SUNSET: 
16The imminent launch of a BlueWalker satellite, with a giant phased array antenna, portends a brightening night sky. Amateur astronomers can help record these changes with the goal of mitigating them.
AST SpaceMobile
The prototype of a new constellation of extremely bright Earth-orbiting satellites is due to launch in early- to mid-September. The AST SpaceMobile company plans to orbit more than 100 of these spacecraft by the end of 2024. Astronomers at the Vera Rubin Observatory and the International Astronomical Union’s Centre for the Protection of Dark and Quiet Skies from Satellite Constellation Interference (IAU CPS) are concerned because these new spacecraft will interfere with celestial observations, adding to the problems already caused by other constellations.
The first member of this new group, called BlueWalker 3, will feature a giant antenna array covering an area of 64 square meters (693 square feet). Observers on the ground will see bright sunlight reflected from this structure. After on-orbit tests of BlueWalker 3 are completed, the operational satellites, called BlueBirds, will be launched. BlueBirds may produce even more glaring light pollution since they are significantly larger. The commercial appeal of these satellites is that they will link directly to cell phones without the need of a cell tower. AST SpaceMobile has already secured a license from the Federal Communications Commission to test the prototype.
The satellites will be stored as compact objects on their launch vehicle and will unfold the large antennas after being released into space. The back side of each antenna has solar cells to collect energy for powering the system. BlueWalker 3 will be launched on a SpaceX Falcon 9 rocket along with a batch of Starlink satellites.
Other bright satellites are waiting in the wings: 30,000 second-generation Starlink satellites are currently awaiting FCC approval. Like the BlueBirds, the new Starlinks may carry antennas for direct connection to cell phones; the antennas are slightly smaller at “only” 25 square meters, but the satellites would be far more numerous than the BlueBird constellation. That development would be very bad news for astronomy.
Get Involved: Measure Satellite Brightness
BlueWalker 3 is expected to be among the brightest objects in the night sky after the antenna unfolds. Amateur astronomers can help record this satellite's brightness, bringing awareness to bright satellites' effects on our night sky and on astronomy.
There are several ways for observers to generate predictions of overhead passes. The Heavens-Above.com website is frequently updated with orbital information on newly launched satellites. Users enter their location’s latitude and longitude and receive a list of upcoming passes along with star maps showing the spacecraft paths. Some planetarium programs such as Stellarium and other apps also forecast artificial satellite visibility.
Sky & Telescope readers can record scientifically useful observations of BlueWalker 3. I have been studying magnitudes recorded by visual observers since Starlink and other spacecraft became an issue for astronomers a few years ago. The brightness data are used to characterize and monitor these space objects. Visual magnitudes revealed that the addition of a sunshade made Starlink satellites fainter than the original design, while omission of that shade for more recently launched satellites has increased their luminosity again.
Observers can determine a satellite’s magnitude by comparing its brightness with that of nearby celestial objects, whose brightness is known. For example, suppose that BlueWalker 3 appeared to be slightly fainter than the star Altair (magnitude 0.8) but distinctly brighter than Deneb (1.2) then the satellite magnitude is 0.9. I’ve provided detailed instructions for measuring and reporting visual magnitudes for satellites.
Institute for Data-intensive Research in Astrophysics and Cosmology (DiRAC) / University of Washington
Astrophotographers can also play an important role in the study of artificial satellites, by uploading celestial images impacted by satellite streaks to the TrailBlazer website. Meredith Rawls and Dino Bektešević (both at University of Washington) are developing this data archive as part of the IAU’s response to the problems posed by spacecraft. Trailblazer stores the impacted images and records selected metadata, so users can search for satellite-streaked images by date, location, and other parameters such as sky position and telescope.
Comments
Martian-Bachelor
September 1, 2022 at 10:23 pm
I don't know about anyone else but I've got better things to do with my time than observe space junk. There was one about magnitude -2 for several seconds in Draco not far from Vega the other night, but I'm not going to bother trying to figure out who to blame.
