A recently-launched communications satellite has become one of the brightest objects in the night sky for an Earth observer, which astronomers say emphasizes the need for better regulation of orbital platforms. However, it’s just one of a whole new planned constellation of satellites - a situation astronomers say is “unacceptable.”
The satellite orbits at an altitude of between 316 miles and 327 miles (508 and 527 kilometers, respectively), which is higher than the International Space Station, as well as some other micro-satellite constellations that have attracted the ire of astronomers and stargazers alike. But BlueWalker 3’s problem isn’t its altitude, it’s the size and design of the spacecraft that’s causing the trouble.
That giant aperture, called a phased-array antenna, is 689 square feet (64 square meters) wide, or about 26.3 feet (8 meters) long on each side. The panels are reflective, turning the satellite into a giant mirror bouncing sunlight down toward Earth.
According to media reports, it’s the largest commercial antenna system ever deployed in low-Earth orbit.
A group of irate astronomers have published a paper documenting the effect the satellite has on Earth, which was published on Monday in Nature.
"Optical observations confirm that BW3 increases in brightness when BW3 is at a higher elevation above the horizon, and indicate that the range between the observer and BW3 is a primary contributor to the apparent/observed magnitude," they wrote. "The apparent brightness of BW3 also shows correlation with solar phase angle and appears brighter at high phase angles."
“The peak brightness of the satellite reached an apparent magnitude of 0.4,” the scientists noted. “This made the new satellite one of the brightest objects in the night sky.”
In other words, the satellite appears brighter than the planet Saturn in the night sky, brighter even than Polaris, the North Star. By comparison, the current International Astronomical Union recommendation is for space objects not to be brighter than magnitude 7, which is close to the dimmest objects the human eye can detect unaided.