Conscious Choice cover

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.


Available everywhere for $3.99 (before discount) at Amazon, Barnes & Noble, and all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

SpaceX begins first tests of Starship’s thermal tiles

Link here. They have already flown some tiles on both a Dragon cargo flight as well as Starhopper’s one flight. They are now accelerating the work by testing the installation of a lot of hexagon-shapped tiles directly onto the steel hull of the Starship prototypes. From the article:

Behind the scenes, SpaceX is assuredly performing extensive laboratory-style tests with tiles and an agreement signed with NASA Ames Research Center confirmed that the company is using the facility’s arcjet to physically simulate the conditions of orbital-velocity reentry. Tests on the scale of a full Starship, however, are an entirely different story.

The first signs of large-scale heat shield installation testing appeared on July 9th when local resident and photographer Andrew Goetsch (Nomadd) captured photos of a test coupon covering half of an entire steel Starship ring. In April 2020, CEO Elon Musk confirmed on Twitter that the current design involved affixed heat shield tiles directly to Starship’s steel hull with steel studs. It’s unclear how exactly the company is installing steel studs directly onto the ~4mm (0.15 in) thick skins of a pressure vessel or if an off -the-shelf solution was available but Nomadd’s July 9th photos explicitly show the process required to refine the settings on the mystery stud installer.

The article has some good pictures. Expect to see a lot of these tiles on the surface of future prototypes.


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  • LocalFluff

    Ceramic tiles work well in my kitchen, but were a big problem for the space shuttle. One of them burned and killed its crew because of lacking heat tiles. SpaceX’ rockets and Dragons land without tiles. Why do they need tiles?

    If ceramics is needed to make a high velocity landing on Mars, then why not mold the ceramics in a single, or at a least only a few, large segments?

  • MDN

    I would expect the studs are resistance welded to the tank in a manner similar to stud guns used for dent pulling studs in auto repair. It is very simple and reliable and imposes very localized thermal effects. And, being able to use this technique vs adhesives is probably a significant benefit of going with the stainless steel tank structure instead of composites. Not only should initial installation be far easier and reliable, but so will rework and repair. Those SpaceX guys are smart!

    Wrt the size of the tiles I think many smaller units are likely preferred to accommodate thermal expansion. This way they can leave a small gap between adjacent tiles which would be packed/filled with a flexible thermal material (I believe the shuttle used a thermal rope if memory serves). Starship t’s a BIG structure and re-entry will generate a BIG delta T, so this is something you really need to factor into the design.

  • Edward


    The problem is similar to the problem NASA had with the Space Shuttle. Large structures flex during flight. It is also why they are using 304L instead of 301 stainless steel. The 304L flexes better.

    MDN’s comment about thermal expansion is another important consideration. The heat shield, being hotter than the main structure, undoubtedly will expand more during reentry and the main structure contract more during propellant loading. It is difficult to find matching materials that also perform the other needed functions.

    I’m sure that putting the thermal material onto current flight test vehicles is an attempt to avoid big surprises later, as happened with the space shuttle, when they first flew Columbia on their 747 and some dummy tiles fell off. They were not flight installed, however, just taped in place, but NASA got a lot of bad press about it, and people still talk about it to this day.

  • Alex Andrite

    Perfect, this must be a line from “The Graduate”, … plastics.

    “It is difficult to find matching materials that also perform the other needed functions.”

    Why matching materials ?

  • Edward

    Alex Andrite asked: “Why matching materials ?

    I meant matching in thermal expansion. Depending upon the application, other properties could be desirable to match.

  • LocalFluff

    Thanks, Edward, for your explanations.
    I think the Shuttle lost many tiles every time it landed. I’m afraid this can be a problem for the Starship. Especially after having landed on Mars and then coming back to Earth for a second landing without refurbishment. (Elon Musk in Hernán Cortéz style: “What do you mean, coming back?”) I can imagine how steel and ceramics expand differently in heat and that they are difficult to attach to each other.

    But hasn’t SpaceX presented the idea that the Starship will make a very long gliding flight in the atmosphere before landing? To slowly lose speed and decrease the aerial friction and heat. That’s why it is to have that shark fin wing as a rudder. They (or Elon Musk) have presented, and scrapped, many ideas.

  • Jeff

    LocalFluff – “One of them burned and killed its crew because of lacking heat tiles.”

    Columbia was lost due to a punctured reinforced carbon leading edge of the wing, not a damaged or missing tile.

  • wayne


    here we go…
    The Graduate
    “One Word…”

  • Edward

    LocalFluff wrote: “I think the Shuttle lost many tiles every time it landed. I’m afraid this can be a problem for the Starship.

    The tiles weren’t so much lost as they were damaged, largely due to debris coming up off the runway during landing. No matter how much NASA cleared and swept the runway, there was always some damage to the tiles. Very frustrating.

    Because Starship will not roll along a runway, the problems with their tiles should be different and fewer. Only test flights will tell. Sierra Nevada’s Dream Chaser has already performed a test landing on a runway, but I have not researched whether there was damage to the underside, where their heat shield is or will be.

    But hasn’t SpaceX presented the idea that the Starship will make a very long gliding flight in the atmosphere before landing?

    As I understand it, Starship will not glide like the shuttle but will present the heat shield side into the “wind” like a returning capsule. Starship reenters sideways. The area-to-weight ratio may be sufficient that it slows down more in the upper part of the atmosphere than capsules do, but it does not have lift to keep it high in the atmosphere the way the Shuttle did or that Dream Chaser will. So, it will “fall” sideways until it is slow enough to “fall” more downward.

    They (or Elon Musk) have presented, and scrapped, many ideas.

    If you include more than just Starship then even more ideas have been scrapped. Scott Manley decided to document a few and wound up making three videos, just of SpaceX’s abandoned ideas:

    I think that these tiles are the second or third iteration for the heat shield. SpaceX has been willing to pursue ideas but is also willing to drop them if they don’t pan out well or to change an idea if it takes too long to develop as is. This is why they changed from a composite Starship to a stainless steel Starship. (point is made in the next 30 seconds, but the whole interview is about design and design philosophy)

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