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Anthony-Mallama
September 2, 2022 at 7:59 am
The International Astronomical Union is promoting observation of BlueWalker 3 and other artificial satellites. The brightness of these objects must be characterized and monitored in order to assess their impact on celestial observations. Amateur and professional astronomers who value dark skies are contributing to this effort.
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Martian-Bachelor
September 2, 2022 at 7:53 pm
Observation and monitoring will no more lead to "mitigation" here than it has with general light pollution IME.
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Anthony-Mallama
September 2, 2022 at 11:18 pm
Satellite manufacturers are voluntarily working with the astronomical community to reduce interference with celestial observation. Monitoring spacecraft brightness is an important part of that effort. Spacecraft magnitudes are also an important parameter in planning observations.
Here are a few papers that will inform you:
Gallozzi, S., Scardia, M., and Maris, M. 2020. Concerns about ground based astronomical observations: a step to safeguard the astronomical sky. https://arxiv.org/pdf/2001.10952.pdf.
Hainaut, O.R. and Williams, A.P. 2020. Impact of satellite constellations on astronomical observations with ESO telescopes in the visible and infrared domains. Astron. Astrophys. manuscript no. SatConst. https://arxiv.org/abs/2003.019pdf.
Halferty, G., Reddy, V., Campbell, T., Battle, A. and Furaro, R. 2022. Photometric characterization and trajectory accuracy of Starlink satellites: implications for ground-based astronomical surveys. https://arxiv.org/abs/2208.03226.
Hall, J., Walker, C., Rawls, M.L., McDowell, J., Seaman, R., Venkatesan, A., Lowenthal, J., Green, R., Krafton, K. and Parriott, J. 2021. SatCon2 Working Group Reports. https://noirlab.edu/public/media/archives/techdocs/pdf/techdoc033.pdf.
Hossein, S.H., Cimino, L., Rossetti, M., Gaetano, Z., Mariana, L., Curiano, F., Buccarelli, M., Seitzer, P., Santoni, F., Di Cecco, A. and Piergentili, F. 2022. Photometric characterization of Starlink satellite tracklets using RGB filters. Adv. Space Res., , https://doi.org/10.1016/j.asr.2022.07.082.
Krantz, H., Pearce, E.C. and Block, A. 2021. Characterizing the all-sky brightness of satellite mega-constellations and the impact on astronomy research. https://arxiv.org/abs/2110.10578.
Lawler, S.M., Boley, A.C. and Rein, H. 2022. Visibility predictions for near-future satellite megaconstellations: latitudes near 50° will experience the worst light pollution. Astron. J., 163, 21.
Mallama, A. 2021. The brightness of VisorSat-design Starlink satellites. https://arxiv.org/abs/2101.00374.
Mallama, 2021b. Starlink satellite brightness – characterized from 100,000 visible light magnitudes. https://arxiv.org/abs/2111.09735.
Mallama, A. and Young, M. 2021. The satellite saga continues. Sky and Telescope, vol. 141, June, p. 16.
Mallama, A. 2022. Newest Starlink satellites have gotten brighter again. Sky and Telescope, vol. 144, October, p. 10 and https://skyandtelescope.org/astronomy-news/newest-starlink-satellites-have-gotten-brighter-again/.
McDowell, J. 2020. The low Earth orbit satellite population and impacts of the SpaceX Starlink constellation. ApJ Let, 892, L36 and https://arxiv.org/abs/2003.07446.
Mroz, P., Otarola, A., Prince, T.A., Dekany, R., Duev, D.A., Graham, M.J., Groom, S.L., Masci, F.J. and Medford, M.S. 2022. Impact of the SpaceX Starlink satellites on the Zwicky Transient Facility survey observations. https://arxiv.org/abs/2201.05343.
