites from Spire, a U.S. satellite company; Dove, a satellite from Planet, a U.S. Earth-imaging company; and the upper stage of the Electron rocket. Meanwhile, the Humanity Star, shown in red, has fallen out of its orbit, and fast.
Altitude of Objects Launched by Rocket Lab in Orbit Over Time
So what happened?
When objects travel through an atmosphere, they experience a dragging force in the direction opposite to the direction they’re moving. The atmosphere where low-Earth satellites operate is far less dense than near the planet’s surface, but there’s still enough air particles there to produce some drag and slow satellites down. This interaction is influenced by the sun; when the sun is extra active, it heats up the near-Earth environment, causing the upper atmosphere of the planet to expand and get closer to the orbits of some satellites. This, in turn, increases atmospheric drag. The denser the atmosphere, the greater the drag, the quicker satellites slow down and feel Earth’s gravity beckoning them home.
All objects in low-Earth orbit experience drag and a gradual reduction in their altitude, a phenomenon known as orbital decay. Even the International Space Station, which has to readjust every now and then to stay in its orbit.
Engineers and scientists can predict how long a satellite will stay in orbit based on their understanding of the atmosphere in low-Earth orbit and the sun’s activity. McDowell said Rocket Lab probably gave the Humanity Star nine months because that’s how long objects in similar orbits, under current conditions, are expected to remain stable. But its rapid descent suggests the company may not have taken into account the amount of drag the satellite would experience because of its low mass.
“If you have a small dense object, it won’t feel much drag. If you have a big flappy piece of fabric, it’ll feel a lot of drag,” McDowell said. “Compared to the average satellite, [the Humanity Star] is mostly empty. It’s big for its mass, so therefore it kind of floats. It gets blown around by the wind more.”
Rocket Lab CEO Peter Beck confirmed the Humanity Star would reenter Earth’s atmosphere sooner than expected. “The satellite is very light and was built from 1 millimeter-thick carbon fiber and many reflective surfaces, making its orbit hard to model from Earth,” Beck said Tuesday afternoon in a statement to The Atlantic.“Things often perform differently in a space environment, which is what we discovered with the Humanity Star.”
The exact time and location of the Humanity Star’s reentry on Thursday is difficult to predict, but it will become clearer as the satellite loses altitude in the next coming days. SatView currently predicts the satellite will come down somewhere over the South Pacific Ocean.
Rocket Lab didn’t publicize the Humanity Star until after it launched. The purpose of the satellite, the company said, was to promote interest in the wonders of outer space. “No matter where you are in the world, rich or in poverty, in conflict or at peace, everyone will be able to see the bright, blinking Humanity Star orbiting Earth in the night sky,” Beck wrote on its website. “My hope is that everyone looking up at the Humanity Star will look past it to the expanse of the universe, feel a connection to our place in it and think a little differently about their lives, actions and what is important.”
The reaction to the launch was controversial. Some astronomers were pretty angry, describing the Humanity Star as nothing more than a piece of shiny space junk, a billboard in an already crowded place. There are already thousands of satellites in orbit around Earth, some operational and some defunct, and to add one without a scientific purpose amounted to pollution, they argued.
“It’s hogging some of that precious resource, the dark night sky, polluting part of the last great wilderness,” Caleb Scharf, the director of the Columbia Astrobiology Center, wrote in a post on Scientific American. “Most of us would not think it cute if I stuck a big flashing strobe-light on a polar bear, or emblazoned my company slogan across the perilous upper reaches of Everest. Jamming a brilliantly glinting sphere into the heavens feels similarly abusive.”
Some astronomers warned the bright object could disrupt astronomical observations of both ground- and space-based telescopes.
For no reason at all, here’s what it looks like when a satellite goes through Hubble’s field of view whilst you are trying to image something in the distant solar system. pic.twitter.com/eLWR1ncdqx— Alex Parker (@Alex_Parker) January 25, 2018
To this criticism, Rocket Lab responded, “the Humanity Star will blink across the sky for just a seconds [sic], and it won’t be visible in your region for the full 9 months in orbit. Our hope is that it draws people’s attention to the stars, then leaves them looking to the universe long after The Humanity Star has passed.”
Other astronomers were less peeved. They recognized that the effort was short-lived and, thanks in part to news reports over the controversy, it really would pique the public’s interest.
“I’m not a fan, but I’m not as horrified by it as some people are,” McDowell said. “The worry is that if you launched a lot of things just to be bright, that’ll disrupt astronomy. But the occasional one in a low orbit, that you don’t see most of the night—this one wasn’t such a big deal. I don’t think it was a great thing to do, but it wasn’t a terrible thing to do.”
Either way, the launch of Humanity Star represented another milestone in a shifting spaceflight industry. In a very short time, commercial spaceflight companies like Rocket Lab, SpaceX, and others have staked their claims to a dangerous frontier that for decades was the sole domain of governments. These companies have developed the technology to launch rockets on their own, and they get to decide what to put on board. A shiny disco ball? Sure. A cherry-red Tesla convertible? Why not. It’s an exciting moment in spaceflight history. Of course, it also comes with some risks. The secretive nature of some commercial launches opens the door for rogue actors. In January, a U.S. startup reportedly launched four satellites into orbit without the required approval from the federal government, prompting an investigation into an unprecedented situation.
Rocket Lab says on its website that it doesn’t plan to launch another Humanity Star when this one burns up in Earth’s atmosphere. If its demise is upsetting, don’t worry. We humans have another highly reflective satellite, visible to the naked eye, to carry on Rocket Lab’s goal “to create a shared experience for everyone on the planet”: the moon.