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A newly launched NASA project called Satellite Streak Watcher aims to assess the night sky light pollution caused by low-Earth orbit satellites using images captured by the public. On its SciStarter project page, NASA asks anyone interested in participating to 'Photographically record satellite streaks across the night sky to monitor this form of sky pollution.'
The space agency explains its concerns related to the satellites, stating, 'As more satellites are placed into orbit, they will become an increasing problem to astronomers on the ground.' Participants can use the Heavens-Above website to determine when and where satellites will pass over their local sky; images are uploaded and shared on the project's website.
The new public science project follows announcements from a number of companies that have launched — or plan to launch — large numbers of small satellites into low-Earth orbit.
The most notable example of this comes from SpaceX, which has spent the past few years working on its Starlink mission. The private space company expects to ultimately launch thousands of small satellites into very-low Earth orbit (VLEO) in order to provide Internet access around the world. As of March 1, 2020, the company has delivered 302 of these satellites into space with plans to launch more throughout the year.
Critics have expressed concerns that Starlink and other projects like it will have a negative impact on the night sky, introducing light pollution that will disrupt astronomy. These satellites also impact astrophotography by adding thin, bright streaks of light to long-exposure images, prompting complaints from photographers who increasingly struggle to deal with light pollution.
DPReview reader Guido Forrier shared the below image in our Astrophotography forum, showing a series of fifteen Starlink satellites flying across the sky in one of his night sky photographs. When we asked what his thoughts on the matter, he said ‘I am surprised and incensed that apart from the already high light pollution, those satellites [have] also come to disturb. [There’s] a lot of rubbish is already flying in space and I see it regularly burning in the atmosphere.’
Photograph by Guido Forrier, shared with permission.
Until now, most efforts to combat light pollution have focused on the ground, not the sky. Light produced by street lamps, billboards, parking lot lights and more is reflected in the night sky, making it hard to see and photograph stars, particularly in regions close to big cities. The problem has spurred the creation of a number of Dark Sky Reserves throughout the world; these are regions of public and private land with ample natural darkness and starkly visible stars.
However, experts have expressed concerns over light pollution that results from satellites launched into low-Earth orbit, as well as more ridiculous future concepts like an artificial moon and space billboards. Because this type of light pollution comes from the sky rather than the planet's surface, traveling to Dark Sky Reserves won't help photographers avoid the issue.
According to Astronomy.com, the Starlink satellites are particularly disruptive to the night sky due to their shallow orbit, which is necessary for delivering Internet service to people on Earth. More than 40,000 of these small satellites may eventually be launched under the Starlink mission, and though SpaceX is experimenting with anti-reflective coating on the satellites, it is unclear whether that will be sufficient for reducing the disruption caused by the spacecraft.
MIT Technology Review points out that satellites depend on their reflective nature to help keep them cool; the experimental anti-reflective coating may cause thermal issues for the Starlink satellites. SpaceX applied the coating to the bottom of one of the 60 satellites it launched in December 2019 in order to test its potential impact on performance.
Harvard-Smithsonian Center for Astrophysics astronomer Jonathan McDowell had told Technology Review at the time that while the reflective coating is 'worth a try,' he fears it 'will be offset by the fact that they are moving the constellation to a lower orbit.'
NASA anticipates its Satellite Streak Watcher operating as a long-term project in order to gather data on satellite light pollution over time. The project currently has 136 members and 20 images, which include shots ranging from bright dots on the night sky to several long streaks of light bunched together. Though NASA says citizen scientists can use a basic tripod and most newer smartphones to capture the images, astrophotographers who have more capable camera systems are also welcomed to share their images.
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