Starlink satellite streaks: How big of a problem are they?

By now you have heard about the SpaceX Starlink satellite constellation currently being launched into low Earth orbit (LEO). Already, more than 2,000 satellites have arrived in their 340-mile-high (550 kilometers) orbits, with another 2,400 to be added to this Generation-1 constellation in the next few years.

Furthermore, the U.S. Federal Communications Commission (FCC) has already given SpaceX approval for the 40,000-satellite Generation-2 constellation, to be completed sometime in 2027. The final $10 billion constellation will generate over $30 billion annually from subscription and hardware sales.

There is no way to stop this profitable train from leaving the station. With already a quarter of a million subscribers and millions more on the way, Starlink will be a boon for connecting people with high-speed internet even from the middle of the Sahara Desert.

Profitable — but problematic?

But against all these successes, we must also measure a few technical downsides. At altitudes of 340 miles (550 km), the orbital decay time from atmospheric friction is about 10 years. That means after only a decade, the satellites will slow down enough to essentially fall out of orbit. According to Hugh Lewis, head of the Astronautics Research Group at the University of Southampton in the UK, SpaceX will have to launch over 4,000 of these million-dollar satellites every five years to keep up with re-entries.

Meanwhile, the Sun is no friend to these satellites, either. The recent Feb. 4, 2022, geomagnetic storm caused the deorbit of 40 of 49 Gen-1 satellites launched that day. Space weather conditions will significantly impact this untested constellation — especially as the current sunspot cycle approaches its maximum around 2025.

What this all means to amateur and professional astronomers is by now a well-known story that many of you have probably been tracking carefully.

Twilight observing troubles

When first placed into a transfer orbit minutes after launch, Starlink satellites can be as bright as magnitude 2.6 stars traveling at high angular speed. A dozen or more follow nearly the same path across the sky, like beads on a string. After a week, they have fanned out to their designated 340-mile (550 km) orbit and fade to about magnitude 5.5 thereafter. This spans the entire domain of apparent magnitudes easily visible with the naked eye, even in some urban environments.

Many of you have by now seen Starlink satellites streaking across the twilight sky. You might have even intentionally captured them using wide-aperture star field photography — or unintentionally seen their presence while imaging through your telescope as they photobomb your picture of the Orion Nebula. Services such as Heavens-Above even provide daily forecasts of when and where to look, making it easy for you to capture them. In many ways, this is reminiscent of the Iridium flares that were so popular to watch for in the early 2000s.

But by the time Gen-2 is complete in five years, 10 times as many streaks will cross the twilight sky and you will not even need a forecasting service to help you spot them and plan your shots! Luckily, at apparent magnitudes of 4 to 6, the satellites will be largely invisible to the light-polluted urban/suburban observer. Since twilight is generally when you are still driving to your dark site, letting your telescope cool down, or perhaps observing the brighter planets, the satellites may not actually be that problematic for amateur astronomers in the hour or so after sunset or before sunrise.

But spiritually and esthetically, for many people, they are a horrific intrusion on what should have been a pristine moment to reflect on the majesty of space and our place in it.