# Internet of Spacecraft for Multi-Planetary Defense and Prosperity
## 2 Extra-Terrestrialization: Make Life Multi-Planetary
### An Interplanetary Spacecraft Design Example: Starship  
Starship (without the booster) is 48-m long, and its dry mass is around 85 tons. The ship will contain 1100 tons of propellant with an ascent design of 150 tons and a return mass of 50 tons [27]. SpaceX has designed the engine section in the rear, the propellant tanks in the middle, and an eight-story tall payload bay in the front. In particular, the giant deep cryo-liquid oxygen tank made of carbon fiber is 1000 cubic meters of volume inside and more pressurized volume than an A380 airliner [27]. The delta wing at the back will enable Starship to handle the balancing challenges under various situations including zero/thin/dense atmosphere and/or with zero/low/heavy payload in the front [27]. Eventually, Starship can facilitate almost all types of entry/landing challenges in either a moon or a planet in the solar system.  
Moreover, Starship (without booster) is expected to carry 240 tons of sub-cooled methane (CH) and 860 tons of oxygen as the propellant. The ship engine section consists of four vacuum Raptor engines and two sea-level engines, and all six engines are capable of gimbling [27]. However, in another reference [27], the interplanetary spacasibp is specified to have three sea-level engines with six vacuum engines. There might be more Starship design versions when the deployment and testing are carried out. Moreover, the booster, or Super Heavy rocket is equipped with 42 Raptor engines. The main body of the whole Starship including the Super Heavy rocket is currently made of SAE 304 L stainless steel thanks to its low cost, high melting point, strength at cryogenic temperature, and ease of manufacturing. The heat shield attached to the ship body is composed of thousands of black hexagon tiles that contain silica. By using hexagon tiles, hot plasma on atmospheric entry cannot accelerate through zigzag gaps, and the heat shield can withstand up to 1400 \"C [34]. More importantly, they can be used many times without maintenance.  
Furthermore, the Mars transit configuration (MTC) of Starship consists of 40 cabins that can hold more than 100 people per flight taking approximately 6 months (3 months in very good scenario [27]). In addition, Starship-MTC is expected to facilitate life-support and other requirements of a long interplanetary trip such as storage, entertainment, and solar-storm shelter which can resist a solar flare, which is the abrupt eruption of electromagnetic (EM) radiation in the Sun's atmosphere, and the resulting energetic protons that can pass through the human body, causing biochemical damage.  
Take the Mars transportation for example, the system architecture and flow chart are illustrated in Figure 7 based on [26,27]. The Super Heavy rocket launches the crewed and/or uncrewed Starship spacecraft to the Earth orbit first, then is refilled by uncrewed Starship tankers that are already deployed in Earth orbit [26,27]. Refilling the propellant (liquid oxygen (O\({}_{2}\)) and methane (CH\({}_{4}\))) in orbit is essential as it can maximize the spaceship payload on the trip to the final destination such as the Moon or Mars, which eventually  
Figure 6: Payload to LEO comparison of several worldwide launch vehicles, based on concept and data in [27].  
could reduce the vehicle size and cost by 5-10 times and increase the launch rate [26]. It is worth mentioning that by establishing a self-sustaining base on the Moon, Mars, or other celestial bodies, a large number of spacecraft, likely to be several thousand with tens of thousands refilling operations, will require many launches every day [27]. Then, the refilled Starships will continue the travel to Mars, while the tanker refill ships will return to Earth for refilling and the next launch.