Near-Earth satellites are ruining the images taken by the Hubble telescope

(Sandor Kruk et al. / Nature Astronomy, 2023 https://go.nature.com/3ZEnGMD)

Astronomers led by Sandor Kruk of the Max Planck Institute for Extraterrestrial Physics have presented the first estimates of the pollution left by satellite tracks in Hubble images.

On average, they have corrupted 3.7% of all individual frames over the past 19 years, with the number of corrupted shots increasing over time.

The creation and launch into low Earth orbit of constellations and large constellations of satellites is causing increasing concern among the astronomical community

The satellite tracks fall on images obtained by ground-based telescopes, especially survey ones, which will lead to limited observation time and increased costs.

In particular, the recently launched test satellite of the SpaceMobile constellation was visible as a bright star.

However, the deterioration in the quality of the received data will take place not only for ground-based observatories, but also for space telescopes in low Earth orbit.

These include the famous Hubble, whose orbit is gradually decreasing and now has an average altitude of 538 kilometers.

Thus, satellites in higher orbits, under certain conditions, can spoil the Hubble images, in addition, there is a possibility of a telescope colliding with fragments of spent satellites.

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THE STUDY
Now Kruk’s team has published the first estimates of the negative impact of near-Earth satellites on Hubble data.

They analyzed single frames (average exposure time 11.2 minutes) and composite images (average exposure time 35 minutes) from ACS/WFC cameras taken between March 22, 2002 and October 3, 2021

They also analyzed images obtained with WFC3 tools/UVIS between June 25, 2009 and October 3, 2021.

The results of the analysis were disappointing.

Between 2002 and 2021, an average of 2.7% of the images in our sample of individual Hubble frames contained at least one satellite track.

Due to the different fields of view and observation ranges, there is a difference between the instruments

• in the case of ACS / WFC, 3.2% of the images were corrupted
• in the case of WFC3 / UVIS - 1.7%.

There has been an increase in image track contamination over time, from 2.8% to 4.3% for ACS/WFC and from 1.2% to 2% for WFC3/UVIS.

If we consider the distribution of satellites across the sky from the point of view of Hubble, then the probability of spotting a satellite during observations in the equatorial plane is twice as high as anywhere else.

In addition, there is a slight overabundance of images with tracks at latitudes above 60 degrees, possibly due to satellites in highly elliptical and inclined orbits.

So far, the proportion of images with tracks is small, but as the number of satellites increases, it will grow.

If by 2030 the number of satellites in low orbit becomes 60-100 thousand pieces, then the probability of finding a track on the Hubble images will already be 20%-50%.

This is an issue that needs to be dealt with as quick as possible.

Sources:

• Nature Astronomy: https://www.nature.com/articles/s41550-023-01903-3
• EarthSky: https://earthsky.org/space/satellites-are-photobombing-hubble-effect-on-research/
• Nature: https://www.nature.com/articles/d41586-023-00620-1

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