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My February birthday fund-raising campaign for Behind the Black it now over. I sincerely and with deep gratitude thank all those who donated. Without your support I could not keep doing this, not so much because of the need for income to pay the bills, but because it tells me that there are people out there who want me to do this work. For those who did not contribute during the campaign, please consider adding your vote of support to Behind the Black, by giving either a one-time contribution or a regular subscription, in any one of the following ways:


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.


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Images confirm LightSail-2 deployment success

LightSail-2 sail deployed
Click for full resolution image.

Capitalism in space: The LightSail-2 engineering team has now confirmed, based on images from the cubesat, that its light sail has successfully deployed.

Flight controllers at Cal Poly San Luis Obispo in California commanded the spacecraft to deploy its solar sails yesterday at about 11:47 PDT (18:47 UTC). Images captured during the deployment sequence and downloaded today show the 32-square-meter sail, which is about the size of a boxing ring, deploying as the spacecraft flew south of the continental United States.

Image caption: This image was taken during the LightSail 2 sail deployment sequence on 23 July 2019 at 11:48 PDT (18:48 UTC). Baja California and Mexico are visible in the background. LightSail 2’s dual 185-degree fisheye camera lenses can each capture more than half of the sail. This image has been de-distorted and color corrected.

To the right is a reduced version of this image. As they note, the sail is distorted because of the fisheye nature of the camera lens. Nonetheless, it looks like the sail is deployed, and will be able to do its job, testing how one maneuvers in space using only sunlight.

UPDATE: Rex Ridenoure from Ecliptic Enterprises emailed me to explain that the distortion is only seen in the image above, that the image at the link has been corrected for this (as noted in the caption above). If you compare the two, you will see that the Earth is round in the corrected image.

Since the sail is much closer to the lens, I remain unsure how much of what we see of its shape is real, or a function of the fisheye lens. Later thumbnails show the sail more flat and tightly stretched, suggesting that this image was taken during deployment.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!


From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.


Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.


  • Max

    I am disappointed to see that the material is shiny on both sides. A radiometer is driven from light on a black surface. It would been interesting to see which side creates more thrust even though it’s in a vacuum.
    Hopefully it is high enough and will not be compromised by Earth’s atmosphere which is a significant drag on low Earth orbit satellites.

  • Edward

    Max wrote: “I am disappointed to see that the material is shiny on both sides.

    It does not matter that the back side is shiny, as only the side toward the light source (the sun) will do the propulsive work. A solar sail is very different from a radiometer. An advantage to having two shiny sides is that it does not matter which side is toward the sun and doing the propulsion, which may give the controllers more options and freedom.

    Making the “other” side not shiny would make the sail heavier, reducing its performance.

  • Edward

    One scientist’s recommendations for what to do if you find a meteorite.

    Pay particular attention to the rude admonishments, because in all likelihood:
    I’m sorry, but you have not found a meteorite.

    Amazingly: “most things that fall from the sky are not meteorites.

  • Edward

    Sorry, wrong post.

  • Andi

    I was rather amazed at the amount of pressure the Sun exerts. From Wikipedia: “A typical spacecraft going to Mars, for example, will be displaced thousands of kilometers by solar pressure”

  • Alex

    The answer my friends is blown in the wind … or was it blowing …?
    or some such.

    Sail needs Solar Winds, and good Solar activity.
    Sunspots ON ! Flares, STANDBY !

    Fair winds and following Seas LightSail-2 !!

  • pzatchok

    If they had placed it into a polar orbit it would have lasted longer in orbit.
    As it is, as one side of its orbit moves away from the Earth the other side of the orbit moves closer until it hits atmosphere.

  • pzatchok wrote: “If they had placed it into a polar orbit it would have lasted longer in orbit.”

    And if unicorns had wings we’d all be saints. The Planetary Society purchased the satellite and the launch vehicle it could afford. In the past few decades it has been hard enough to get anything like this even into orbit. To nitpick them because they are doing this technology test in Earth orbit is quite unseemly. It does not do you credit.

  • pzatchok

    If they were in a polar orbit would they be able to face the sun for the whole orbit?
    If so could they use the solar thrust, light pressure to slowly break orbit? Or at least raise their orbit.

    I fully understand their budgetary concerns.

  • pzatchok: I can’t answer your specific question. However, I do know the Japanese in 2010 did put a solar sail in a solar orbit, called Ikaros, and used sunlight to adjust its orbit. Unfortunately their website never provided much additional information. See the links here.

  • Edward

    pzatchok asked: “If they were in a polar orbit would they be able to face the sun for the whole orbit? If so could they use the solar thrust, light pressure to slowly break orbit?

    The object of this exercise is to learn how to use and control a solar sail. Ikaros gave an excellent proof of concept, as it showed that it changed its velocity due to light pressure. The orbit that LightSail 2 is in gives the flight controllers plenty of opportunity to turn the sail “with the wind” and “into the wind.”* My expectation is that something will go wrong, they will lose the sail, and they will learn an important lesson about the hazards to sailing with photons. If nothing goes wrong, then they will have to wait for another sail before learning that lesson.

    In the case of a polar orbit, one in which the sail is always in sunlight, then the acceleration would always be away from the sun, perpendicular to its orbital plane around the Earth, and not in a direction that changes the apogee or perigee. Counterintuitively, its orbit would not change as dramatically in such a polar orbit. Most likely the plane of the orbit would change by a few feet, or less, away from the Earth’s center of mass, where the direction of gravity would keep the plane from moving any farther (sine of the gravity vector balances the solar force on the sail).

    * Everyone, please note that solar sails use the momentum of photons, not the particles of the solar wind.

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