Otarola, A. (chairman) and Allen, L., Pearce, E., Krantz, H.R., Storrie-Lombardi, L., Tregloan-Reed, J, Unda-Sanzana, E., Walker, C. and Zamora, O. 2020. Draft Report of the Satellite Observations Working Group commissioned by the United Nations, Spain and the International Astronomical Union as the Workshop on Dark and Quiet Skies for Science and Society. https://owncloud.iac.es/index.php/s/WcdR7Z8GeqfRWxG#pdfviewer.
Tregloan-Reed, J., Otarola, A., Ortiz, E., Molina, V., Anais, J., Gonzalez, R., Colque, J.P. and Unda-Sanzana, E. 2020. First observations and magnitude measurement of Starlink’s Darksat. Astron. Astrophys. 637, L1. https://www.aanda.org/articles/aa/full_html/2020/05/aa37958-20/aa37958-20.html.
Tyson, J.A., Ivezić, Ž., Bradshaw, A., Rawls, M.L., Xin, B., Yoachim, P., Parejko, J., Greene, J., Sholl, M., Abbott, T.M.C., and Polin, D. (2020). Mitigation of LEO satellite brightness and trail effects on the Rubin Observatory LSST. arXiv e-prints, arXiv:2006.12417.
Walker, C., Hall, J., Allen, L., Green, R., Seitzer, P., Tyson, T., Bauer, A., Krafton, K., Lowenthal, J., Parriott, J., Puxley, P., Abbott, T., Bakos, G., Barentine, J., Bassa, C., Blakeslee, J., Bradshaw, A., Cooke, J., Devost, D., Galadí-Enríquez, D., Haase, F., Hainaut, O., Heathcote, S., Jah, M., Krantz, H., Kucharski, D., McDowell, J.loan-Reed, J., Wainscoat, R., Williams, A., and Yoachim, P. 2020a. Impact of satellite constellations on optical astronomy and recommendations toward mitigations. Bulletin of the Astronomical Society, 52(2), 0206. 10.3847/25c2cfeb.346793b8.
Walker, C., Di Pippo, S., Aube, M., Barentine, J., Benkaldhoun, Z., Benvenuti, P., Bourossis, C., Green, R., Hernshaw, J., Liszt, H., Lowenthal, J.D., Munoz-Tunon, C., Nield, K., Ricard, N., Espinosa, J.M.R., Sanhueza., P., Varela, A., Williams, A. 2020b. Dark and quiet skies for science and society. dqskies-book-29-12-20.pdf (iau.org)
Walker, C. and Benvenuti, P. (Eds.) 2022. Dark and Quite Skies for Science and Society II. Working group reports. https://noirlab.edu/public/media/archives/techdocs/pdf/techdoc051.pdf.
Williams, A, Hainaut O., Otarola A., Tan G.H., Rotola, G. 2021a. Analysing the impact of satellite constellations and ESO's role in supporting the astronomy community. https://arxiv.org/abs/2108.04005.
Williams, A, Hainaut O., Otarola A., Tan G.H., Biggs, A., Phillips, N. and Rotola, G. 2021b. A report to ESO Council on the impact of satellite constellations. https://arxiv.org/abs/2108.03999.
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Richard Cole
September 2, 2022 at 4:29 am
That antenna panel looks similar in colour/reflectivity to the antenna panels on the original Starlinks. Given the difference in antenna area and the 400km orbit I am going to bet on a Bluewalker3 magnitude of 1.2 in the zenith, if the panel is directly facing the Earth. That's quite bright.
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Alex86a
September 2, 2022 at 5:25 pm
In my opinion there will be no point in collecting measurements on satellites.... The truth is another, the starry sky will be lost, as well as humanity itself, because of the scum of those in power...
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Martian-Bachelor
September 4, 2022 at 1:03 pm
Okay, here's a dumb question: if these solar panels are pointed at the sun, why aren't their reflections just heading back in the sun's direction rather than down here on the ground?
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Richard Cole
September 5, 2022 at 2:46 am
The solar array is presumably always pointing to the zenith.
