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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:


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Two defunct satellites barely miss each other

Missed it by that much: According to the US Space Command, two defunct satellites, one the first infrared space telescope ever launched and the other a military technology test satellite, apparently did not collide tonight, barely missing each other.

Prior to impact it was estimated they could get within as little as 40 feet. Since the military satellite had booms 60 feet long, the possibility of impact was quite real, especially because there was also a margin of error in the calculations and the two satellites were traveling almost 33,000 mph relative to each other. Had they hit each other the cloud of debris would have caused enormous problems, as the pieces would have been a threat to many other satellites presently in orbit.

Fortunately they missed each other. The problem of many such defunct satellites and upper stages and general space junk still exists however. Someone could make some good money providing a service to clean this stuff up. I suspect governments would be willing to pay to have it done.

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.


  • Phill O

    If the AGW model is correct, the answer is burn more carbon reserves so the atmosphere increases to add drag to the debris.

    However, I am not an AGW advocate at the problem will be more complex.

  • Michael

    If orbital velocity is somewhere around 17,000 mph, and the relative motion of these two is around 33,000 mph, it sounds like a meeting situation. The impact would result in a reduced orbital speed for both, deorbiting in a relatively short space of time. Most of the pieces, anyway.
    So, what am I missing here?
    I never understood the escape velocity concept-taught in elementary school (a loong time ago). Wouldn’t escape velocity become less and less the further out the gravity well one got? Maybe the answer to the original question has something to do with that.

  • Craken

    Nothing happens to prevent the Kessler Syndrome because it is a classic tragedy of the commons.

  • larry land

    Elon, cleanup on LEO 4!

    …actually, his equipment did snare one cowling yesterday from the Starlink launch and return it.

  • The idea of retrieving and repairing wayward satellites was part of the inspiration behind the original Space Shuttle program, as I recall. (I know for a fact that it was the main goal of the genius Atari 2600 game “Space Shuttle.”) It wouldn’t be too hard to adapt such craft to cleanup and salvage operations… had we not suddenly decided it was too much of a bother to go to space under our own power.

  • wayne

    take a look at–

    “Gravity at altitude”
    Prof Matt Anderson

    He also has equally short & concise explanations of escape velocity, stable orbits, rocket launch, etc. (good stuff)

  • DaRueStir

    Northrop Grumman launched MEV-1 (Mission Extension Vehicle) late last year to rescue an IntelSat by latching on to it and maintaining its orbital station for 5 or more years, MEV-2 will be launched soon to move another IntelSat and position it very close to an existing Satellite.
    MEV-3, MEV-4, and MEV-5 will have even greater capabilities including robotic arms, refueling capabilities, de-orbiting capabilities, etc.
    Every MEV has a working life of approximately 15 years and can do much to clean-up or re-position spacecraft.

  • Ryan Lawson

    The biggest limit for cleaning up all the debris is fuel consumption. If one could maneuver around with a solar sail or ion engine you could do more with one vehicle, otherwise from one piece of debris to another the cost in fuel to switch between orbits is enormous.

    Maybe Elon could make a swarm of single use smallsats for this. They could latch onto objects and then deploy a solar sail that slowly drags them both out into a higher orbit where they will be less dangerous and can be mined for scrap later on. I would call this Project Dandelion.

  • Edward

    Robert wrote: “Someone could make some good money providing a service to clean this stuff up. I suspect governments would be willing to pay to have it done.

    It looks like this is coming soon to launch pads near everyone.

    The real importance of this contract is its nature. ESA is not taking the lead in designing or building the robot to do this work. Instead, it is acting merely as a customer, hiring ClearSpace to develop and build it. Afterward the robot design will belong to ClearSpace, which will then be able to sell that design for further space junk removal contracts.

    The European Space Agency has demonstrated that governments are willing to pay to clean up space debris, and the commercial company that it hired can make a profit doing it.

    Michael wrote: Most of the pieces, anyway. So, what am I missing here?

    You are missing two things. First, if there were only a glancing blow, such as antennas striking each other or an antenna striking a larger part, then most of the pieces would still be travelling in a similar direction and about the same speed, but there may be fewer pieces. Second, even a direct collision would still result in many, many pieces still travelling in the similar directions and about the same speed. Some pieces would be slower and could fall out of orbit, but there would still be a very large number of pieces creating a hazard to satellite navigation.

    Wouldn’t escape velocity become less and less the further out the gravity well one got?

    This is correct, but velocity must be added in order to get further out of the gravity well. Essentially you trade speed for altitude, like an airplane does if the pilot does not add power, and this is why a car driver adds power in order to keep up his speed as he goes up a hill.

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