Scroll down to read this post.


On February 5, 2023 I will celebrate my 70th birthday. Yay! As I do every year during this birthday month, I run a campaign to raise money to support my work here at Behind The Black. I do not run ads. My only support comes from my readers, which leaves me utterly free to speak my mind openly about space, culture, and politics. Please consider supporting me in this work 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.


2. Donate through Gabpay, using my email address zimmerman @ nasw dot org.

3. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.

4. A Paypal Donation:

4. A Paypal subscription:

5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

Fuel leak scrubs launch of Dragon cargo capsule this week

A fuel leak detected during fueling of hydrazine in a Dragon cargo capsule as it was being prepared for a June 10th launch has forced SpaceX and NASA to delay the launch.

SpaceX detected “elevated vapor readings” of monomethyl hydrazine, or MMH, fuel in an “isolated region” of the Dragon spacecraft’s propulsion system during propellant loading ahead of this week’s launch, NASA said in a statement.

The fueling of the Dragon spacecraft is one of the final steps to prepare the capsule for flight, and typically occurs just before SpaceX moves the craft to the launch pad for integration with its Falcon 9 rocket.

The Dragon spacecraft has propellant tanks containing hydrazine fuel and nitrogen tetroxide oxidizer. The two propellants ignite upon contact with each other, providing an impulse for the cargo ship’s Draco thrusters used for in-orbit maneuvers.

Each Dragon spacecraft has 16 Draco thrusters, small rocket engines that generate about 90 pounds of thrust. The Draco engines are used for orbit adjustment burns and control the spacecraft’s approach to the space station, then fire at the end of the mission for a deorbit burn to guide the capsule back into the atmosphere for re-entry and splashdown.

According to the article, it is not yet confirmed that the leak came from the capsule. If so, however, it could become a more serious issue, especially with the recent story — denied strongly by NASA — that a hydrazine leak caused damage to the heat shield of Endeavour during the return of its Axiom commercial passenger flight.

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.


  • Jeff Wright

    Hydrazine is mispelled- delete this post

  • Jeff Wright: Typo fixed. Thank you.

  • wayne

    For all your hydrazine needs–>

    [Arch Chemical, a division of Lonza (Swiss chemical firm)]

    “In 1953, Arch pioneered U.S. production of hydrazine to fuel the first Titan rocket. In the more than sixty years since that first flight into space there have been countless new applications for this versatile chemical. Used directly, it is an oxygen scavenger and energy source. Used as an intermediate, it is essential to the production of a number of important chemicals and polymers. Arch operates an ISO 9002-certified hydrazine plant near Lake Charles, LA. In addition, we have a long-term partnership with another hydrazine producer for supply of hydrazine solutions to the United States and other parts of the world. We keep a large inventory of product at our plant and operate a blending facility at our Lake Charles plant. We can quickly meet our customers’ demands for any special hydrazine solution blend.”

  • Col Beausabre

    OK, Chemystery Major (and son of Chemical Engineer) gotta post.

    It’s hugely toxic and corrosive as well as being a carcinogen, requiring “moon suit” HAZMAT protection when working with it

    “Symptoms of acute (short-term) exposure to high levels of hydrazine may include irritation of the eyes,
    nose, and throat, dizziness, headache, nausea, pulmonary edema, seizures, and coma in humans. Acute
    exposure can also damage the liver, kidneys, and central nervous system in humans.”

    “Hydrazines and its methyl derivatives are toxic but LD50 values have not been reported. It is a precursor to dimethylnitrosamine, which is carcinogenic. According to scientific data, usage of UDMH in rockets at Baikonur Cosmodrome has had adverse effects on the environment and local population.”

    LD50 is the dosage at which 50 percent of the exposed population will die (“Lethal Dose 50 Percent”)

    A typical application is Unsymmetrical Dimethyl Hydrazine (UDMH) and Red Fuming Nitric Acid (RFNA), the two are hypergolic, burning on contact. I first encountered them when they were used on the Vanguard upper stages back in the late Fifties when I was an elementary student.

    “Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (HNO3), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks down partially to form nitrogen dioxide. The nitrogen dioxide dissolves until the liquid is saturated, and produces toxic fumes with a suffocating odor. RFNA increases the flammability of combustible materials and is highly exothermic when reacting with water.

    It is usually used with an inhibitor (with various, sometimes secret, substances, including hydrogen fluoride;any such combination is called inhibited RFNA, IRFNA) because nitric acid attacks most container materials.”

    Great stuff to work with

    More than you ever wanted to know about hydrazine

  • Cloudy

    There was a hypergollic propellant tested on the “Green Propellent Infusion Mission” that was supposed to be cheaper, much safer and less expensive to handle, and have better performance than Hydrazine. Has this started to replace Hydrazine on newer missions? It is to late to replace it on Dragon as that would require a near complete redesign.

Readers: the rules for commenting!


No registration is required. I welcome all opinions, even those that strongly criticize my commentary.


However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.


Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.

Leave a Reply

Your email address will not be published. Required fields are marked *