But the antenna side of that large panel (that's the side visible in the image above) reflects the Sun when the spacecraft is visible from the ground because that's the side that is illuminated at those times. The image does not indicate that AST SpaceMobile have taken *any* steps to mitigate the refectivity of the antenna.
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OldDogZeroOne
September 5, 2022 at 9:48 am
Isn't it obvious? Elon Musk is covering the skies with Starlink satellites so all the amateur and professional astronomers will sign up to emigrate to Mars, which will have the only dark skies in the inner solar system!
I'm all for colonizing other worlds, but damn it, paying for it (Starships to Mars) by making it almost impossible to see them (other worlds) seems counterproductive!
Quote by Ralph Waldo Emerson: “If the stars should appear one night in a thousand years, how would men believe and adore, and preserve for many generations the remembrance of the city of God!”
Isaac Asimov used that quote in his story Nightfall (1941). Who could have imagined that Earthlings could someday be in such a circumstance, less than a century later, of being unable to see stars in a dark night sky?
Perhaps IDA should start investing in researching turbo-lasers to vaporize offending satellites. Of course they will retaliate by making the satellites MORE reflective to reflect the beams away...
On making satellites less visible, I wonder if Stuart Semple's Black 2.0 or 3.0 paint holds up in vacuum and undiluted sunlight? (maybe someone should research this?)
BTW, to: Martian-Bachelor, it's not just solar panels, but the antennas that reflect sunlight towards Earth.
Maybe my comment is a bit over the top, tongue in cheek, but maybe not?
Frank J. Cernik
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Don-Kerouac
September 5, 2022 at 6:34 pm
KN4EQN??
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Spacewiz
September 6, 2022 at 11:25 pm
And thus humanity creeps ever forward towards being yet another page in the fossil record…further polluting our cosmic playpen.
And what happens to all these satellites when China or another country decides to stage another explosion in orbit? I hope I’m wrong here, but satellite communications infrastructure seems awfully fragile.
I’ll take the ugly, but inherently redundant, and easier to maintain, earth-bound cell towers.
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Brad Young
September 8, 2022 at 5:43 am
If you'd like to see an article that is more useful for the typical amateur, see mine at https://hafsnt.com/index.php/recent-articles/ at "Megaconstellation Satellites Practical Ways Amateurs Can Help" It also appeared in the March 2022 Reflector Magazine. I reviewed the arXiv article Anthony Mallama lists above as his way of determining visual magnitudes of satellites, He had my article for review and stated he would cite it in his paper, but chose not to.
Hopefully, the IAU effort will begin in earnest soon to crowd source this data. Having a very few niche amateurs and professionals is not good data gathering. I know that Meredith Rawls is working very hard on this, and that industry has been cooperative (so far). But BlueWalker is a tep change in the amount of damage that could be done.
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Anthony-Mallama
September 8, 2022 at 8:35 am
Actually, I do cite your paper in mine. I don't highlight it because the reporting format that you specify lacks some of the data needed for analysis.
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Brad Young
September 8, 2022 at 5:07 pm
I stand corrected - you added it in "Further Reading" in version 2. As for the data needed for analysis, that would be phase angle and range, both of which are typically calculated by the analyst, as they are known points based on the location of observer, time, and orbit of object. They are also the least popular items to recalculate or report and likely to discourage crowd sourcing (refer to first comment, and others, above). The IOD format I use as an example in my article is one way to report these objects, there are others - that decision needs to be made by the IAU CPS and training done based on the format chosen.
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Anthony-Mallama
September 10, 2022 at 7:30 am
I am a member of the IAU CPS planning observations of BlueWalker. I do not ask observers to report phase angle or range.
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Brad Young
September 10, 2022 at 5:19 pm
So am I, such as it is right now. Individual members don't appear on the list yet: https://cps.iau.org/about/
Where can I find your instructions on how to report what is seen and where that data goes within the CPS Sathub process?
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