Amateur astronomer detects changes in the reflective light coming off of NASA’s orbiting solar sail
Observations by amateur astronomer Marco Langbroek of Delft Technical University in the Netherlands has detected significant changes in the reflective light coming off of the giant orbiting solar sail that NASA engineers recently deployed in orbit.
I observed the Solar Sail again in the evening of September 1, 2024, and this time the brightness of the Solar Sail was quite different. As it rose in the south, it became very bright, reaching magnitude 0 (as bright as the brightest stars in the sky). It then faded again, and next displayed a slow brightness variation with multiple bright maxima and very faint minima.
…The brightness seems to indicate a slow cycle of around half a minute. … The brightness variation could be suggestive of a slow tumble or wobble (a gyration around an axis) that must have been initiated after August 29, when it appeared more steady (apart from a brief bright flare, probably due to a favourable sun-sail-observer geometry).
The sail, dubbed the Advanced Composite Solar Sail System, was launched on April 23rd, and after some initial technical issues it was deployed from its small cubesat on August 30th, expanding to 860 square feet.
The changes Langbroek detected have all occurred after that deployment, and suggest one of two things. Either the NASA engineers are testing the sail’s maneuverability, as planned, and thus the sunlight reflecting off it changes, or there is a problem controlling it that NASA has not yet revealed. We will have to wait to find out.
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Observations by amateur astronomer Marco Langbroek of Delft Technical University in the Netherlands has detected significant changes in the reflective light coming off of the giant orbiting solar sail that NASA engineers recently deployed in orbit.
I observed the Solar Sail again in the evening of September 1, 2024, and this time the brightness of the Solar Sail was quite different. As it rose in the south, it became very bright, reaching magnitude 0 (as bright as the brightest stars in the sky). It then faded again, and next displayed a slow brightness variation with multiple bright maxima and very faint minima.
…The brightness seems to indicate a slow cycle of around half a minute. … The brightness variation could be suggestive of a slow tumble or wobble (a gyration around an axis) that must have been initiated after August 29, when it appeared more steady (apart from a brief bright flare, probably due to a favourable sun-sail-observer geometry).
The sail, dubbed the Advanced Composite Solar Sail System, was launched on April 23rd, and after some initial technical issues it was deployed from its small cubesat on August 30th, expanding to 860 square feet.
The changes Langbroek detected have all occurred after that deployment, and suggest one of two things. Either the NASA engineers are testing the sail’s maneuverability, as planned, and thus the sunlight reflecting off it changes, or there is a problem controlling it that NASA has not yet revealed. We will have to wait to find out.
Readers!
My annual February birthday fund-raising drive for Behind the Black is now over. Thank you to everyone who donated or subscribed. While not a record-setter, the donations were more than sufficient and slightly above average.
As I have said many times before, I can’t express what it means to me to get such support, especially as no one is required to pay anything to read my work. Thank you all again!
For those readers who like my work here at Behind the Black and haven't contributed so far, please consider donating or subscribing. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Every one of those 2020 conclusions has turned out right.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
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You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
Spaceweather.com has an article about ACS-3 and a video of the sail passing close to Vega.
https://www.spaceweather.com/archive.php?view=1&day=06&month=09&year=2024
According to the article, the tumble is intentional.