#Starship #SpaceShuttle #NASA #SpaceX #Heatshield
Many of you probably know the Space Shuttle Columbia disaster, in which 7 NASA astronauts lost their lives while preforming re-entry maneuver after a successful orbiter mission. The disaster was caused by damage to the heat shield from a piece of foam detached from the main fuel tank two weeks before the crash, during Columbia’s launch from Kennedy Space Center.
Heat shields have been a pain in the Space Shuttle from the beginning. It was the thermal
protection that caused the shuttles to fly a maximum of 4 times a year, and their launch cost was over 1.5 billion dollars.
So what about these shields?
The shuttle was made mostly of fast-melting aluminum, so every square millimeter of the leading site had to be protected to prevent disaster. Unfortunately, the shuttle, as a vehicle that uses the physics of flight and has wings to create aerodynamic force, had a very complicated geometry. So complicated that it needed hundreds, if not thousands, of different types of TPS tiles. Additionally, the time required to install one tile was approximately 40 hours.
If that wasn’t enough, the placement of the tiles on the shuttle’s structure was very complicated. One reason for this is the high expansion of aluminum when heated. There was a possibility that the tile would just pop off. The way the space shuttle and rocket were configured for launch also left much to be desired.
The shuttle flew into space attached to a large tank of foam insulation with a heat shield facing it. As a result, a piece of ice or foam detached from the main tank was enough to literally tear the tile out of the fastening at supersonic speeds.
NASA didn’t fix the problem until the end of the shuttle program in 2011, even though it costed the lives of 7 people and endangered virtually all of the astronauts who flew the vehicle. The preventative measure turned out to be a heat shield inspection by… astronauts on the ISS! The shuttle rotated 180 degrees and you coul review the condition of its tiles before returning to Earth.
Okay, we know what went wrong. So how is SpaceX going to take the consequences of the Space Shuttle program and create the true reusable vehicle that NASA so desperately wanted?
The whole thing can be divided into several subsections:
– One: Ship has a less complex geometry. Except for the four flaps, it’s a regular roller. It doesn’t need to soar, only slow down on landing, so it doesn’t need complicated wings, tail, stabilizers, and a contoured beak.
– Two: In the event that a tile falls off, the Ship has a good chance of surviving re-entry into the atmosphere and returning safely to Earth. That’s because the SpaceX vehicle is made of stainless steel instead of aluminum, so without heat shields, it can withstand more than twice the temperature.
– Three: Lower temperature expansion of steel relative to aluminum. This ensures that the changes in mechanical stress are small, making the tiles less likely to detach from the vehicle.
– Four: Ship’s simple tile mounting system. The heat-insulating mat allows some of the heat to be absorbed and the clip system means that each tile should take literally minutes to install. Additionally, the tile mounts are designed in such a way that each tile has some play, which should prevent the tiles from cracking during the temperature swings they experience during flight.
– Five: Steel has another interesting property when re-entering the atmosphere: when the windward side covered with thermal plates absorbs as much heat as possible, the heated plasma flows around the Ship’s sides and heats the leeward side. In Space Shuttles, this side was painted white to most effectively reflect heat radiation into space. The ship needs no such treatment, as it just so happens that steel itself is an almost perfect heat reflective material!
Considering the above changes, I’m sure SpaceX has learned from the failure of the STS program.