What Is So Special About Starship’s Heat Shield?
A heat shield is one of the most important parts of a rocket. When entering the Earth’s atmosphere Starship is going to be exposed to thousands of degrees Fahrenheit. While its stainless steel construction helps withstand the heat it is not enough by itself. This is why SpaceX has installed a massive array of heat shield tiles covering more than 50% of Starship.
Starship’s heat shielding is so special thanks to a uniform design, simple construction, easy installation, and heat resistance. All of which are necessary for keeping costs low, speeding up production, and ensuring Starship can safely enter the Earth’s atmosphere.
Heat shields have always been a complicated and important feature of a rocket. On other partially reusable rockets in the past such as the Space Shuttle, there were big problems because of heat shielding. SpaceX is working on not only avoiding problems but finding the best possible all-around heat shield option for their next-generation rocket.
Why Does Starship Need A Heat Shield?
With Starship’s goal of full reusability, it will need to be capable of returning to Earth. When entering Earth’s atmosphere, Starship will be exposed to around 3000 degrees Fahrenheit. This extreme heat is exactly why Starship needs a heat shield. A unique aspect of the next-generation launch vehicle is its main build material. Rather than use highly machined carbon composites like a lot of other companies, SpaceX is just using stainless steel. One of the benefits of this material is the high heat resistance. This by itself however will not be enough for Starship to reenter the atmosphere in one piece. Starship still needs some extra protection but the stainless steel helps.
Benefits Of Starship’s Heat Shield
Uniform Design – One of the most important parts of Starship’s heat shield is the uniform design. Looking at the heat shield almost every single tile is exactly the same. The heat shield on Starship consists of a large array of thousands of small hexagonal tiles that cover over 50% of the body. SpaceX has managed to install the majority of the heat shield using a uniform tile.
With the exception of a few tiles at the flaps and some near the nosecone, every tile is the same. This is extremely important for many factors including installation, cost, speed, replacement, and more. An example could be Starship returning from a mission where it landed and some of the tiles need to be replaced. SpaceX could easily install the exact tile needed for the replacement and move on. This comes in stark contrast to other reusable rockets such as the Space Shuttle.
Simple Construction – The uniform construction along with a few other factors plays into the construction process as well. While we don’t know a lot about how exactly the tiles are made, we do know some things. Specifically, the tiles come from what SpaceX and others often call the bakery in Cape Canaveral Florida. Here they are able to construct and ship the tiles directly to Boca Chica Texas. Judging by the speed of deliveries and the large number of tiles available in such a short time, we can assume the construction process is not extremely complicated. As I mentioned before, with almost all the tiles being exactly the same the company can also mass produce and get very experienced in the process of making tiles for Starship. This in the long run can end up being a big benefit in Starship development.
Easy Installation – If SpaceX wants to build 100 Starships in one year in the future they will need to construct them at a rapid pace. Prior to such a big goal SpaceX still has been focusing on speed and producing as many Starship prototypes as possible. In this process, they need to install the entire heat shield. Standing at 50m tall and 9m wide, SpaceX has a large amount of space that needs to be covered by tiles. Specifically, then need to cover the entire belly, flaps, and a bit of extra space along the sides to ensure Starship is capable of re-entry.
So far SpaceX has only been installing either a partial or full heat shield for a few months but they are getting fast already. An example could be SN20. This Starship prototype had its entire heat shield installed in a very short period of time. As SpaceX gets more experienced and confident in the process they will be able to install the tiles even faster. The installation process consists of creating small mounting points for each tile, applying a white material on the inside, and finally attaching each tile to a mount. This simple process helps the speed significantly. Robots have even been spotted working on part of the installation.
Heat Resistance – One of the final and most crucial aspects of the heat shield is its heat resistance. None of the other benefits of the shield matter if it cant handle the high temperatures of reentry. However, this is not looking like the case. The tiles have already been through a lot of tests including exposing them to thousands of degrees. In a tweet from Elon Musk, it showed nine of the tiles exposed to multiple high-powered blow torches shooting flames. These high temps and close proximity tested the tiles with thousands of degrees and made them turn red hot. This heat resistance will help ensure Starship is capable of withstanding the high temps of Earth re-entry.
Space Shuttle Comparison
An example can help put in perspective how innovative and important Starship’s heat shield design is. Looking in the past, NASA’s Space Shuttle was also reusable and after leaving the earth for space, ended up coming back and entering the atmosphere. In fact both the Space Shuttle and Starship plan to enter the atmosphere almost exactly the same. The only main difference is once each rocket has gotten through the majority of the atmosphere. Both launch vehicles have a large belly that is covered with a heat shield array. Taking a closer look at the Space Shuttle’s heat shield there were a lot of problems. One of the biggest Starship has addressed which is non-uniform tiles.
The Space Shuttle’s heat shield consisted of over 21,000 tiles, many of which were completely unique. After returning to Earth, a large team would have to inspect and replace a lot of different tiles. However, with the majority of tiles being completely unique, this process ended up taking a very long time. Not only did the process take a long time but it added costs and slightly compromised the safety. Each tile was a lot more expensive and if one slight error was made in this complicated process it could end up causing significant issues during re-entry. SpaceX has learned from past reusable rockets and is considering a lot of different factors when constructing a Starship heat shield.
Conclusion
Starship’s heat shield is just another unique and innovative piece of technology that SpaceX has added to their next-generation rocket. This heat shield is not only supposed to keep the rocket safe while entering the atmosphere but also improve on many different factors. These include cost, production speed, safety, and more. SpaceX has been able to achieve these thanks to a uniform design, simple construction, easy installation, and high heat resistance. All of these improvements are necessary if SpaceX wants to send humans to Mars in the future. With the first orbital test flight very soon we are likely to see these tiles in action for the first time ever.