Scroll down to read this post.


Please consider supporting my work here at Behind the Black. I keep the website clean from pop-ups and annoying demands. Instead, I depend entirely on my readers to support me. Though this means I am sacrificing some income, it also means that I remain entirely independent from outside pressure. By depending solely on donations and subscriptions from my readers, no one can threaten me with censorship. You don't like what I write, you can simply go elsewhere.


You can support me either by giving a one-time contribution or a regular subscription. There are five 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:

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


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. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.

Two mouse embryos successfully grown on ISS

Mouse embryos from experiment
Taken from figure 2 of the paper

In a paper just published, scientists reveal that in 2021 they successfully grew two mouse embryos in weightlessness on ISS, suggesting that “perhaps mammalian space reproduction is possible, although it may be somewhat affected,” as they note in the conclusion of their paper [pdf].

From the papers abstract:

The embryos cultured under microgravity conditions developed into blastocysts with normal cell numbers, ICM, trophectoderm, and gene expression profiles similar to those cultured under artificial-1 g control on the International Space Station and ground-1 g control, which clearly demonstrated that gravity had no significant effect on the blastocyst formation and initial differentiation of mammalian embryos.

The images to the right come from the paper’s second figure, and compare the blastocysts from a ground control (top), an 1g artificial sample on ISS (middle), and the weightless result (bottom).

The experiment has many uncertainties, with the low number of embryos tested the most important. Quoting the paper’s conclusion again, the possibilities of refining this experiment for better results are great:

Unfortunately, the number of blastocysts obtained from the ISS experiment was not abundant; and we have not been able to confirm the impact on offspring because we have not produced offspring from embryos developed in space. We believe that the ETC [the experiment itself] will allow blastocysts to be frozen on the ISS if a cryoprotectant is used in place of PFA [a solution of formaldehyde]. Then, the frozen blastocysts could be brought back to Earth for transfer to a female recipient, and the viability of the blastocysts could be evaluated. Moreover, we could design a device to launch frozen oocytes and spermatozoa to the ISS, where in vitro fertilization experiments could be performed in microgravity. The use of this approach would be cheaper. Furthermore, the study of mammalian reproduction in space is essential to start the space age, making it necessary to study and clarify the effect of space environment before the ISS is no longer operational.

Despite the uncertainties, these results are significant. They suggest that human reproduction in zero gravity is possible, which also suggests it will be even more possible in lower gravity environments like the Moon or Mars.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.

The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News


  • David Eastman

    It boggles my mind that this experiment is being done nearly 70 years after we first started sending animals to orbit.

  • Ian C.

    Very interesting and useful.
    As one comment on the New Atlas website suggests, it could also mean to grow animals as a food source. (In case the lab-grown meat doesn’t work as intended.) It also means we’re perhaps bringing our co-evolving ecosystem with us, willingly and accidentally.

  • pzatchok

    An experiment that should have been done years ago.

    By now we should have a few generations of mice on the station living just fine.

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 *