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We’ve posted plenty of reports here on UT Alert about the potential impact of Starlink and similar satellites on the field of astronomy. We’ve gone so far as to point out that the granddaddy of space telescopes—Hubble—has already had some of its images smeared by passing Starlink satellites.
However, SpaceX has been aware of the problem and is working to limit the product’s brightness. The recently launched Gen2 satellites seem to have taken a significant step forward – research from a team of amateur astronomers shows that the new Gen2 Starlinks are more than 10x fainter than previous Gen1 iterations.
Admittedly, this conclusion comes with many caveats. But the pedigree of the team doing the research is not in doubt. It was led by Anthony Mallama, a senior engineer at Raytheon and the author of numerous technical papers and articles on Starlink brightness. He and six other amateur astronomers collected their own data for this paper, which was recently published on arXiv preprint server. They compared the satellite’s brightness with data previously collected by Mallama, among other things, on the Gen1 spacecraft.
The Gen1 Starlinks are about four times smaller than the Gen2 craft, so logically, while they might not be as luminous, they should at least appear larger. Their first launch was in February, and while some of the new satellites malfunctioned and had to spin out of orbit, three from that round were able to reach their intended orbit, about 300 miles up. And there was the change.
While the satellites were orbiting “on station” they were actually brighter than the previous generation Starlink. However, once they reached their orbital altitude, they changed to an “on station” mode, where their orientation changed, and most importantly, a new type of reflective material was adjusted specifically to reduce their glare to ground observers.
SpaceX has a stated goal of making their new generation of satellites invisible to the naked eye, and they seem to be well on their way to achieving that goal. In some cases, observers trying to calculate the brightness of the satellites couldn’t even see them with their observing equipment — meaning they were less bright than even the dimmest stars — by about eight magnitudes at the time.
However, there were also outliers in the other direction. Occasionally, a large increase in brightness was also recorded. The company explained in writing to the astronomers that some maneuvers, such as maintaining orbit and sometimes avoiding collisions, would throw off the satellite’s trajectory and limit the effectiveness of both that trajectory and the reflectors it uses.
Another caveat to these total brightness numbers is that the Gen2 satellites have all been “mini” configurations so far. Although they are effectively four times the size of Gen1 satellites, SpaceX plans to launch up to 7500 Gen2 satellites that are even larger than the ones currently considered “Mini”.
Clearly, the company is taking the problem of adversely affecting astronomy seriously, and they are also taking steps to mitigate those concerns while remaining a commercially viable satellite company. It’s also clear that a dedicated group of astronomers will hold the company accountable for its design decisions and the impact it has on their interests. Ultimately, there will be a middle ground for astronomers and satellite companies. But for now, both camps still need to decide where that middle ground will be.
Anthony Mallama et al., Starlink Generation 2 Mini Satellites: Photometric Characterization, arXiv (2023). DOI: 10.48550/arxiv.2306.06657
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