The sun strikes back
In the book of unintended consequences, a whole new chapter is being written on satellite constellations. These small but numerous low orbit communication satellites are intended to bring fast internet to underserved regions. Their appearance as a strings of lights arcing across the evening sky may be a brief wonder to casual observers, but poison to astronomers who have yet to find an antidote. Reflected sunlight from the satellites is bright enough to cause serious problems for professional observatory instruments and for amateur astrophotography. Throughout the space age, previous satellites such as Iridium were placed into much higher orbits and were far fewer in number. The geometry of fast data transmission around the planet envisioned by Starlink and other commercial projects requires great numbers of satellites (tens of thousands) at relatively low altitudes (typically ~130 miles). Our guest speaker in April will address the challenges to the astronomy community, so I won’t go into more detail here, except to say that the situation has caught the astronomy community off guard.
A brief potential remedy recently came to light. We might think of our sun as being very stable and constant in its energy output, but solar physics and the new solar orbiting satellites are showing how turbulent it can be. On Feb 15 2022, Solar Orbiter spacecraft run by the European Space Agency (ESA) was well positioned to observe the largest solar prominence since its launch last year. This event reached millions of miles into space, though perhaps fortunately for us it originated on the side of the sun. Prominences are often associated with coronal mass ejections which, if aimed towards Earth, can be energetic enough to destroy technology and disrupt human society. NASA’s Parker Solar Probe has also been studying these events and providing new insights into the physics of the huge structures of solar plasma controlled by the sun’s magnetic fields.
Maybe these coronal mass ejections are just what is needed to slow down the satellite constellation projects until plans to prevent their damage to the dark night sky can be developed. Another significant outburst from the sun occurred before the recent launch by SpaceX of another round of 49 Starlink satellites on Feb 3. As summarized by the New York Times in article on Feb 9, a geomagnetic storm triggered by that solar outburst caused increased atmospheric drag on the newly launched satellites as they approached their intended 130 mile orbits above the earth’s surface. This led to premature deorbiting of 40 of the 49 satellites, which are in the process of re-entering Earth’s atmosphere where they will be incinerated. The solar wind has a strong effect on the Earth’s magnetosphere and energetic events from the sun can cause changes in the density of the upper layer of the atmosphere. Solar experts say that it’s possible and even likely that future solar outbursts could eliminate more newly deployed Starlinks n the future. The sun has an 11 year activity cycle and is now in an uptrend with peak expected in 2025, perhaps just in time to put the brakes on the deployment of the satellite constellations.