President’s Message May 2020
During the early dawn of February 16th I obtained a glimpse of the future. After months of almost perpetual overcast, skies finally cleared. While looking northward towards Cassiopeia I noticed a long precession of fairly bright evenly spaced satellites moving from left to right. It took about 10 minutes for this parade to pass. I realized that this must be the Starlink Constellation that had been mentioned in the news. When I searched the Internet to learn more I was in for a surprise.
Starlink is a bold ingenious project with an ambitious mission to deliver high speed broadband internet to locations where access is unreliable, expensive, or completely unavailable. It plans to achieve this by deploying a vast constellation of communication satellites. The parent company SpaceX was founded by Elon Musk in 2002 and has developed a remarkable capacity to launch Falcon 9 rockets and successfully land them for reuse. This greatly reduces the launch costs. The communication satellites are stacked aboard the Falcon 9 in two columns of 30 and they gradually drift apart once they reach orbit. Each satellite is powered by a single solar panel which gently unfolds. The satellites are maneuvered by ion jets using Krypton. This elaborate scheme sounds unwieldy but when Starlink V0.9 was launched in May 2019 it actually worked!
Satellites are usually expensive “one off” devices that take years to build but by employing the manufacturing expertise that Elon Musk honed at Tesla, Starlink can assemble 6 satellites a day at their Redmond Washington plant. This production rate allows Starlink to launch 60 satellites every two weeks! At that launch rate Starlink can place 1584 satellites in a shell 550 km about the Earth by the end of 2021. They will be placed in 72 orbital planes inclined at 53 degrees. 22 satellites will occupy each plane and when in position they will form an exotic mesh surrounding the globe. Animation of this configuration reveals that the concentration of satellites is greatest between latitudes of 50 to 53 degrees. While this network will provide coverage over most of the globe, two additional phases have been approved by the FCC to increase capacity and speed. Phase two will add an additional 2800 satellites in a 1125 km altitude shell and phase three will add 7500 more satellites in a lower 340 km altitude shell.
When completed an additional 12000 satellites will be in orbit! This exceeds the 9000 satellites that have been launched during the last 50 years and the 5000 that are still in orbit. The first batch of 60 operational satellites were launched on Starlink 1 on November 11th 2019 and the sixth Starlink mission occurred on April 22nd bringing the total to 420. While Starlink obtained the necessary frequency approvals from the FCC to prevent interference with radio astronomy there was no governance regarding visual and infrared ground based astronomy. The initial Starlink v0.9 group was much brighter than anticipated and generated alarm from visual astronomers. Elon Musk is embarrassed about this oversight and is working with the Astronomical Community to mitigate the impact of this massive network. On April 27th Musk announced VisorSat, an innovative sunshield that may significantly reduce the albedo of the satellites. Some of these shields will be tested during the next Starlink launch.
The satellites must be illuminated by the Sun to be visible. Due to the low altitude the Phase 1 cohort will only be visible near twilight. The higher altitude Phase 2 will remain visible longer. Satellites are brightest when just launched but will become dimmer as they ascend to operational altitude. Since twilight lingers into the late evening near the Summer Solstice the presence of this constellation will be most pronounced in the area of highest density over Canadian skies this summer. So keep on the lookout for this new swarm of satellites while stargazing this summer. Please share your observations on the Virtual Astro Cafe web page or during the Astro Cafe Webinar which will take place every Monday evening at 7:30 PM. In someways the unintended consequence of this mission resembles an outbreak of a “stellar virus”. And it could get worse as SpaceX has requested permission to place another 30000 satellites in orbit! Let’s hope that the Starlink team creates a stellar vaccine soon and that skies will remain useable.
Wishing everyone good health and useable skies